Human and Machine Consciousness

Authors David Gamez

Plaintext

Human and Machine
Consciousness

DAVID GAMEZ
HUMAN AND MACHINE
CONSCIOUSNESS
Human and Machine
Consciousness

David Gamez
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David Gamez. Human and Machine Consciousness. Cambridge, UK: Open Book Publishers,
2018. https://doi.org/10.11647/OBP.0107

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ISBN Paperback: 978-1-78374-298-1
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This book is dedicated to the first artificial system that understands it.
A flash, a mantling, and the ferment rises,
Thus, in this moment, hope materializes,
A mighty project may at first seem mad,
But now we laugh, the ways of chance forseeing:
A thinker then, in mind’s deep wonder clad,
May give at last a thinking brain its being.
[…]
Now chimes the glass, a note of sweetest strength,
It clouds, it clears, my utmost hope it proves,
For there my longing eyes behold at length
A dapper form, that lives and breathes and moves.
My mannikin! What can the world ask more?
The mystery is brought to light of day.
Now comes the whisper we are waiting for:
He forms his speech, has clear-cut words to say.

Goethe, Faust
Acknowledgements

I am extremely grateful to Barry Cooper and the John Templeton
Foundation for supporting this work (Project ID 15619: ‘Mind,
Mechanism and Mathematics: Turing Centenary Research Project’).
This grant gave me the time that I needed to sit down and write this
book.

I have really appreciated the help of Anil Seth, who supported my
application for a Turing Fellowship and was very welcoming during
my time at the University of Sussex. I am also grateful to the Sackler
Centre for Consciousness Science and the Department of Informatics at
the University of Sussex for giving me a place to work. I greatly enjoyed
conversations about consciousness with my colleagues at Sussex.

I would also like to thank Owen Holland, whose CRONOS project
started my work on human and machine consciousness, and the
reviewers of this book, who had many helpful suggestions. I owe a
warm debt of gratitude to my parents, Alejandro and Penny Gamez,
who have always given me a great deal of support and encouragement.
Contents

List of Illustrations 1

1. Introduction 3
2. The Emergence of the Concept of Consciousness 9
3. The Philosophy and Science of Consciousness 33
4. The Measurement of Consciousness 43
5. From Correlates to Theories of Consciousness 69
6. Physical Theories of Consciousness 85
7. Information Theories of Consciousness 93
8. Computation Theories of Consciousness 103
9. Predictions and Deductions about Consciousness 113
10. Modification and Enhancement of Consciousness 125
11. Machine Consciousness 135
12. Conclusion 149

Appendix: Definitions, Assumptions, Lemmas and Constraints 159
Endnotes 165
Bibliography 201
Index 219
List of Illustrations

All images are © David Gamez, CC BY 4.0.

2.1. Visual representation of a bubble of perception. 12
2.2. The presence of an invisible god explains regularities 14
in the visible world.
2.3. Colour illusion. 17
2.4. Primary and secondary qualities. 19
2.5. The relationship between a bubble of experience and a 21
brain.
2.6. Interpretation of physical objects as black boxes. 23
2.7. The relationship between a bubble of experience and 25
an invisible physical brain.
2.8. The emergence of the concept of consciousness. 28
3.1. The use of imagination to solve a scientific problem. 35
3.2. Imagination cannot be used to understand the 38
relationship between consciousness and the invisible
physical world.
3.3. Learnt association between consciously experienced 39
brain activity and the sensation of an ice cube.
4.1. Problem of colour inversion. 51
4.2. Some of the definitions and assumptions that are 53
required for scientific experiments on consciousness.
4.3. The relationship between macro- and micro-scale 58
e-causal events.
4.4. Assumptions about the relationship between CC sets, 60
consciousness and first-person reports.
5.1. The measurement of an elephant’s height in a 70
scientist’s bubble of experience.
5.2. Theory of consciousness (c-theory). 79
2 Human and Machine Consciousness

7.1. Information c-theory. 97
8.1. Soap bubble computer. 104
9.1. Testing a c-theory’s prediction about a conscious state. 114
9.2. Testing a c-theory’s prediction about a physical state. 115
9.3. Deduction of the conscious state of a bat. 119
10.1. Modifications of a bubble of experience. 128
10.2. A reliable c-theory is used to realize a desired state of 129
consciousness.
11.1. A reliable c-theory is used to build a MC4 machine. 138
11.2. A reliable c-theory is used to deduce the consciousness 139
of an artificial system.
1. Introduction

Consciousness is extremely important to us. Without consciousness,
there is just nothingness, death, night. It is a crime to kill a person who
is potentially conscious. Permanently unconscious people are left to die.
Religious people face death with hope because they believe that their
conscious souls will break free from their physical bodies.

We know next to nothing about consciousness and its relationship
to the physical world. The science of consciousness is mired in
philosophical problems. We can only guess about the consciousness
of coma patients, infants and animals. We have no idea about the
consciousness of artificial systems.

This book neutralizes the philosophical problems with consciousness
and clears the way for scientific research. It explains how we can
develop mathematical theories that can make believable predictions
about consciousness.

The first obstacles that need to be overcome are the metaphysical
theories of consciousness. Some people claim that consciousness is a
separate substance; other people believe that it is identical to the physical
world. These theories generate endless debates and it is very difficult to
prove or refute them. This book eliminates some of these theories and
suspends judgement about the rest.

The next obstacle is the hard problem of consciousness. This typically
appears when people try and fail to imagine how colourful conscious
sensations are related to the colourless world of modern physics. This
book breaks the hard problem of consciousness down into a pseudo
problem, a difficult problem and a set of brute regularities.

Some problems with consciousness cannot be solved. For example,
we cannot prove that a person is conscious. These problems affect our
ability to measure consciousness through first-person reports. This book

neutralizes these problems by making assumptions. The results from the
science of consciousness can then be considered to be true given these
assumptions.

When these obstacles have been overcome the scientific study of
consciousness becomes straightforward. We can measure consciousness,
measure the physical world and look for mathematical relationships
between these measurements. We can use artificial intelligence to
discover mathematical theories of consciousness.

Eventually we will discover mathematical theories that map between
states of consciousness and states of the physical world. We will use
these theories to make believable predictions about the consciousness of
infants, animals and robots. We will measure the consciousness of brain-
damaged patients. We will build conscious machines, repair damaged
consciousnesses and create designer states of consciousness.

The scientific study of consciousness is clarified by this book. As
you read it the philosophical problems will dissolve and you will gain a
clear vision of consciousness research. You will no longer worry about
whether consciousness is a separate substance. You will not be troubled
by a desire to reduce consciousness to particles or forces. You will
understand that a scientific theory of consciousness is a mathematical
relationship between a formal description of consciousness and a formal
description of the physical world.

This book starts with a definition of consciousness. In daily life
we treat colour, sound and smell as objective properties of the world.
Over the last three hundred years science has developed a series of
interpretations of the world that have stripped objects of their sensory
properties. Apples used to be red and tasty; now physical apples are
colourless collections of jigging atoms, probability distributions of
wave-particles. The physical world has become invisible. When science
eliminated sensory properties from the physical world it was necessary
to find a way of grouping, describing and explaining the colours,
sounds and smells that we continued to encounter in daily life. We
solved this problem by inventing the modern concept of consciousness.
‘Consciousness’ is a name for the sensory properties that were removed
from the physical world by modern science.
1. Introduction 5

The next chapter examines some ‘hard’ problems with consciousness.
First, it is impossible to imagine the relationship between consciousness
and the invisible physical world. Second, we find it difficult to imagine
the connection between conscious experiences of brain activity and
other conscious experiences. Third, there are brute regularities between
consciousness and the physical world that cannot be broken down or
further explained. None of these problems are unique to consciousness
research. They can also be found in physics and they do not affect
our ability to study consciousness scientifically. We can measure
consciousness, measure the physical world and look for mathematical
relationships between these measurements.

Scientists measure consciousness through first-person reports,
which raises problems about the reliability of these reports, the
possibility of non-reportable consciousness and the causal closure of the
physical world. The fourth chapter addresses these issues by making
assumptions that explain how consciousness can be measured. First,
we need to identify the systems that we believe are conscious. Then we
need to make other assumptions to ensure that consciousness can be
accurately measured in these systems.

The fifth chapter explains how we can develop mathematical theories
of the relationship between consciousness and the physical world.
Scientists have carried out pilot studies that have looked for correlations
between consciousness and brain activity. We are now starting to create
compact mathematical theories that can map between physical and
conscious states. Computers could be used to discover these theories
automatically.

Chapter 6 discusses theories that link consciousness to patterns in
physical materials—for example, electromagnetic waves or neuron
firing patterns. With physical theories the materials in which the patterns
occur are critical—if the same patterns occur in different materials,
they are not claimed to be linked to consciousness. Physical theories of
consciousness are similar to scientific theories in physics, chemistry and
biology.

Some people have claimed that information patterns are linked to
consciousness, regardless of whether they occur in a brain, a computer
6 Human and Machine Consciousness

or a pile of sand. The seventh chapter shows that this approach fails
because information is not a property of the physical world and any
given information pattern can be extracted from both the conscious and
unconscious brain. Information theories of consciousness should be
reinterpreted as physical theories of consciousness.

Other people believe that consciousness is linked to the execution
of computations. They claim that some computations are linked to
consciousness regardless of whether they are executing in a brain or
a digital computer. Chapter 8 argues that computations cannot be
linked to consciousness because computing is a subjective use that we
make of the world. Computation theories of consciousness should be
reinterpreted as physical theories of consciousness.

Chapter 9 explains how theories of consciousness can be
experimentally tested. This can only be done on systems that we assume
are conscious, such as normally functioning adult human brains. We
can also use our theories of consciousness to make deductions about
the consciousness of brain-damaged people, animals and robots.
These deductions cannot be verified because we cannot measure the
consciousness of these systems.

When we have discovered a reliable theory of consciousness we will
be able to use it to modify and enhance our consciousness. For example,
we could change the shape of our conscious body or increase our level
of consciousness. Chapter 10 explains how we can use a theory of
consciousness to identify the physical state that is linked to a desired
conscious state. If we could realize this physical state in our brains, we
would experience the desired conscious state. It will be many years
before this will become technologically possible.

The eleventh chapter suggests how a reliable theory of consciousness
could be used to create conscious machines and make believable
deductions about the consciousness of artificial systems. Silicon brain
implants and consciousness uploading are interpreted as forms of
machine consciousness, and the chapter discusses whether conscious
machines could threaten human existence and how they should be
ethically treated.
1. Introduction 7

The conclusion summarises the book, highlights its limitations and
suggests future directions of research. The appendix lists the definitions,
assumptions, lemmas and constraints.

The main text of this book is short and self-contained and can be
read through without referring to the endnotes or bibliography. The
endnotes contain more detailed discussions of individual points and
full references to the scientific and philosophical literature.
2. The Emergence of the Concept
of Consciousness

2.1 Naive Realism
I am immersed in a colourful moving noisy tasty smelly painful spatially
and temporally extended stream of things. During a nuclear explosion
I see a grey mushroom cloud, hear a detonation, feel heat, touch wind
and taste synthetic strawberry bubblegum in my mouth. I do not infer
the presence of these things—they are just there before me as the world
at this place and time seen from my perspective.

When Cro-Magnon man peered out of his cave he saw a bright
pattern of green leaves, heard a river and tasted sweet-tart berries in his
mouth. The green of the leaves was present to him, framing the entrance
to his cave, just as the river was crashing and roaring to his left. No
complicated theories about consciousness troubled Cro-Magnon man:
the world was simply present to him. In this idealised naive and simple
time people simply saw the world, unclouded by theories of perception.

When a child opens its eyes it does not see a collection of qualia1 or
conscious representations: just a red balloon ascending into the warm
summer sky.

Most modern adults most of the time have a direct relationship
with the world around them. We are immersed in a world of colourful
moving noisy tasty smelly things. As we slog through our workaday
lives we are not philosophizing—the blue of my computer screen is the
colour of an object in the world; the tinny speaker sound is part of the
world. We go outside and see cold grey skies and are lashed by cold
lashing rain.

For me at least, the colourful cheerful world is the most important
thing there is. I long to drink in more of the visible audible tasty moving

world. What I hope for in any afterlife is that some kind of a world
will continue, ideally in a reasonably pleasant way. While one can make
abstract ethical points about the value of life, its real value for me is this
immersion in a sensuous world.

This relationship with the world is often called naive realism: an
interpretation of perception in which we directly see the world and the
world is as we see it. However, there is nothing naive or realistic in our
everyday encounters with the world—‘naive realism’ is a convenient
label that we use to contrast our everyday immersion in the world with
other theories of perception.

I am standing in my sitting room staring dully through dirty net
curtains at nothing in the street outside. I cannot see the body of my
aunt. It is out there in the garage. I walk into the garage and open the
blue plastic sack. Now I can see the body of my aunt.

When I look at my aunt’s body it appears as three-dimensional,
although I can only see part of it at one time. From one perspective I can
see my aunt’s grey lips and clouded eyes, but I cannot see her whole
head or body. I have to move relative to her body to see her thin grey
hair and the matted dried blood on the back of her head.

My aunt’s body changes independently of my interactions with
it. Each time I return to the garage I observe subtle changes in colour
as her body decays. Her body has an objective existence that can be
systematically probed in different ways. I can perform chemical tests; I
can measure its hardness and weight.

Other people cannot see the body of my aunt. The police cannot see it.
Uncle Henry, on holiday in Tahiti, is staring at the gyrating buttocks of a
young woman in a grass skirt. He is not looking at the body of my aunt.

Naive realism is not simultaneous and all-embracing access to every
object in existence. We see a small number of the world’s objects from
one perspective. Objects have an independent existence that enables them
to be perceived by other people. Different people see different things.
We can perceive the same object on multiple occasions. Objects can be in
different states at different times.
2. The Emergence of the Concept of Consciousness 11

In our naively realistic encounters with the world we use the
language of perception to indicate those things and those aspects of
things that are present to us and to acknowledge that objects continue
to exist when they are not being perceived. Instead of saying that my
aunt’s body is there, I talk about perceiving my aunt’s body to indicate
that it is currently present to me. Uncle Henry is not perceiving her
body: it is not present to him in Tahiti.

Perception is similar to a bubble that we ‘carry around’ with us that
contains the objects that are currently present to us. I will call this a
bubble of perception. We are immersed in our bubbles of perception. When
an object appears in my bubble of perception I see it from a perspective
that is centred on my body.2

A visual representation of a bubble of perception is shown in Figure
2.1b. This is inaccurate because it shows the person’s body from a third-
person perspective, whereas we experience our bubbles of perception
from the inside—we look out from our bodies onto the world. This
illustration has the further limitation that it only shows the visual aspect
of a bubble of perception. Bubbles of perception also include tastes,
sounds, smells, body sensations and emotional states.

In naive realism objects have the properties that we perceive them
to have. The plastic sack is blue; my aunt’s body is cold; her clothes have
a mothball and urine odour. Objects have these properties independently
of whether they are inside or outside a bubble of perception. The plastic
sack continues to be blue when it is in the garage and not being perceived
by anyone (Figure 2.1a).

I sit in the kitchen and imagine my aunt’s body in the garage. Now
the contents of the sack are fleeting and unstable, colours are washed
out and the smell of moth balls and urine is not present. I dream of my
aunt’s body. This is more vivid than imagination, but my aunt’s face
changes from moment to moment, and it is difficult to inspect details
and maintain consistency over time. I go for a walk in the forest and eat
a mushroom. One hour later my aunt rises from the ground before me:
her eyes are dark geometric spirals; her hair is a writhing mass of white
maggots.
12 Human and Machine Consciousness

Figure 2.1. Visual representation of a bubble of perception. a) Domestic scene. In
naive realism the sack in the garage continues to be blue when no-one is looking
at it. b) A visual representation of a bubble of perception. This uses a third-person
perspective to represent our sense of inhabiting a body and looking out at a world.
Although this is substantially different from an actual bubble of perception,
which we experience from inside our bodies, it is the best way that I have found of
depicting a bubble of perception. Image © David Gamez, CC BY 4.0.

We no longer believe that imagined, dreamt or hallucinated objects
are objectively present in a second spiritual world. It no longer makes
sense to say that we perceive imagined, dreamt or hallucinated objects.
This is particularly true now that perception is associated with theories
about electromagnetic waves, sound vibrations, and so on. To address
this issue I will replace ‘bubble of perception’ with the more inclusive
term ‘bubble of experience’, and distinguish between two types of
bubble of experience:
• Online bubbles of experience are connected to the world: their
states change in response to changes in the world and detailed
information about the world can be accessed on demand.
2. The Emergence of the Concept of Consciousness 13

They typically have vivid colours, clear sounds, strong
odours and intense body sensations. In an online bubble of
experience objects are stable, we can view the same object on
multiple occasions and people generally agree on an object’s
properties. We are immersed in online bubbles of experience
when we perceive and interact with the world.
• Offline bubbles of experience are not connected to the current
environment, although they might correspond to past or
future states. They are often unstable, low resolution and low
intensity. Colours are washed out; smells, tastes and body
sensations are rarely present. Offline bubbles of experience are
typically weakly perceptual—we cannot interact with objects
in a systematic way, and it can be difficult to repeatedly view
the same object from multiple perspectives or to examine
small details. People typically do not agree about the objects
that they encounter in offline bubbles of experience. We are
immersed in offline bubbles of experience when we dream,
remember, hallucinate and imagine.

A bubble of experience can have a mixture of online and offline
contents. When I hallucinated my aunt the forest was an online
component of my bubble of experience; the aunt and maggots were
offline.3

2.2 Invisible Explanations
The flowers in my living room appear in my online bubble of experience
on multiple occasions. I can see them from multiple perspectives and
uncover more of their properties. They appear in other people’s bubbles
of experience. The flowers are part of an independent world, which is
often called the physical world.
The physical world has regularities. If I throw a pig out of a window,
its pink colour and screams move together and its rate of acceleration
can be calculated using a simple equation. If I mix one part glycerine
with three parts nitric acid, I obtain an explosive mixture that can
alleviate angina.
We explain these regularities by postulating the existence of invisible
objects and properties in the physical world. These do not appear in
14 Human and Machine Consciousness

our bubbles of experience—we believe in their existence because they
improve our ability to make predictions about objects in our bubbles of
experience.

X-rays are invisible waves that were posited to explain the appearance
of patterns on photographic plates. These patterns can easily be
explained if there is a form of radiation that cannot be perceived with the
human eye. Our belief in X-rays was strengthened by the development
of other methods for detecting them. Only the effects of X-rays appear in
our bubbles of experience—the rays themselves are invisible.

Visible and invisible gods are often used to explain regularities in
our bubbles of experience. A statue of Tlaloc might be considered to be
Tlaloc himself, something that Tlaloc inhabits to some extent or just a
representation of Tlaloc. Sometimes the Judeo-Christian god is depicted
as a beardy bloke floating in the clouds; more often he is assumed to be
invisible.

Prayers, sacrifices and moral rectitude encourage the gods to bestow
rain, fertility and a good harvest on their virtuous subjects (see Figure
2.2). Murder, incest and eating prawns anger the gods, who inflict
earthquakes, floods and infertility on people who stray from the path
of righteousness.

Figure 2.2. The presence of an invisible god explains regularities in the visible
world. a) Worshippers of Tlaloc offer up sacrifices and prayers for rain. b) The
psychology and actions of the invisible god explain the appearance of the rain.
Image © David Gamez, CC BY.
2. The Emergence of the Concept of Consciousness 15

Early astronomers explained the regular movements of the heavenly
bodies by claiming that they are embedded in concentric crystalline
spheres. These spheres were invisible to human observers on Earth, but
they probably believed that they could have touched them if they could
have reached them.

Newton explained the movements of the heavenly bodies by
claiming that they exert an invisible gravitational force on each other,
whose strength is given by a simple equation. Newton could not explain
how masses attract each other at a distance—at best he could point to
magnetism as an example of a similar force. However, the invisible
gravitational force, along with the equations describing it, made good
predictions about the movements of the heavenly bodies, and so it
became an accepted part of the physical world. While we can observe
the effects of gravity in our bubbles of experience—a feeling of heaviness,
movement of objects towards the Earth—gravity itself is invisible.

The ancient atomists hypothesized that the world is composed of
invisible entities called atoms. They used the movements, swerves
and interactions of the atoms to explain the visible properties of the
world.4 This view was revived in the seventeenth century and later
used to explain phenomena, such as the pressure and temperature
of a gas. Although our theories about elementary particles have been
substantially revised, atomism continues to play an important role in
our understanding of the physical world.

Atoms and their constituent particles are invisible explanations
because they never directly appear in our bubbles of experience. An
atom might emit an electromagnetic wave that leads to an experience
of red, but we experience the red, not the atom itself. We can generate
pictures of atoms using a scanning tunnelling microscope, but these are
the result of a complex technological process—not a direct view of the
atoms themselves.

Our modern invisible explanations have become increasingly
abstract. We now use complex mathematical equations to describe the
behaviour of wave-particles and highly folded fields. These invisible
explanations can be used to make accurate predictions about the
behaviour of objects in our bubbles of experience.
16 Human and Machine Consciousness

Invisible physical explanations are extremely important to us. For
non-religious people the physical world is all there is: a complete
understanding of it would be a complete understanding of everything.

Whichever invisible explanations you accept, their common factor is
that they are, by definition, invisible. They are hypotheses that go beyond
our experiences in order to explain and make sense of our experiences.
The effects of invisible entities appear in our bubbles of experience, never
the invisible entities themselves.

2.3 Primary and Secondary Qualities
The particular bulk, number, figure, and motion of the parts of fire, or snow, are
really in them, whether anyone’s senses perceive them or no: and therefore
they may be called real qualities, because they really exist in those bodies.
But light, heat, whiteness, or coldness, are no more really in them, than sickness
or pain is in manna. Take away the sensation of them; let not the eyes see
light, or colours, nor the ears hear sounds; let the palate not taste, nor the
nose smell, and all colours, tastes, odours, and sounds as they are such
particular ideas, vanish and cease, and are reduced to their causes, i.e.
bulk, figure, and motion of parts.
John Locke, An Essay Concerning Human Understanding5

Some honey is in my bubble of experience. It feels warm and sticky. It
is a dark semi-translucent brown colour. I taste the honey—it is sweet. I
put the honey in a box and close the lid. Although the honey is no longer
in my bubble of experience, it is natural to assume that it continues to be
sweet, warm, sticky, and semi-translucent dark brown in colour.

I pass the honey to Zampano. He tastes the honey. ‘Cor blimey stab
me vitals,’ he says, ‘that’s some bitter honey.’ In his bubble of experience
the honey is bitter. So is the honey sweet, bitter, both sweet and bitter, or
neither when it is outside our bubbles of experience?6

The honey changes colour when I put it in different contexts and
expose it to light of different colours (see Figure 2.3). What is the colour
of the honey in and of itself? What is the colour of the honey when it
is outside my bubble of experience? When it is in the dark? When it is
viewed by a snake?
2. The Emergence of the Concept of Consciousness 17

These contradictions in an object’s
properties can be resolved by an account
of perception that attributes some
properties to the physical world and other
properties to the interaction between the
physical world and the senses. A good
example of this approach is Galileo’s and
Locke’s distinction between primary and
secondary qualities.7 Primary qualities,
such as size, shape and movement, are
properties of the objects themselves.
Secondary qualities, such as colour,
smell and sound, arise when the physical
world interacts with the senses—they are
not properties of physical objects.

The size, shape and movement of
honey are primary qualities: properties
that honey has regardless of whether it
is perceived or not. These properties are
intrinsic to all physical objects. The colour Figure 2.3. Colour illusion.
The jars of honey are identical;
and sweetness of honey are secondary the shaded background makes
qualities that arise when honey interacts the top jar appear to be darker
in colour. Image © David
with a person’s senses. When honey is
Gamez, CC BY 4.0.
outside all bubbles of experience it is not
sweet, bitter or coloured in any way.

Different bodies have different sense organs and interact in
different ways with their environment. This explains how the same
physical object can produce different secondary qualities in different
people. When honey interacts with my senses it produces sensations of
warmth, sweetness and a dark semi-translucent brown colour. When
it interacts with Zampano’s senses it produces coldness, bitterness
and a dark semi-translucent orange colour. This account of perception
avoids the attribution of contradictory properties to the same physical
object. It explains how honey can be perceived as sweet by some people
18 Human and Machine Consciousness

and as bitter by others; why the same patch has different colours in
different contexts.8

The distinction between primary and secondary qualities was
developed in response to the revival of atomism in the seventeenth
century. Atoms were hypothesized to be the fundamental constituents
of the physical world and primary qualities were properties of the
atoms. Interactions between atoms in the environment and atoms in our
bodies led to the appearance of secondary qualities, such as redness and
sweetness (see Figure 2.4).

Locke believed that the primary qualities in our bubbles of experience
resemble primary qualities in the physical world:

[…] the ideas of primary qualities of bodies, are resemblances of them, and
their patterns do really exist in the bodies themselves; but the ideas,
produced in us by these secondary qualities, have no resemblance of them at
all. There is nothing like our ideas, existing in the bodies themselves.
They are in the bodies, we denominate from them, only a power to
produce those sensations in us: and what is sweet, blue or warm in idea,
is but the certain bulk, figure and motion of the insensible parts in the
bodies themselves […]9

When I am hugging a moving medium-sized bear in my online
bubble of experience there is a moving medium-sized bear in the
physical world. According to Locke the size, shape and motion of the
bear in my bubble of experience match the size, shape and motion of the
bear in the physical world. However, there is no growling sound, brown
colour or pungent bear-smell in the physical world. Air vibrations,
electromagnetic waves and molecules in the physical world interact
with my sense organs to produce the growling sound, brown colour,
and pungent bear-smell in my bubble of experience.

The primary qualities of physical objects are perceived through their
secondary qualities. We cannot discover the size, shape or motion of
an object without perceiving its colour, hearing its sound or touching
it. Objects might possess their primary qualities independently of our
perception of them, but these primary qualities can only appear in our
bubbles of experience when they are clothed in secondary qualities.
Physical objects are completely invisible without secondary qualities.
2. The Emergence of the Concept of Consciousness 19

Figure 2.4. Primary and secondary qualities. The physical world consists of atoms
with primary qualities, such as size, movement and shape. When atoms interact
with a person’s sense organs they give rise to secondary qualities, such as colour,
smell, taste and warmth, that appear in their bubble of experience. Image © David
Gamez, CC BY 4.0.

2.4 Bubbles of Experience and the Brain
When I hit my head my bubble of experience is filled with bright
points of light. Stimulation of my brain with electrodes evokes visual,
auditory and somatic sensations. Brain damage damages my bubble
of experience. My experiences can be altered by changing my brain’s
chemical state.
20 Human and Machine Consciousness

The link between my bubble of experience and my brain is not
logically necessary—it would not be a contradiction if a blow to my liver
produced bright points of light. However, in this world, with these laws
of nature, the strong correlations between my bubble of experience and
my brain suggest that without my brain I would not have a bubble of
experience at all.

Some people believe that bubbles of experience are linked to
spatiotemporal patterns that are distributed across the brain, body and
environment.10 This can be broken down into two claims:
1. Offline bubbles of experience are linked to spatiotemporal
patterns in the brain, body and environment.
2. Rich vivid stable bubbles of experience are linked to
spatiotemporal patterns in the brain, body and environment.

Offline bubbles of experience occur when there is little or no
interaction between the brain, body and environment. This suggests that
the first claim is false and offline bubbles of experience are solely linked
with brain states. The second claim is difficult to test because rich vivid
stable bubbles of experience typically occur when a brain is interacting
with its environment (when a bubble of experience is online). However,
given everything that we know about the brain, I believe that it is more
reasonable and economical to assume that all bubbles of experience are
linked with brain activity alone.11 This assumption cannot be proved
at the present time, and it should be revised if it can be shown that
a body and environment are essential for rich vivid stable bubbles of
experience.12

When we are immersed in an online bubble of experience our bodies
are interacting with our environment and our sense organs are passing
streams of spikes13 down our nerves and changing the states of our
brains (see Figure 2.5). When we are immersed in an offline bubble of
experience the states of our brains are changing independently of our
body and environment. In both cases I will assume that our bubbles of
experience are only linked with states of our brains.

In the previous section it was suggested that primary qualities are
perceived through secondary qualities and that the primary qualities in
2. The Emergence of the Concept of Consciousness 21

Figure 2.5. The relationship between a bubble of experience and a brain. I have
assumed that the brain is the only part of the body that is linked to a bubble of
experience. Signals from the world interact with the sense organs, which send
streams of spikes down the nerves to the brain. The resulting brain state is linked
with a bubble of experience. Image © David Gamez, CC BY 4.0.

an online bubble of experience directly correspond to primary qualities
in the world. The pungent bear-smell did not exist in the physical world;
the size, shape and movement of the bear in my bubble of experience
matched or resembled the size, shape and movement of the physical bear.

Modern science has interposed the brain between bubbles of
experience and objects in the physical world. Our experiences of size,
shape and movement are now thought to be linked to firing patterns
22 Human and Machine Consciousness

in populations of neurons. Now there is no direct connection between
bubbles of experience and the physical world. Why, then, should we
assume that primary qualities in our bubbles of experience resemble
primary qualities in the physical world? Why should we believe that
space and time in our bubbles of experience resemble space and time in
the physical world?14

A computer is driving a car. Its memory consists of voltages that
are updated by cameras, lasers and GPS. As the information in the
sensors changes the voltage patterns change, and the program uses
this information to calculate signals that are sent to control the brakes,
accelerator, gears and steering. The computer’s voltage patterns are
connected to the environment through the sensors, but they do not
resemble the environment. The voltage pattern that encodes the shape
of the road does not curve and it is not the same size as the road. The
motion of the car is held as a single voltage pattern that does not move
like the car and only changes when the measured velocity changes.

Back in Locke’s day the physical world was believed to be composed
of atoms, which were easy to imagine as tiny bouncing grey spheres.
It was natural to assume that the physical world was just like the
perceived world, except for the secondary qualities, which were added
by the process of perception. The motion, size and shape of the objects
were identical to the motion, size and shape of our experiences of the
objects—we were indeed seeing the things themselves.

Today the physical world has become unimaginable. We cannot
imagine what a wave-particle or a ten-dimensional superstring is like.
We have lost all reasons for believing in resemblance between our
bubbles of experience and the physical world. We have no grounds for
attributing either the primary or the secondary qualities of our bubbles
of experience to the invisible world described by modern physics.15

We cannot prove that a physical bear is not identical to the appearance
of a bear in a bubble of experience. And we have little reason to believe
that a physical bear does resemble a bear in a bubble of experience. We
just don’t know and cannot know. We cannot reach beyond our senses to
see the physical world as it is in itself. We have to suspend judgment
about what the physical world is really like.16
2. The Emergence of the Concept of Consciousness 23

Figure 2.6. Interpretation of physical objects as black boxes. We have to suspend
judgement about the appearance of the physical flowers and treat them as a
black box that is a source of electromagnetic waves, molecules and mechanical
stimulation. These signals stimulate the sense organs, which pass streams of spikes
along nerves to the brain. The resulting brain activity is linked with a bubble of
experience in which coloured, smelly, tasty, spatially and temporally extended
flowers appear. Image © David Gamez, CC BY 4.0.17

As far as we are concerned physical objects are black boxes that
interact with each other in accordance with the laws of physics. They
are also sources of signals that enter our senses and are processed into
spiking patterns that are sent along nerves to our physical brains, where
24 Human and Machine Consciousness

they are transformed into more spiking patterns, which have some
kind of connection with bubbles of experience that contain the coloured
warm smelly faces of the people we love (see Figure 2.6). Russell makes
this point well:

Modern physics, therefore, reduces matter to a set of events which
proceed outward from a centre. If there is something further in the
centre itself, we cannot know about it, and it is irrelevant to physics.
[…] Physics is mathematical, not because we know so much about the
physical world, but because we know so little: it is only its mathematical
properties that we can discover. For the rest, our knowledge is negative.
In places where there are no eyes or ears or brains there are no colours
or sounds, but there are events having certain characteristics which
lead them to cause colours and sounds in places where there are eyes,
ears and brains. We cannot find out what the world looks like from
a place where there is nobody, because if we go to look there will be
somebody there; the attempt is as hopeless as trying to jump on one’s
own shadow.18

You are holding a brain in your hands: it is soft, warm and slightly
sticky with blood. You lick it. It tastes of blood. You smell it—a humid,
fresh, slightly meaty smell. It is reddish grey in colour. You drop it
onto a marble worktop—a thwacking splat of sound. It has a size and a
convoluted texture. It moves when slapped or thrown through the air.
This is how the brain appears in your bubble of experience.

Now remove the properties that appeared when the brain interacted
with your senses. Now the brain is colourless, silent, odourless; it is
neither warm nor cold, neither soft nor hard; in fact it has no perceptible
properties at all. Drop the illusion that the motion, size, shape,
and spatiotemporal properties of the physical brain are preserved
unchanged in your bubble of experience. All of these properties are
transformed beyond all recognition by the neural encoding process.
The physical brain vanishes: it can no longer appear as it is in itself in
your bubble of experience. As far as you are concerned, physical brains
are black boxes, just like every other object in the physical world. This
is illustrated in Figure 2.7.
2. The Emergence of the Concept of Consciousness 25

Figure 2.7. The relationship between a bubble of experience and an invisible
physical brain. As far as we are concerned all objects in the physical world,
including our bodies and brains, are black boxes. The arrows show the interactions
between these objects in accordance with the laws of physics. Objects in the
environment are sources of signals that lead to brain activity that has some kind
of connection with a bubble of experience. Image © David Gamez, CC BY 4.0.

2.5 The Emergence of the Concept of
Consciousness
I look to the right and see a dirty grey wall. I look to the left and see a
black lamppost with scratches and flaking paint. Ahead of me a decrepit
old man hobbles along a derelict street. I am awake, not dead, but
consciousness is not present anywhere—there is no consciousness in the
man’s stained trousers, no consciousness in the dirt, no consciousness
in the smell of dog piss. Nor does consciousness appear when I turn my
attention to my ulcerating stomach and painful feet. Consciousness is
completely absent from my bubble of experience as I view the street. My
reports are not driven by a thing or property called consciousness. I can
describe everything without mentioning consciousness once.
26 Human and Machine Consciousness

Within naive realism there is no need for a concept of consciousness.
People perceive different things with different levels of clarity and have
different levels of wakefulness. Primary and secondary qualities are
properties of the objects themselves, which they possess independently
of whether they are being perceived.

The scientific revolution revived atomic theories and led to an
unimaginable world of superstrings and wave-particles. As our physics
developed, the objects that we encountered in naive realism were
stripped of their colours, sounds, tastes and smells and sank into an
invisible physical world. A tree ceased to be a tree—it became a colourless
collection of jigging atoms, a probability distribution of wave-particles.

Physical trees became black box sources of signals; green trees
continued to creak and sway in our bubbles of experience. We
attempted to explain them away, and yet there they were in front of us
with properties that could not be neatly shoehorned into the world of
physics. We had to find a way of grouping, describing and explaining
the colourful, smelly, noisy properties that were originally attributed to
objects in naive realism.

We solved this problem by inventing the modern concept of
consciousness. ‘Consciousness’ became a name for bubbles of experience,
which were reinterpreted in relation to an invisible physical world. This
is formally stated as follows:19

D1. Consciousness is another name for bubbles of experience. A state of
a consciousness is a state of a bubble of experience.20 Consciousness
includes all of the properties that were removed from the physical
world as scientists developed our modern invisible explanations.

Initially the modern concept of consciousness emerged in response
to the renaissance of atomism. In the seventeenth century the physical
world was believed to only have primary qualities—secondary qualities
were excluded from this world and developed a separate existence of
their own that demanded an explanation. The solution was to package
up secondary qualities with the concepts of mind, thinking substance
and consciousness. This interpretation of consciousness is nicely
summarized by Galileo:
2. The Emergence of the Concept of Consciousness 27

Now I say that whenever I conceive any material or corporeal substance,
I immediately feel the need to think of it as bounded, and as having
this or that shape; as being large or small in relation to other things,
and in some specific place at any given time; as being in motion or at
rest; as touching or not touching some other body; and as being one in
number, or few, or many. From these conditions I cannot separate such
a substance by any stretch of my imagination. But that it must be white
or red, bitter or sweet, noisy or silent, and of sweet or foul odour, my
mind does not feel compelled to bring in as necessary accompaniments.
Without the senses as our guides, reason or imagination unaided would
probably never arrive at qualities like these. Hence I think that tastes,
odours, colors, and so on are no more than mere names so far as the
object in which we place them is concerned, and that they reside only
in the consciousness. Hence if the living creature were removed, all
these qualities would be wiped away and annihilated. But since we have
imposed on them special names, distinct from those of the other and real
qualities mentioned previously, we wish to believe that they really exist
as different from those.21

The twentieth century developed the concept of consciousness to
its logical conclusion. Our theories about the physical world became
mathematical and abstract—they make beautiful predictions, but they
are no longer based on the everyday properties and objects that we
encounter in our bubbles of experience. The twentieth century also
developed theories about how bubbles of experience are linked to the
brain. This eliminated our reasons for believing that primary qualities
in our bubbles of experience resemble primary qualities in the physical
world. While physics is perceived to be the true or ultimate reality, we
continue to be immersed in bubbles of experience in our daily lives:
our need to express and address this issue led to the modern concept of
consciousness. This trajectory from naive realism to twentieth century
science and consciousness is illustrated in Figure 2.8.

The contents of a person’s consciousness are the objects and properties
in their bubble of experience. When a burning bush is in my bubble of
experience, the colour, smell, taste, heat and sound of the burning bush
are the contents of my consciousness. When I say ‘I am conscious of
hissing sap and orange flames,’ I am stating that hissing sap and orange
flames are in my bubble of experience.
Figure 2.8. The emergence of the concept of consciousness. a) Naive realism. Objects have the properties that they are perceived to have and continue
to have these properties when they are not being perceived. b) Naive realism is supplemented with a theory of perception, which I described using the
idea of a bubble of perception. This was reinterpreted as a bubble of experience to handle dreams, hallucinations, etc. c) The revival of atomism in the
seventeenth century led to a distinction between primary qualities, which are properties of physical objects, and secondary qualities that arise when the
physical world interacts with the senses. The concept of consciousness was invented to accommodate the secondary qualities that were excluded from
the physical world. d) Twentieth century science eliminates all resemblance between bubbles of experience and the physical world. Everything in our
bubbles of experience is interpreted as consciousness. Image © David Gamez, CC BY 4.0.
2. The Emergence of the Concept of Consciousness 29

Many consciousness experiments are based on the idea that a
person has a particular level of consciousness. A person’s overall level
of consciousness can be defined as the average intensity of the contents
of their bubble of experience.22 A high intensity, vivid, stable bubble
of experience with high resolution is consciousness at a high level. A
bubble of experience that contains a few faint and unstable objects is
consciousness at a low level. We say that Zampano is conscious when
his physical brain is associated with a bubble of experience that has non-
zero intensity.23 We say that Zampano is unconscious when his physical
brain is not associated with a bubble of experience.

The distinction between online and offline bubbles of experience can
be expressed in terms of online and offline conscious contents:24
• Online conscious contents are linked to states of the
environment and are updated in response to changes in the
environment. The environment is functionally connected to
online conscious contents.25
• Offline conscious contents are independent of the environment.
There is no functional connection between the current
environment and offline conscious contents.

Consciousness can contain a mixture of online and offline contents.
When I worship at the tombs of my ancestors the shadowy form of
my grandfather rises from his grave, winks and raises his hat. My
grandfather and his hat are offline conscious contents; the tombs and
surrounding graveyard are online conscious contents.26

A suggestive piece of evidence for a link between the rise of science
and the emergence of the concept of consciousness is Wilkes’ observation
that there was no word for consciousness in the English language prior
to the seventeenth century or in ancient Greek or Chinese:

Two intriguing facts. First, the terms ‘mind’ and ‘conscious(ness)’ are
notoriously difficult to translate into some other languages. Second, in
English (and other European languages) one of these terms—‘conscious’
and its cognates—is in its present range of senses scarcely three
centuries old. […] In ancient Greek there is nothing corresponding to
either ‘mind’ or ‘consciousness’ […] In Chinese, there are considerable
problems in capturing ‘conscious(ness)’. And in Croatian, ‘mind’ poses
interesting difficulties.27
30 Human and Machine Consciousness

There are contexts in which our modern English word for consciousness
can be translated into ancient Greek or Chinese—for example, by
‘psyche’, ‘Sophia’, ‘nous’, ‘metanoia’ or ‘aesthesis’ in ancient Greek, or
by ‘yìshì’ in Chinese. However, Wilkes claims that there is no generally
adequate translation that captures our current use of ‘consciousness’.

According to Wilkes, this linguistic data shows that the modern
concept of consciousness covers a number of disparate phenomena:
• Whether someone is awake or asleep.
• Body sensations, such as itches and pains.
• Sensory experience—for example, colours, tastes and smells.
• Ascription of propositional attitudes, such as deliberating,
pondering, desiring and believing.

This leads Wilkes to conclude that consciousness is unlikely to be a
natural kind or something that we can study scientifically:

Essentially, I am trying to say two distinguishable things. First, that in all
the contexts in which it tends to be deployed, the term ‘conscious’ and
its cognates are, for scientific purposes, both unhelpful and unnecessary.
The assorted domains of research, so crudely indicated by the ordinary
language term, can and should be carved up into taxonomies that cross-
classify those which emphasis on ‘consciousness’ would suggest. Second,
that we have little if any reason to suppose that these various domains
have anything interesting in common: that is, consciousness will not just
be a (cluster) natural kind.28

However, Wilkes’ observations about ‘consciousness’ can be
interpreted to support the idea that consciousness is a modern name
for a bubble of experience. Bubbles of experience are natural kinds that
are common to all people speaking all languages. We all see red objects,
feel heat, smell flowers and taste meat. However, scientific theories
about an invisible physical world are a recent product of a great deal
of conceptual, technological and experimental effort. Earlier societies
lacked our interpretation of physical reality, so it is not surprising that
our modern concept of consciousness is absent from ancient Greek,
Chinese and the English language prior to the seventeenth century.
Bubbles of experience were once understood in relation to an invisible
2. The Emergence of the Concept of Consciousness 31

world of gods and spirits. Once we started to believe in a physical world
of atoms and forces, the colourful conscious world (that is manifestly not
composed of atoms and forces) emerged as a separate area of inquiry.

One potential problem for this interpretation of consciousness is
that it was not developed by the ancient atomists. Since they believed
that colours, sounds and smells are not properties of atoms, it would
have been natural to place them in a second substance, such as mind or
consciousness. So why was consciousness (or a similar concept) absent
from ancient Greek, but developed by atomists in the seventeenth
century?

This problem would be resolved if the ancient atomists did invent
a word for consciousness that did not enter common usage and was
lost, or if they expressed the concept in a more indirect way. Although
very little material is left from the ancient Greek atomists, it might be
possible to find traces of a concept of consciousness in their work. A
second possibility is that the ancient atomists might have believed that
secondary qualities could be reduced to primary qualities. Plenty of
people today believe that consciousness can be reduced to the physical
world, so it would not be surprising if the ancient atomists had a similar
view.29 It is also possible that the consequences of ancient atomism were
not fully worked out. At the time atomism was one of a large number of
highly speculative theories about the world and it is conceivable that the
small number of people who believed in atomism did not have the time
or resources to develop it fully. Today our theories about the physical
world are subject to wide agreement, which has led to a general need
for a concept of consciousness to contain the properties that have been
excluded from the physical world.

2.6 Summary
Most of our lives are spent in a state of naive realism in which we attribute
colours, sounds and smells to objects in our environment. I developed
the concept of a bubble of experience to describe how we only perceive
part of the world at one time, and to accommodate observations about
dreams, imagination and hallucination.
32 Human and Machine Consciousness

The physical world is an invisible source of signals that interact with
our sense organs to produce patterns in our brains that are somehow
connected with our bubbles of experience. There is unlikely to be any
resemblance between the contents of our bubbles of experience and the
physical world.

When science eliminated sensory properties from the physical world
it was necessary to find a way of grouping, describing and explaining
the colours, sounds and smells that we continue to encounter in
daily life. We solved this problem by inventing the modern concept
of consciousness. ‘Consciousness’ is another name for our bubbles of
experience, which contain the sensory properties that science removed
from the physical world.
3. The Philosophy and Science of
Consciousness

3.1 Understanding Consciousness
How should I understand and explain my wife? I can describe the
changes in her hair and skin colour as she moves about in the light. I can
objectify her body or relate to her as the Other—she faces me, crushes
me, makes me feel guilty. I can use Eros and Thanatos to analyze her
psychology, or interpret her mind as an intricate neural mechanism. I
can provide an evolutionary explanation of her features (noting a trace
of Homo heidelbergensis in her face).

How should we understand and explain consciousness?

Phenomenologists bracket off the physical world and describe the
structure of consciousness from a first-person perspective.1 The starting
point for phenomenology is our immersion in conscious experience;
the end point is a description of consciousness that sets aside scientific
theories about the physical world.

Science has triumphed in the last three hundred years. We send
people to the moon and grow babies in test tubes. Many people believe
that science provides a complete description of the world. The predictive
success of science exerts a commanding weight: we believe in the physical
world; we are convinced by our scientific explanations and cannot ignore
them. We need phenomenological descriptions of consciousness, but we
cannot bracket out scientific theories. Phenomenology is not enough.

Many people explain consciousness by reducing it to features of
the physical world.2 This is not convincing. It is far from obvious that

colours, sounds and smells can be reduced (with a wave of the hand) to
wave-particles, superstrings or fields. Colour appears in consciousness
when colourless electromagnetic waves interact with the physical sense
organs and change the brain’s activity. But brain activity is silent and
without smell. Colour and smell are linked to brain activity; they are not
identical to colourless odourless brain activity.

Bubbles of experience and the physical world are both important
phenomena. It would be premature to bracket either out or to claim
that one can be reduced to the other. Both have to be taken seriously. We
have detailed descriptions of consciousness and a good understanding
of the physical world—the key gap in our knowledge is the relationship
between them.

3.2 The Limits of Imagination
Imagination is an offline bubble of experience.3 We can change the
contents of this bubble of experience without changing our physical
environment. We fill it with novel things—recombine the elements of
our experience in new ways. As I sit at my desk I imagine that I have lost
my limbs and lie naked on a rocky plain beneath a burning sky. A raven
is feeding on my liver.

We use our imagination to solve scientific problems. On separate
unrelated occasions mutating DNA, tumours, cigarette smoke and
unregulated cell growth appear in my bubble of experience. I use my
empirical knowledge about the links between these phenomena to
visualize the correct sequence from smoking to the appearance of a
tumour. I do not need direct knowledge of the physical world to do
this. It is enough that the appearance of cigarette smoke in my bubble of
experience corresponds to the presence of smoke in the physical world,
that the appearance of mutating DNA in my bubble of experience
corresponds to the presence of mutating DNA in the physical world,
and so on (see Figure 3.1). We have an intuitively satisfying explanation
of the relationship between phenomena when we can visualize the
intermediate steps between them.
3. The Philosophy and Science of Consciousness 35

Figure 3.1. The use of imagination to solve a scientific problem. a) On separate
occasions mutating DNA, tumours, cigarette smoke and unregulated cell growth
appear in my bubble of experience. I observe sequential relationships between
pairs of these phenomena, but never the whole story. b) My empirical knowledge
about the connections between these phenomena enables me to imagine the
correct sequence of steps from smoking to the appearance of a tumour in the
lungs. Image © David Gamez, CC BY 4.0.

Online and offline bubbles of experience have the same properties—
colour, smell, taste, sound and body sensations. These are typically less
intense in offline bubbles of experience and some are not present at all.
Objects can vary in wild ways in an offline bubble of experience, but we
cannot imagine new properties. We cannot imagine properties that we
have not encountered in an online bubble of experience.

Imagination is an inductive engine that reassembles previous
experiences. We can imagine pigs playing the piano because we have
seen pigs and pianos before. If we had never seen pianos and pigs, then
it is unlikely that piano-playing pigs would enter our imagination.4
36 Human and Machine Consciousness

We have a limited ability to wilfully transform our offline bubbles
of experience. It is difficult to imagine radically different forms of
consciousness. It is difficult or impossible to wilfully morph our bubbles
of experience into a bat’s bubble of experience (assuming it has one).5

We cannot imagine things that cannot become conscious. We cannot
imagine an invisible physical world that has none of the properties that
we encounter in our bubbles of experience. We can imagine large brains,
small brains, blue brains, green brains, brains made of cheese, and so
on. But the physical brain cannot be imagined as it is in itself, outside all
bubbles of experience.6

3.3 A Failure of Imagination
How is it possible for conscious states to depend upon brain states? How
can technicolour phenomenology arise from soggy grey matter? What
makes the bodily organ we call the brain so radically different from
other bodily organs, say the kidneys—the body parts without a trace of
consciousness? How could the aggregation of millions of individually
insentient neurons generate subjective awareness? We know that brains
are the de facto causal basis of consciousness, but we have, it seems, no
understanding whatever of how this can be so. It strikes us as miraculous,
eerie, even faintly comic. Somehow, we feel, the water of the physical
brain is turned into the wine of consciousness, but we draw a total blank
on the nature of this conversion. Neural transmissions just seem like
the wrong kind of materials with which to bring consciousness into the
world, but it appears that in some way they perform this mysterious feat.
Colin McGinn, Can We Solve the Mind-Body Problem?7

In 1989 the philosopher Colin McGinn asked the following question
“How can technicolor phenomenology arise from soggy gray matter?”
[…] Since then many authors in the field of consciousness research
have quoted this question over and over, like a slogan that in a nutshell
conveys a deep and important theoretical problem. It seems that almost
none of them discovered the subtle trap inherent in this question. The
brain is not gray. The brain is colorless.
Thomas Metzinger,
Consciousness Research at the End of the Twentieth Century8

With furrowed brow, buried deep in his leather-bound armchair, the
Philosopher seeks to untangle the mysteries of consciousness. One of
3. The Philosophy and Science of Consciousness 37

the greatest and hardest problems of his time, or so he has read. He
imagines the physical world, a grey lifeless sort of place. He imagines
the brain, a squishy grey thing floating dismally in the air above his
dirty glass coffee table. He imagines the colour RED. Bracing himself for
the challenge, he attempts to solve the Hard Problem of Consciousness.
Many have failed before him, but his obvious brilliance and intellectual
arrogance will surely enable him to triumph. Perspiration breaks out on
his brow. ‘Gee this is a tough one.’ He struggles to imagine how activity
in the grey brain could cause or be the colour red. Or how the colour
red could be reduced to activity in the grey brain. He changes position,
scratches his crotch, picks his nose. He is sure that he can solve it, write
that brilliant paper, receive the rapturous admiration of his peers. ‘Just
a bit more time; perhaps a coffee will help.’

The relationship between consciousness and the physical world is
often addressed in a thought experiment in which we bring to mind an
image of the brain (coloured grey) and an image of something conscious
(the colour red), and try to imagine how they are related. This is often
described as a hard problem of consciousness because it is impossible
for us to imagine how neural activity could cause or be the colour red.9

The physical brain has none of the properties that are present in
consciousness. It is not grey; it is not soggy—it is invisible and cannot
be imagined by us. So thought experiments and imagination cannot be
used to study the relationship between invisible physical brains and
conscious experiences. They can only be used to study the relationship
between our conscious experiences of brains and other conscious
experiences. This is illustrated in Figure 3.2.

3.4 Regularities in Conscious Experiences
We can observe regularities in our conscious experiences. Suppose I am
connected to a device that shows the state of my brain on a screen. When
an ice cube is placed in my left hand I observe brain pattern p1 on the
screen. When I have memorized p1 I can make an imaginative transition
from p1 to a cold sensation: whenever I think about p1 I imagine an ice
cube. This is illustrated in Figure 3.3.10
38 Human and Machine Consciousness

Figure 3.2. Imagination cannot be used to understand the relationship between
consciousness and the invisible physical world. A philosopher imagines a child
with her brain exposed holding a red balloon. He wants to understand the
relationship between the colour red and the invisible physical brain, but he can
only imagine the relationship between the colour red and his conscious experience
of a grey brain. Image © David Gamez, CC BY 4.0.

We find it hard to imagine how our conscious experiences of brains
are related to other conscious experiences because we have had little
exposure to this relationship.11 Imagination is an inductive engine—it
needs to be exposed to an association between A and B before it can
imagine a transition from A to B. As technology develops we will have
more conscious experiences of brain activity, which will enable us to
develop intuitive links between our conscious experiences of brain
patterns and other conscious experiences. This is nicely illustrated by
Rorty’s example of the Antipodeans:12

In most respects, then, the language, life, technology, and philosophy of
this race were much like ours. But there was one important difference.
Neurology and biochemistry had been the first disciplines in which
3. The Philosophy and Science of Consciousness 39

Figure 3.3. Learnt association between consciously experienced brain activity and
the sensation of an ice cube. a) The subject wears a device that displays his brain
activity on a screen. When an ice cube is placed in his left hand he observes and
memorizes the brain pattern, p1, that appears on the screen. b) At a later time the
subject views p1 when he is not holding an ice cube. He makes an imaginative
transition from his conscious experience of p1 to a conscious experience of an ice
cube. Image © David Gamez, CC BY 4.0.
40 Human and Machine Consciousness

the technological breakthroughs had been achieved, and a large part
of the conversation of these people concerned the state of their nerves.
When their infants veered towards hot stoves, mothers cried out,
“He’ll stimulate his c-fibers.” When people were given clever visual
illusions to look at, they said, “How odd! It makes neuronic bundle
G-14 quiver, but when I look at it from the side I can see that its [sic]
not a red rectangle at all.” Their knowledge of physiology was such
that each well formed sentence could easily be correlated with a readily
identifiable neural state.13

We can observe regularities in our consciousness without raising
hard philosophical problems. But our rudimentary brain scanning
technology does not show us the relationship between conscious
experiences of brain activity and other conscious experiences, so we
cannot imagine this relationship. The Antipodeans have better access to
their brains, so they can easily imagine the connection between activity
in neuronic bundle G-14 and a conscious experience of a red rectangle.14

3.5 Brute Regularities
We might still ask how or why activity in the physical brain is linked to
conscious states.

When we observe a connection between two physical events we
can typically drill down to a more detailed account of the relationship
between them. In the smoking example, we can fill in the link between
cigarette smoke and DNA mutations with a more detailed story about
biochemical reactions, which can be explained in terms of atomic and
subatomic events. We can have conscious experiences that very roughly
correspond to each intermediate stage.

In the case of consciousness we are looking for a relationship between
something that is physical and properties that are not attributed to the
physical world (colour, smell, etc.). However much data we gain about
consciousness and the brain there is bound to be a gap in the imaginative
story. We can learn everything there is to know about links between
conscious experiences of brain activity and other conscious experiences,
but we will still reach a point at which we simply have to accept that a
particular brain state is connected with a particular conscious state. A
physical brain activity pattern could simply be associated with red—this
3. The Philosophy and Science of Consciousness 41

might be a brute regularity that cannot be broken down and analyzed
any further.

Brute regularities exist in the other sciences. At a certain point we
simply have to accept that the physical world works in a way that we can
describe but cannot explain. For example, the behaviour of superstrings
or elementary wave-particles can be described but not explained—it
is the starting point for higher level physical explanations.15 Scientists
cannot say why physical brute regularities exist. They are simply how
the universe works.

Physics gives a detailed hierarchical description of the relationships
between physical things, ranging from the interactions between
elementary wave-particles up to the behaviour of planets and galaxies.
Brute regularities lie at the bottom of this hierarchy—at the level of
superstrings and elementary wave-particles.16

Our understanding of the relationship between consciousness and
the physical world is at an early stage of development. We have no idea
what the brute regularities of consciousness science will be. They could
be simple relationships between novel physical properties and atoms of
conscious experience, or they could be more complex regularities linking
distributed brain activity patterns to complex conscious experiences.

Some people think that brute regularities are hard problems. But
genuine brute regularities are not problems at all. They are basic facts
about the way the universe works. Other phenomena pose problems
that can be solved in terms of brute regularities. The brute regularities
themselves can only be described—they cannot be understood or
explained.

3.6 Summary
Idealists reject the physical world; phenomenologists suspend
judgement about it; physicalists claim that consciousness is the physical
world. None of these positions is convincing. Consciousness and the
physical world both have to be taken seriously as real phenomena. We
can study the relationship between them and suspend judgement about
the metaphysical debates.
42 Human and Machine Consciousness

We cannot imagine the invisible physical world. So thought
experiments and imagination cannot be used to study the relationship
between invisible physical brains and conscious experiences. They can
only be used to study the relationship between our conscious experiences
of brains and other conscious experiences. As brain-scanning technology
improves we will find it easier to make imaginative transitions between
conscious experiences of brain states and other conscious experiences.

At some point the science of consciousness will encounter brute
regularities in the relationship between consciousness and the physical
world that can be described, but not explained. Brute regularities exist
in the other sciences. We have no idea what the brute regularities of
consciousness science will be.

The rest of this book suggests how a systematic science of
consciousness can be developed. We can measure consciousness,
measure the physical world and develop mathematical theories of
the relationship between these measurements. Scientists measure
consciousness using first-person reports, which raises traditional
philosophical problems of zombies, solipsism, colour inversion and
inaccessible consciousness. These problems cannot be solved, but they
can be neutralized using the framework of definitions and assumptions
that is set out in the next chapter.
4. The Measurement of
Consciousness

Consciousness just is not the sort of thing that can be measured directly.
What, then, do we do without a consciousness meter? How can the
search go forward? How does all this experimental research proceed?
I think the answer is this: we get there with principles of interpretation,
by which we interpret physical systems to judge the presence of
consciousness. We might call these preexperimental bridging principles.
They are the criteria that we bring to bear in looking at systems to say (1)
whether or not they are conscious now, and (2) which information they
are conscious of, and which they are not.
David Chalmers,
On the Search for the Neural Correlates of Consciousness1

4.1 First-Person Reports about Consciousness
(C-Reports)
I am standing with my friend Olaf in a field of poppies. ‘Look Olaf,’ I
say, ‘the poppies are red, the sky is blue and the leaves are green.’ ‘By
the blood of Grendel,’ he replies, ‘I can hear the sound of a bird singing
and feel a sensation of warmth in my left foot.’

In earlier times my chat with Olaf would have been interpreted
as a conversation about the world. Over the last three hundred years
science has sucked colour, sound and warmth out of the world and
reinterpreted them as consciousness. Statements like ‘The poppies are
red’ or ‘There is a rusty helmet on the ground’ have become descriptions
of consciousness.2

I am certain that I can speak about my consciousness. I cannot
doubt that ‘The poppies are red’ is a true statement about my bubble

of experience. I would be more willing to jettison the entire edifice of
science, than abandon my belief that I can describe my consciousness.3

I can speak about my consciousness. I can describe my consciousness
by pushing buttons and pulling levers. I can reply to questions about
my consciousness by putting my brain into different states in a fMRI
scanner.4

Olaf is alert. He can flexibly respond to novel situations. He can
inwardly execute a sequence of problem-solving steps. He can execute
a delayed reaction to a stimulus and respond to verbal commands.5 He
is willing to bet a large amount of money that there is a rusty helmet
in the field of poppies.6 These behaviours can be used to make reliable
inferences about the contents and level of Olaf’s consciousness, even
when he is not explicitly reporting his consciousness.7

I punch Olaf in the face. He falls to the ground and lies still. His
stillness and lack of response are external signs that his brain is not
associated with a bubble of experience, that his level of consciousness
is zero.

When Olaf regains consciousness he exhibits groggy behaviour.
l interpret this as a sign that he has a low level of consciousness. He
is never quite the same again and often behaves in a similar way to a
patient described by Damasio:

Suddenly the man stopped, in midsentence, and his face lost animation;
his mouth froze, still open, and his eyes became vacuously fixed on some
point on the wall behind me. For a few seconds he remained motionless.
I spoke his name but there was no reply. Then he began to move a little,
he smacked his lips, his eyes shifted to the table between us, he seemed
to see a cup of coffee and a small metal vase of flowers; he must have
because he picked up the cup and drank from it. I spoke to him again
and again he did not reply. He touched the vase. I asked him what was
going on and he did not reply, his face had no expression. […] Now he
turned around and walked slowly to the door. I got up and called him
again. He stopped, he looked at me, and some expression returned to
his face—he looked perplexed. I called him again and he said, “What?”8

When Olaf is in this state he is not capable of executing a sequence of
problem-solving steps. He does not flexibly respond to novel situations.
4. The Measurement of Consciousness 45

He cannot execute a delayed reaction to a stimulus. We interpret his
behaviour as a sign that he has zero consciousness, that he is not
immersed in a bubble of experience.

Any behaviour that can be interpreted as a measurement of the
level and/or contents of a person’s consciousness will be referred to as
a c-report:

D2. A c-report is a physical behaviour that is interpreted as a report
about a person’s consciousness.

A c-report is a measurement of consciousness. This measurement is
indirect—Olaf’s bubble of experience does not appear in my bubble of
experience.

Indirect measurements are standard scientific practice. When I
measure the path of a particle, the particle does not directly appear in
my bubble of experience. I have to create an experimental situation in
which the particle creates a visible trace, such as a track of bubbles in a
chamber. Theories about the physical world link the bubble track to the
path of the invisible particle.

4.2 Reports about Non-Conscious
Mental Content (NC-Reports)
Olaf thinks a lot about his sweetheart Olga. As he crosses the field of
poppies he is thinking about her corn-blond plaits, her inviting smile,
her chequered billowing skirt, her strong smooth thighs. He is not aware
of the stones in his boots, the white crosses in the field or the hot sun
on his face. None of these are in his bubble of experience, although he
could bring them into his bubble of experience if he stopped thinking
about Olga’s thighs and focused on his body and surroundings.

As Olaf walks and thinks about Olga, the sensory data from the
field of poppies is used by his brain to generate control signals that are
sent to his muscles. This sensory data does not appear in his bubble of
experience. It is unconscious or non-conscious information.
46 Human and Machine Consciousness

I present a picture of Olga to Olaf’s right eye and a picture of Olaf’s
ex-wife Ingrid to his left eye. He experiences a phenomenon called
binocular rivalry in which Olga’s picture is perceived for a few seconds
while Ingrid’s is non-conscious, and then Ingrid’s picture becomes
conscious and Olga’s non-conscious. When Ingrid’s picture is non-
conscious it is still being processed by Olaf’s brain, which responds to
the shape of her sharp tongue in her hard mouth.9

I show Ingrid’s picture to Olaf for 30 ms in the middle of a sequence
of scrambled images. Under these conditions Ingrid’s picture does not
enter Olaf’s bubble of experience, but it does cause Olaf to complete
word fragments with Ingrid-related words and alters the conductivity
of his skin.10 When I ask Olaf to guess which picture was shown he picks
Ingrid’s picture more often than chance.11

All of these behaviours can be used to identify mental contents that
are being processed non-consciously. They are nc-reports:

D3. A nc-report is a physical behaviour that is interpreted as a report
about non-conscious mental content.

4.3 Platinum Standard Systems
C-reports about consciousness can be found everywhere. The sigh of
waves can be interpreted as a c-report. Or consider the following snippet
of code:
1. string input = "";
2. cout<<"Hello"<<endl;
3. while (input != "Goodbye"){
4. getline(cin, input);
5. if (input == "Are you conscious?")
6. cout<<"Yes"<<endl;
7. else if (input == "Are you a cute leetle kitten?")
8. cout<<"Yes, my eyes are blue and I cry 'Mew mew mew'."<<endl;
9. else if (input == "Goodbye")
10. cout<<"Goodbye"<<endl;
11. else
12. cout<<"Nice weather for the time of year."<<endl;
13. }
4. The Measurement of Consciousness 47

A computer running this code will claim that it is conscious. It will also
claim that it is a cute leetle kitten. Neither claim is convincing.

My wife is a zombie. She hides from light and shuffles home from
work with dead eyes, drinks in the pub with dead eyes, makes love
with dead eyes. Her physical body is not associated with a bubble of
experience. Her zombie statements about ‘consciousness’ are not
descriptions of a bubble of experience. They are just empty sounds
produced by biochemical processes.

My wife is a professional phenomenologist. She says many things
that appear to be descriptions of a bubble of experience. I cannot
directly observe her lack of consciousness, so how can I prove that
she is a zombie? How can I prove that other people’s bodies are really
associated with bubbles of experience? This is the traditional problem
of other minds.

To scientifically study consciousness we need a physical system
that is associated with consciousness. Since it is impossible to prove
that particular physical systems are conscious, we have to set aside
philosophical worries about solipsism and zombies and assume that
one or more physical systems are actually conscious. I will do this by
introducing the concept of a platinum standard system:

D4. A platinum standard system is a physical system that is assumed to
be associated with consciousness some or all of the time.12

The term ‘platinum standard system’ is a reference to the platinum-
iridium bar that was the first working definition of a metre.13 Other
objects were directly or indirectly compared to this platinum-iridium
bar to measure their length. The length of this bar could not be checked
because it was defined to be one metre long: when this bar expanded,
everything else contracted.14

Platinum standard systems are the starting point for consciousness
science. Consciousness is simply assumed to be associated with
these systems. When we have identified the relationship between
consciousness and the physical world in platinum standard systems,
we can use this knowledge to make inferences about the consciousness
of other systems.
48 Human and Machine Consciousness

I was awarded a grant to study consciousness and ordered a
platinum standard system from the supplier. It was delivered yesterday.
I poured myself a coffee and strolled over to inspect it. A decent enough
specimen with a bushy red beard, around 2 m tall. It made angry noises
and rattled the bars of its cage. I prodded it with a stick and topped up
its bowl of brown nuggets.

The supplier states that this system is associated with a bubble of
experience. They are a reputable firm, so I have confidence in their claim.
On the first day of our experiments we strapped the platinum standard
system into a chair, held up a red apple and asked it for a c-report. It
stated that it was conscious of a red apple. A promising start, but it had
a crafty look in its eye—it might have been lying. Or its consciousness
might be a delusional world that is completely disconnected from its
behaviour. I was assured that this system shipped with a bubble of
experience, but the supplier did not guarantee that I would be able to
use c-reports to measure its bubble of experience.

Scientists studying consciousness need to measure consciousness.
While a platinum standard system’s c-reports can be cross-checked for
consistency, there is no ultimate way of establishing whether they are
correct. Since c-reports are the only way in which consciousness can be
measured, it has to be explicitly assumed that c-reports from a platinum
standard system co-vary with its consciousness:

A1. During an experiment on consciousness, the consciousness
associated with a platinum standard system is functionally connected
to the platinum standard system’s c-reports.

A functional connection between consciousness and c-reports is a
deviation from statistical independence—not necessarily a causal
connection.15

A1 captures the idea that our consciousness is connected to our
c-reports. When our consciousness changes, our c-reports change. This
assumption does not specify the amount of functional connectivity
between consciousness and c-reports, which will vary with the
type of c-reporting. A1 is also explicitly limited to experiments on
consciousness.16
4. The Measurement of Consciousness 49

Outside of experiments on consciousness it is possible that a system’s
consciousness could be disconnected from its behaviour. Information
gathered by consciousness experiments could be used to make inferences
about the presence of consciousness in these situations. It could also be
used to make deductions about the consciousness of systems that are not
platinum standards, such as brain-damaged patients (see Section 9.2).

I contact the supplier. They issue me with a certificate that guarantees
that their platinum standard systems’ c-reports are functionally
connected to their consciousness (A1). We resume our experiments and
identify a neural firing pattern that always occurs when the platinum
standard system is conscious, and never occurs when it is not conscious.
We have found the correlates of consciousness! We write up the results
and submit our paper for publication.

The paper is rejected. We are devastated and enraged. One
reviewer argues that our platinum standard system could have several
consciousnesses. The second reviewer suggests that its bubble of
experience could have features that are impossible to c-report under any
circumstances. The third reviewer points out that it might be conscious
when it is not c-reporting—it would just be unable to remember or
report its consciousness. At best we have identified a correlate of part of
its consciousness, not a true correlate of consciousness.

The systematic study of consciousness will be difficult or impossible
if platinum standard systems are potentially associated with ghostly
ecosystems of unreportable consciousnesses, or if many aspects of
consciousness cannot be c-reported. Scientific studies have to assume
that this is not the case:

A2. During an experiment on consciousness all conscious states
associated with a platinum standard system are available for c-report
and all aspects of these states can potentially be c-reported.17

This assumption states that every aspect of all of the conscious states
that are associated with a platinum standard system can potentially be
c-reported, even if they are not actually reported during an experiment.18
So we can use a variety of c-reports to extract a complete picture of a
platinum standard system’s consciousness (see Section 4.8).19
50 Human and Machine Consciousness

A2 is incompatible with panpsychism.20 If all matter is conscious all
the time, then c-reports cannot be used to measure all of a platinum
standard system’s consciousness. If panpsychism was true, an
apparently unconscious brain that was c-reporting zero consciousness
would be associated with a bubble of experience.21

4.4 Pinning Consciousness to the Physical World
When I was a lad my father shone 700 nm light into my eyes and said
‘Red … red … red.’ My mother shone 450 nm light into my eyes and
said ‘Blue … blue … blue.’ At a later point in time I c-report that there
is a red patch in my bubble of experience. To make this report I use the
association that I have learnt between an experience and a word. When
I say that I am conscious of the red patch I am saying that I am having
approximately the same colour experience that I had when I learnt the
word ‘red’. The incoming electromagnetic waves have activated the
same brain areas that were activated when I learnt the word ‘red’ as a
child, which presumably are associatively linked to particular language
or conceptual areas. My description of my conscious experience is a
comparison with earlier experiences.22

We are sitting in a bare whitewashed room. A human ear is on the
table in front of us. The colour of the torn edge of the ear is similar to the
colour that I experienced when my father shone 700 nm light into my
eyes. I make a c-report: ‘I am experiencing the colour red.’ The colour
of the torn edge of the ear in your bubble of experience is similar to the
colour that you experienced when your father shone 700 nm light into
your eyes. You make a c-report: ‘I am experiencing the colour red.’

We both report that we are experiencing ‘red’, so we are apparently
having the same conscious experience. But what if the colour produced by
700 nm electromagnetic waves in my bubble of experience is completely
different from the colour produced by 700 nm electromagnetic waves in
your bubble of experience? We have learnt the same mapping between
incoming electromagnetic wave frequencies and colour names, so we
will both make identical reports about the electromagnetic waves that
we are exposed to, but nothing guarantees that these reports correspond
to identical colour experiences. This is the classic problem of colour
inversion, which is illustrated in Figure 4.1.23
Figure 4.1. Problem of colour inversion. a) A person teaches us the word ‘red’
by pointing to a coloured patch and making the sound ‘red’. Your colours
are inverted relative to mine, so my red is your turquoise, and so on. We
both learn to associate the colour that we experience with the sound ‘red’. b)
We observe a severed ear on a table. The colour of the torn edge of the ear is
similar to the colour that we experienced when we learnt the word ‘red’, so
we both report that we are experiencing the colour red. The colours in our
bubbles of experience are very different, but there is no way of detecting this
in our external behaviour. Image © David Gamez, CC BY 4.0.
52 Human and Machine Consciousness

In the standard colour inversion scenario a single set of colours
is linked in different ways to electromagnetic waves. Our bubbles of
experience could also contain completely different sets of ‘colours’
that have no overlap between them. Or our consciousnesses could
be different in more radical ways—different geometries, different
experiences of space and time, differences that I am unable to imagine
because I cannot imaginatively transform my bubble of experience into
these other states.
In these scenarios two systems in similar physical states are associated
with radically different bubbles of experience. Since they are making
the same c-reports the differences between their bubbles of experience
will not show up in scientific experiments. It will be impossible to
systematically study the relationship between consciousness and the
physical world under these conditions.
To address this issue scientists studying consciousness have to assume
that identical states of the physical world are associated with identical
conscious states. This can be expressed using the philosophical concept
of supervenience.24 Since we are only concerned with a pragmatic
approach to the science of consciousness, it is not necessary to assume
that consciousness logically or metaphysically supervenes on the
physical world. We just need to assume that the natural laws are such
that consciousness cannot vary independently of the physical world:
A3. The consciousness associated with a platinum standard system
nomologically supervenes on the platinum standard system. In our
current universe, physically identical platinum standard systems are
associated with indistinguishable conscious states.

4.5 Which Systems are Platinum Standards?
It is not known when consciousness emerges in the embryo or infant.25
We do not know whether birds or cephalopods are conscious.26 Brain-
damaged people can inaccurately report their consciousness.27 No-one
knows whether computers are capable of consciousness. We try and fail
to use our imagination to decide whether consciousness is present in
these systems.
4. The Measurement of Consciousness 53

I am an adult. I can smoke, drive and vote. Ten doctors claim that
my brain is functioning normally. My brain does not contain unusual
chemicals that might affect its operation. I am certain that this normally
functioning adult human brain is associated with consciousness some of
the time. If consciousness supervenes on the physical world (A3), then
similar brains will be associated with similar consciousness:

A4. The normally functioning adult human brain is a platinum
standard system.28

The normally functioning adult human brain is the only system that
we confidently associate with consciousness. At a later point in time we
might make further assumptions that extend the number of platinum
standard systems. For example, we might assume that the red nodules
on the genitals of an alien race are platinum standard systems.29

Figure 4.2. Some of the definitions and assumptions that are required for scientific
experiments on consciousness. The normally functioning adult human brain is
a platinum standard system (A4), which is associated with consciousness (D4).
Consciousness nomologically supervenes on the platinum standard system (A3)
and all of it can be c-reported (A1, A2). Image © David Gamez, CC BY 4.0.
54 Human and Machine Consciousness

The science of consciousness is limited by the set of systems that
we assume to be platinum standards. It is a science of the relationship
between consciousness and platinum standard systems. Many
relationships between consciousness and the physical world might
not appear in normally functioning adult human brains. This would
reduce the accuracy of our deductions about consciousness in non-
human systems (see Section 9.2).

Some of the definitions and assumptions that have been introduced
so far are illustrated in Figure 4.2.

4.6 The Correlates of a Conscious State
Yesterday I lost consciousness in the street. My body lay crumpled
on the concrete. Insects crawled over my face. Cappuccino-carrying
commuters stepped over me on the way to the office. My body was just
a thing—a part of the physical world that was not associated with a
bubble of experience.

I am conscious now. The state of my brain now is different from the
state of my brain when I lay unconscious on the street. If consciousness
supervenes on the physical world (A3), something must be present in
my brain now that is absent when consciousness is absent. This is a
correlate of consciousness, which is defined as follows:

D5. A correlate of conscious state is a minimal set30 of one or more
spatiotemporal structures in the physical world. This set is present
when the conscious state is present and absent when the conscious
state is absent. This will be referred to as a CC set.31

‘Spatiotemporal structures’ is a deliberately vague term that captures
anything that might be correlated with consciousness, such as activity
in brain areas, electromagnetic waves or quantum events. Chapters 6–8
discuss some of the spatiotemporal structures that might be members
of CC sets.

Correlates defined according to D5 will be associated with
consciousness wherever they are found.32 Suppose CC sets only contain
electromagnetic wave patterns. When a particular electromagnetic wave
4. The Measurement of Consciousness 55

pattern occurs in your brain, you are immersed in a particular bubble of
experience. When the electromagnetic wave pattern is absent, you have
a different bubble of experience or no consciousness at all. None of the
other types of spatiotemporal structure in your brain have any effect on
your bubble of experience.

I distract you with a soft toy: ‘Here reader, look at this, look… look…
look at Teddy.’ While you are playing with its ears I extract your brain
from your skull and keep it alive in a jar. I provide stimulation patterns
that mimic the sensory-motor responses of your discarded body. I
ensure that the electromagnetic wave pattern in your brain is identical
to the one that was present when you were playing with Teddy. This is
associated with a bubble of experience in which you are playing with
Teddy, so you continue to have this experience.

I discard your brain’s biological tissue and replace it with silicon chips
that are programmed to produce the same pattern of electromagnetic
waves. You remain contentedly unaware of what is going on and
continue to play with Teddy’s ears in your bubble of experience. Suppose
that the same pattern of electromagnetic waves occurs by chance when I
drop my phone. This will also be associated with a bubble of experience
in which you are playing with Teddy’s ears.

Definition D5 enables me to state assumption A3 more precisely:

A3a. The bubble of experience that is associated with a CC set
nomologically supervenes on the CC set. In our current universe,
physically identical CC sets are associated with indistinguishable
conscious states.

A correlation between A and B is the same as a functional connection
between A and B—they are different ways of stating that A and B deviate
from statistical independence.33 So a CC set can be described as a set
of spatiotemporal structures that is functionally connected to a conscious
state. This way of describing the relationship between consciousness
and the physical world will play a role in what follows, so it will be
formally stated as a lemma:

L1. There is a functional connection between a conscious state and its
corresponding CC set.34
56 Human and Machine Consciousness

4.7 A Causal Relationship between Consciousness
and the Physical World?
A science that invokes mental phenomena in its explanations is
presumptively committed to their causal efficacy; for any phenomenon
to have an explanatory role, its presence or absence in a given situation
must make a difference—a causal difference.
Jaegwon Kim, Mind in a Physical World35

I was looking for love on the Internet. ButiDD’s profile looked promising:
witty lines, sexy curves, hot pics. We arranged a date on Friday 5 August
2005 at 15:00 in a cafe on Hampstead Heath. When we met there was no
chemistry. Conversation ground to a halt. I ate my cake. To cut through
the boredom and silence I remarked ‘I am conscious of a sweet taste in
my mouth.’ These sound vibrations led, through a complex chain of
causes and effects, to Hurricane Katrina.

C-reports have physical effects. Speech vibrates the air, writing makes
marks, gestures depress buttons and pull levers. These physical effects
lead to further chains of causes and effects, which can be amplified into
a hurricane or dissolve into background noise. Consciousness appears
to be the source of c-reports, so it is natural to assume that it is the sort
of ‘thing’ that can cause effects in the physical world.

A clearer definition of causation will help us to understand
the relationship between consciousness and c-reports. First I will
distinguish between conceptual and empirical theories of causation.36
Conceptual theories of causation elucidate how we understand and use
causal concepts in our everyday speech. Empirical theories of causation
explain how causation operates in the physical world—by reducing it
to the exchange of physically conserved quantities, such as energy and
momentum, or linking it to physical forces.37

Conceptual analyses of causation are popular in philosophy, but it is
difficult to see how our use of ‘causation’ in everyday speech can help
us to understand the causal interactions in the brain’s neural networks
and the relationship between consciousness and the physical world.

Empirical theories of causation can precisely identify causal events
and exclude cases of apparent causation between correlated events. They
can easily relate the causal laws governing macro-scale objects, such
4. The Measurement of Consciousness 57

as cars and people, to the micro-scale interactions between molecules,
atoms and quarks. Empirical theories of causation are a much more
appropriate starting point for studying the causal relationships between
consciousness and c-reports.

A detailed discussion of the advantages and disadvantages of
different theories of empirical causation is beyond the scope of this book,
but it will be easier to analyze the c-reporting of consciousness with
a concrete theory in mind. For this purpose I will use Dowe’s theory
of empirical causation. This is the most fully developed conserved
quantities approach and it has the following key features:38
• A conserved quantity is a quantity governed by a conservation
law, such as mass-energy, momentum or charge.
• A causal process is a world line39 of an object that possesses a
conserved quantity.
• A causal interaction is an intersection of world lines that
involves the exchange of a conserved quantity.

This account of causation will be referred to as e-causation. The
framework developed in this book relies on there being some workable
theory of e-causation, but it does not depend on the details of any
particular account. If Dowe’s theory is found to be problematic, an
improved version can be substituted in its place.40

A car moves along a road at 5 m/s and knocks a fat man down (Figure
4.3a). In this e-causal interaction energy-momentum is transferred from
the car to the man. This macro-scale e-causal interaction can be reduced
down to the micro-scale e-causal interactions between the physical
constituents of the car and man, in which atoms in the car’s bumper
pass energy-momentum to atoms in the man’s legs (Figure 4.3b).

We can distinguish between true and false causes of this event. The
car’s engine temperature is a macro-scale property of the physical world
that moves along at the same speed as the car and also collides with the
man (Figure 4.3c). However, the macro property of engine temperature
does not exchange energy-momentum with the man, so it does not e-cause
him to fall down, although it can e-cause other macro-scale effects, such
as skin burns. Similar e-causal accounts can be given of the laws of other
macro-scale sciences, such as geology, chemistry and biology.41
58 Human and Machine Consciousness

Figure 4.3. The relationship between macro- and micro-scale e-causal events. a) A
car moving at 5 m/s collides with a fat man and knocks him down. This is a macro-
scale e-causal event in which the car passes energy-momentum to the man. b) The
macro-scale e-causal interaction between the car and man can be reduced down
to the micro-scale exchanges of energy-momentum between atoms in the car and
man. c) The temperature of the car’s engine is a macro-scale property that moves
at 5 m/s and collides with the man. The engine temperature exchanges a small
amount of energy-momentum with the man in the form of heat, but not enough
to e-cause him to fall down. Image © David Gamez, CC BY 4.0.

It is generally assumed that the amount of energy-momentum in
the physical universe is constant (as long as the reference frame of the
observer remains unchanged). When part of the physical world gains
energy-momentum, this energy-momentum must have come from
elsewhere in the physical universe. It is also generally assumed that the
net quantity of electric charge in the universe is conserved. If part of
the physical world gains electric charge, another part of the physical
world must have lost charge or there must have been an interaction in
which equal quantities of positive and negative charge were created
or destroyed. Similar arguments apply to other physically conserved
quantities, which leads to the following assumption:

A5. The physical world is e-causally closed.
4. The Measurement of Consciousness 59

According to A5, any change in a physical system’s conserved quantities
can in principle be traced back to a set of physical e-causes that led the
system to gain or lose those conserved quantities at that time.

In everyday language we say that a person reports or describes
their consciousness. This might naively be interpreted as the idea that
consciousness directly or indirectly alters the activity of the brain’s
speech areas, sending spikes to the larynx that lead to sound vibrations
in the air.

The problem with this naive picture is that consciousness could
only e-cause a chain of events leading to a c-report if it could pass a
physically conserved quantity, such as energy-momentum or charge,
to neurons in the c-reporting chain—for example, if it could push them
over their threshold and cause them to fire.42 If the physical world is
e-causally closed (A5), then a conserved quantity could only be passed
from consciousness to a brain area if consciousness is a physical
phenomenon, i.e. if consciousness is the correlates of consciousness.43

Consciousness is the correlates of consciousness if physicalism
is correct. But it would be premature and controversial to base the
scientific study of consciousness on this assumption. It is also absurd to
claim that a bubble of experience is a pattern of invisible wave-particles.
It would be much better to find a way of measuring consciousness that
does not depend on the assumption that physicalism is true.

I have assumed that a conscious state is functionally connected
to a CC set (L1) and that c-reports are functionally connected
to consciousness (A2). To fully account for the measurement of
consciousness we need an e-causal connection between CC sets and
c-reports. This can be addressed by introducing a further assumption
that fits in naturally with the current framework:

A6. CC sets e-cause a platinum standard system’s c-reports.

This states that the correlates of consciousness are the first stage in a
chain of e-causation that leads to c-reports about consciousness.44,45 It
can be difficult to measure e-causation, so in some circumstances A6 can
be substituted for the weaker assumption:
60 Human and Machine Consciousness

A6a. CC sets are effectively connected to a platinum standard
system’s c-reports.46

Assumption A6 is illustrated in Figure 4.4.

By themselves A6 and A6a do not say anything about the strength
of the relationship between CC sets and c-reports. There could be a
very weak e-causal chain leading from a CC set to a c-report, which
could primarily be driven by unconscious brain areas. The weaker the
connection between CC sets and c-reports, the more experiments will be
required to identify CC sets.

Figure 4.4. Assumptions about the relationship between CC sets, consciousness
and first-person reports. The labels S1, CC1, R1, etc. refer to any kind of
spatiotemporal structure in the brain, such as the activation of a brain area, neural
synchronization, electromagnetic waves, quantum events, and so on. They are
only illustrative and not intended to correspond to particular anatomical paths or
structures. An e-causal chain of sensory spatiotemporal structures, S1-S3, leads to
the appearance of a spatiotemporal structure, CC1, that is functionally connected
to consciousness. In this example the contents of consciousness are determined by
sensory events, but in principle they could be independent of S1-S3—for example,
if the subject was dreaming. CC1 is assumed to be the first stage in an e-causal
chain of spatiotemporal structures, R1-R3, that lead to a verbal description of
consciousness. Image © David Gamez, CC BY 4.0.47
4. The Measurement of Consciousness 61

4.8 The Limits of C-Reporting
You are looking at your reflection in a mirror. You see greying hair, burst
capillaries, lengthening deepening lines. A tired sad sagging face. Your
youth has gone. You will die soon. A sense of helpless fatality washes
over you. You imagine how your face will look in the grave, under the
wet earth, your empty eye sockets staring blankly at blackness, while
the world rolls along and your existence fades away without trace.

Stick up your thumbs and interlace your fingers. Extend your arms
to their full length in front of you. Look directly at your thumbnails.
The area covered by your thumbnails is the high resolution part of your
visual field. The rest is low resolution. When you look at your nose in the
mirror only sketchy information is coming in from your gold earrings
and beard. You cannot detect substantial changes that occur outside of
the high resolution area.48

The limited extent of our high resolution vision is not a problem in
daily life. When we require more information about a feature of our
environment we make a rapid eye movement (known as a saccade) to
bring this feature into high resolution vision. As you look in the mirror
you are moving your eyes every ~200 ms. You inspect the pores on your
nose, flick across to your left cheek, look up at your eyebrow, and so on.49

Depressed you pluck out a protruding hair. You squeeze a painful
spot and wipe a stain from the mirror. A chewed-up cabbage leaf is
trapped between your teeth. You remember your dental appointment
tomorrow.

Your consciousness changes several times per second.50 As you look
at your face in the mirror you are receiving fresh sensory information
from your eyes and body and attending to different senses (moving from
vision, to touch, to audition, etc.). You are shifting between past, present
and possible futures: between memory, perception and imagination.

Describe your consciousness now. You were in a reverie—try again.
The clock reads 22:59:50.874. Describe your consciousness when it
changes to 23:00:00.000. Get ready … now.

When you started to describe your consciousness you were alert and
speaking coherently. This external behaviour was a c-report of a high
62 Human and Machine Consciousness

level of consciousness. Immobility and incoherent mumbling would
have been a c-report of a low level of consciousness.

When the clock changed to 23:00:00.000 you started to describe your
consciousness in natural language. But your consciousness changed when
you uttered the first word—it became consciousness of that word. The
consciousness that you had at 23:00:00.000 vanished when you started
to describe it. Natural language is too slow to c-report consciousness in
real time.

Ok, try a different strategy. The clock reads 23:01:46.340. Describe
your consciousness when it changes to 23:02:00.000. Get ready … now.

This time you tried to remember your state of consciousness at
23:02:00.000. You converted an online bubble of experience into an
offline bubble of experience. This memory preserves some washed-out
unstable information about the visual consciousness that you had at
23:02:00.000. It holds little detail about the sounds, smells, tastes and
body sensations that were in your bubble of experience at that moment.
Your memory is also fragile—it is not like a computer file. As you
describe your memory of your consciousness at 23:02:00.000 it becomes
contaminated with details that came before or after the moment that
you are trying to remember.

One more attempt. The clock reads 23:05:51.087. Describe your
consciousness when it changes to 23:06:00.000. Get ready … now.

You could not accurately remember what your nose looked like at
23:06:00.000. So when I asked you to describe your consciousness you
moved your eyes to look at your nose. You used the world as external
memory.51 Your face is pretty stable, so perhaps you could use this
method to generate a complete description of your consciousness at
23:06:00.000. However, this would not provide a description of your
consciousness at 23:06:00.000: it would be a description of a series of
moments of consciousness in which different aspects of your face enter
the high resolution part of your bubble of experience. When you moved
your eyes to obtain information about your nose, your consciousness at
23:06:00.000 was replaced with a new bubble of experience in which you
were ‘zoomed in’ on your nose.
4. The Measurement of Consciousness 63

We cannot accurately describe a state of our consciousness. Natural
language is too slow and vague. Our memory does not store enough
details. Our consciousness at a given moment cannot be reconstructed
by re-accessing information from our environment.52

Fixate your eyes on the small cross in the centre of the screen. Rest
your index finger on the button in front of you. When I say ‘now’ I want
you to press the button if there is a small red square in the bottom left
hand corner of your visual field. Get ready … now.

Under controlled experimental conditions I can extract a small
amount of accurate information about a specific aspect of your
consciousness at a given time. The details of the measurement are set
by the experimental conditions. The subject is only required to answer
a simple yes/no question, without any need for memory or natural
language.

This measurement method has the limitation that a subject can only
answer one or two yes/no questions before their consciousness changes.
This problem can be partly overcome by resetting their consciousness
after each measurement. We can then use a large number of high
precision probes to obtain a detailed measurement of one state of a
subject’s consciousness.53

As an example, consider an experiment that measures a subject’s
visual consciousness. To begin with the subject is asked to fixate on
a cross on a screen. When they are looking at the cross it is replaced
with a picture that remains on the screen for 200ms. This is long enough
to ensure that the subject becomes conscious of the picture, and short
enough to prevent them from moving their eyes while they are looking
at it. The brief exposure attracts their attention—reducing the chance
that their visual consciousness is remembering or imagining something
else. The subject’s fixation on the cross ensures that their bubble of
experience contains the same part of the picture each time. When the
subject’s visual consciousness is put into this state one aspect of it can
be measured with high precision. Repetition of this procedure can be
used to progressively build up a detailed description of this state of
consciousness.54
64 Human and Machine Consciousness

High precision measurement combined with the resetting of
consciousness under experimental conditions is the most promising
method for obtaining detailed descriptions of consciousness. But
there are limits to the types of consciousness that can be reset, and a
subject’s consciousness cannot be put into exactly the same state each
time. These problems will reduce our ability to obtain detailed accurate
measurements of consciousness.55

4.9 Formal Descriptions of Consciousness
(C-Descriptions)
At present we are completely unequipped to think about the subjective
character of experience without relying on the imagination—without
taking up the point of view of the experiential subject. This should
be regarded as a challenge to form new concepts and devise a new
method—an objective phenomenology not dependent on empathy or
the imagination. Though presumably it would not capture everything,
its goal would be to describe, at least in part, the subjective character
of experiences in a form comprehensible to beings incapable of having
those experiences.
Thomas Nagel, What Is It Like to Be a Bat?56

Alice and Bob measure your consciousness at 14:02:00.050 and submit
written reports of the results. Alice’s report contains several thousand
words of natural language, similar to the work of Husserl, Heidegger
and Merleau-Ponty. Bob’s report contains natural language descriptions
of the experimental probes that he ran on your consciousness. It is
written in the style of a methods section in a paper on experimental
psychology. When you read either of these reports you are satisfied that
they are a complete and accurate description of your consciousness at
14:02:00.050.

This verification process is inexact. It relies on an inaccurate memory
of your state of consciousness. It is far from a complete validation. But it
will have to do—it is all we can do.57

Formal descriptions play an important role in science. We have
formal descriptions of many aspects of the physical world (mass,
charge, voltage, magnetic field, etc.) that can be used to generate testable
4. The Measurement of Consciousness 65

predictions. The Earth and Sun can be described as point masses of 5.97
× 1024 kg and 1.99 × 1030 kg. We can use this description of the Earth and
Sun to predict the gravitational force between them (by substituting the
masses for m1 and m2 in Newton’s equation F=Gm1m2/r2).58

Scientific theories of consciousness will eventually use mathematics
to map between descriptions of consciousness and descriptions of the
physical world (see Section 5.5). This will enable us to make strong
testable predictions about the conscious state that is associated with a
physical state. This will only become possible when consciousness can
be described in a formal way that can be manipulated by algorithms
and mathematical equations. This will be referred to as a c-description:

D6. A c-description is a formal description of a conscious state.

C-descriptions must be compatible with mathematics and they must be
applicable to both human and non-human consciousness. We will have
to develop methods for converting c-reports into c-descriptions and vice
versa.

Natural language cannot be used for c-descriptions. It is vague,
ambiguous, highly compressed and context dependent. Natural
language descriptions of consciousness are difficult to analyze with
algorithms and it is not obvious how they can be integrated with
mathematical equations. Natural language also cannot be used to
describe the consciousness of non-human systems, such as infants, bats
or robots.59

C-descriptions could be written in a markup language, such as XML
or LMNL. Markup languages are more precise and tightly structured
than natural language, and they can be read by both humans and
computers. They can capture complex nested hierarchies, which would
enable them to describe the relationships between different parts and
aspects of a conscious state.60

Mathematics could be used for c-descriptions. For example, Balduzzi
and Tononi have suggested how conscious states can be described
using high dimensional mathematical structures.61 Other mathematical
techniques could be used to describe consciousness, such as category
theory or graph theory.
66 Human and Machine Consciousness

An adequate c-description format is essential for the scientific study
of consciousness. C-descriptions are at a very early stage of development
and we are only just starting to explore solutions.

4.10 Summary
Scientists studying consciousness need to accurately measure
conscious states. Consciousness is measured through first-person
reports (c-reports), such as speaking or body gestures, which cannot
be independently checked. This raises the philosophical problems
of zombies, solipsism, colour inversion and the causal relationship
between consciousness and the physical world. These problems
cannot be solved. They can be neutralized by making assumptions that
guarantee that consciousness can be accurately measured. The results
of the science of consciousness can then be considered to be true given
these assumptions.

I started by assuming that consciousness is functionally connected
to first-person reports (A1). I then assumed that everything about a
conscious state can be reported during an experiment and that there are
no ghostly consciousnesses floating around that cannot be reported (A2).
I handled colour inversion scenarios by assuming that consciousness
supervenes on the brain (A3, A3a). First-person reporting does not break
the causal closure of the physical world (A5) because reports about
consciousness are e-caused by the correlates of consciousness (A6). All
of these assumptions apply to systems that are assumed to be conscious
(platinum standard systems) during experiments on consciousness. I
assumed that normally functioning adult human brains are platinum
standard systems (A4).

Consciousness cannot be described in real time using natural
language, so we have to use experimental probes to measure specific
aspects of a conscious state, and then reset the state and apply more
probes until a complete measurement is obtained. The final output of
a measurement of consciousness should be a c-description written in
a tightly structured formal language, such as category theory or XML,
that will support the development and testing of mathematical theories
of consciousness.
4. The Measurement of Consciousness 67

This chapter also introduced the concept of a CC set. A CC set is a
set of spatiotemporal structures in the physical world that is correlated
with a conscious state (D5). The science of consciousness attempts to
develop mathematical theories that describe the relationship between
CC sets and conscious states. This is covered in the next five chapters.
5. From Correlates to Theories of
Consciousness

5.1 Measurement of the Physical World
Randy is an elephant who lives at the bottom of my garden. Six blind men
often come round to feel Randy. Sometimes I like to measure Randy. To
measure his height, I compare my conscious experience of Randy with
my conscious experience of a stick that has been calibrated against the
distance light travels in a vacuum during 1⁄299,792,458 seconds.1 The
ratio between Randy and the stick is his height in metres. Randy is three
sticks (three metres) high (see Figure 5.1).2

The science of consciousness studies the relationship between
consciousness and the physical world. It measures consciousness,
measures spatiotemporal structures in the physical world and attempts
to identify minimal sets of spatiotemporal structures (CC sets) that are
linked to conscious states.

Physical objects do not directly appear in our bubbles of experience.
We do not directly perceive their mass, chemical composition or size.
To measure a property of a physical object I cause it to interact with
another physical object that has been calibrated in some way and observe
this interaction in my bubble of experience. This typically results in a
number. Eddington describes this process:

Let us then examine the kind of knowledge which is handled by exact
science. If we search the examination papers in physics and natural
philosophy for the more intelligible questions we may come across
one beginning something like this: “An elephant slides down a grassy
hillside…” The experienced candidate knows that he need not pay much
attention to this; it is only put in to give an impression of realism. He
reads on: “The mass of the elephant is two tons.” Now we are getting
down to business; the elephant fades out of the problem and a mass of

two tons takes its place. What exactly is this two tons, the real subject
matter of the problem? It refers to some property or condition which
we vaguely describe as “ponderosity” occurring in a particular region
of the external world. But we shall not get much further that way; the
nature of the external world is inscrutable, and we shall only plunge into
a quagmire of indescribable. Never mind what two tons refers to; what is
it? How has it actually entered in so definite a way into our experience?
Two tons is the reading of the pointer when the elephant was placed on
a weighing-machine. Let us pass on. “The slope of the hill is 60°.” Now
the hillside fades out of the problem and an angle of 60° takes its place.
What is 60°? There is no need to struggle with mystical conceptions of
direction; 60° is the reading of the plumb-line against the divisions of a
protractor. Similarly for the other data of the problem.3

Figure 5.1. The measurement of an elephant’s height in a scientist’s bubble of
experience. The scientist compares Randy with a stick that has been calibrated
against the distance light travels in a vacuum during 1⁄299,792,458 seconds. The
ratio between Randy and the calibrated stick is his height in metres. Randy is
three sticks (three metres) high. Image © David Gamez, CC BY 4.0.
5. From Correlates to Theories of Consciousness 71

When I monitor Randy’s brain activity using electrodes, my
equipment compares the effect of his brain on each electrode with
the effect of a standard voltage: the ratio between these effects is the
electrode’s voltage. A computer converts the electrode voltages into an
attractive image of brain activity. Randy’s colourless physical brain does
not directly appear to me when I am measuring it. Within my bubble of
experience I am conscious of black wires emerging from a pinkish-grey
brain and a 3D display of brain activity on a computer screen.

The physical world can be measured automatically without the
instruments or measured objects appearing in a bubble of experience. A
robot could measure Randy with a stick and write down the result on a
piece of paper.

Measurements can be processed into numbers that correspond to
different properties of an object. Electrode voltages can be processed
into neuron firing events, which can be processed into firing frequencies,
synchronization patterns, and so on.

Measurement assigns numbers to aspects of objects, properties or
events.4 Objects, properties and events are typically described in natural
language. When I measured Randy, 3 metres was the height of an elephant;
30 mV was the membrane potential of a neuron.

Objects, properties and events are tightly defined in physics and
chemistry. For example, we have clear definitions of quarks and carbon.
Physicists and chemists can state exactly what it means for a physical
object to contain quarks or carbon; their instruments can reliably detect
whether quarks or carbon are present in a physical object.

Context plays an important role in the description of biological
objects, properties and events. Suppose I want to measure the membrane
potential of a neuron. I do not use an abstract definition of a neuron to
identify physical objects that are neurons—I look for a particular type of
cell in the brain of an animal. The definition of a neuron only has to be
precise enough to distinguish neurons from other cells in the brain. The
context of a neuron (in the brain of an animal) is part of its definition.
72 Human and Machine Consciousness

A neuron is well defined inside a brain—but what exactly is a
neuron? Does a neuron continue to be a neuron if I remove its nucleus,
give it a chrome cytoskeleton and change its resting potential to 100
V? Synthetic biologists could construct a series of intermediate cases
between neurons and liver cells—it would be difficult to classify the
intermediate cases. Neurons are defined in a specific biological context;
no formal definition exists that can unambiguously decide whether an
arbitrary physical object is a neuron.

This vague definition of biological structures is a problem
for consciousness science. We want to use what we know about
consciousness in the brain to make inferences about the consciousness
of non-biological systems. Suppose we identify neural correlates of
consciousness and want to make inferences about the consciousness
of synthetic neurons. This cannot be done without an unambiguous
context-free definition of a neuron.

To address this problem we need formal ways of describing the
spatiotemporal structures that form CC sets. These will be referred to
as p-descriptions:

D7. A p-description is a formal description of a spatiotemporal
structure in the physical world. A p-description unambiguously
determines whether a spatiotemporal structure is present in a
sequence of physical states.

When a spatiotemporal structure can be completely described
by physics or chemistry (for example, an electromagnetic field or
a molecule), the p-description is identical to the standard scientific
description. We will have to find more formal context-free ways of
describing biological structures that can resolve ambiguous cases.
For example, we need a p-description that can determine whether an
arbitrary part of the physical world contains neurons. This should not
rely on the fact that neurons are found in biological creatures, and it
should provide definite classifications of synthetic neurons, which lack
some of the attributes of biological neurons. If the members of a CC
set cannot be captured in a p-description, then we will only be able to
make inferences about the consciousness of systems that are similar to
platinum standards.5
5. From Correlates to Theories of Consciousness 73

5.2 Constraints on CC Sets
There are constraints on the spatiotemporal structures that can form
CC sets. These derive from the assumptions that were introduced to
measure consciousness (A1-A6) and from the requirements of scientific
methodology:

C1. The spatiotemporal structures in a CC set are independent of the observer.
My consciousness is a real phenomenon that does not depend on
someone else’s subjective interpretation. CC sets must be formed
from objective spatiotemporal structures, such as electromagnetic
waves and neuron firing patterns.

C2. The members of CC sets are intrinsic properties.6 A conscious state
supervenes on a CC set (A3a), so each duplicate of a CC set must be
associated with an identical conscious state, regardless of the spatial
and temporal context in which the duplicate appears.

C3. A non-conscious system does not contain a CC set that is 100% correlated
with a conscious state.7 If A and B are 100% correlated, then A cannot
occur without B. If a CC set is 100% correlated with a conscious state,
then all brains that contain that CC set will be conscious.

C4. CC sets e-cause c-reports during consciousness experiments (A6).8 It is
not necessary for every member of a CC set to e-cause c-reports. But
some parts or aspects of the CC set must e-cause them. So when I say
‘I am conscious of a green tomato’, this c-report can be traced back
to the CC set that e-caused it, which is functionally connected to a
bubble of experience in which there is a green tomato.

A set of spatiotemporal structures that does not conform to these
constraints cannot be a correlate of a conscious state.

5.3 Pilot Studies on the Correlates of Consciousness
We are in a beastly state of ignorance about the relationship between
consciousness and the physical world. We have no idea which
spatiotemporal structures form CC sets. Our intuitions are useless.
We have to start with the assumption that everything in a platinum
74 Human and Machine Consciousness

standard system that conforms to the constraints is a potential member
of a CC set.

How can we reduce our ignorance? We can carry out pilot studies.
We can attempt to identify the CC set that is associated with a particular
conscious state.9

Briony is an adult human with a normally functioning brain. I strap
her into a chair and connect electrodes to her temples. At intervals I
display a red square at the centre of her visual field, play a loud 500Hz
tone and deliver an electric shock. Briony’s attention is completely
consumed by these stimuli. They are so compelling that the same
conscious state can be induced on multiple occasions. This is conscious
state c3.

Each time c3 is induced I ask Briony to c-report one aspect of it. On
subsequent occasions she c-reports the size of the square, the colour of
the tone and the shocking sensations in her body. Over time I build up a
c-description of c3 that has a tolerable amount of detail.

I want to identify the minimal set of spatiotemporal structures that is
correlated with c3. When c3 is induced I measure the neuron activity in
Briony’s brain as well as the electromagnetic waves, blood movements,
glia activity, and so on.10 Some of these spatiotemporal structures could
form the CC set by themselves—a pattern of neuron activity might be
the sole correlate of c3. Or a combination of spatiotemporal structures
might form the CC set that is correlated with c3. For example, a pattern
of neuron activity might only be associated with consciousness when it
is immersed in blood—the same neuron activity without blood would
not be linked to consciousness.

I must systematically consider all possible combinations of
spatiotemporal structures that could form the CC set. This will enable
me to identify the spatiotemporal structures that only occur when c3 is
present. Suppose I want to demonstrate that a pattern of neuron activity,
p2, is the sole member of the CC set. I will need to measure c3 when p2 is
present and blood is present, measure c3 when p2 is present and blood
is absent, measure c3 when just blood is present, and measure c3 when
neither p2 nor blood are present. Further experiments will be required
5. From Correlates to Theories of Consciousness 75

to distinguish p2 from glia activity, cerebrospinal fluid, and so on. This
methodology is illustrated in Table 5.1.11

Spatiotemporal Structures Conscious States

A B C D c1 c2
0 0 0 0 0 0
0 0 0 1 0 0
0 0 1 0 0 1
0 0 1 1 0 1
0 1 0 0 0 0
0 1 0 1 0 0
0 1 1 0 0 1
0 1 1 1 0 1
1 0 0 0 0 0
1 0 0 1 0 0
1 0 1 0 0 1
1 0 1 1 0 1
1 1 0 0 1 0
1 1 0 1 1 0
1 1 1 0 1 1
1 1 1 1 1 1

Table 5.1. Simple example of correlations that could exist between spatiotemporal
structures in a physical system and two conscious states. It is assumed that
conscious states c1 and c2 can occur simultaneously. The physical structures A, B, C
and D could be dopamine, haemoglobin, neural synchronization, electromagnetic
waves, etc. These are assumed to be the only possible features of the system. ‘1’
indicates that a feature is present; ‘0’ indicates that it is absent. In this example
D is not a correlate of consciousness because it does not systematically co-vary
with either of the conscious states. {A,B} is a set of spatiotemporal structures that
correlates with conscious state c1. {C} is a set of spatiotemporal structures that
correlates with conscious state c2.

Many pilot studies have been carried out on the correlates of
consciousness. They have identified areas of the brain and features of
neuron activity (for example, recurrent connections) that are potential
members of CC sets.12 Most of these pilot studies have focused on
neural patterns that might form CC sets. No attempt has been made to
show that neuron activity patterns form CC sets by themselves, or to
demonstrate that glia, electromagnetic waves and haemoglobin are not
members of CC sets.
76 Human and Machine Consciousness

5.4 Natural and Unnatural Experiments
Consciousness experiments are carried out on platinum standard
systems. Assumptions A1-A6 enable us to measure the consciousness of
platinum standard systems during these experiments.

Normally functioning adult human brains are our only platinum
standard systems (A4). They change as they interact with the world
and learn from their experiences. Most of these changes are part of
their normal behaviour—they do not affect their status as platinum
standards.

Brian’s skull contains a normally functioning adult human brain (a
platinum standard system). I ask him to raise his right arm. He raises
his right arm. I shave off his hair and slowly smear chocolate sauce on
his face. These modifications do not affect the normal functioning of his
adult human brain.

I inject Brian with 5 mg of LSD. After a brief spell of bliss he goes
wild, bangs his head against the wall, yells in an uncontrollable manner
and claws at his face. His brain is not functioning normally. I shoot him
in the head. He lies still on the laboratory floor. Blood pours out of his
head. His brain is no longer a platinum standard system.

A platinum standard system must remain a platinum standard
system throughout an experiment on consciousness. If it ceases to be
a platinum standard system, then assumptions A1-A6 no longer hold
and it becomes an open question whether we can interpret its external
behaviour as a c-report of its consciousness.

Some experiments preserve a system’s status as a platinum standard;
other experiments transform a system into something that is not a
platinum standard. This distinction will be expressed as follows:

D8. In a natural experiment the test system preserves its status
as a platinum standard. Assumptions A1-A6 remain valid and
consciousness can be measured throughout the experiment.

D9. In an unnatural experiment the test system is transformed into
something that is not a platinum standard. A1-A6 cease to apply and
we lose our ability to measure the system’s consciousness.
5. From Correlates to Theories of Consciousness 77

Natural experiments preserve a system’s physical integrity and
normal behaviour. The system can be monitored using passive
techniques, such as fMRI, EEG and electrodes.13 These manipulations
do not affect our belief that it can c-report its consciousness.

Unnatural experiments alter the physical constitution of a platinum
standard system. They remove material, add unusual chemicals or replace
brain parts with functionally equivalent chips. Unnatural experiments
undermine our ability to measure a system’s consciousness. They cannot
be used to identify CC sets or to test theories of consciousness.

Suppose we replace part of a subject’s brain with a functionally
equivalent chip. This would not affect their behaviour—they would
continue to make the same reports as before. This experiment has
been put forward as a way of testing the hypothesis that functions
or computations in the brain are linked to consciousness, rather than
patterns in biological materials.14

Prior to the experiment the subject’s brain was a platinum standard
system and we interpreted its speech as a c-report of its conscious
states. The implantation of the chip transforms the subject’s brain into
a freak neuro-silicon hybrid that is not a platinum standard system.
We have no idea whether brains with implanted chips are associated
with consciousness. Assumptions A1-A6 do not apply—we have not
assumed that the external behaviour of this type of system is a c-report
that can be used to measure consciousness. Similar problems occur with
other unnatural experiments, such as the replacement of haemoglobin
with an artificial blood substitute, the removal of glia, and so on.15,16

We could add brains with implanted chips to our list of platinum
standard systems. This would transform an unnatural chip implantation
experiment into a natural experiment. Both the original system and the
transformed system would be platinum standards, so we could measure
consciousness throughout the experiment.

New assumptions about platinum standard systems should not
be made lightly. Pilot studies look for CC sets in the systems that are
assumed to be platinum standards. A science of consciousness that
studied brains with implanted chips would be very different from our
current science of consciousness.17
78 Human and Machine Consciousness

It will be difficult or impossible to identify all the members of a CC
set using natural experiments. The members of a CC set can only be
identified by systematically varying the physical world to test the link
between each combination of candidate structures and consciousness
(see Table 5.1). When a combination does not occur naturally it is
impossible to test its link with consciousness. So natural experiments
cannot test the connection between consciousness and biological
neurons, because we cannot remove biological neurons from the brain
without compromising its status as a platinum standard system.

5.5 Theories of Consciousness (C-Theories)
It is possible to interpret the ways of science more prosaically. One might
say that progress can ‘… come about in only two ways: by gathering new
perceptual experiences, and by better organizing those which are available
already’. But this description of scientific progress, although not actually
wrong, seems to miss the point. It is too reminiscent of Bacon’s induction:
too suggestive of his industrious gathering of the ‘countless grapes, ripe
and in season’, from which he expects the wine of science to flow: of his
myth of a scientific method that starts from observation and experiment
and then proceeds to theories […] The advance of science is not due to
the fact that more and more perceptual experiences accumulate in the
course of time. […] Bold ideas, unjustified anticipations, and speculative
thought, are our only means for interpreting nature: our only organon,
our only instrument, for grasping her.
Karl Popper, The Logic of Scientific Discovery18

What’s the matter with consciousness, then, and how should we
proceed? Early on, I came to the conclusion that a genuine understanding
of consciousness is possible only if empirical studies are complemented
by a theoretical analysis. […] This state of affairs is not unlike the one
faced by biologists when, knowing a great deal about similarities and
differences between species, fossil remains, and breeding practices, they
still lacked a theory of how evolution might occur. What was needed,
then as now, were not just more facts, but a theoretical framework that
could make sense of them.
Giulio Tononi, Consciousness as
Integrated Information: A Provisional Manifesto19

When people studied the heavens they were not seeking an infinitely
long list of the planets’ positions. They wanted a compact theory that
5. From Correlates to Theories of Consciousness 79

could calculate the positions of the planets at an arbitrary point in time.
Ptolemy developed a model based on deferents and epicycles. This was
superseded by Newton’s and Einstein’s equations.

Pilot studies might identify the correlates of some conscious states.
This would be a major scientific achievement. It would help us to find
the correlates of other conscious states. It would tell us something about
the consciousness of non-platinum standard systems, such as coma
patients, bats and robots.

The wine of a science of consciousness will not flow from industrious
gathering of data about the correlates of individual conscious states.
There are an effectively infinite number of conscious states—we cannot
identify the CC sets associated with each one. Instead we need a compact
mathematical theory that can map physical states onto conscious states
and vice versa. This will be referred to as a c-theory:20

D10. A c-theory is a compact expression of the relationship between
consciousness and the physical world. A c-theory can generate a
c-description from a p-description, and generate a p-description
from a c-description.21

The role of c-theories is illustrated in Figure 5.2.

Figure 5.2. Theory of consciousness (c-theory). On the left, a measurement of the
invisible physical world is converted into a formal p-description of a physical
state. On the right, consciousness is measured with a c-report, which is converted
into a formal c-description of a conscious state. The c-theory maps between the
p-description and the c-description. Image © David Gamez, CC BY 4.0.
80 Human and Machine Consciousness

C-theories specify which types of spatiotemporal structures form
CC sets. For example, neuron activity patterns, information patterns
or computations might be members of CC sets. The most popular
types of c-theory are covered in the next three chapters.

C-theories should be based on mathematics.22 This is the most
compact way of linking p-descriptions to c-descriptions. Philosophical
theories of consciousness might inspire c-theories. But the relationship
between c-descriptions and p-descriptions cannot be expressed in
natural language. Natural language is too weak and vague—it cannot
make strong testable predictions.

Suppose we discover a neuron whose firing rate is correlated with
a bubble of experience in which there is a single point of red light.
We develop a c-theory that uses the equation ln(r)=2i to connect the
neuron’s firing rate, r, with the intensity of the conscious red light,
i. This theory predicts that when the neuron fires at 7 Hz it will be
associated with conscious red light that has intensity 0.97. It also
predicts that the neuron will fire at 20 Hz when conscious red light
occurs with intensity 1.5.23

C-theories map between conscious states and sets of spatiotemporal
structures in the physical world. These spatiotemporal structures
must be valid members of CC sets. So the constraints on the members
of CC sets (Section 5.2) are constraints on c-theories. C-theories must
generate p-descriptions of valid CC sets from c-descriptions, and they
must generate c-descriptions from p-descriptions of valid CC sets.
C-theories that do not conform to the constraints should be excluded
from the science of consciousness.

C-theories become scientifically credible when their predictions
pass experimental tests. It is not enough for c-theories to match
data gathered during pilot studies—they have to generate strong
predictions that can be experimentally confirmed. The most compact
5. From Correlates to Theories of Consciousness 81

and accurate c-theory will be considered to be a correct description of
the relationship between consciousness and the physical world.24

Our final c-theories will describe brute regularities in the relationship
between consciousness and the physical world (see Section 3.5). As the
science of consciousness progresses we are likely to develop c-theories
that describe regularities which can be further decomposed into more
basic relationships. It might be impossible to tell whether a c-theory
describes a genuine brute regularity.25

Some people base c-theories on their conscious experiences.26
But the source of inspiration of a c-theory is irrelevant to its success.
We cannot directly imagine the relationship between consciousness
and the invisible physical world (see Section 3.3), so the intuitive
plausibility of a c-theory has no bearing on whether it is correct.
C-theories stand or fall on their ability to make falsifiable predictions
that pass experimental tests.

C-theories are not likely to provide intuitively satisfying explanations
of the relationship between consciousness and the physical world.
Since we cannot imagine the physical world, a mathematical c-theory
cannot help us to make an imaginative transition from the invisible
physical world to consciousness. At most a c-theory could help us to
make an imaginative transition from a conscious experience of brain
activity to another conscious experience (see Section 3.4).

People might use particles, forces or novel aspects of the physical
world to explain why a particular relationship between c-descriptions
and p-descriptions holds (see Section 6.3). Such explanations might be
scientifically fruitful—they might help us to develop new mathematical
c-theories. But they are unlikely to make a c-theory more intuitively
plausible. Newton could not imagine how gravity acted at a distance.
We cannot explain why brute regularities exist between consciousness
and the physical world.
82 Human and Machine Consciousness

5.6 The Computational Discovery of Theories of
Consciousness
[…] the era of simple mathematics effectively modelling parts of the
world is drawing to a close. It is possible that new areas of investigation
will lend themselves to simple models, but the evidence is that within
existing areas of investigation, the domain of simple models has been
extensively mined to the point where the rewards are slim.
Paul Humphreys, Extending Ourselves27

Traditional science is based on the idea that people identify regularities in
the physical world. It is a working assumption that physical regularities
are simple enough to be found by humans. When a human finds a
regularity s/he might use a novel property to explain it. A mathematical
description of the regularity can be experimentally tested. Humans find
this satisfying—they like solving puzzles. But it is not necessarily the
most effective approach.

Humans are biased and stupid. They have small working memories
and little imagination. They cannot process large data sets. These
limitations will prove fatal to consciousness science if there are complex
relationships between c-descriptions and p-descriptions.28

We have little or no idea about the spatiotemporal structures that form
CC sets. The mathematical relationships between c-descriptions and
p-descriptions are unknown. They might be simple—a few differential
equations. Or the mathematical complexity of these regularities could
be way out of reach of human capabilities. Macro-scale laws of the brain
could extend to thousands of pages of differential equations.

We should drop the assumption that there are simple relationships
between p-descriptions and c-descriptions. We have no reason to
believe that this is the case. If we persist with the assumption that
there are simple relationships, we could spend large amounts of time
and money on a fruitless quest for something that does not exist. It
is better to assume that the relationships between c-descriptions and
p-descriptions are potentially complex, and develop a methodology
that can identify simple and complex relationships (or prove that no
relationships exist).
5. From Correlates to Theories of Consciousness 83

We could use computers to identify the relationships between
p-descriptions and c-descriptions. This would require a large amount
of data, spanning multiple levels of the brain. C-descriptions and
p-descriptions would have to be recorded for many different conscious
states. This data could be gathered by human scientists. Or robots could
capture it automatically.29

Machine-learning techniques could be applied to this data. The
patterns that were found could be used to make predictions, which
could be tested in further experiments. C-theories could be automatically
tested against new data as it came in.

C-theories that are discovered by computers should be expressed in
a format that can be read by both humans and machines (they should
not be stored as weights in a complex neural network). This would
enable them to be partly viewed and verified by humans—but there
would be no expectation that an individual human scientist could check
or comprehend them in their entirety. Sets of differential equations
would be a good choice of output format—there is a long tradition of
using differential equations to describe complex relationships in the
physical world. Or perhaps we could use graph theory to describe the
relationships between c-descriptions and p-descriptions.30

This computational approach to the science of consciousness could
identify simple relationships between c-descriptions and p-descriptions.
It could find regularities that are too complex to be identified by
humans. Or it could prove that no simple or complex laws exist in the
current data.

This approach could be prototyped on a simulated human brain.31
This would generate reports ‘about consciousness’ that are similar to
c-reports and could be converted into c-descriptions.32 The computer
could search for relationships between these c-descriptions and
different aspects of the neural model. It could control the simulation
(rewinding it, rewiring it, changing its parameters) to robustly
test its hypotheses.33 The relationships between c-descriptions and
p-descriptions that were identified by this method could be tested on
platinum standard systems.34
84 Human and Machine Consciousness

5.7 Summary
This chapter has described how we measure the physical world. Physical
measurements have to be expressed in a formal way (a p-description),
so that we can use our knowledge about CC sets in humans to make
inferences about the consciousness of non-biological systems.

Pilot studies could identify the CC sets that are linked to individual
conscious states. These must use natural experimental methods, which
preserve our ability to measure consciousness in platinum standard
systems.

In the longer term we need to develop mathematical c-theories that
map between p-descriptions and c-descriptions (see Figure 5.2). These
c-theories must conform to the constraints on CC sets (C1-C4).

Humans might be incapable of discovering complex mathematical
relationships between p-descriptions and c-descriptions. To avoid this
potential problem, computers should be used to discover c-theories.
6. Physical Theories of
Consciousness

6.1 Physical C-Theories
The physical world contains elementary wave-particles (quarks, leptons,
bosons). These are arranged into structures at different spatial scales.
Quarks and electrons form atoms. Atoms are the constituent parts of
molecules, which are the constituent parts of neurons, blood and bone.
A structure at one level of the physical world will be referred to as a
material:

D11. A material is an arrangement of elementary wave-particles at a
particular spatial scale.

The constituent parts of materials are formed from other materials—
carpets are made from nylon, which is made from molecules, and so
on. Some of a material’s properties are not attributable to its constituent
parts: water is wet; the electrons, protons and neutrons in water are not
wet. Spatiotemporal patterns occur in materials (tartan, waves, etc.).

Physical c-theories are defined as follows:

D12. A physical c-theory links consciousness to spatiotemporal
patterns in materials. Physical CC sets consist of one or more patterns
and the materials in which these patterns occur.1

Physical c-theories map p-descriptions of patterns in materials onto
c-descriptions of conscious states. They also map c-descriptions of
conscious states onto p-descriptions of patterns in materials.

In a physical c-theory the materials are essential members of the
CC sets: each pattern has to occur in a particular material. A physical
c-theory that links a conscious state to an electromagnetic wave pattern

would not attribute consciousness to a pile of beer cans that happened
to instantiate the same pattern.

Physical c-theories fit in neatly with the standard sciences (physics,
chemistry, biology, geology), which identify patterns in particular
physical things (planets, molecules, proteins, glaciers). They have the
same level of objectivity as these other sciences (C1).

6.2 Potential Physical CC Sets in the Brain
The normally functioning adult human brain is our only platinum
standard system (A4). So the science of consciousness can only look
for physical CC sets that contain one or more of the materials that are
present in the human brain and one or more of the spatiotemporal
patterns that occur in these materials.

Some of the brain’s properties depend on other parts of the physical
world. For example, brains reflect electromagnetic waves and every
neuron is a particular distance from the North Pole. These are not
intrinsic properties, so they are not potential members of CC sets (C2).2

Physical CC sets can exchange physically conserved quantities,
so they can e-cause c-reports during consciousness experiments (C4).
It is not necessary that everything in a CC set e-causes c-reports, but
the set as a whole must be capable of this. The changes in the balance
of oxygenated and de-oxygenated blood that are measured by fMRI
cannot e-cause c-reports because they peak several seconds after the
c-report. Blood flow patterns that occur on an appropriate time scale are
potential members of CC sets.3

The materials that could be members of CC sets include neurons,
glia, blood, cerebrospinal fluid, electromagnetic waves, quantum states
and novel materials.4 With the possible exception of novel materials (see
Section 6.3), a physical CC set cannot solely consist of materials, which
are typically present when the brain is unconscious (C3). Some of the
materials in a physical CC set must contain patterns that only occur
when the brain is conscious.
6. Physical Theories of Consciousness 87

The patterns in physical CC sets could be computational structures,
such as a global workspace,5 or patterns in the functional or effective
connectivity between neurons.6 I have suggested elsewhere that the
neural patterns caused by sensory input could be linked to conscious
sensations, and that a combination of sensory and sensorimotor patterns
might be linked to our conscious perception of a three-dimensional
world.7 We could also use Tononi’s information integration algorithms
to identify patterns in materials that might be linked to consciousness.8

Some examples of physical CC sets:
• {neuron firing pattern p3}
• {neuron firing pattern p3, electromagnetic wave pattern p4}
• {quantum pattern p5}
• {neuron firing pattern p3, haemoglobin}

In the last example the simple presence of haemoglobin is a member of
the CC set. It does not matter which pattern occurs in the haemoglobin:
a conscious state would only occur when p3 is present in neurons
surrounded by blood.

It is essential that the members of a physical CC set can be precisely
and unambiguously described. Mathematical c-theories work with
formally structured p-descriptions—they cannot convert natural
language descriptions of the physical world into c-descriptions. It is
easy to construct p-descriptions of elementary wave-particles, atoms
and molecules. It is much harder to p-describe biological materials, such
as neurons (see Section 5.1).9

6.3 Novel Materials?
It has been suggested that consciousness could be linked to unknown
materials, such as a novel wave-particle.10 The novel material could
contain patterns that are linked to conscious states. Or it could be a
passive member of CC sets that include patterns in other materials. It
is conceivable that each conscious state is linked to a different novel
material.
88 Human and Machine Consciousness

Novel materials must have e-causal powers. Novel materials without
e-causal powers could not e-cause c-reports (C4) and they could not
be detected with scientific instruments. So we could not verify their
existence or use them to infer the presence of consciousness. This type
of material should be sliced off with Ockham’s razor.

Up to this point it has not been necessary to posit novel materials to
explain the brain’s operation.11 Most scientists believe that the known
physical properties of the brain can account for the firing patterns that
send spikes to the larynx and lead to c-reports. Novel materials might
be needed if we observed brain events that did not have an identifiable
cause—this might lead us to hypothesize new wave-particles. But no
such cases have come to light.

The most plausible novel material is something with weak e-causal
powers that plays a minor role in the e-causation of c-reports. Such
a consciousness force or particle might be detectable by special
instruments, but it would be invisible to our current technology. There
is no pressing need for a consciousness force or particle, but we might
believe in it if it was a necessary consequence of a c-theory that had been
thoroughly tested in other ways.12

6.4 Simplifying Assumptions about Physical
C-Theories
Experiments on physical c-theories have to demonstrate that some
patterns in some materials are linked to consciousness and other patterns
in other materials are not. For example, a physical c-theory might claim
that some neuron activity patterns form CC sets. To prove this we would
need to show that consciousness is correlated with the proposed neuron
activity patterns independently of glia patterns, electromagnetic wave
patterns, other neuron activity patterns, and so on.

The best way to prove that consciousness is linked to patterns in
particular materials is to carry out studies that test all combinations of
materials (see Section 5.3). However, the link between consciousness
and particular materials cannot be fully tested in natural experiments,
because the brain does not naturally change into different materials,
6. Physical Theories of Consciousness 89

such as silicon (see Section 5.4). So we are unlikely to be able to identify
the minimal sets of spatiotemporal structures that form physical CC sets.
For example, we will be unable to experimentally distinguish between
these potential CC sets:
• {neuron firing pattern p3}
• {neuron firing pattern p3, haemoglobin}
• {neuron firing pattern p3, haemoglobin, cerebrospinal fluid}

Some potential CC sets can be eliminated by assuming that passive
materials are not members of CC sets. For example, we can assume that
the simple presence of haemoglobin is not linked to consciousness. This
assumption should only be made when natural experiments cannot
prove the link between consciousness and the simple presence of a
material:

A7. CC sets do not contain passive materials. If the link between
consciousness and the simple presence of a material cannot be
demonstrated in a natural experiment, then this material can be
excluded from potential CC sets.

Passive materials are only passive relative to consciousness—
the materials could contain patterns that are not correlated with
consciousness.

We can also assume that constant patterns are not members of CC
sets:

A8. CC sets do not contain patterns that are present when the system is
conscious and unconscious. If the link between consciousness and a
constant pattern cannot be demonstrated in a natural experiment,
then this pattern can be excluded from potential CC sets.

This assumption only applies to constant patterns that occur in the same
materials as the patterns that are linked to consciousness. Constant
patterns that occur in other materials can be excluded using assumption
A7.

Suppose a conscious brain has neuron activity patterns p6 and p7, and
the unconscious brain has neuron activity patterns p6 and p8. If a natural
90 Human and Machine Consciousness

experiment cannot demonstrate that p6 is correlated with consciousness,
then it can be excluded from the CC set using A8. The CC set would just
consist of neuron activity pattern p7.

There are strong connections between the brain’s materials. When a
neuron fires, there are chemical changes, fluctuations in electromagnetic
fields and an altered balance between oxygenated and de-oxygenated
blood. These changes are partially correlated with each other, but only
one of them might be linked to consciousness.

Some of these partially correlated changes can be excluded from
potential CC sets on the basis of their timing relationship with c-reports.
It is more difficult to identify the correlation between consciousness and
patterns that occur simultaneously. This could be done by replacing the
brain’s materials, but there is little scope for this in natural experiments.
To address this problem we can exclude weakly correlated patterns
from potential CC sets:

A9. CC sets do not contain partially correlated patterns. When several
different materials have the same spatiotemporal pattern, the
material(s) in which the spatiotemporal pattern is strongest will
be considered to be the potential member(s) of the CC set that is
associated with the conscious state, unless the partially correlated
patterns can be separated out in a natural experiment.13

Suppose a conscious brain has neuron activity pattern p9 with
strength 7, and p9 occurs in the glia with strength 5 and in the
electromagnetic waves with strength 8. p9 is completely absent from
the unconscious brain. A natural experiment cannot demonstrate that
p9 in neurons and glia should be excluded from the CC set, so the CC
set could consist of p9 in any combination of the three materials. We
can set this possibility aside by making assumption A9. The CC set
would just consist of electromagnetic wave pattern p9.

A7-A9 enable us to develop more compact c-theories from
ambiguous experimental data. They should not be rigidly adhered to
because they are motivated by pragmatic considerations and go beyond
the experimental evidence. CC sets might contain passive materials,
constant patterns and partially correlated patterns.
6. Physical Theories of Consciousness 91

6.5 Summary
A physical c-theory is a mathematical relationship between patterns
in materials (captured in p-descriptions) and formal descriptions of
conscious states (c-descriptions). Physical c-theories conform to the
constraints and fit in well with mainstream scientific methodology.

A large number of materials and patterns are potential members of
physical CC sets. We are unlikely to be able to completely separate them
out in natural experiments, but we can reduce the number of potential
CC sets by making assumptions A7-A9, which exclude passive materials,
constant patterns and partially correlated patterns from CC sets.
7. Information Theories of
Consciousness

[…] to the extent that a mechanism is capable of generating integrated
information, no matter whether it is organic or not, whether it is built of
neurons or of silicon chips, and independent of its ability to report, it will
have consciousness.
Giulio Tononi, Consciousness as
Integrated Information: A Provisional Manifesto1

Information is notorious for coming in many forms and having many
meanings. It can be associated with several explanations, depending on
the perspective adopted and the requirements and desiderata one has
in mind.
Luciano Floridi, Information: A Very Short Introduction2

7.1 What Is Information?
In this ‘information age’ people see information everywhere. Some say
that we are living in a simulation or a digital universe; others claim that
information patterns are consciousness.

I open up your head and rummage around inside. I feel bones, blood
and tapeworm cysts. Through the microscope I observe neurons, glia
and bacteria. I cannot see information anywhere. I cannot detect it using
scientific instruments. There is just soggy oozing physical stuff.

Computers are information processors. There must be information
inside a computer. I open up a computer and rummage around inside.
I feel silicon chips, copper circuits, dust and two dead flies. Just more
physical stuff—no information anywhere.

I flick through the computer manual. It states that information is
stored in the memory units of the computer (the DRAM storage cells).

I switch on the computer and examine the DRAM storage cells. They
contain electrons. When I measure the voltages I obtain the following
values: 0.7, 0.8, 1.1, 1.0, 0.2, 0.7, 0.9, 0.1, 0.0, 1.5, 1.4, 0.5, 0.1, 1.5, 0.7, 0.8,
0.3, 1.2, 1.3, 0.0, 0.4, 0.9, 0.7 and 0.6. These voltages change all the time as
the computer operates. If an engineer looked these voltages, s/he would
note that the DRAM is operating in its specified range.

I apply a threshold of 0.75 V to the voltages, and interpret voltages
above the threshold as 1 and voltages below the threshold as 0. This
yields 011100100110010101100100. This means something to me—it is
a string of 1s and 0s. A computer scientist exclaims, ‘Ah, binary, that’s
726564 in hexadecimal.’ A child interprets it as an adder.

I group the 1s and 0s into three 8-bit binary numbers: 01110010,
01100101 and 01100100. These correspond to the decimal numbers 114,
101 and 100. I map the decimal numbers onto letters using the standard
ASCII codes (114=’r’; 101=’e’; 100=’d’). This yields ‘red’. It is a word in the
English language (the colour of apples; the colour of blood). ‘red’ does
not mean much to people who do not speak English—it is just a string
of letters, similar to ‘nob’.

Initially the computer was an invisible physical object. I did not
attribute any properties to it. It was something beyond my bubble of
experience that did not exist for me. Its physical states were not 1s and
0s; they were not letters or numbers; they were not even voltages.3

Voltages, binary numbers and ‘red’ are information patterns
that appear when we measure a system’s states and interpret the
measurements in different ways. This combination of measurement and
interpretation will be referred to as an interface, which specifies:
• The material that holds the information. In a computer the
information could be in the DRAM, CPU, etc.
• The type of information. Is it binary, decimal, drawn from the
set of letters, and so on?
• How information of the appropriate type can be read from
spatiotemporal patterns in the material. In the computer
example I specified how the DRAM voltages could be
measured and converted into binary numbers and letters.
7. Information Theories of Consciousness 95

Interfaces enable us to extract information from the invisible physical
world. They can be applied in sequence to extract different kinds of
information. There is no information without an interface.4

An infinite number of different interfaces can be applied to a physical
system. Instead of a threshold of 0.75 V I could have used a threshold
of 0.55 V. This would have yielded 111101100110011101100111. I can
group these 1s and 0s into four 6-bit binary numbers: 111101, 100110,
011101 and 100111, which correspond to the decimal numbers 61, 38,
29 and 39. I can use a different mapping of numbers onto letters (for
example, 61=’b’, 38=’l’, 29=’u’ and 39=’e’). This interface extracts ‘blue’
from the voltages in the computer’s memory.

‘Red’ and ‘blue’ appear when I apply different interfaces to the
DRAM voltages. There is no correct answer about which sequence of
letters is really in the computer’s memory. Different interfaces produce
different sets of information.

Once I have selected an interface, the information is determined by
the physical system. If I interpret the DRAM voltages using a threshold
of 0.75 V, 8-bit numbers and standard ASCII codes, I inevitably end up
with the word ‘red’—I cannot change the fact that the application of this
interface to this system results in the word ‘red’. While information can
only appear through a subjectively chosen interface, it is fixed by the
physical system once the interface has been selected—it is objectively
present on the basis of this interface.

Custom interfaces can be designed to read most and possibly all
information patterns from a physical system in a particular state.
I can extract the text of Madame Bovary from the lines on my wife’s
face.5 Think of a four letter word—I can extract it from the DRAM
voltages by changing the number-to-letter mappings. Time-indexed
interfaces might be required to extract complex information from
simple systems6 and to extract sequences of information patterns from
sequences of physical states.7

Some people distinguish data from information. They define data
as the differences that are extracted from a physical system using
an interface. These differences become information when they are
96 Human and Machine Consciousness

well-formed and meaningful.8 The problem with this distinction is
that any measured set of differences is meaningful to some extent:
Voltages are meaningful to engineers; binary numbers are meaningful
to computer scientists; letters are meaningful to literate people. The only
differences that are completely without meaning cannot be accessed by
us because they are part of the invisible physical world. This leaves
us with the notion that information might be well-formed data. But we
do not need a data/information distinction to capture the difference
between well-formed and badly-formed data.

Shannon’s work on the transmission of information has led some
people to interpret information as the reduction of uncertainty.9
Consider my snake, Sam. Sam is dead. Sam is not Lazarus: he will not
rise—he will always be dead. You do not need to tell me that Sam is
dead because I know that he is dead and this is not going to change. I do
not gain any information when you send me a message stating that Sam
is dead. Now consider a coin that can be in two states (heads and tails).
I gain information (I reduce uncertainty) if you tell me that it is tails
because I can only guess this with 50% accuracy. Now consider a six-
sided dice. You roll the dice and it shows a two. I can only guess that it
is showing two with 17% accuracy, so a message informing me that it is
two considerably reduces my uncertainty about it. The more a message
reduces my uncertainty about the state of a system, the greater the
information content of that message. Shannon used this interpretation
of information to develop his measure of information entropy.

This interpretation of information is a useful way of quantifying the
amount of information in a system. But it is not an adequate definition
of information. Before we can talk about the reduction of uncertainty
of our knowledge about a system, we need an interface that defines
the information states that are available in the system. We can only
reduce uncertainty about the state of a coin once we have an interface
that converts the physical coin into two possible outcomes, ‘heads’
and ‘tails’. Once a system’s information states have been defined, it is
possible to measure its information entropy and state how rapidly its
information can be passed over a channel.
7. Information Theories of Consciousness 97

7.2 Information C-Theories
Information c-theories are defined as follows:

D13. An information c-theory links consciousness to spatiotemporal
information patterns. Information CC sets only contain information
patterns, which can occur in any material.

Suppose we discover a neuron firing pattern, p10, that is correlated
with conscious state c4. We could apply an interface, i1, to this pattern
to extract an information pattern, ip1. An information c-theory would
claim that c4 is correlated with ip1. This c-theory would predict that c4
would be present if ip1 was extracted from a pile of stones or from a set
of traffic lights (see Figure 7.1).

Figure 7.1. Information c-theory. An experiment demonstrates that conscious
state c4 is correlated with neuron firing pattern p10. Interface i1 converts neuron
firing pattern p10 into information pattern ip1. An information c-theory would
claim that it is the information pattern, ip1, that is linked to c4, not the neuron
firing pattern p10. Information pattern ip1 can also be extracted from traffic lights
through interface i2. The information c-theory would claim that ip1 is linked to c4
regardless of whether it has been extracted from a neuron firing pattern or a set of
traffic lights. Image © David Gamez, CC BY 4.0.
98 Human and Machine Consciousness

Tononi has developed an impressive information c-theory. His
algorithm analyzes the information patterns in a system, and outputs
the parts that are linked to conscious states, the level of consciousness
and a high-dimensional mathematical structure that is intended to
correspond to the contents of consciousness. Preliminary experiments
have been carried out to test this c-theory.10

Physical c-theories use interfaces to gather information about the
physical world. The interface acts as a window onto the materials, and
physical c-theories link patterns in these materials to consciousness.
In an information c-theory the information pattern that is extracted
through an interface is not a measurement of something else—it is
linked to consciousness independently of the interface or the material
in which it occurs.

Information c-theories can be converted into physical c-theories by
adding material(s) to the CC sets.11 Physical c-theories can be converted
into information c-theories by removing the material(s). The experiments
that support Tononi’s information c-theory can be interpreted as
evidence for a link between neuron firing patterns (identified using his
algorithm) and consciousness.

Information c-theories are a radical departure from standard scientific
practice. Scientific laws apply to specific aspects of the physical world. It
is not the pattern that counts, but the presence of the pattern in a particular
material. Newton’s theory of gravity describes how masses behave on a
particular spatiotemporal scale. His equations would produce incorrect
results if they were applied to electric charges. Information c-theories
break free from the material—they treat information patterns as if they
had an objective existence of their own—as if they were something in
the physical world that could be linked to consciousness.

7.3 The Subjectivity of Information
A brain is in state s1; conscious state c5 is present. My laboratory carries
out a pilot study to identify the information pattern that is correlated with
c5. Tony chooses one interface and claims that the resulting information
pattern, ip2, is correlated with c5. George chooses a different interface
and claims that the resulting information pattern, ip3, is correlated with
c5. Which information pattern is correlated with c5—ip2, ip3 or both?
7. Information Theories of Consciousness 99

Tony is my pal. George broke my microscope. I want to accept
Tony’s claim that ip2 is correlated with c5. I want to reject the information
pattern gathered by clumsy George. But the selection of ip2 would be an
arbitrary subjective choice. If I want to conform to constraint C1, I have
to accept that any and potentially all of the information patterns that can
be extracted from the brain in state s1 are potentially correlated with c5.
To avoid subjectivity my pilot study will have to measure them all. This
is impossible because there is an infinite number of them.12

Suppose I use all possible interfaces to measure all of the information
patterns that can be extracted from the brain in state s1. I now need to
identify the ones that are correlated with c5. Which of these information
patterns are not present in the unconscious brain?

My pilot study will have to use all possible interfaces to measure
all possible information patterns in the unconscious brain. I can then
compare these infinite sets to find the information patterns that are only
present in the conscious brain. These are the members of the information
CC set that is correlated with c5. The practical impossibility of this task
suggests that a subjective choice of interface cannot be avoided in real
world experiments on information c-theories.

These practical difficulties are irrelevant if interfaces can be custom
designed to extract arbitrary information patterns from the brain (see
Section 7.1). This would enable any information pattern to be read from
the unconscious brain, including the information patterns that were
extracted from the conscious brain in the first stage of the experiment.
Custom designed interfaces that can extract arbitrary information
patterns would break constraint C3. CC sets cannot consist of
information patterns if all of the conscious brain’s information patterns
can be extracted from the unconscious brain.13

7.4 E-Causal Powers of Information
I define an interface that interprets voltages in a computer’s memory
as 1 if they are above 0.75 V, and as 0 if they are below 0.75 V. The
information changes as the voltages change. This interface makes no
difference to the patterns of e-causation in the computer—with and
without the interface the computer moves through the same sequence
of physical states.14
100 Human and Machine Consciousness

I alter the interface and specify that voltages above 0.8 V should
be interpreted as 0, and voltages below 0.8 V should be interpreted
as 1. Now the information patterns are completely different, but the
computer continues to move through the same sequence of physical
states. It does not matter which interface I apply to the computer: its
e-causal exchanges and sequence of physical states remain the same. The
information does not e-cause or constrain the behaviour of the physical
system. This suggests that information cannot e-cause c-reports, so
information patterns cannot be sole members of CC sets (C4).15

7.5 Is Information Intrinsic?
Information appears when an interface, defined by an observer, is
applied to a physical system. Information patterns that depend on an
external interface cannot be intrinsic properties.

It is conceivable that the interface could be inside the system, so that
one part reads information from another.16 In this case the information
might be an intrinsic property of the system as a whole. There are problems
with this proposal. For example, the location of the information patterns
in the system would be ambiguous, and information c-theorists have
not proposed how we can measure this type of ‘intrinsic’ information
without applying an external interface to the system.

7.6 Separating Information from Material
Suppose we identify a neuron firing pattern that is correlated with a
conscious state. There are two interpretations of this result:
• A pattern of information is linked to the conscious state
(information c-theory).
• A pattern in a material (neurons) is linked to the conscious
state (physical c-theory).

We want an experiment that can decide between these two claims. This
would show that an information pattern is correlated with consciousness
(information c-theory), or that the pattern is only correlated with
consciousness when it occurs in biological neurons (physical c-theory).
7. Information Theories of Consciousness 101

The best way of deciding between these claims would be to change
the brain’s materials while preserving its information patterns. If it had
the same conscious state when its neurons were replaced with silicon,
then the information pattern might be the sole member of the CC set. But
if we exchange a person’s neurons for silicon, we cannot be confident
that their c-reports are functionally connected to their conscious states.
We will have lost our ability to measure consciousness (see Section 5.4).

We have to use natural experiments to decide between the two
claims. We could monitor the system and hope that the pattern moves
between materials during its normal behaviour. Suppose the subject has
conscious state c6 when there is information pattern ip4 in the neurons
and nowhere else in the brain. At a later point in time the subject has c6
when ip4 is in the glia and nowhere else in the brain. We would conclude
that c6 is correlated with the information pattern, and that the material
has no effect on consciousness.17

We have no reason to believe that information patterns move
between materials during natural experiments on the brain. If we
cannot observe this, it will be impossible to experimentally distinguish
between physical and information c-theories.

7.7 Summary
Information appears when interfaces are applied to the physical world.
Interfaces specify how information of a particular type can be extracted
from a particular material. Information does not exist in the physical
world—it is partly determined by the interface and partly determined
by the physical world. Information c-theories claim that information
patterns are linked to consciousness independently of the material in
which they occur.

Information patterns cannot be correlated with consciousness because
they can be read from both the conscious and unconscious brain using
custom-designed interfaces (C3). Information patterns are subjective
and incapable of e-causing c-reports (C1, C4). It is unlikely that evidence
in favour of them can be obtained through natural experiments. Until
these problems have been resolved information c-theories should be set
aside or interpreted as physical c-theories.18
8. Computation Theories of
Consciousness

Useful computation is in the eye of the beholder. […] It requires an
underlying system of whose autonomous dynamics we have a predictive
model. […] To solve a problem computational we need to map the
problem to be solved onto the underlying behavior of the system and
hence produce a starting state from which the autonomous dynamics of
the system will produce a solution.
Robert Kentridge, Symbols, Neurons, Soap-Bubbles
and the Computation Underlying Cognition1

8.1 Calculators, Special-Purpose Computers and
General-Purpose Computers
We can solve many problems in our heads. But it is often easier to use
the physical world to solve problems. Suppose you want to calculate
10+4+18+2. Put ten stones in a box, then four, and so on. Count the
number of stones in the box to get the result. This is a simple calculator.
The abacus, slide rule and Pascaline are more sophisticated calculators.
When you enter a problem into a calculator the solution is immediately
displayed. As each stone is put in the box you can immediately read
off the total number of stones—there is no waiting while the system
‘computes’.

Special-purpose computers take time to solve problems. We enter the
problem by modifying the system’s state (turning knobs, pressing keys,
etc.). We set the special-purpose computer running and it transforms the
starting state into the final state. We read off the result from the final state.

Special-purpose computers can only solve a limited number of
closely related problems. A special-purpose computer that uses water to

model an economy2 cannot process words or simulate an aircraft wing.
Turing machines are special-purpose computers.

Soap bubble computers can find a short path between multiple points
(see Figure 8.1). Other special-purpose computers are Turing’s Bombe,
which was used to crack German encryption during the Second World
War, and Babbage’s difference engine—a mechanical system that uses
gears, cams, rods, levers and springs to compute polynomial functions.

Figure 8.1. Soap bubble computer. a) Pins are placed between two Perspex sheets
to indicate the positions of some points. b) The sheets are dipped in soap solution
and the resulting bubble contracts to minimize its surface tension, producing a
short path between the points. Image © David Gamez, CC BY 4.0.3

General-purpose computers run programs. Programs turn a general-
purpose computer into a special-purpose computer for a limited period
of time. The operator specifies the program by connecting wires,
punching cards, typing code into a terminal, and so on. The program
puts the computer into a starting state. Then the computer’s components
interact according to the laws of physics, and the result is read off from
the computer’s finishing state. Universal Turing machines are general-
purpose computers.
8. Computation Theories of Consciousness 105

Babbage’s Analytical Engine is a design for a general-purpose
computer that uses gears, cams, rods, levers and springs to run
programs. The ENIAC was the first general-purpose computer to be
built. By manipulating switches and cables it could be rewired into a
special-purpose computer that corresponded to a desired program.
The innovation of the ENIAC was that it was designed to be rewired
easily—previous computers could only run a limited range of programs
without being heavily modified (by adding components, re-soldering
circuits, etc.). The Manchester Baby was the first general-purpose
computer that could ‘rewire’ itself electronically from a program stored
in a cathode ray tube.

Modern digital computers are general-purpose computers. Their
programs are typically written in a high level language, such as C++.
Another program, called a compiler, converts this human-readable
list of instructions into binary machine code, which is stored as a set
of voltages in the computer’s memory. When the program runs, the
voltages in the computer’s memory interact with the CPU and other
components. This causes the computer to change states in a sequence
determined by the program. When the program finishes the result is
read back from the computer’s memory.

Special-purpose computers can execute the same computations as
general-purpose computers (the same computations can be executed by
Turing machines and universal Turing machines). The key difference
is that general-purpose computers can be dynamically reconfigured to
run different programs. Special-purpose computers have to be custom-
built to run a particular program.

When a general-purpose computer runs a program it is executing
the computations that are specified in the program—its potential ability
to execute other programs does not affect its current computations.
General-purpose computers operate as special-purpose computers
when they are running a program.4

The brain can operate as a general-purpose computer. I can manually
execute a program, using pen and paper to keep track of the variables.5
When a brain is not manually executing programs, it is not operating
106 Human and Machine Consciousness

as a general-purpose computer. In ordinary life the brain works as a
special-purpose computer: its state transitions are determined by
complex biological structures that are mostly hardwired.

8.2 Computation C-Theories
Computers are artificially intelligent—they can chit-chat, fly planes and
play games. A computer that was simulating your brain might behave
just like you. In a few short years computers will conquer the world and
grind our weak human flesh into fertilizer.

Computation c-theories are defined as follows:

D14. A computation c-theory links consciousness to the execution of
computations. Computation CC sets only contain computations,
which can be executed by many different types of computer.6

Computation c-theories are motivated by the observation that
computers can do the same things as brains. So it is hypothesized that
brains work in a similar way to computers. Computation c-theories
are encouraged by the fact that a program can run on many different
types of machine. This suggests that computations could be objectively
present in many different materials.

Computation c-theories claim that computation CC sets are linked to
consciousness independently of the system that is executing them. So a
computation CC set would be linked to consciousness if it was executed
manually, if it ran on the cogs of Babbage’s Analytical Engine or if it was
executed on the voltages of a modern digital computer.

The brain is conscious when it is operating as a special-purpose
computer. So any computations that might be linked to consciousness
can be executed on special-purpose computers. The convenient features
of general-purpose computers are irrelevant to computation c-theories.7

8.3 The Subjectivity of Computing
My mate Crystal has asked me to father her children. She wants to be
impregnated when the planets are aligned. That way, her children will
8. Computation Theories of Consciousness 107

inherit my good looks and become great warriors. To calculate the date
I need a model of the solar system.

The solar system can be simulated on a digital computer. I write
a program that uses Newton’s equations to manipulate numerical
representations of the masses, positions and velocities of the sun and
planets. A compiler converts the program into machine code. When
I load the compiled program it becomes a pattern of voltages in the
computer’s memory. When I run the program the components in the
computer interact according to the laws of physics. After a few seconds
the program terminates and I interpret the pattern of output voltages as
the date of planetary alignment.

The solar system can be modelled by an orrery, which uses a
clockwork mechanism to move metal balls representing the planets
around a ball representing the sun. To calculate the date of planetary
alignment, I put the spheres into the planets’ current positions, set the
mechanism running and read off the date when they align.8

I can increase the accuracy of my orrery by discarding its clockwork
mechanism and replacing its balls with metal spheres that have the
same masses as the sun and planets. To set up this gravity-powered
orrery I put the spheres into positions that correspond to the sun and
planets and give them the same velocity. I allow them to rotate under
the influence of gravity and note when they align.

It makes no difference to my model if it uses metal spheres or the
actual sun and planets. The latter approach requires less effort. The
planets are already in their starting state and moving under the influence
of gravity. I allow them to rotate and read off the date when they align.

All of these systems are computing the same global function: the
date when the planets align. If any of these systems have computational
properties (that are potentially linked to consciousness), then all of these
systems have computational properties (that are potentially linked to
consciousness). Computers can be made from silicon, metal or planets—
it does not matter if they are powered by clockwork or gravity.

Prior to my intervention the solar system was not a special-purpose
computer: it was not calculating the paths of the planets. It was just a
108 Human and Machine Consciousness

group of massy bodies whose state changes were dictated by the laws of
physics. The solar system became a computer when I used it to calculate
the paths of the planets. But its new status did not affect its material
properties or behaviour—it continued to follow the laws of physics
in exactly the same way as before. This suggests that computers are
subjective interpretations of the physical world—part of the physical
world becomes a computer when I use it to solve problems.

When I use my iPad to bang in a nail it can be useful to describe it
as a hammer. Some of its properties can be understood by comparing it
with other hammers. But my iPad does not contain ‘hammutations’—I
do not need to invoke ‘hammutations’ to explain how I can bang in a
nail with my iPad.

When we use part of the physical world to add numbers, it can
be useful to describe it as a calculator. Some of its properties can be
understood by comparing it with other calculators. But the physical
world does not contain calculations. Stones and a box do not contain
calculations—I use them to add numbers.

When we use the state changes of physical objects to solve problems
it can be useful to describe them as computers. Some of their properties
can be understood by comparing them with other computers (a digital
computer is faster and more flexible than an orrery). But I do not need
to invoke the objective presence of computations in the physical world
to explain how I can use digital computers, orreries and solar systems to
compute the dates of planetary alignment.

The key difference between digital computers, orreries and solar
systems is the extent to which they have been engineered to facilitate
our use of them as computers. The solar system has not been engineered
at all—it is difficult to set up in a desired starting state and it works on
the same time scale as the system it is modelling. Clockwork orreries
can be set up easily and work faster, but they can only model one type
of system. Digital computers can run many different programs and they
typically operate much faster than the systems they are modelling.

If computing is a use that we make of physical objects, then
computations cannot be members of CC sets (C1). My consciousness
does not appear when someone uses my brain as a computer.
8. Computation Theories of Consciousness 109

8.4 Information Processing in Computers
Computers are often described as information processing technology.
Chapter 7 explained how we use interfaces to extract information from
the physical world. Interfaces can also be used to store information in
the physical world.9 I can write and read the same number, the same
information, to and from many different physical systems.

Information that is stored in the physical world can be altered by
changes in the physical world. I write Felicity’s number on a piece of
paper and store it as a sequence of pits on a compact disc. A tea stain
blurs ‘7’ into ‘8’. A scratch on the disc scrambles Felicity’s number.

We use changes in the physical world to process information. We
construct a system that changes in a systematic way. Then we modify
part of the system to encode the information that we want to transform
(this modification is determined by the interface). We allow the system
to change state (to compute). When it has finished we use the same
interface to read back the processed information from the system.10

We know that soap bubbles contract to minimize their surface area,
but we do not know exactly how they will contract between a given set
of pins—if we knew this, there would be no point in using a soap bubble
computer to identify a short path. The encoding of positions using
pins, the dipping in soap solution and the examination of the resulting
bubble are worthwhile because they enable us to read back a short path
solution that would be more complicated to obtain in other ways.

Digital computers are engineered to carry out fast and flexible
information processing. We initialize a computer by creating voltage
patterns in its DRAM that correspond to a program and initial data.
The computer then moves through the sequence of physical states that
is determined by the data and the program. Digital computers also
include a physically implemented interface that uses carefully designed
interactions between components in the screen, circuitry and chips
to convert the DRAM voltages into graphical shapes painted in light,
which we interpret as letters, numbers, etc.

The information processing that is carried out by a physical system
depends on the interface that is used to read and write the information.
110 Human and Machine Consciousness

The soap bubble computer can be interpreted as processing information
about the shortest roads between cities or about the optimal wiring of
electronic components.

Suppose a computer’s memory changes from 011100100110010
101100100 to 011100110111010101101110.11 The information extracted
through one interface (8-bit numbers, standard ASCII codes, 114=’r’,
101=’e’, 100=’d’, 115=’s’, 117=’u’, 110=’n’) changes from ‘red’ to ‘sun’.
Through a different interface (6-bit numbers, 28=’r’, 38=’u’, 21=’i’, 36=’n’,
55=’a’, 46=’d’), the information changes from ‘ruin’ to ‘raid’. There is no
single correct or objective answer about the information processing that
is being carried out by this computer. At most we can say that at least
one interface exists that leads to the processing of ‘red’ into ‘sun’.12

Information processing is not a unique attribute of computers or
brains. Any system can be interpreted as an information processor. A
digital computer does not process any more information than a tub of
worms. But we can carry out more useful information processing with a
digital computer.

Any system that is interpreted as an information processor inherits
all of the problems with information that were highlighted in the
previous chapter. Information is subjective (C1), it is not likely to be
intrinsic (C2) and it does not have e-causal powers (C4). Most or all
information sets can be read from the conscious and unconscious brain
(C3). If computation is information processing, it cannot be a member
of a CC set.

8.5 Digital Physics and Theories of
Implementation
Keith is taking time out from his IT support work. He flops into a chair,
pushes back his lank long hair, sparks up a joint and relaxes. Suddenly
he has a vision of the universe as a giant computer.

Digital physicists claim that digital computation is a fundamental
property of the universe.13 Computation cannot be subjective if
everything is computing all the time, regardless of whether we are
using it to process information. This claim needs to be supported with
8. Computation Theories of Consciousness 111

a definition of what it means to implement a computation. Digital
physicists cannot claim that everything is X without specifying the
nature of X. When we have a theory of implementation, we can look
for computational structures in the universe. If they are ubiquitous
and play a fundamental physical role, then it can be claimed that the
universe is a giant computer.

A theory of implementation is also required to test computation
c-theories. Suppose we want to carry out a pilot study that looks for
the computation CC set that is linked to a conscious state. We will need
a theory of implementation that maps the brain’s physical states onto
computations. This will enable us to identify the computations that are
executed in the conscious brain and not executed in the unconscious
brain.14

Many theories of implementation have been put forward. None
of them are convincing. Theories based on finite state automata lead
to panpsychism.15 Combinatorial state automata don’t work.16 Some
theories of implementation are based on features of modern digital
computers, such as string processing, which do not generalize easily to
biological systems.17 Many digital physicists favour cellular automata,
but it is far from obvious whether cellular automata can provide a
plausible interpretation of the physical world or the systems we call
computers.18

Digital physics cannot rescue computation c-theories from
subjectivity without a plausible theory of implementation. Computation
c-theories cannot get off the ground without a theory of implementation
that would enable them to be experimentally tested. We do not have a
workable theory of implementation.

8.6 Summary
Computation c-theories claim that computations are sole members of
CC sets—the architecture and material of the systems that are executing
the computations are irrelevant. The convenient features of general-
purpose computers are not necessary to computation c-theories. Any
computation that is potentially linked to consciousness can be executed
on a special-purpose computer.
112 Human and Machine Consciousness

If computation is a subjective use we make of the world, then
computations cannot be members of CC sets (C1). If computers are
information processors, computation c-theories will have the same
problems as information c-theories (C1-C4). Digital physicists claim
that digital computation is a fundamental property of the universe. But
no one has developed a theory of implementation that convincingly
supports digital physics or would enable us to identify computational
correlates of consciousness in the brain. Until these problems have been
resolved, computation c-theories should be set aside or interpreted as
physical c-theories.19
9. Predictions and Deductions
about Consciousness

9.1 Predictions about Consciousness
I shall certainly admit a system as empirical or scientific only if it is
capable of being tested by experience. These considerations suggest that
not the verifiability but the falsifiability of a system is to be taken as a
criterion of demarcation. In other words: I shall not require of a scientific
system that it shall be capable of being singled out, once and for all, in a
positive sense; but I shall require that its logical form shall be such that
it can be singled out, by means of empirical tests, in a negative sense: it
must be possible for an empirical system to be refuted by experience.
Karl Popper, The Logic of Scientific Discovery1

Information and computation c-theories do not conform to constraints
C1-C4. The rest of this book will focus on physical c-theories, which are
based on the idea that patterns in one or more materials are linked to
conscious states (D12).

Physical c-theories convert descriptions of physical states into
descriptions of conscious states. This enables them to be tested in the
following way:
1. Measure aspect of the physical world that is specified by the
c-theory.
2. Convert measurement into p-description, pd1.
3. Use mathematical c-theory to convert p-description into
c-description, cd1.
4. Obtain c-report from test subject.
5. Convert c-report into c-description, cd2.
6. Compare cd1 and cd2. If they match, the c-theory passes the test
for this physical state and this conscious state.

For example, we could measure the state of a person’s brain and use
a c-theory to generate a prediction about their consciousness. This is
illustrated in Figure 9.1.

Figure 9.1. Testing a c-theory’s prediction about a conscious state. 1) Scientific
instruments measure the physical state of the brain. 2) Scientific measurements are
converted into a formal p-description of the brain’s physical state, pd1. 3) C-theory
converts p-description, pd1, into a formal c-description of the brain’s predicted
conscious state, cd1. 4) The human brain generates a c-report about its conscious
state. 5) The c-report is converted into a formal description of the measured
conscious state, cd2. 6) The measured and predicted conscious states are compared.
If they do not match, the c-theory should be revised or discarded. Image © David
Gamez, CC BY 4.0.

The validation of the predicted consciousness (stages 4–6) could be
carried out by the subject. First the predicted conscious state could be
induced in the subject. Then the subject would compare the induced
state of consciousness with their memory of their earlier conscious state
(the state they had when their physical state was measured).2

Virtual reality could be used to induce predicted states of
consciousness in the subject. The c-description of the predicted
9. Predictions and Deductions about Consciousness 115

consciousness would be converted into a virtual reality file.3 This
would be loaded into a virtual reality system and the user would
decide whether their consciousness in the virtual reality system
was similar to their earlier conscious state.4 We could also develop
algorithms that convert c-descriptions of predicted conscious states
into natural language. The subject could decide whether the natural
language description corresponded to their memory of their earlier
conscious state.

Figure 9.2. Testing a c-theory’s prediction about a physical state. 1) The human
brain generates a c-report about its conscious state. 2) The c-report is converted
into a formal description of the measured conscious state, cd3. 3) C-theory converts
the c-description, cd3, into a formal p-description of the brain’s predicted physical
state, pd2. 4) Scientific instruments measure the physical state of the human brain.
5) Scientific measurements are converted into a formal p-description of the brain’s
physical state, pd3. 6) The measured and predicted physical states are compared.
If they do not match, the c-theory should be revised or discarded. Image © David
Gamez, CC BY 4.0.

C-theories can convert descriptions of conscious states into
descriptions of physical states. So they can also be tested in the following
way (see Figure 9.2):5
1. Obtain c-report from test subject.
116 Human and Machine Consciousness

2. Convert c-report into c-description, cd3.
3. Use mathematical c-theory to convert c-description into
p-description, pd2.
4. Measure aspect of the physical world that is specified by the
c-theory.
5. Convert measurement into p-description, pd3.
6. Compare pd2 and pd3. If they match, the c-theory passes the
test for this physical state and this conscious state.

For example, a c-theory might predict that a conscious experience of a
red rectangle is associated with a particular neuron activity pattern. We
can measure the brain of a person who c-reports a red rectangle to see if
the predicted neuron activity pattern is present.

C-theories can only be tested on platinum standard systems. On a
platinum standard system we can compare a c-theory’s prediction with
a measurement of consciousness. Or we can generate a prediction about
a physical state from a measurement of consciousness. This type of
testable prediction is formally defined as follows:

D15. A testable prediction is a c-description that is generated from a
p-description or a p-description that is generated from a c-description.
Predictions can be checked by measuring consciousness or they are
generated from measurements of consciousness. Predictions can only
be generated or confirmed on platinum standard systems during
experiments on consciousness. It is only under these conditions that
consciousness can be measured using assumptions A1-A6.

Good c-theories generate many testable predictions. We believe
c-theories to the extent that their predictions have been successfully
tested. Different c-theories can make different testable predictions—we
use this to experimentally discriminate between them.

The tests described in this section only check that a c-theory maps
between conscious states and particular aspects of the physical world.
They do not check that a c-theory is based on minimal and complete sets of
spatiotemporal structures (D5). Suppose we have shown that a c-theory
9. Predictions and Deductions about Consciousness 117

maps between neuron activity patterns and consciousness in normally
functioning adult human brains. To test the theory fully we have to
check that this mapping exists independently of the presence of other
materials in the brain, such as electromagnetic waves, glia, haemoglobin
and cerebrospinal fluid.

To prove that a c-theory is based on minimal and complete sets
of spatiotemporal structures we need to vary the physical world
systematically in the manner described in Section 5.3. Many variations
of the physical world cannot be achieved with natural experiments. So
it is extremely unlikely that the predictions of a c-theory can be fully
tested.

9.2 Deductions about Consciousness
I put your head into a guillotine and chop it off. It falls into a basket. I
watch your face. Your eyes move; your mouth opens and closes; your
tongue twitches. These movements cease. I connect an EEG monitor
to your brain. It is silent. After a couple of minutes a wave of activity
occurs that fades away after twenty seconds.6

Your decapitated head might be associated with a bubble of experience
long after it has been cut off. I cannot measure its consciousness
because it is not a platinum standard system. But I can use a theory
of consciousness that has been tested on platinum standard systems to
make inferences about the consciousness of your decapitated head.

How does consciousness change during death? Which coma patients
are conscious? When does consciousness emerge in the embryo or
infant? How will my consciousness be affected by a brain operation?
Can I copy my consciousness by simulating my brain on a computer?
What are the bubbles of experience of bats, cephalopods and plants?
Are robots conscious?

Suppose we converge on a c-theory that is commonly agreed
to be true. Some of its predictions have been successfully tested. We
are confident that it accurately maps between conscious states and
physical states on platinum standard systems during consciousness
118 Human and Machine Consciousness

experiments. We can use this reliable c-theory to make inferences about
the consciousness of decapitated heads, bats and robots.

In an experiment on a platinum standard system a c-theory’s
predictions can be checked because assumptions A1-A6 hold and we can
measure consciousness. These assumptions do not apply to decapitated
heads, bats and robots. We cannot obtain a believable c-report from these
systems, so we cannot compare a c-description generated by a c-theory
with a c-description generated from a c-report. Inferences about the
consciousness of these systems cannot be confirmed or refuted. This
type of untestable prediction will be referred to as a deduction, which is
defined as follows:

D16. A deduction is a c-description that is generated from a
p-description when consciousness cannot be measured. Deductions
are blind logical consequences of a c-theory. They cannot be tested
because assumptions A1-A6 do not apply. The plausibility of a
deduction is closely tied to the reliability of the c-theory that was
used to make it.

Predictions are testable. Deductions are not. However much data
I gather about a physical system I cannot ever test the deductions
that I make about its consciousness. The assumptions that enable us
to measure consciousness do not apply to the systems that we make
deductions about.

I grab a bat, measure its physical state, and use a mathematical c-theory
to convert a p-description of its physical state into a c-description of
its consciousness (see Figure 9.3). If the bat’s consciousness is radically
different from my own, then it will be difficult for me to understand
this c-description. I might find it impossible to imagine what it is like
to be this bat. (How could I imaginatively transform my bubble of
experience into the bat’s bubble of experience?)7 While solutions to this
problem have been put forward,8 at some point we will have to accept
that we have a limited ability to imaginatively transform our bubbles of
experience. This failure of imagination does not affect our ability to make
scientific deductions about a bat’s consciousness. A reliable c-theory
should be able to generate a complete and accurate c-description of a
bat’s conscious state from a p-description of its physical state.9
9. Predictions and Deductions about Consciousness 119

There are strong ethical motivations for making deductions about
the consciousness of brain-damaged people, embryos and infants.
Deductions have implications for abortion, organ donation and the
treatment of the dead and dying. We could use deductions to reduce
the suffering of animals that are raised and slaughtered for meat.10
Deductions could satisfy our curiosity about the consciousness of
artificial systems.

Deductions will be based on c-theories that have not been fully tested. Poor
access to the brain and limited time and money hamper our ability to
test c-theories. We cannot check that a c-theory holds across all conscious
and physical states. Multiple competing c-theories might be consistent
with the evidence and exhibit different trade-offs between simplicity
and generality. These problems are common to all scientific theories.

Figure 9.3. Deduction of the conscious state of a bat. 1) Scientific instruments
measure the physical state of the bat’s brain. 2) The measurements are converted
into a formal p-description of the physical state of the bat’s brain, pd5. 3) A reliable
well-tested c-theory converts the p-description into a formal c-description, cd5, of
the bat’s deduced conscious state. Image © David Gamez, CC BY 4.0.

Deductions will be based on c-theories that are impossible to fully test.
C-theories can only be tested in natural experiments on platinum
standard systems. Under these conditions it will be difficult or impossible
to prove that a c-theory is based on minimal sets of spatiotemporal
structures. So there are likely to be residual ambiguities about CC sets
that cannot be experimentally resolved. This is illustrated in Table 9.1.
120 Human and Machine Consciousness

Results of
experiments Deductions about c7 in a
Spatiotemporal
on platinum non-platinum standard
structures
standard system
systems
Deductions Deduction
Conscious
A B C D of t1 based of t2 based
state c7
on {B,C} on {B,C,D}
0 0 0 0 ? 0 0
0 0 0 1 0 0 0
0 0 1 0 ? 0 0
0 0 1 1 0 0 0
0 1 0 0 ? 0 0
0 1 0 1 0 0 0
0 1 1 0 ? 1 0
0 1 1 1 1 1 1
1 0 0 0 ? 0 0
1 0 0 1 0 0 0
1 0 1 0 ? 0 0
1 0 1 1 0 0 0
1 1 0 0 ? 0 0
1 1 0 1 0 0 0
1 1 1 0 ? 1 0
1 1 1 1 1 1 1

Table 9.1. Deductions about consciousness based on limited experimental evidence.
A, B and C are spatiotemporal structures in the physical world, such as neuron firing
patterns or electromagnetic waves. D is a passive material, such as cerebrospinal fluid.11
‘1’ indicates that a feature is present; ‘0’ indicates that it is absent. The second column
presents the results of experiments on platinum standard systems in which different
combinations of A, B, C and D are tested and conscious state c7 is measured. ‘1’ indicates
that c7 is present; ‘0’ indicates that c7 is absent. The shaded rows are physical states in
which D is absent. In this example D cannot be removed from a platinum standard
system in a natural experiment, so the link between D and consciousness is unknown.
A question mark in these rows indicates that it is not known whether c7 is present
when D is absent. On the basis of this data we can develop two c-theories, t1 and t2. t1
links B and C to c7; t2 links B, C and D to c7. Both of these theories are compatible with
the experimental data. They make the same deductions about c7 in the white rows and
different deductions about c7 in the shaded rows.

Many biological systems are similar to normally functioning adult
human brains. With these systems we do not have to worry about
whether a c-theory includes all of the spatiotemporal structures that
9. Predictions and Deductions about Consciousness 121

might be linked to consciousness, because the normally functioning
adult human brain and the target system contain similar patterns in
similar materials. This will be expressed using the notion of a physical
context:

D17. A physical context is everything in a system that is not part of
a CC set that is used to make a deduction. Two physical systems
have the same physical context if they contain approximately the
same materials and if the constant and partially correlated patterns
in these materials are approximately the same.12

When two systems share the same physical context we can make
deductions about their consciousness that are as strong and believable as
the original theory. These will be referred to as conservative deductions,
which are defined as follows:

D18. In a conservative deduction a c-theory generates a c-description
from a p-description in the same physical context as the one in which
the theory was tested.

Suppose a c-theory links some electromagnetic patterns to
consciousness. In this case the physical context is everything in the
brain apart from these electromagnetic patterns, such as neurons,
haemoglobin, cerebrospinal fluid, glia, other electromagnetic patterns,
and so on. If these patterns and materials are approximately the same
in another system, then they provide the same physical context for the
electromagnetic patterns that the c-theory uses to make its deductions
about consciousness.13

Other systems, such as cephalopods and robots, lack some of the
spatiotemporal structures that are present in normally functioning
adult human brains. The link between these spatiotemporal structures
and consciousness cannot be tested in natural experiments. We can still
make deductions about the consciousness of these systems, but they are
likely to be less accurate than conservative deductions. These will be
referred to as liberal deductions, which are defined as follows:

D19. In a liberal deduction a c-theory generates a c-description from
a p-description in a different physical context from the one in which
the theory was tested.14,15
122 Human and Machine Consciousness

Suppose we have identified a mathematical relationship between
neuron firing patterns and conscious states in the normally functioning
adult human brain, and none of the brain’s other materials need to be
included to make accurate predictions about consciousness. We could
use this mathematical relationship to make conservative deductions
about the consciousness of a damaged brain, an infant’s brain and
possibly a bat’s brain. In these brains, most of the same patterns and
materials are present, so we would not have to prove that the c-theory is
based on minimal sets of spatiotemporal structures. We could also use
this relationship to make liberal deductions about the consciousness of
neurons in a Petri dish or about a snail’s consciousness. We would have
less confidence in these deductions because these physical contexts lack
some of the materials that are potential members of CC sets.

In the system described in Table 9.1, t1 and t2 make conservative
deductions about consciousness in the physical states that are coloured
white. These deductions are made in the same physical context as the
one in which the theories were tested (D is always present), and both
theories make identical deductions. t1 and t2 make liberal deductions
about the physical states in the shaded rows. The theories have not
been tested in this physical context, which lacks D, and they make
different deductions. These liberal deductions cannot be confirmed or
refuted—all that can be confirmed or refuted is the c-theory on which
the deductions are based. For example, we might give preference to
the liberal deductions of t2 if it has performed better in experiments on
platinum standard systems.

All well-tested c-theories should make the same conservative
deductions. If two c-theories make different conservative deductions,
then it should be possible to devise an experiment that can discriminate
between them.

There can be contradictions between the liberal deductions that
are made by equally reliable c-theories (see Table 9.1). Our reaction to
this will depend on our motivation for making the deductions. If they
are made out of interest, then we can say that the system is conscious
according to t1 and not conscious according to t2. If they are made for
ethical reasons, then we could base our treatment of the system on
9. Predictions and Deductions about Consciousness 123

whether it has been deduced to be conscious according to any reliable
c-theory. An artificial intelligence should not be switched off if it has
been deduced to be conscious according to t1, even if t2 claims that it is
unconscious.

The distinction between conservative and liberal deductions can be
dropped if assumptions A7-A9 are made and a c-theory is considered to
be true given these assumptions. In this case, the presence or absence of
a physical context does not matter because passive materials, constant
patterns and partially correlated patterns have been assumed to be
irrelevant to consciousness. All deductions would then be equally valid.

9.3 Summary
A c-theory can generate testable predictions about consciousness or the
physical world. Testable predictions can only be made about platinum
standard systems during consciousness experiments. It is only under
these conditions that we can use measurements of consciousness to
generate or confirm the predictions.

When a c-theory has been rigorously tested, we might judge that
it can reliably map between c-descriptions and p-descriptions. We can
then use it to make deductions about the consciousness of non-platinum
standard systems, such as coma patients and bats. These deductions
cannot be checked because we cannot measure consciousness in these
systems. We make deductions for a variety of ethical, practical and
intellectual reasons.

Conservative deductions are made in the same physical context as the
one in which the c-theory was tested. They are as reliable as the c-theory
and all c-theories should make the same conservative deductions. Liberal
deductions are made about systems that are substantially different from
the platinum standard systems on which the c-theory was tested. They
are less reliable than conservative deductions and different c-theories
are likely to make different liberal deductions.
10. Modification and
Enhancement of Consciousness

[…] our normal waking consciousness, rational consciousness as we call
it, is but one special type of consciousness, whilst all about it, parted from
it by the filmiest of screens, there lie potential forms of consciousness
entirely different. We may go through life without suspecting their
existence; but apply the requisite stimulus, and at a touch they are there
in all their completeness…
William James, The Varieties of Religious Experience1

10.1 Heaven on Earth
When we have understood the relationship between consciousness
and the physical world we will be able to systematically modify and
enhance our consciousness. We will achieve heaven on Earth without
leaving home.

Why blow yourself up for Allah when you can deflower ten virgins
per hour in a scientifically constructed consciousness? Or you could stuff
your face with roast pig without feeling sated or sick. You could dress in
cloth of gold and drink from diamond cups without rising from your silver
bed. Or give free reign to your wrath and watch your schoolmaster being
rogered with a red hot iron while badly-dressed dwarves bludgeon your
boss to death. The pain of envy would be eliminated in a consciousness in
which you are supreme dictator of the world—a consciousness rich with
the sensation of a vast and satisfying pride.

The meek and mild might prefer the less earthy pleasures of prudence,
justice, temperance, courage, faith, hope and charity. Or scientists could
engineer mystical ecstatic experiences in which acolytes are penetrated

by darts of divine love. Family audiences might enjoy the rich radiance
of a sunset or the emotions induced by the birth of a child.

The modification and enhancement of consciousness has medical
applications. Some people have damaged consciousness, a low
level of consciousness or no consciousness at all. Other bubbles of
experience are full of demons and intrusive thoughts. Some people
have a sad sagging consciousness that they seek to escape through
death. Many consciousnesses are permeated with relentless agonizing
pain. A scientific approach to the modification and enhancement of
consciousness would enable us to fix damaged consciousnesses, treat
people with depression and eliminate pain. Some of the people who
are diagnosed as schizophrenic might benefit from adjustments to their
consciousness.

The modification and enhancement of consciousness could increase
our empathy. I could experience things from your point of view. My
consciousness could be merged with your consciousness when we
make love.2

10.2 Types of Modification and Enhancement
Virtually every aspect of our bubbles of experience can be changed.
Some of the main modifications are as follows:
• Level of intensity. The average level of intensity of a bubble of
experience can be increased or decreased as well as the level of
intensity of particular contents (Figure 10.1b).3
• Contents. The contents of bubbles of experience vary widely.
There are bubbles of experience filled with black limitless
space and bubbles of experience filled with dirty headless
singing chickens (Figure 10.1c).4
• Body location. The location of our bodies in our bubbles of
experience can be altered without changing the location of our
physical bodies. This is known as an out-of-body experience.
Suppose I am standing on a cliff looking out to sea. Without
changing the location of my physical body, I can relocate my
10. Modification and Enhancement of Consciousness 127

body in my bubble of experience, so that I am floating in the
air and looking back at myself on the cliff (Figure 10.1d).5
• Body size. The size of my body in my bubble of experience can
be varied so that I am as small as a flea or as tall as the trees
(Figure 10.1e).6
• Body shape. I can become a crow or grow an extra head (Figure
10.1f).7
• Emotions. The intensity of emotions can be increased or
decreased.8
• Space. Our bubbles of experience can be expanded or contracted
to hold more or fewer things in greater or less detail (Figure
10.1g).9
• Time. The present moment has a temporal thickness (the
specious present), which could be expanded or contracted.
Our short term memory could be increased or reduced and
we could enhance our access to previous events (long term
memory).10
• Novel sensations. Our bubbles of experience are limited to
five or six senses. It might be possible to experience novel
sensations.11
• Mystical states. Many of the states described by mystics can
be interpreted as variations of the modifications that have
already been described. For example, if our sense of body
ownership is extended to our entire bubble of experience,
then we experience a profound sense of oneness with our
environment. A glowing vision of Jesus can be added to a
bubble of experience. Mystical journeys can be interpreted as
modifications of body location and contents. Our bubbles of
experience could also be modifiable in completely novel and
unimaginable ways (see Section 10.5).

None of these modifications and enhancements involve spooky stuff.
They can all be brought about by changes to the physical brain.
128 Human and Machine Consciousness

Figure 10.1. Modifications of a bubble of experience. a) Bubble of experience whose
associated CC set is determined by sensory input from a lightly wooded landscape.
b) Reduction of the average level of intensity. c) Change in contents. d) Change in the
location of the body. e) Increase in the size of the body. f) Change in body shape. g)
Spatial expansion of bubble of experience. Image © David Gamez, CC BY 4.0.
10. Modification and Enhancement of Consciousness 129

10.3 Scientific Modification and Enhancement
of Consciousness
We modify our consciousness all the time by changing sensory input,
imagining and ingesting chemicals. These techniques require no
knowledge of the relationship between consciousness and the physical
world.12

Scientific research on consciousness will enable us to modify and
enhance our consciousness. Once we have identified the relationship
between consciousness and the physical world, we can use this
knowledge to create desired states of consciousness. This is a multi-
stage process:
1. Generate a c-description, cd6, of the desired state of
consciousness.
2. Use a reliable c-theory to convert cd6 into a p-description, pd6,
of the associated CC set.
3. Realize this CC set in the human brain.

This is illustrated in Figure 10.2.

Figure 10.2. A reliable c-theory is used to realize a desired state of consciousness.
1) The desired state of consciousness is specified in a formal c-description, cd6. 2) A
reliable c-theory converts the c-description into a formal description of a physical
state, pd6. 3) The brain is modified using optogenetics, electrodes, etc. (see Section
10.4) so that it contains the CC set described in pd6. Image © David Gamez, CC BY 4.0.
130 Human and Machine Consciousness

Suppose I want to sleep with the Queen. First I generate a formal
detailed description of this state of consciousness. Then I use a reliable
c-theory to convert this c-description into a p-description of the state
of the physical world (the CC set) that is associated with this state of
consciousness. Finally I use the methods described in Section 10.4 to put
my brain into this state. I realize my dream—I am tucked up in bed in
my PJs with the Queen.13

This approach could be used to modify an animal’s consciousness.
My guinea pig’s conscious body could be enhanced with an extra leg.
Or I could reduce its pain when I exploit it for meat.

This technology could be commercialized. In the distant future we
might have designers of consciousness, who work with a customer to
generate a c-description of the consciousness they want to achieve. The
designers would then realize the corresponding CC set in the customer’s
brain. People could experience the consciousness of Jenna Jameson or
John Malkovich. Instead of watching a film, we could experience it from
a first-person perspective—we would really feel the actors’ pains and
pleasures.14

10.4 Methods
To modify and enhance consciousness we need to realize CC sets in
the brain. The methods that we will use for this will depend on the CC
sets—if they consist of neuron activity patterns, then we will need to
manipulate neuron activity patterns. We will need different methods if
CC sets contain electromagnetic fields, glia or haemoglobin.15

The non-invasive methods for manipulating neuron activity and
electromagnetic fields include transcranial magnetic stimulation (TMS)
and transcranial direct current stimulation (tDCS). Transcranial focused
ultrasound (tFUS) uses the mechanical effects of sound waves to modify
neuron activity.16 These techniques crudely alter the activity of tens of
thousands of neurons, so they are unlikely to play much of a role in the
modification of consciousness based on c-theories.

Invasive technologies provide detailed control over the firing
behaviour of individual neurons. Electrodes can control up to a hundred
10. Modification and Enhancement of Consciousness 131

neurons at a time;17 optogenetics can potentially control thousands
of neurons.18 In the longer term nanotechnology might lead to higher
resolution methods for brain control.19

Chemicals are usually delivered to the brain through the blood,
which exposes the entire brain to the chemical. In the future it might
be possible to target chemicals more precisely. We could develop drugs
that are specific to CC sets, inject chemicals directly into the brain or
genetically engineer neurons to make them more selectively responsive
to chemicals.

More tissue could be added to the brain,20 which could self-organize
in response to stimulation patterns. Synthetic neurons could be
implanted (if they were valid members of CC sets).21 These could have
enhanced properties, such as a higher firing rate.22

Some of these methods might require implanted silicon chips.23
These would not form part of the CC sets or be associated with
consciousness by themselves. The link between implanted electronics
and consciousness is part of the research on machine consciousness,
which is covered in the next chapter.

We are a long way from realizing specific CC sets in the human
brain. It is possible that the technology for realizing CC sets will have
substantially improved by the time that we have reliable c-theories and
good formats for c-description and p-description.24

Some modifications of the human brain can be done in natural
experiments. For example, many foods and most sensory inputs do
not jeopardize the status of normally functioning adult human brains
as platinum standards. If A1-A6 apply to the modified brain, then we
can measure its consciousness to check that we have created the desired
bubble of experience.

Other methods preserve the physical context of the brain that is
being modified. For example, optogenetics and electrodes modify the
activity of a small number of neurons and have little effect on the rest
of the brain. If the physical context is preserved, we will be able to
conservatively deduce that the desired state of consciousness is present.
132 Human and Machine Consciousness

Some methods change the physical context when they realize a CC
set in the brain. These include chemicals delivered through the blood
and crude methods for modifying brain activity, such as TMS, tDCS and
tFUS. Under these conditions we can only make liberal deductions about
the presence of a desired state of consciousness.

10.5 Beyond What We Can Imagine
It is difficult, it is all but impossible, to speak of mental events except
in similes drawn from the more familiar universe of material things.
If I have made use of geographical and zoological metaphors, it is not
wantonly, out of a mere addiction to picturesque language. It is because
such metaphors express very forcibly the essential otherness of the
mind’s far continents, the complete autonomy and self-sufficiency of their
inhabitants. A man consists of what I may call an Old World of personal
consciousness and, beyond a dividing sea, a series of New Worlds—the
not too distant Virginias and Carolinas of the personal subconscious and
the vegetative soul; the Far West of the collective unconscious, with its
flora of symbols, its tribes of aboriginal archetypes; and, across another,
vaster ocean, at the antipodes of everyday consciousness, the world of
Visionary Experience.
Aldous Huxley, Heaven and Hell25

The Romans could have built steam engines, but they had no idea about
this technology. They did not imagine it and did not build it. When I
was two I had no inkling about my adult life. We cannot imagine the
consciousness of fish or bats.

We use previous experiences to imagine how our consciousness
could change. But the most interesting modifications and enhancements
probably cannot be imagined by us. Mystics and hippies have peered
into these realms. Many more states and modifications might be possible.

C-descriptions can help us to understand what lies beyond the limits
of our imagination. If we had a good c-description format, we would be
able to generate c-descriptions of all possible states of consciousness.
We might be able to glimpse aspects of them in virtual reality. To enter
these unknown regions we need reliable c-theories and better methods
for realizing CC sets in the brain.
10. Modification and Enhancement of Consciousness 133

10.6 Summary
When we have reliable c-theories we will be able to modify and enhance
our consciousness in different ways. Eventually we will be able to write
down a c-description of a desired state of consciousness, use a reliable
c-theory to map the c-description onto a p-description, and then modify
the human brain so that the subject experiences the desired state of
consciousness.

At the present time we do not have reliable c-theories and we have not
solved the problems of c-description and p-description. We have a very
limited ability to realize CC sets in the brain. The scientific modification
and enhancement of consciousness has great potential, but we might
have to wait 50, 500 or 500,000 years.
11. Machine Consciousness

To actually create a technical model of full blown, perspectivally
organized conscious experience seems to be the ultimate technological
utopian dream. It would transpose the evolution of mind onto an
entirely new level […]. It would be a historical phase transition. […] But
is this at all possible? It certainly is conceivable. But can it happen, given
the natural laws governing this universe and the technical resources at
hand?
Thomas Metzinger, Being No One1

“Could a machine think?” My own view is that only a machine could
think, and indeed only very special kinds of machines, namely brains
and machines that had the same causal powers as brains. And that is
the main reason strong AI has had little to tell us about thinking, since it
has nothing to tell us about machines. By its own definition, it is about
programs, and programs are not machines. […] No one would suppose
that we could produce milk and sugar by running a computer simulation
of the formal sequences in lactation and photosynthesis, but where the
mind is concerned many people are willing to believe in such a miracle
because of a deep and abiding dualism: the mind they suppose is a
matter of formal processes and is independent of quite specific material
causes in the way that milk and sugar are not.
John Searle, Minds, Brains and Programs2

11.1 Types of Machine Consciousness
A team of scientists labours to build a conscious machine. They ignite
its consciousness with electricity and it opens its baleful eye. It declares
that it is conscious and complains about its inhuman treatment. The
scientists liberally deduce that it is really conscious. They run tests to
probe its reactions to fearful stimuli. Terrified, it snaps its chains and
runs amok in the lab. It rips one intern apart and bashes out the brains
of another. With a wild rush it bursts through the door and disappears
into the night.

This machine exhibited conscious external behaviour and really was
conscious. It could have been controlled by a model of a CC set or a
model of phenomenal consciousness. These different types of machine
consciousness will be labelled MC1-MC4:3
• MC1. Machines with the same external behaviour as conscious
systems. Humans behave in particular ways when they are
conscious. They are alert, they can respond to novel situations,
they can inwardly execute sequences of problem-solving steps,
they can execute delayed reactions to stimuli, they can learn
and they can respond to verbal commands (see Section 4.1).
Many artificially intelligent systems exhibit conscious human
behaviours (playing games, driving, reasoning, etc.). Some
people want to build machines that have the full spectrum
of human behaviour.4 Conscious human behaviours can be
exhibited by systems that are not associated with bubbles of
experience.5
• MC2. Models of CC sets. Computer models have been built of
potential CC sets in the brain.6 This type of model can run on
a computer without a bubble of experience being present. A
model of a river is not wet; a model of a CC set would only
be associated with consciousness if it produced appropriate
patterns in appropriate materials. This is very unlikely to
happen when a CC set is simulated on a digital computer.
• MC3. Models of consciousness. Computer models of bubbles
of experience can be built.7 These could be based on the
phenomenological observations of Husserl, Heidegger
or Merleau-Ponty. These models can be created without
producing patterns in materials that are associated with
bubbles of experience.
• MC4. Machines associated with bubbles of experience. When we
have understood the relationship between consciousness
and the physical world we will be able to build artificial
systems that are actually conscious. These machines would be
associated with bubbles of experience in the same way that
human brains are associated with bubbles of experience. Some
11. Machine Consciousness 137

of our current machines might already be associated with
bubbles of experience.

Several different types of machine consciousness can be present at the
same time. We can build machines with the external behaviour associated
with consciousness (MC1) by modelling CC sets or consciousness (MC2,
MC3).8 We could produce a machine that exhibited conscious external
behaviour (MC1) using a model of CC sets (MC3) that was associated
with a bubble of experience (MC4).

The construction of MC1, MC2 and MC3 machines is part of standard
computer science. The construction of MC4 machines goes beyond
computer models of external behaviour, CC sets and consciousness.
MC4 machines contain patterns in materials that are associated with
bubbles of experience.

11.2 How to Build a MC4 Machine
MC4 machine consciousness would be easy if computations or
information patterns could form CC sets by themselves. Unfortunately
computations and information patterns do not conform to constraints
C1-C4, so they cannot be used to build MC4 machines (see Chapters 7
and 8).

To construct a MC4 machine we need to realize particular patterns
in particular physical materials. If we had a reliable c-theory, we could
design and build a MC4 machine in the following way:
1. Generate c-description, cd7, of the consciousness that we want
in the machine.
2. Use reliable c-theory to convert cd7 into a p-description, pd7, of
the CC set that corresponds to this conscious state.
3. Realize this CC set in a machine.

This is illustrated in Figure 11.1.

We do not have a reliable c-theory. So we can only guess about the
patterns and materials that might be needed to build MC4 machines.
138 Human and Machine Consciousness

If CC sets contain patterns in electromagnetic fields, then we could use
neuromorphic chips to generate appropriate electromagnetic patterns in
an artificial system.9 If CC sets contain biological neurons, then we could
build an artificial MC4 system using cultured biological neurons.10

Figure 11.1. A reliable c-theory is used to build a MC4 machine. 1) The state of
consciousness that we want to realize in the machine is specified in a formal
c-description, cd7. 2) A reliable c-theory converts the c-description into a formal
description of a physical state, pd7. 3) 3D printing, neuromorphic chips, etc. are
used to build a machine that contains the CC set described in pd7. Image © David
Gamez, CC BY 4.0.

11.3 Deductions about the Consciousness
of Artificial Systems
Last year I purchased a C144523 super-intelligent mega-robot from our
local store. It cooks, cleans, makes love to the wife and plays dice. Last
week I saw a new model in the shop window—it is time to dispose of
C144523. On the way to the dump it goes on and on about how it is a
really sensitive robot with real feelings. It looks sad when I throw it in
the skip. The wife is sour. Little Johnny screams ‘How can you do this
to C144523? She was conscious, just like us. I hate you, I hate you, I
hate you!’ Perhaps C144523 really had real feelings? I probably should
have checked.
11. Machine Consciousness 139

We want to know whether the MC1-MC3 machines that we have
created are really conscious. We want to know whether we have built a
MC4 machine.

We can use reliable c-theories to make deductions about the MC4
consciousness of artificial systems. These are likely to be liberal
deductions because most machines do not have the same physical
context as our current platinum standard systems (see Section 9.2).

Suppose we have a reliable c-theory that maps electromagnetic
patterns onto conscious states. We would analyze an artificial system
for MC4 consciousness in the following way:
1. Measure its electromagnetic patterns.
2. Convert measurement into p-description, pd8.
3. Use reliable c-theory to convert pd8 into a c-description, cd8, of
the artificial system’s consciousness.

This is illustrated in Figure 11.2. The plausibility of the resulting
c-description depends on the reliability of the physical c-theory and on
whether it is a conservative or a liberal deduction.11

Figure 11.2. A reliable c-theory is used to deduce the consciousness of an
artificial system. 1) Scientific instruments are used to measure the physical state
of the artificial system. 2) Scientific measurements are converted into a formal
p-description of the artificial system’s physical state, pd8. 3) A reliable c-theory
converts the p-description into a formal description of the artificial system’s
conscious state, cd8. Image © David Gamez, CC BY 4.0.
140 Human and Machine Consciousness

11.4 Limitation of this Approach to MC4
Consciousness
This approach to MC4 machine consciousness is based on c-theories
that are developed using platinum standard systems. But our platinum
standard systems might not contain all of the patterns and materials
that are linked to bubbles of experience.

One type of pattern and material could be linked to consciousness
in the human brain; a different type of pattern and material could be
linked to consciousness in an artificial system. It is impossible to find
out whether this is the case. We cannot measure the consciousness of
systems that are not platinum standards, so we cannot prove that the
patterns in their materials are not associated with conscious states. At
best we can be confident that a machine is MC4 conscious—we cannot
be confident that it is not MC4 conscious.

In the future we might be seduced by a machine’s MC1 behaviour
and assume that it is a platinum standard system. However, assumptions
about platinum standard systems should be not made lightly—they have
radical implications for the science of consciousness (see Section 5.4).

11.5 Conscious Brain Implants
Artificial devices could be implanted in our brains to extend our
consciousness.12 In a MC4 implant the CC set would be distributed
between the brain and the implant, forming a hybrid human-machine
system. MC4 implants would enable us to modify and enhance our
consciousness more easily. We could become conscious of different
types of information (from our environment, the Internet, etc.).

MC4 implants have medical applications. CC sets could be damaged
by tumours, strokes or accidents. The damaged area could be replaced
with an implant that was deduced to have the missing consciousness.

MC4 implants would have to produce specific patterns in specific
materials. The patterns could be distributed between the brain and the
11. Machine Consciousness 141

implant. For example, if CC sets consisted of electromagnetic patterns,
then neuromorphic chips13 could be implanted, which would work
together with the brain’s biological neurons to create electromagnetic
patterns that would be associated with consciousness.

Brains with implants are not platinum standard systems, so we
cannot measure their consciousness using c-reports. Only conservative
or liberal deductions can be made about their consciousness.

11.6 Uploading Consciousness into a Computer
It will soon be technologically possible to scan a dead person’s brain
and create a simulation of it on a computer.14 Some people think that a
simulation will have the same consciousness as their biological brain.
They believe that they can achieve immortality by uploading their
consciousness into a computer.15

It is extremely unlikely that a simulation of your brain on a digital
computer will have a bubble of experience. Simulations have completely
different electromagnetic fields from real brains and lack the biological
materials that might be members of CC sets.

Your consciousness can only be uploaded into an artificial system
that reproduces the CC sets in your brain. We do not know which of
the brain’s materials are present in CC sets, so the only certain way of
uploading your consciousness is to create an atom-for-atom copy of
your brain.

The advantage of the brain-uploading approach is that the patterns
linked to consciousness are blindly copied from the original brain.
Suppose we could show that electromagnetic fields are the only materials
in CC sets. I could then upload my consciousness by realizing my brain’s
electromagnetic field patterns in a machine. This could be done without
any knowledge of the patterns that are linked to consciousness.

When I upload a file to the Internet the file remains on my computer.
The same would be true if I uploaded my consciousness by scanning
142 Human and Machine Consciousness

my living brain using non-destructive technology. My consciousness
would continue to be associated with my biological brain. A copy of
my consciousness would be created in the computer. Scanning and
simulating my brain would not transfer my consciousness—it would not
enable my consciousness to survive the death of my biological body.16

11.7 Will Conscious Robots Conquer the World?
Science fiction fans know that conscious machines will take over the
world and enslave or eliminate humans. Prescient science fiction writing
helped us to prepare for the Martian invasion. Perhaps we should take
drastic action now to save humanity from conscious killer robots?17

The next section argues that a takeover by superior MC1 or MC4
machines could be a good thing. This section examines the more
common (and entertaining) belief that humanity will be threatened by
malevolent machine intelligences.

MC1 machines carry out actions in the world—they fire lasers, hit
infants on the head and steal ice cream. Research on MC2, MC3 and
MC4 systems might improve our ability to develop MC1 machines, but
MC2, MC3 and MC4 machines cannot achieve anything unless they
are capable of external behaviour. Only MC1 machines could threaten
humanity.18

It is extremely difficult to develop machines with human-level
intelligence. We are just starting to learn how to build specialized
systems that can perform a single task, such as driving or playing
Jeopardy. This is much easier than building MC1 machines that learn
as they interact with the world and exhibit human-like behaviour in
complex dynamic environments.19

Let us take the worst-case scenario. Suppose super-intelligent
computers control our aircraft, submarines, tanks and nuclear weapons.
There are billions of armed robots. Every aspect of power generation,
mining and manufacturing is done by robots. Humans sit around
all day painting and writing poetry. Under these conditions MC1
machines could take over. However, if humans were involved in the
11. Machine Consciousness 143

manufacture and maintenance of robots, if they managed the mines and
power production, then complete takeover is very unlikely—the robot
rebellion would rapidly grind to a halt as the robots ran out of power
and their parts failed.

People who worry about machines taking over should specify the
conditions under which this would be possible.20 When we get close to
fulfilling these conditions we should take a careful look at our artificially
intelligent systems and do what is necessary to minimize the threat.

Some people have suggested that artificial intelligence could run
away with itself—we might build a machine that constructs a more
intelligent machine that constructs a more intelligent machine, and so
on. This is known as a technological singularity.21 The fear that we might
build a machine that takes over the world is replaced by a higher-
order fear that we build a machine that builds a machine that builds
a machine that takes over the world. We have little idea how to build
such a machine.22 Just a sickening sense of fear when we imagine an evil
super-intelligence hatching from a simple system.

Suppose we write an intelligent program that writes and executes
a more intelligent program, and so on at an accelerating rate. What
can this super-intelligent system do? In what way could it pose an
existential threat to humanity? Physically it can do nothing unless it
is connected to a robot body. And what can one robot do against ten
billion humans? On the Internet the super-intelligence will be able to
do everything that humans do (make money through gambling, hire
humans to do nefarious deeds, purchase weapons, etc.). But it is very
unlikely to pose more of a threat than malevolent humans. Large,
well-funded teams of highly intelligent humans struggle to steal small
sums of money, copy business secrets, and carry out physical and
online attacks. There is little reason to believe that a super-intelligent
system could achieve much more. A runaway intelligence would
only pose a threat if many other conditions were met. We are very far
from building this type of system and we will have plenty of time to
minimize the risks if it becomes a real possibility.23
144 Human and Machine Consciousness

Machines are much more likely to accidentally destroy humanity as a
result of hardware or software errors. Killer robots with appropriate kill
switches might make better decisions on the battlefield and cause less
collateral damage. However, if we have thousands of such robots, then
there is a danger that a software error could kill the kill switch and set
them on the rampage. Protecting humans against software errors is not
straightforward because most modern weapons systems are under some
form of computer control and humans can make calamitous decisions
based on incorrect information provided by computers.24

Science fiction reflects our present concerns—it tells us little about
a future that is likely to happen. Over the next centuries our attitudes
towards ourselves and our machines will change. As our artificial
intelligences improve we will get better at understanding, regulating
and controlling them. Po-faced discussions about the existential threat
of artificial intelligence will become as quaint as earlier fears about
Martian invaders.

11.8 Should Conscious Robots Conquer the World?
It is very unlikely that intelligent machines could possibly produce more
dreadful behaviour towards humans than humans already produce
towards each other, all round the world even in the supposedly most
civilised and advanced countries, both at individual levels and at social
or national levels.
Aaron Sloman, Why Asimov’s Three Laws of Robotics Are Unethical25

Many humans are stupid useless dangerous trash. Scum rises to the
top. People have killed hundreds of millions of people in grubby quests
for power, pride, sexual satisfaction and cash. We have come close to
nuclear catastrophe.

Super-intelligent MC1 machines might run the world better than
ourselves and make humanity happier. They could systematically
analyze more data without the human limitations of boredom and
self-interest. MC1 machines could maximize human wellbeing without
petty political gestures.26
11. Machine Consciousness 145

Positive states of consciousness have value in themselves. We fear
death because we fear the permanent loss of our consciousness. Crimes
are ethically wrong because of their effects on conscious human beings.27
Nothing would matter if we were all zombies.

Many human consciousnesses are small and mediocre. People
pour out unclean and lascivious thoughts to their confessors. We
are guilty of weak sad thoughts and pathetically wallow in negative
states of consciousness. Human bubbles of experience fall far short of
consciousness’ potential.

Reliable c-theories would enable us to engineer MC4 machines with
better consciousness. If consciousness is ethically valuable in itself, then
a takeover by superior MC4 machines would be a good thing. This
could be a gradual process without premature loss of life that we would
barely notice. We would end up with 100 billion high quality machine
consciousnesses, instead of 10 billion human consciousnesses full of
hate, lies, gluttony and war. A pure brave new world without sin in
thought or deed.28

We have species-specific prejudices, a narrow-mindedness, that causes
us to recoil with shock and horror from the suggestion that we should
meekly step aside in favour of superior machines. This does not mean
that the ethical argument is wrong or that the replacement of humans
with MC4 machines would be bad—merely that it is against the self
interest of our species. Looked at dispassionately a good case can be
made. Can we rise above our prejudices and create a better world?

The world might be a better place if MC4 machines took over. But
it is very unlikely that this utopian scenario will come to pass. The
science of consciousness has a long way to go before we will be able
to design better consciousnesses. And we are only likely to be able to
make liberal deductions about the consciousness of artificial systems,
which are not completely reliable. We should only replace humans with
MC4 machines when we are certain that the machines have superior
consciousnesses.
146 Human and Machine Consciousness

11.9 The Ethical Treatment of Conscious Machines
What would you say if someone came along and said, “Hey, we want
to genetically engineer mentally retarded human infants! For reasons of
scientific progress we need infants with certain cognitive and emotional
deficits in order to study their postnatal psychological development—
we urgently need some funding for this important and innovative kind
of research!” You would certainly think this was not only an absurd and
appalling but also a dangerous idea. It would hopefully not pass any
ethics committee in the democratic world. However, what today’s ethics
committees don’t see is how the first machines satisfying a minimally
sufficient set of constraints for conscious experience could be just like
such mentally retarded infants. They would suffer from all kinds of
functional and representational deficits too. But they would now also
subjectively experience those deficits. In addition, they would have no
political lobby—no representatives in any ethics committee.
Thomas Metzinger, Being No One29

The science of consciousness should enable us to build MC4 machines
that are associated with bubbles of experience. Some of our MC1, MC2
or MC3 machines could already be MC4 conscious. These systems might
suffer; they might be confused; they might be incapable of expressing
their pain.

We want machines that exhibit the behaviours associated with
consciousness (MC1). We want to build models of CC sets (MC2)
and models of consciousness (MC3). But we might have to prevent
our machines from becoming MC4 conscious if we want to avoid the
controversy associated with animal experiments.

It would be absurd to give rights to MC1, MC2 or MC3 machines.
Ethical treatment should be limited to machines that are really MC4
conscious.

We can use reliable c-theories to deduce which machines are MC4
conscious (see Section 11.3). One potential problem is that a large number
of physical objects (phones, toasters, cars etc.) might be deduced to be
MC4 conscious according to the most reliable c-theory. It is also highly
unlikely that we will reach the stage of designing systems with zero
or positive states of consciousness without building systems that have
‘retarded’ or painful consciousness.
11. Machine Consciousness 147

11.10 Summary
There are four types of machine consciousness. There are machines
whose external behaviour is similar to conscious systems (MC1),
there are models of CC sets (MC2), models of consciousness (MC3),
and systems that are associated with bubbles of experience (MC4).
Reliable c-theories can be used to deduce which machines are really
MC4 conscious. Some implants and brain scanning/upload methods are
potentially forms of MC4 machine consciousness.

The production of conscious machines raises ethical questions, such
as the potential danger to humanity of MC1 machines, whether MC1 or
MC4 machines should take over the world, and how we should treat
MC4 machines.

It could take hundreds or thousands of years to develop artificial
systems with human levels of consciousness and intelligence. It might
be impossible to build super-intelligent machines. Current discussion of
these issues is little more than speculation about a distant future that we
cannot accurately imagine.
12. Conclusion

Science does not rest on solid bedrock. The bold structure of its theories
rises, as it were, above a swamp. It is like a building erected on piles. The
piles are driven down from above into the swamp, but not down into
any natural or ‘given’ base; and if we stop driving the piles deeper, it is
not because we have reached firm ground. We simply stop when we are
satisfied that the piles are firm enough to carry the structure, at least for
the time being.
Karl Popper, The Logic of Scientific Discovery1

12.1 A Framework for the Science of
Consciousness
This book has set out a systematic framework for the scientific study
of consciousness. It has tried to shift consciousness research into a
paradigmatic state.2 The key points are as follows:
• Consciousness is a bubble of experience. It consists of colours,
sounds, smells, tastes, etc., which are arranged in a bubble of
space centred on our bodies.
• The physical world is invisible. It has none of the secondary
qualities that are present in a bubble of experience. Primary
qualities in a bubble of experience are unlikely to resemble
primary qualities in the physical world.
• There are three hard problems of consciousness. First, it is
impossible to imagine the relationship between consciousness
and the invisible physical world. Second, we find it difficult
to imagine the connection between conscious experiences of
brain activity and other conscious experiences. Third, there
are brute regularities between consciousness and the physical

world that cannot be broken down or further explained. None
of these issues affect scientific research on consciousness.
• To scientifically study consciousness we need to measure
consciousness, measure the physical world and look for
mathematical relationships between these measurements.
• Consciousness is measured through the external behaviour
(c-reports) of systems that we assume to be conscious (platinum
standard systems).
• Normally functioning adult human brains are platinum
standard systems.
• Measurements of consciousness need to be expressed in a
formal way (a c-description), so that they can be incorporated
into mathematical theories of consciousness.
• The correlates of a conscious state are a set of spatiotemporal
structures in the physical world (a CC set) that is only present
when the conscious state is present. A CC set is functionally
connected to a bubble of experience and it e-causes c-reports about
the bubble of experience.
• CC sets need to be described in a formal context-free way
(a p-description), so that they can be incorporated into
mathematical theories of consciousness.
• Pilot studies attempt to identify the CC sets that are associated
with individual conscious states.
• C-theories are mathematical relationships between
c-descriptions of conscious states and p-descriptions of CC
sets.
• Computational methods should be used to discover c-theories.
• Information c-theories claim that information patterns could
form CC sets by themselves. Computation c-theories claim that
computations could form CC sets by themselves. These types
of c-theory do not conform to the constraints on scientific
theories of consciousness (C1-C4).
12. Conclusion 151

• Physical c-theories link patterns in particular materials to
conscious states. They conform to the constraints on CC sets
and fit in well with other scientific theories.
• C-theories can generate predictions about consciousness or the
physical world. Predictions can only be tested on platinum
standard systems.
• C-theories can make conservative and liberal deductions about
the consciousness of non-platinum standard systems, such as
bats, infants and robots. Deductions are logical consequences
of a c-theory that cannot be checked.

This framework handles or sets aside most of the philosophical
problems with consciousness.3 We cannot solve these problems. We can
only show that they are pseudo problems, suspend judgement about
them or set them aside with assumptions.

This framework is compatible with some of the metaphysical
approaches to consciousness, such as physicalism and
epiphenomenalism. It suspends judgement about which (if any) are
correct. It is not compatible with panpsychism, dualism,4 or with
information and computation c-theories.

This framework prescribes the form that legitimate theories of
consciousness should take. Our final c-theories will not be lengthy
pieces of natural language. They will be mathematical relationships
between c-descriptions and p-descriptions.

This framework is neutral about which physical c-theory is correct.
While I have often used neurons and electromagnetic fields as examples,
I have no idea about which patterns and materials are actually linked
to consciousness. This question should be addressed by scientific
experiments.

A person who accepts this framework can focus on measuring
consciousness, measuring the physical world and identifying the
relationships between these measurements. Their results can be
considered to be true given assumptions A1-A6—they cannot be
obtained or justified without these assumptions.5
152 Human and Machine Consciousness

12.2 Technological Limitations
The science of consciousness can only fully develop when we have
accurate high resolution measurements of consciousness and the
physical world.

The problems with measuring consciousness are mostly conceptual
and methodological (see Chapter 4). If enough effort is spent, we should
be able to obtain detailed and reasonably complete measurements of
conscious states.

To accurately measure the physical world we need p-description
methods that avoid the heavy reliance on context that is common
in biology (see Section 5.1). We also need better access to the 100
billion neurons in the living human brain. The most commonly used
technologies are as follows:
• Functional Magnetic Resonance Imaging (fMRI). An indirect
measure of brain activity with a spatial resolution of a few
thousand voxels. Each voxel corresponds to the activity of
approximately 50,000 neurons averaged over several seconds.
• Diffusion Magnetic Resonance Imaging (dMRI). Identifies
structural connections between brain areas, but does not
show their direction. Can only help to identify CC sets when
combined with other methods.
• Electroencephalography (EEG). Approximately 300 electrodes
are placed on the scalp to measure the brain’s electrical
field with good temporal resolution and very poor spatial
resolution.
• Magnetoencephalography (MEG). Measures the magnetic fields
generated by groups of 50,000 neurons at approximately 300
points on the head with good temporal resolution.
• Implanted electrodes. Up to 300 electrodes can be implanted
in the brain to measure electromagnetic fields and neuron
activity with good spatial and temporal resolution.6 Electrodes
are rarely implanted in human subjects.
• Optogenetics. Neurons can be genetically engineered to emit
light when they fire, which enables their individual activity to
12. Conclusion 153

be recorded using light sheet microscopy. This technique can
be used to record from 100,000 neurons in a zebrafish larva in
close to real time.7 It is more challenging to use optogenetics in
mammalian brains and for ethical reasons it has not been used
on human subjects.

The data that is extracted using these techniques can be processed
into higher level properties. For example, we can use Granger causality
or dynamic causal modelling to identify effective connections between
brain areas. These connectivity patterns can be further analyzed using
graph theory.8

Optogenetics is the most promising technology for obtaining high
resolution data from living brains. However, there are ethical and safety
concerns about using it on humans. To get around these problems we
can use animal brains to make inferences about CC sets in humans. Or
we can assume that monkeys and mice are platinum standard systems.9

C-theories can be based on patterns that have higher resolution than
our current measurement technologies. For example, we could develop
c-theories based on neuron activity patterns and predict how these
neuron activity patterns would appear in EEG data or a fMRI scan.

The scanning and uploading of a human brain could help to address
our measurement problems. We could identify the structures in a
simulated brain that cause its simulated c-reports. This might help us
to develop c-theories that are not limited by our current technologies.

12.3 Other Limitations
I did not get my picture of the world by satisfying myself of its
correctness; nor do I have it because I am satisfied of its correctness. No:
it is the inherited background against which I distinguish between true
and false.
Ludwig Wittgenstein, On Certainty10

The framework presented in this book cannot be shown to be correct. It
is a condition of possibility of experimental work on consciousness that
cannot be verified by experimental work on consciousness.11 Scientific
research within this framework might be fruitful and yield reliable
154 Human and Machine Consciousness

c-theories. Or a science of consciousness based on this framework might
reach a point at which it no longer coherently hangs together. We might
have to formulate a completely new set of framing principles. Or we
might have to abandon the attempt to scientifically study consciousness.

The inappropriate use of intuition, thought experiments and
imagination has led to many problems in the philosophy of
consciousness. I have tried to banish these as much as possible, but
they cannot be completely eliminated. For example, I have assumed
that normally functioning adult human brains are platinum standard
systems. But which systems count as normally functioning adult human
brains? What counts as a legitimate chemical modification? There are no
natural boundaries—we have to use our intuition and imagination to
decide which human brains are platinum standard systems.

This framework leaves many questions unanswered. It does
not explain what consciousness is, what consciousness does, what
consciousness is for, how consciousness arose, why there is a functional
connection between consciousness and the physical world or how this
connection actually works.

These questions are about consciousness in general. But it makes
no sense to ask about the physical world in general. We can ask about
the origin and function of particular physical structures—we cannot
meaningfully ask about the origin and function of the entire universe.
The case is similar with consciousness—it is meaningless to ask most of
these questions about consciousness in general.

Let’s rephrase these questions. Consider a state of consciousness, c8.
c8 is a bubble of experience in which you are peeping through a hole at
an old woman in a bath. We can ask what c8 is, what c8 does, what c8 is for,
how c8 arose, why c8 is functionally connected to the physical world and
how this connection actually works.

These questions can be answered if we assume that c8 is identical
to its associated CC set, cc8. This explains the connection between c8
and the physical world. As the science of consciousness progresses we
will get a better understanding of what cc8 is, what cc8 does and how it
12. Conclusion 155

arose through e-causal processes, such as evolution. All of our questions
about c8 can be answered by transferring them to cc8.

Our questions about c8 can also be answered by assuming that it is a
teapot. This tells us what c8 is (a teapot), how it arose (a factory in China)
and what it is for (making tea). But assumptions about consciousness
have to be valid, they have to make sense. An assumption’s validity has
to be decided independently of our desire to obtain cheap and easy
answers about consciousness. No answers are better than bad answers.

It makes little sense to say that colourful smelly noisy bubbles of
experience are identical to something that is invisible, silent and without
smell. This discards the properties of bubbles of experience and ignores
the reality of our day-to-day world. We could equally well discard the
physical world and declare that it is a fairytale told by simple folk to
explain regularities in consciousness.12 Neither reduction is part of the
framework that is set out in this book. Consciousness and the physical
world are both taken as basic realities that can be measured and
scientifically studied.

The physical sciences’ assumption that the physical universe exists
leaves many questions unanswered. Many questions will remain
unanswered if conscious states are not reduced to physical states. We
will simply have to accept that consciousness exists and study the brute
regularities between consciousness and the physical world.

12.4 Future Research
If we take in our hand any volume; of divinity or school metaphysics, for
instance; let us ask, Does it contain any abstract reasoning concerning
quantity or number? No. Does it contain any experimental reasoning
concerning matter of fact and existence? No. Commit it then to the
flames: For it can contain nothing but sophistry and illusion.
David Hume, An Enquiry Concerning Human Understanding13

The following types of consciousness research are likely to be productive:
• Revision of the assumptions. We might be able to reduce the
number of assumptions, improve their consistency and
156 Human and Machine Consciousness

enhance the way in which they relate to general principles in
the philosophy of science and the study of consciousness.
• Creation of c-description format. We need a precise formal way
of describing states of consciousness that can be incorporated
into mathematical c-theories.
• Improvement of methods for measuring consciousness. More work
is required on how we can obtain detailed measurements of
conscious states.
• Creation of a context-free p-description format. We need a formal
context-free way of describing biological structures, such as
neurons.
• Development of a precise definition of a physical context.
Conservative and liberal deductions can only be distinguished
when we have a precise definition of a physical context.
• Increase the spatial and temporal resolution of our brain
measurements. We can refine existing methods, develop new
technologies and create better mathematical techniques for
processing data into higher level properties.
• Pilot studies on the correlates of consciousness. More pilot studies
could help us to identify the patterns and materials that form
CC sets.
• Development of physical c-theories. In the medium to longer
term we need to move beyond pilot studies and identify
mathematical relationships between bubbles of experience
and physical states.14
• Experimental testing of physical c-theories. Physical c-theories
will only be considered to be reliable when their predictions
have been experimentally confirmed.
• Construction of computer models of CC sets that simulate c-reports.
This could help us to identify the patterns and materials that
form CC sets. These models could also be used to develop
methods for the computational discovery of c-theories.
• Development of methods for the computational discovery of
c-theories. This could apply existing work on the computational
12. Conclusion 157

discovery of scientific theories to data from consciousness and
the brain.
• Deductions about the consciousness of non-platinum standard
systems. When we have a reliable c-theory we will be able to
answer questions about the consciousness of bats, infants and
robots. Deductions also have important medical applications.
• Experimental work on the modification and enhancement of
consciousness. When we have reliable c-theories and better
technology for modifying the brain we will be able to
systematically modify and enhance human consciousness.
• Construction of MC1-MC4 machines. This has many practical
applications and could be a useful way of studying human
consciousness.

A book or paper on consciousness that describes none of these things
should be committed to the flames. Or carefully checked for sophistry
and illusion.
Appendix: Definitions,
Assumptions, Lemmas and
Constraints

Definitions
D1. Consciousness is another name for bubbles of experience. A state of
a consciousness is a state of a bubble of experience. Consciousness
includes all of the properties that were removed from the physical
world as scientists developed our modern invisible explanations (2.5).1

D2. A c-report is a physical behaviour that is interpreted as a report
about a person’s consciousness (4.1).

D3. A nc-report is a physical behaviour that is interpreted as a report
about non-conscious mental content (4.2).

D4. A platinum standard system is a physical system that is assumed to be
associated with consciousness some or all of the time (4.3).

D5. A correlate of conscious state is a minimal set of one or more
spatiotemporal structures in the physical world. This set is present
when the conscious state is present and absent when the conscious state
is absent. This will be referred to as a CC set (4.6).

D6. A c-description is a formal description of a conscious state (4.9).

D7. A p-description is a formal description of a spatiotemporal structure
in the physical world. A p-description unambiguously determines

1 The number in brackets is the section in which the definition, assumption, lemma
or constraint can be found.

whether a spatiotemporal structure is present in a sequence of physical
states (5.1).

D8. In a natural experiment the test system preserves its status as a
platinum standard. Assumptions A1-A6 remain valid and consciousness
can be measured throughout the experiment (5.4).

D11. A material is an arrangement of elementary wave-particles at a
particular spatial scale (6.1).

D12. A physical c-theory links consciousness to spatiotemporal patterns
in materials. Physical CC sets consist of one or more patterns and the
materials in which these patterns occur (6.1).

D13. An information c-theory links consciousness to spatiotemporal
information patterns. Information CC sets only contain information
patterns, which can occur in any material (7.2).

D14. A computation c-theory links consciousness to the execution of
computations. Computation CC sets only contain computations, which
can be executed by many different types of computer (8.2).

D16. A deduction is a c-description that is generated from a p-description
when consciousness cannot be measured. Deductions are blind logical
Definitions, Assumptions, Lemmas and Constraints 161

consequences of a c-theory. They cannot be tested because assumptions
A1-A6 do not apply. The plausibility of a deduction is closely tied to the
reliability of the c-theory that was used to make it (9.2).

D17. A physical context is everything in a system that is not part of a CC
set that is used to make a deduction. Two physical systems have the
same physical context if they contain approximately the same materials
and if the constant and partially correlated patterns in these materials
are approximately the same (9.2).

D18. In a conservative deduction a c-theory generates a c-description
from a p-description in the same physical context as the one in which the
theory was tested (9.2).

D19. In a liberal deduction a c-theory generates a c-description from a
p-description in a different physical context from the one in which the
theory was tested (9.2).

Assumptions
A1. During an experiment on consciousness, the consciousness
associated with a platinum standard system is functionally connected
to the platinum standard system’s c-reports (4.3).

A2. During an experiment on consciousness all conscious states
associated with a platinum standard system are available for c-report
and all aspects of these states can potentially be c-reported (4.3).

A3. The consciousness associated with a platinum standard system
nomologically supervenes on the platinum standard system. In our
current universe, physically identical platinum standard systems are
associated with indistinguishable conscious states (4.4).

A4. The normally functioning adult human brain is a platinum standard
system (4.5).
162 Human and Machine Consciousness

A5. The physical world is e-causally closed (4.7).

A6. CC sets e-cause a platinum standard system’s c-reports (4.7).

A6a. CC sets are effectively connected to a platinum standard system’s
c-reports (4.7).

A7. CC sets do not contain passive materials. If the link between consciousness
and the simple presence of a material cannot be demonstrated in a
natural experiment, then this material can be excluded from potential
CC sets (6.4).

A8. CC sets do not contain patterns that are present when the system is
conscious and unconscious. If the link between consciousness and a
constant pattern cannot be demonstrated in a natural experiment, then
this pattern can be excluded from potential CC sets (6.4).

A9. CC sets do not contain partially correlated patterns. When several
different materials have the same spatiotemporal pattern, the material(s)
in which the spatiotemporal pattern is strongest will be considered to
be the potential member(s) of the CC set that is associated with the
conscious state, unless the partially correlated patterns can be separated
out in a natural experiment (6.4).

Lemmas
L1. There is a functional connection between a conscious state and its
corresponding CC set (4.6).

Constraints
C1. The spatiotemporal structures in a CC set are independent of the observer.
My consciousness is a real phenomenon that does not depend on
someone else’s subjective interpretation. CC sets must be formed from
objective spatiotemporal structures, such as electromagnetic waves and
neuron firing patterns (5.2).

C2. The members of CC sets are intrinsic properties. A conscious state
supervenes on a CC set (A3a), so each duplicate of a CC set must be
Definitions, Assumptions, Lemmas and Constraints 163

associated with an identical conscious state, regardless of the spatial
and temporal context in which the duplicate appears (5.2).

C3. A non-conscious system does not contain a CC set that is 100% correlated
with a conscious state. If A and B are 100% correlated, then A cannot occur
without B. If a CC set is 100% correlated with a conscious state, then all
brains that contain that CC set will be conscious (5.2).

C4. CC sets e-cause c-reports during consciousness experiments (A6). It is
not necessary for every member of a CC set to e-cause c-reports. But
some parts or aspects of the CC set must e-cause them. So when I say ‘I
am conscious of a green tomato’, this c-report can be traced back to the
CC set that e-caused it, which is functionally connected to a bubble of
experience in which there is a green tomato (5.2).
Endnotes

2. The Emergence of the Concept of Consciousness
1 Qualia (singular: quale) is a technical philosophical term that refers to the
qualitative or subjective properties of experiences. For exaple, the colour
red, the taste of chocolate and the sound of a bell are qualia.

2 See Gamez (2007, Chapter 2) and Lehar (2003) for more detailed
descriptions of bubbles of perception. Husserl (1964) has a good analysis
of the temporal structures of our bubbles of perception.

3 It might be thought that a bubble of experience is a version of Dennett’s
(1992) Cartesian Theatre, in which a homunculus observes the contents of
consciousness. This appears to require a second homunculus inside the
head of the first, and so on ad infinitum. However, bubbles of experience
do not have the same problems as Cartesian Theatres because there is no
perception within a bubble of experience. My physical brain perceives its
physical environment using electromagnetic waves, etc.; my conscious
experience of my body does not perceive my conscious experience of my
environment using a conscious experience of electromagnetic waves—
there is no transmission of information within a bubble of experience. I
have discussed this in more detail elsewhere (Gamez 2007, pp. 47-8).

4 For example, Lucretius (2007).

5 Locke (1997, p. 137).

6 This example is taken from ancient scepticism. Studies have shown that
people have different perceptions of bitterness (Hayes et al. 2011) and
there is substantial variability in people’s olfactory perception (Mainland
et al. 2014).

7 See Galilei (1957) and Locke (1997). This distinction was also developed by
the ancient atomists—see Taylor (1999) for a discussion.

8
It might be claimed that honey is sweet in itself and produces sensations
of sweetness (or bitterness) through the interaction of its sweetness with

our senses. In this case the different properties perceived by different
observers would be due to the different ways in which the physical
sweetness interacts with their senses. The problem with this proposal is
that it is impossible to decide whether the honey is sweet and produces a
false bitter sensation when it interacts with Zampano’s senses, or whether
it is bitter and produces a false sweet sensation when it interacts with
my senses. It is much simpler to attribute all sensory properties to the
interaction between the physical world and the sense organs.

9 Locke (1997, pp. 136-7).

10
For example, O’Regan and Noë claim: ‘There can therefore be no one-to-
one correspondence between visual experience and neural activations.
Seeing is not constituted by activation of neural representations. Exactly
the same neural state can underlie different experiences, just as the
same body position can be part of different dances.’ (O’Regan and Noë
2001, p. 966). A less radical position can be found in Noë’s later work: ‘A
reasonable bet, at this point, is that some experience, or some features of
some experiences, are, as it were, exclusively neural in their causal basis,
but that full-blown, mature human experience is not.’ (Noë 2004, p. 218).

11 This is formally stated as assumption A4 in Section 4.5.

12 Noë’s (2004) bet that this type of conscious experience is not exclusively
correlated with neural activity is a different working assumption that
can be experimentally tested. I have discussed this point in more detail
elsewhere (Gamez 2014b).

13 When a neuron fires it emits a short electrical pulse known as an action
potential or spike. This electrical pulse has an amplitude of ~100 mV, a
duration of ~2ms and it can be transmitted to other neurons or passed
along the nerves.

14
As Dennett puts it: ‘The representation of space in the brain does not always
use space-in-the-brain to represent space, and the representation of time
in the brain does not always use time-in-the-brain.’ (Dennett 1992, p. 131).
The distinction between space and time in the mind and space and time
in the objective world was introduced by Kant (1996), who claimed that
space and time are forms of intuition. According to Kant it is unknowable
whether space and time are present in the objective noumenal world.

15 It might be thought that the traditional primary property of number is an
exception. However, number is not a physical property, but the magnitude
of a physical property, which is obtained through a measurement
procedure and varies with the system of units. For example, we can carry
Endnotes 167

out an act of counting that results in a number, or extract the ratio of two
masses as a number. Consider a ball that weighs 7.3 kilos (16.1 pounds):
the mass is a physical property of the ball, not the numbers 1, 7.3 or 16.1.

16 Kant’s (1996) metaphysics expresses a similar idea: the noumenal physical
world is an invisible source of signals that are processed through the
categories to become phenomenal experiences.

17 This use of discrete black boxes to illustrate objects in the physical world
is not strictly correct because the boundaries between physical objects
depend on the observer’s sensory apparatus and ontology (Gamez 2007,
Chapter 5).

18 Russell (1927, p. 163).

19 Many people today have a different interpretation of our bubbles of
experience, which is often aligned with idealism and rejects the scientific
interpretation of physical reality—Tibetan Buddhism is one example. This
book will not examine these other interpretations of consciousness and the
physical world.

20
‘Consciousness’ is sometimes used to refer to an individual person’s
consciousness and sometimes used as a mass term to refer to all of the
consciousness in existence—just like ‘water’ is used to refer to all of the
water in existence. ‘What is consciousness?’ and ‘What is water?’ treat
consciousness and water as mass terms. In this definition I have tried to
limit the ambiguity by linking a state of a consciousness to a state of a
bubble of experience.

21 Galilei (1957, p. 274).

22
Suppose a person’s bubble of experience contains three objects, P, Q and
R. P appears with intensity 0.7, Q appears with intensity 0.8 and R appears
with intensity 0.3 (these values are purely illustrative). According to the
proposed definition, this person’s overall level of consciousness would be
the average of these intensity values: (0.7+0.8+0.3)/3 = 0.6.

23
This is similar to our use of ‘awake’, except a person can be awake without
having a bubble of experience. For example, vegetative state patients are
presumed to be unconscious, but they can have cycles of wakefulness in
which they open their eyes and move their body in meaningless ways
(Laureys et al. 2002).

24 Metzinger (2003) has a good discussion of online and offline conscious
experience.
168 Human and Machine Consciousness

25
Functional connectivity (a deviation from statistical independence
between A and B) is typically contrasted with structural connectivity (a
physical link between A and B) and from effective connectivity (a causal
link from A to B)—see Friston (1994; 2011). A number of algorithms exist
for measuring functional and effective connectivity.

26
The research on change blindness, attentional blindness and change
detection in peripheral vision suggests that the amount of online conscious
content is less than we think (Cohen and Dennett 2011; Rensink et al. 1997;
Simons and Chabris 1999; Simons and Rensink 2005).

27 Wilkes (1988b, pp. 16-7).

28 Wilkes (1988b, p. 38).

29 Lucretius (2007) claims that the soul (a combination of spirit [anima, the
vital principle] and mind [animus, the intellect]) is a subtle particle. See
Chapter 6, Footnote 10.

3. The Philosophy and Science of Consciousness
1 See Husserl (1960).

2 For example, Smart (1959).

3 See Section 2.1.

4 For example, piano-playing pigs are unlikely to have entered the Aztecs’
imaginations.

5 See Nagel (1974).

6 Other problems with thought experiments and imagination have been
discussed by Wilkes (1988a) and Gamez (2009). The Stanford Encyclopedia
of Philosophy has a good overview (Brown and Fehige 2014).

7 McGinn (1989, p. 349).

8 Metzinger (2000, p. 1).

9 The quote by McGinn at the beginning of this section is a typical description
of the hard problem of consciousness. Chalmers (1995b) made a popular
distinction between easy and hard problems of consciousness. Strawson
(2015) gives a historical overview.

10 This example has been simplified. If the brain-imaging device showed the
complete state of my brain on the screen, then the conscious experience
Endnotes 169

of p1 would be linked to everything that was going on in my brain, both
consciously and unconsciously—it would not just be the pattern associated
with my conscious experience of the ice cube. Multiple experiments would
be required to identify and selectively display the brain activity that was
linked to my conscious experience of the ice cube.

11 To make the text easier to read I have separated conscious experiences
of brains from other conscious experiences. However, our conscious
experience of a brain is a conscious experience. So in this example, some
of the brain patterns on the screen will be associated with our conscious
experience of the brain patterns on the screen.

12 Our finite cognitive capacities (long and short term memory, etc.) will
limit our ability to learn associations between conscious experiences of
brain patterns and other conscious experiences. For example, it is unlikely
that we will be able to learn all of the details of a complex brain pattern.

13 Rorty (1980, p. 71).

14 I have told this story from the perspective of consciousness. It can also be
told in terms of physical brain activity. If we knew enough about the brain,
we could describe how it learns to associate sensory stimuli from brains
with other sensory stimuli.

15 Elementary wave-particles and superstrings are only put forward as
examples. Future advances in physics might explain the behaviour of
elementary wave-particles and superstrings in terms of brute regularities
at a lower level.

16
Boyle’s law is a good example of a scientific law that can be explained
in terms of regularities at a lower level. It states that the pressure of a
gas is inversely proportional to its volume in a closed system at constant
temperature. This macro-scale experimental observation can be explained
in terms of the behaviour of atoms and molecules, which was formerly
treated as a brute regularity that was the starting point for scientific
explanations.

4. The Measurement of Consciousness
1 Chalmers (1998, p. 220).

2 Descriptions of consciousness can be interpreted as statements about the

physical world. When I report that I have a conscious experience of a rusty
helmet beside my conscious experience of my left foot, I am also reporting
that there is a rusty helmet beside my left foot in the physical world.
170 Human and Machine Consciousness

3 Wittgenstein (1969) discusses how our knowledge is underpinned by
a framework of certainties that cannot be doubted without putting
everything into question.

4
When we imagine different motor tasks, such as walking around a house or
playing tennis, we activate different brain areas that can be discriminated
in a fMRI scanner. This enables people to answer yes/no questions about
their consciousness by imagining that they are performing one of two
actions. This method has been used to communicate with patients in
vegetative or minimally conscious states, who were incapable of other
forms of voluntary behaviour (Monti et al. 2010; Owen et al. 2006).

5 This list of behaviours includes suggestions from Shanahan (2010), Koch
(2004) and Teasdale and Jennett (1974).

6 Post-decision wagering is a method that is used to measure consciousness
in psychology (Persaud et al. 2007). A person is asked to make a decision
and to bet on the accuracy of that decision. It is assumed that the person
will bet more money on decisions that are based on conscious information.
See Sandeberg et al. (2010) for a comparison of post-decision wagering, the
perceptual awareness scale and confidence ratings.

7 An overview of some of the techniques for measuring consciousness is
given by Seth et al. (2008).

8 Damasio (1999, p. 6).

9 An overview of binocular rivalry is given by Blake (2001).

10
This is a simplified summary of the large number of experiments that
have been carried out on visual masking and non-conscious perception.
For example, Dell’Acqua and Grainger (1999) showed that unconsciously
perceived pictures influenced subjects’ ability to consciously name
pictures and categorize words. Schütz et al. (2007) showed that masked
prime words can influence how subjects complete gap words. Merikle and
Daneman (1996) played words to patients under general anaesthesia and
found that when they were awake they completed word stems with words
that they had heard non-consciously. A change in the skin’s conductivity
is known as a galvanic skin response, which can indicate that information
is being processed unconsciously (Kotze and Moller 1990). Öhman and
Soares (1994) showed that subjects’ skin conductance response changed
when they unconsciously perceived phobic stimuli, such as pictures of
snakes or spiders. A review of experimental work on visual masking and
non-conscious perception is given by Kouider and Dehaene (2007).
Endnotes 171

11 This is known as forced choice guessing. While some people believe that
above chance results on a forced choice guessing task demonstrate that
conscious information is present, blindsight patients can guess the identity
of visual stimuli above chance while reporting no subjective awareness
(Weiskrantz 1986). Seth et al. (2008) discuss these issues.

12 By ‘associated’ it is meant that consciousness is linked to a platinum
standard system, but no claims are being made about causation or
metaphysical identity.

13 The metre used to be defined as one ten-millionth of the distance from the
Earth’s equator to the North Pole at sea level. Since this was difficult to
measure, a platinum-iridium bar was used instead. Rulers were directly
or indirectly calibrated against this bar, which was kept in Paris.

14 Ifthe platinum-iridium standard metre doubled in size, an object that
used to be 1 metre long (1 platinum-iridium standard metre bar) would
have a new length of 0.5 metres (0.5 platinum-iridium standard metre
bars). This would only be strictly true if the platinum-iridium bar was
the actual definition of the metre, rather than the working definition. The
same argument applies to the actual definition of the metre.

15
Functional connectivity (a deviation from statistical independence
between A and B) is typically contrasted with structural connectivity (a
physical link between A and B) and from effective connectivity (a causal
link from A to B)—see Friston (1994; 2011). A number of algorithms exist
for measuring functional connectivity (for example, mutual information),
and it can be measured with a delay.

16
While phenomenal consciousness and access ‘consciousness’ might be
conceptually dissociable (Block 1995), the idea that non-measureable
phenomenal consciousness could be present during experiments on
consciousness is incompatible with the scientific study of consciousness.
Block’s non-accessible phenomenal consciousness does not appear in
c-reports, so everything that Block has ever written or said about it is
meaningless or false.

17 A possible exception to this would be a situation in which non-reportable
consciousness is present but does not interfere with our ability to identify
the correlates of consciousness. This is discussed in more detail in Chapter
9, Footnote 13.

18 This is similar to Block’s (2007) idea of cognitive accessibility.
172 Human and Machine Consciousness

19 Dennett questions the idea that there is a single stream of consciousness
with a fixed content: ‘the Multiple Drafts model avoids the tempting
mistake of supposing that there must be a single narrative (the ‘final
or ‘published’ draft, you might say) that is canonical—that is the actual
stream of consciousness of the subject, whether or not the experimenter (or
even the subject) can gain access to it.’ (Dennett 1992, p. 113). Personally I
do not find Dennett’s arguments for his multiple drafts model convincing.
We will find out if he is correct, because it will be impossible to obtain
systematic stable measurements of consciousness.

20 Panpsychism is the view that all matter is linked to consciousness. For
example, some versions of panypsychism claim that individual electrons,
quarks, etc. are associated with simple bubbles of experience.

21 A2 is also likely to be incompatible with Zeki and Bartels’ (1999) proposal
that micro-consciousnesses are distributed throughout the brain.

22
The perceived colour of an object does not just depend on the frequencies
of the electromagnetic waves that are reflected, transmitted or emitted
by it. Our visual system also uses the spectrum of illuminating light and
the colour of surrounding objects to identify an object’s colour, which
enables us to attribute the same colour to objects under different lighting
conditions. I have used electromagnetic wave frequencies to simplify the
presentation of the colour inversion argument, which also applies to a
more accurate account of colour perception.

23 There are likely to be subtle behavioural differences between two colour-
inverted people—see Palmer (1999) for a discussion of behaviourally
equivalent inversion scenarios. These differences would disappear if
completely different sets of ‘colour’ experiences were linked to frequencies
of electromagnetic waves.

24
If a set of properties, A, supervenes on another set of properties, B, then
it is impossible for two things to have different A properties without also
having different B properties. This is not a causal relationship.

25 Kouider et al. (2013) and Dehaene (2014) discuss infant consciousness.

26 Animal consciousness is discussed by Dehaene (2014), Edelman and Seth
(2009) and Feinberg and Mallatt (2013).

27 People with Anton-Babinski syndrome are blind, but claim that they
can see and confabulate to cover up the contradictory evidence. Other
anosognosia patients are completely paralyzed on one side, but claim that
their body is working perfectly.
Endnotes 173

28
Section 2.4 discusses theories that link consciousness to sensorimotor
interactions between the brain, body and environment. In previous work I
made the assumption that the awake normal adult human brain is a platinum
standard system (Gamez 2011; Gamez 2012a). The more developed account
of c-reports presented in this book makes the assumption that the brain is
awake unnecessary—immobility, unresponsiveness, etc. are c-reports of
zero consciousness.

29
Although brain-damaged patients have played an important role in
consciousness research, they should not be uncritically assumed to be
platinum standard systems. There can be ambiguities about whether the
damage has knocked out the memory and reporting functions and left
the consciousness intact, or knocked out the consciousness and left the
memory and reporting functions intact. For example, locked-in patients
are thought to be fully conscious, but they are only capable of moving their
eyes, and some of the patients studied by Owen et al. (2006) and Monti
et al. (2010) are likely to be conscious but unable to display this in their
external behaviour. The use of brain-damaged patients in consciousness
research has the further problem that the damage is typically non-localized
and some brain areas are likely to perform several different functions. One
way of addressing this issue is to assume that brain-damaged patients are
platinum standard systems on a case-by-case basis, taking the details of the
damage into account and its likely impact on memory and/or reporting.
A similar ambiguity applies to the use of anaesthetics in consciousness
research. For example, midazolam, xenon and propofol are used to induce
unconsciousness, so that scientists can compare the state of the conscious
and unconscious brain (Casali et al. 2013). This raises the question whether
the anaesthetic completely removes consciousness, or just paralyzes the
body and prevents the subject from remembering and reporting their
consciousness. This issue can also be addressed on a case-by-case basis.
We can examine the mechanism of each anaesthetic and decide whether it
is likely to affect the areas linked to memory and/or reporting. Normally
functioning adult human brains containing anaesthetics that do not
affect memory and/or reporting can be assumed to be platinum standard
systems.
Animal experiments can also be handled on a case-by-case basis.
We can assume that the brains of monkeys or mice are associated
with consciousness, so that we can use these animals in consciousness
research.

30 The notion of a minimal set is intended to exclude features of the brain that
typically occur at the same time as consciousness, whose removal would
not lead to the alteration or loss of consciousness. For example, a CC set
174 Human and Machine Consciousness

might have prerequisites and consequences (Aru et al. 2012; de Graaf et al.
2012) that typically co-occur with consciousness, but the brain would be
conscious in exactly the same way if the CC set could be induced without
these prerequisites and consequences.

31 This is similar to Chalmers’ (2000) definition of the total correlates of
consciousness, which he distinguishes from the core neural basis: ‘A
total NCC builds in everything and thus automatically suffices for the
corresponding conscious states. A core NCC, on the other hand, contains
only the “core” processes that correlate with consciousness. The rest of
the total NCC will be relegated to some sort of background conditions
required for the correct functioning of the core.’ (Chalmers 2000, p. 26).
Block (2007) makes a similar distinction.

32 This will not be correct if some spatiotemporal structures can inhibit
consciousness. For example, we might have a CC set, cc1, that is a correlate
of consciousness according to D5. In most circumstances consciousness
would be present whenever cc1 was present. However, if consciousness
was inhibited by ih1, then there could be a situation in which cc1 and ih1
were present together and there was no consciousness.

33
Footnote 15 explains the relationship between functional and effective
connectivity. These are typically inferred from data using algorithms, such
as Granger causality or mutual information, and they are distinct from
physical causation, which is discussed in the next section.

34
There are many spurious correlations—for example, see Vigen (2016).
These can be divided into false correlations, which are the result of poor
statistical procedures, and true but unlikely correlations that might be
due to an underlying cause. When there is a true correlation between A
and B it is possible to obtain information about B by measuring A and
vice versa (the amount of information that one can obtain depends on
the strength of the correlation). In this book I am presenting a framework
that is based the assumption that there is a true statistical correlation
(functional connection) between consciousness and the physical world.
So we can obtain information about consciousness by measuring parts of
the physical world and obtain information about the physical world by
measuring consciousness.

35 Kim (1998, p. 31).

36 This distinction is taken from Dowe (2000). It is similar to Fell et al.’s
(2004) distinction between efficient and explanatory causation. Efficient
causation is concerned with the physical relation of two events and the
exchange of physically conserved quantities. Explanatory causation refers
to the law-like character of conjoined events.
Endnotes 175

37 Predominantly conceptual accounts of causation include Lewis’ (1973)
counterfactual analysis and Mackie’s (1993) INUS conditions. Empirical
theories based on the exchange of physically conserved quantities have
been put forward by Aronson (1971a; 1971b), Fair (1979) and Dowe (2000).
Bigelow et al. (1988) and Bigelow and Pargetter (1990) link causation to
physical forces.

38 See Dowe (2000).

39 A world line is the path of an object through space and time.

40 If all empirical theories of causation are unworkable, then we might have
to limit causal concepts to ordinary language and abandon the attempt
to develop a scientific understanding of the causal relationship between
consciousness and the physical world.

41 Kim (1998) has a good discussion of the relationship between macro and
micro physical laws.

42 Wilson (1999) discusses the minimum amount of physical effect that
would be required for consciousness to influence the physical brain.

43 A related point is made by Fell et al. (2004), who argue that the neural
correlates of consciousness cannot e-cause conscious states.

44
Controversial experiments by Libet (1985) have indicated that our
awareness of our decision to act comes after the motor preparations for the
act (the readiness potential). This suggests that our conscious will might
not be the cause of our actions, and Wegner (2002) has argued that we
make inferences after the fact about whether we caused a particular action.
These results could be interpreted to show that CC sets do not e-cause
c-reports about consciousness because motor preparations for verbal
output (for example) would precede the events that are correlated with
consciousness. This problem could be resolved by measuring the relative
timing of a proposed correlate of consciousness (CC1 in Figure 4.4) and the
sequence of events leading to the report about consciousness, including
the readiness potential (R1-R3 in Figure 4.4). If the framework presented
in this book is correct, then it should be possible to find CC sets with the
appropriate timing relationship. If no suitable CC sets can be found, then
the framework presented in this book should be rejected as flawed. It is
worth noting that Libet’s measurement of the timing of conscious events
implicitly depends on a functional connection between consciousness and
c-reporting behaviour—the relative timing of consciousness and action can
only be measured if consciousness is functionally connected to c-reports
about consciousness (in this case with a delay).
176 Human and Machine Consciousness

45
It is reasonably easy to see how the contents of consciousness that are
c-reported could be e-caused by physical events. For example, we can
tell a simple story about how light of a particular frequency could lead to
the activation of spatiotemporal structures in the brain, and how learning
processes could associate these with sounds, such as ‘red’ or ‘rojo’. This
might eventually enable a trained brain to produce the sounds ‘I can see
a red hat’ or ‘I am aware of a red hat’ when it is presented with a pattern
of electromagnetic waves. Since consciousness does not appear to us as a
particular thing or property in our environment and many languages do
not contain the word ‘consciousness’ (Wilkes 1988b), it is not necessary
to identify sensory stimuli that the physical brain could learn to associate
with the sound ‘consciousness’. The concept of consciousness can be more
plausibly interpreted as an abstract concept that is acquired by subjects
in different ways (see Chapter 2). So it is conceivable that the scientific
study of consciousness could be carried out without subjects ever using
the word ‘consciousness’ in their c-reports.

46 See Footnote 15 for the distinction between structural, functional and
effective connectivity. Effective connectivity can be measured using
algorithms, such as transfer entropy (Schreiber 2000) or Granger causality
(Granger 1969), which works on the assumption that a cause precedes and
increases the predictability of the effect. However, effective connectivity
does not always coincide with e-causation—for example, when a signal is
connected to two areas with different delays.

47 In the real brain many areas are reciprocally connected to each other and
there is a great deal of recurrent processing. This simplified diagram only
shows the general flow of activity from perception to reporting.

48 Cohen and Dennett (2011) illustrate the low resolution of our peripheral
vision.

49 Our ability to access high resolution information on demand contributes
to our sense that we perceive the world in uniformly high resolution
(O’Regan 1992).

50
This is a conservative estimate based on eye-movement driven changes
and the assumption that consciousness consists of a series of discrete
moments (the specious present). It is also possible that consciousness
changes continuously.

51 See O’Regan (1992).

52
People can be trained to make more accurate reports about their
consciousness (Lutz et al. 2002) and there has been a substantial amount
Endnotes 177

of work on the use of interviews to help people describe their conscious
states. In the explication interview (EI) a trained person interviews a
subject about a conscious state to help them provide an accurate report
(Petitmengin 2006). In descriptive event sampling (DES) the subject carries
a beeper, which goes off at random several times per day. When they hear
the beep the subject makes notes about their consciousness just before the
beep. This is followed by an interview that is designed to help the subject
to provide faithful descriptions of the sampled experiences (Hurlburt and
Akhter 2006). Froese et al. (2011) discuss some of the first- and second-
person methods for measuring consciousness. These techniques place
a heavy reliance on memory, so it is unlikely that they can address the
problems highlighted in this section.

53 Shanahan (2010) suggests how an omnipotent psychologist could measure
a person’s consciousness by reversing time and carrying out different
interventions.

54 Mental techniques could also be used to reset consciousness. For example,
people with a high level of mental focus, possibly gained through
meditation, might be capable of putting their consciousness into a
particular state and maintaining this state for an extended period of time.

55 It might be possible to use what we know about the relationship between
a stimulus and consciousness to make reliable inferences about a person’s
state of consciousness. Suppose we knew that an awake expectant person
always has a conscious experience of a red rectangle when a red rectangle
is presented at the centre of their visual field. If this inference was reliable,
it might not be necessary to measure their consciousness using c-reports
when we expose them to a red rectangle—we could simply infer that
since they are looking at a red rectangle, they must be conscious of a red
rectangle. However, the limited resolution and active nature of the visual
system means that a complex model will be required to map between
stimuli and conscious states. Furthermore, this method of inference can
only be developed by measuring consciousness using c-reports, which
depends on the assumptions that have been presented in this chapter.

56 Nagel (1974, p. 449).

57 You might think that you could validate the descriptions by resetting your
consciousness to the state that is being described. But then you would
have to compare a remembered description with your current state of
consciousness without modifying your current state of consciousness.

58 Formal descriptions of the physical world are covered in Section 5.1.
178 Human and Machine Consciousness

59 These problems are discussed by Chrisley (1995a) and Gamez (2006).

60 The use of XML to describe consciousness is discussed by Gamez (2006;
2008a).

61 See Balduzzi and Tononi (2009).

5. Correlates and Theories of Consciousness
1 This is the current definition of a metre.

2 This is our conscious experience of measurement. I could also describe
how Randy’s height is measured by the physical brain of the scientist.

3 Eddington (1928, pp. 251-2).

4 This definition of measurement is a simplified version of the one put
forward by Pedhazur and Schmelkin (1991), who take it from Stevens
(1968). According to Stevens, most measurement involves ‘the assignment
of numbers to aspects of objects or events according to one or another rule
or convention.’ (Stevens 1968, p. 850). Pedhazur and Schmelkin stress that
numbers are assigned to aspects of objects, not to objects themselves. We
measure the height, width and colour of a box, not the box itself.

5 For example, if we cannot devise a way of p-describing neurons, then it
will be difficult to make inferences about the consciousness of animals
with larger neurons, such as snails and insects, and we will not be able to
say anything about the consciousness of artificial systems.

6
Intrinsic properties are tied to an object’s physical nature. They are held
by an object independently of its spatial and temporal context. Extrinsic
properties depend on an object’s relationships with other parts of the
world. The chemical composition of a neuron is an intrinsic property. The
distance of a neuron from the North Pole is an extrinsic property, which
would change if the North Pole changed location.

7 It is conceivable that some CC sets could be 60% correlated with conscious
states. Experimental work could determine whether this is the case. C3
will not apply if there are inhibitors of consciousness (see Chapter 4,
Footnote 32).

8 Elsewhere I distinguished between type A and type B correlates of
consciousness (Gamez 2014c). Type A correlates can e-cause c-reports
and are compatible with C4. Type B correlates are not compatible with C4
because they cannot e-cause c-reports.
Endnotes 179

9 This discussion assumes that there is a 1:1 ratio between CC sets and
conscious states.

10 The technologies that are available for measuring the brain are covered in
Section 12.2.

11 I have discussed elsewhere how the correlates of consciousness can be
experimentally separated out from their prerequisites and consequences
and from sensory and reporting structures (Gamez 2014c). Pitts et al.
(2014) describe experimental work that attempts to separate the correlates
of conscious perception from reporting structures. This is also discussed
by Koch et al. (2016).

12 Rees et al. (2002), Tononi and Koch (2008), Dehaene (2014) and Koch et
al. (2016) describe some of the research that has been carried out on the
neural correlates of consciousness.

13 Any kind of ‘passive’ monitoring or measurement involves the passage
of physically conserved quantities from the system to the measuring
device. In a natural experiment this is small compared to the exchange of
physically conserved quantities within the system, so it does not affect our
assumption that the system is a platinum standard.

14 This experiment has been extensively discussed—for example, by Moor
(1988), Chalmers (1996a), Van Heuveln et al. (1998) and Prinz (2003). Part
of the brain could be replaced by any functionally equivalent system, such
as a giant lookup table or the population of China communicating with
radios and satellites (Block 2006).

15
We have an intuition that we would notice if, for example, the implantation
of the chip removed half of our visual consciousness. But according to the
premises of the experiment, our behaviour would be identical, so nothing
in our thoughts or speech would reflect this change in consciousness. If the
implanted chip did affect our consciousness we would not be cognitively
aware of the change and it would not affect our ability to perceive and
respond to the world. We would be like people with anosognosia (see
Chapter 4, Footnote 27), with the difference that our sight and bodies
would be working perfectly, so no external observer could detect the
change in our consciousness.

16
It might be argued that neurons die all the time, so surely replacing one
neuron with silicon should not affect our assumption that the brain is a
platinum standard? And so on with two neurons, three neurons, until
the entire brain has been replaced. Chalmers’ (1995a) fading and dancing
qualia argument proceeds along these lines. One problem with this
180 Human and Machine Consciousness

argument is that it is based on the invalid assumption that we can imagine
the relationship between consciousness and the brain (see Chapter 3).
Another problem is that the brain can be sensitive to individual spikes, so
the replacement of individual neurons could affect its consciousness. For
example, a single neuron could individually encode an abstract concept or
make a significant contribution to a population code. If this neuron was
part of a CC set, then its replacement with a silicon chip could alter the
associated conscious state.

17
The assumption that brains with implanted chips are conscious is
equivalent to the assumption that functionalism is true. This brings in all of
the problems with computation and information theories of consciousness
that are discussed in Chapters 7 and 8.

18 Popper (2002, pp. 279-80).

19 Tononi (2008, p. 217). I also could have quoted Dehaene: ‘Only mathematical
theory can explain how the mental reduces to the neural. Neuroscience
needs a series of bridging laws, analogous to the Maxwell-Boltzmann
theory of gases, that connect one domain with the other. This is no easy
task: the “condensed matter” of the brain is perhaps the most complex
object on earth. Unlike the simple structure of a gas, a model of the brain
will require many nested levels of explanation. In a dizzying arrangement
of Russian dolls, cognition arises from a sophisticated arrangement of
mental routines or processors, each implemented by circuits distributed
across the brain, themselves made up of dozens of cell types. Even a single
neuron, with its tens of thousands of synapses, is a universe of trafficking
molecules that will provide modelling work for centuries.’ (Dehaene 2014,
p. 163).

20 I have discussed the need for c-theories elsewhere (Gamez 2012b).

21 The search for c-theories is closely related to the attempt to discover
the relationship between brain activity and behaviour. Computational
methods could also be used to study this relationship (see Section 5.6).
However, c-theories might be based on non-neural structures in the brain,
such as novel materials, haemoglobin and electromagnetic waves (see
Section 6.2 and Section 6.3), that would not be required by theories that
describe the relationship between neuron activity and external behaviour.

22
‘Mathematics’ should be interpreted in a broad sense that includes
computer algorithms.

23 This example and its intensity values are purely illustrative. More work
needs to be done on the conversion of c-reports into c-descriptions that
Endnotes 181

record the intensity of different aspects of conscious experience. This
could draw on previous work in psychophysics—for example, Gescheider
(1997).

24
This is an unashamedly Popperian approach to the science of consciousness.
Some would argue that Popper (2002) presents an outmoded account of
the philosophy of science, which should be replaced by Kuhn (1962) at
least, or perhaps Feyerabend (1975) or Latour (1987). Some of these later
‘relativist’ ‘constructivist’ ‘postmodern’ accounts reject the possibility of
scientific progress altogether. However, if we are attempting to understand
how a science of consciousness can be developed, we need a model of what
science is. And I would argue that Popper provides a carefully thought
out and convincing account of what good scientific practice should be.
Other philosophies of science can be used to interpret the science of
consciousness, but many of them are considerably less useful as guiding
principles than Popper—how (or why) would we develop a science of
consciousness based on Feyerabend or Latour?

25
C-theories describing brute regularities have some similarity with
Chalmers’ psychophysical laws: ‘Where we have new fundamental
properties, we also have new fundamental laws. Here the fundamental
laws will be psychophysical laws, specifying how phenomenal (or
protophenomenal) properties depend on physical properties. These laws
will not interfere with physical laws; physical laws already form a closed
system. Instead they will be supervenience laws, telling us how experience
arises from physical processes. We have seen that the dependence of
experience on the physical cannot be derived from physical laws, so any
final theory must include laws of this variety.’ (Chalmers 1996a, p. 127).
However, this book suspends judgment about some of the metaphysical
substance-based theories, and the relationship between c-descriptions
and p-descriptions is symmetrical, not a causal relationship in which
consciousness arises from physical processes.

26 For example, Tononi’s (2008) information integration theory is based on
his first-person observations about the differentiation and integration of
consciousness.

27 Humphreys (2004, p. 90).

28 There is also a more general question about whether one human brain
can fully understand another—one might think that a brain could only
be understood by a larger and more complicated system. This issue can
potentially be addressed by using the world as external memory (Clark
2008; O’Regan 1992). This would only work if our understanding of the
brain can be broken down into interrelated modules. For example, we
182 Human and Machine Consciousness

could develop a detailed understanding of how a neuron works, write
it down, and then work on a different aspect of the problem, until we
had written down everything about the brain. Although the final solution
could not be comprehended by a single brain all at once, one or more
brains could check the validity of each part and the links between them.

29 A substantial amount of research has been carried out on the use of
computers for scientific discovery (Dzeroski and Todorovski 2007).
Robotic systems have been developed that can carry out experiments
automatically (Sparkes et al. 2010), and there has been research on the
automatic discovery of differential equations that describe the behaviour
of dynamic physical systems (Schmidt and Lipson 2009). This work
suggests how consciousness could be scientifically studied in the future.

30 For example, Billeh et al. (2014) have developed a way of identifying
functional circuits in recordings of spiking activity from hundreds of
neurons. Using this approach it might be possible to develop a way of
describing brain activity in terms of interacting circuits, which could be
identified automatically by a computer.

31 The Blue Brain Project has developed detailed models of a cortical
column (Markram 2006) and this work is being continued on a larger
scale in the Human Brain Project (www.humanbrainproject.eu). Larger,
less detailed models have also been built of human and animal brains
(Ananthanarayanan et al. 2009; Izhikevich and Edelman 2008). The
feasibility of scanning and simulating a human brain is discussed in
Chapter 11, Footnote 14. None of the current models generates behaviour
that is similar to c-reports and most of them do not include non-neural
components of the brain, such as glia.

32 The ‘c-reports’ of a simulated brain could not be used to measure its
consciousness because a neural simulation is not a platinum standard
system.

33 Simulations are very different from real brains, so this would primarily
be a test of the methodology. However, this type of work might lead to
c-theories that could be tested on real brains.

34 This methodology could also be used to solve the more general problem
of the relationship between an organism’s brain activity and all of its
behaviour (both conscious and non-conscious). Once the behaviour
had been formally described, computers could be used to discover
relationships between the brain activity and behaviour. This approach
could be prototyped on a very simple system, such as a simulated C.
elegans.
Endnotes 183

6. Physical Theories of Consciousness
1 The pattern/material distinction captures a useful way of speaking about
the physical world at different spatial scales. However, one can also
argue that elementary wave-particles are the only material and all other
‘materials’ are patterns in elementary wave-particles. Physical c-theories
can be expressed using either interpretation of the pattern/material
distinction.

2 A neuron’s distance from the North Pole is a property of the neuron and
the North Pole combined—it changes when the location of the North
Pole changes. The brain has intrinsic properties that enable it to reflect
particular frequencies of electromagnetic waves. The set of electromagnetic
waves that is actually reflected depends on the brain’s properties and on
the properties of the waves. If electromagnetic waves altered their nature,
the brain’s reflectance of electromagnetic waves would change.

3 I have discussed this issue in more detail in a paper that distinguishes
between type A correlates of consciousness that meet constraint C4, and
type B correlates of consciousness that do not (Gamez 2014c).

4 A quantum theory of consciousness has been put forward by Hameroff
and Penrose (1996). Electromagnetic theories of consciousness have been
put forward by Pockett (2000) and Macfadden (2002).

5 The potential connection between consciousness and a global workspace
was first elaborated by Baars (1988). A number of computational and neural
models of a global workspace have been built (Franklin 2003; Gamez et al.
2013; Shanahan 2008; Zylberberg et al. 2010) and a substantial amount of
research has been done on the possibility that a global workspace might be
implemented in the brain (Dehaene and Changeux 2011).

6 For example, Bartfield et al. (2015) and Godwin et al. (2015) describe
functional connectivity patterns that are potentially linked to consciousness.

7 See Gamez (2014b).

8 See Tononi and Sporns (2003), Balduzzi and Tononi (2008) and Oizumi
et al. (2014). In a physical c-theory Tononi’s algorithms would connect
patterns in a particular material to a conscious state. This relationship
would only hold for a specific material—the same patterns in a different
material would not be linked to consciousness. This is distinct from
the use of Tononi’s algorithms to identify information patterns that are
linked to consciousness, which is discussed in the next chapter. Liveliness
(Gamez and Aleksander 2011), causal density (Seth et al. 2006) and Casali
184 Human and Machine Consciousness

et al.’s (2013) perturbational complexity index can also be re-interpreted as
descriptions of patterns in materials that might be linked to consciousness.

9 A formal description of biological structures is required if CC sets contain
biological materials and we want to make predictions or deductions
(see Chapter 9) about the consciousness of non-biological systems. For
example, a formal description of neurons could help us to decide whether
a robot controlled by artificial neurons is conscious.

10 Lucretius’ (2007) theory about the soul is similar to this view. He claims
that the soul (a combination of spirit [anima, the vital principle] and mind
[animus, the intellect]) is a minute particle:

The nature of the mind and spirit is such it must consist
Of stuff composed of seeds that are so negligibly small,
Subtracted from the flesh, they don’t affect the weight at all.
Nor should we think this substance is composed of one thing, neat,
For from the dying there escapes a slight breath mixed with heat,
While heat, in turn, must carry air along with it; for there
Is never any heat that is not also mixed with air,
Because heat’s substance, being loose in texture, has to leave
Space for many seeds of air to travel through its weave.
This demonstrates the nature of the mind’s at least threefold –
Even so, these three together aren’t enough, all told,
To generate sensation, since the mind rejects the notion
Any of these is able to produce sense-giving motion,
Or the thoughts the mind itself turns over. And so to these same
Three elements, we have to add a fourth that has no name.
There is nothing nimbler than this element at all –
Nothing is as fine as this is, or as smooth or small.
It’s this that first distributes motions through the frame that lead
To sense, since this is first to bestir, composed of minute seed.
Lucretius (2007, pp 78-9)

11 At most people have invoked the known properties of quantum mechanics,
which are unlikely to play much of a role (Wilson 1993).

12 Novel materials will not help us to imagine the relationship between
consciousness and the physical world. If they are similar to the rest of the
physical world, then they will be invisible, and we will be unable to make
an imaginative transition from the invisible novel material to conscious
experiences (see Section 3.3). If the novel material is more like a spark of
consciousness embedded in matter, then we will be able to imagine the
material, but we will find it difficult to imagine how it relates to other
conscious experiences (see Section 3.4).
Endnotes 185

13 To make this assumption work it will be necessary to find a way of
comparing the strength of patterns in different materials. For example,
how can you compare the strength of electromagnetic field patterns
(measured in volts) with blood flow patterns (measured in cm/s)?

7. Information Theories of Consciousness
1 Tononi (2008, p. 237).

2 Floridi (2010, p. 1).

3 Floridi uses ‘dedomena’ to describe differences in the physical world
that exist independently of us: ‘Dedomena are […] pure data or proto-
epistemic data, that is, data before they are epistemically interpreted. As
“fractures in the fabric of being” they can only be posited as an external
anchor of our information, for dedomena are never accessed or elaborated
independently of a level of abstraction […] They can be reconstructed
as ontological requirements, like Kant’s noumena or Locke’s substance:
they are not epistemically experienced but their presence is empirically
inferred from (and required by) experience. Of course, no example can be
provided, but dedomena are whatever lack of uniformity in the world is
the source of (what looks to information systems like us as) as data, e.g. a
red light against a dark background.’ (Floridi 2009, pp. 17-8).

4 This notion of an interface is based on Floridi’s level of abstraction:
‘[…] data are never accessed and elaborated (by an information agent)
independently of a level of abstraction (LoA) […]. A LoA is a specific set of
typed variables, intuitively representable as an interface, which establishes
the scope and type of data that will be available as a resource for the
generation of information.’ (Floridi 2009, p. 37). Floridi (2008) describes
levels of abstraction in detail.

5 I can also extract the text of Madame Bovary from the DRAM voltages by
defining a mapping between 011100100110010101100100 and the complete
text of Madame Bovary.

6 A time-indexed interface uses a combination of time and the system’s
state to extract information. Suppose an elementary wave-particle shifts
between two states: you can interpret the appearance of state 1 at time 1 as
‘r’, the appearance of state 1 at time 3 as ‘e’, and so on.

7 The notion of a custom interface is inspired by discussions about whether
physical systems implement finite state automata (Bishop 2002; Bishop
2009; Chalmers 1996b; Chrisley 1995b; Putnam 1988).
186 Human and Machine Consciousness

8 According to Floridi’s (2009) formulation of the general definition of
information, σ is an instance of information, understood as semantic
content, if and only if: 1) σ consists of n data, 2) the data are well formed, 3)
the well-formed data are meaningful. My earlier work used this distinction
to analyze Tononi’s information integration theory of consciousness
(Gamez 2011; Gamez 2016). I am indebted to Laurence Hayes for helping
me to see that the data/information distinction is unworkable.

9 See Shannon (1948). Tononi’s (2004; 2008) information integration theory
of consciousness is based on this interpretation of information.

10 There are several versions of Tononi’s information integration theory
of consciousness (Balduzzi and Tononi 2008; Oizumi et al. 2014; Tononi
2004). Tononi (2008) gives a good overview and his book offers a
simple introduction without the mathematical treatment (Tononi 2012).
Experimental work on the information integration theory of consciousness
has been carried out by Lee et al. (2009), Massimini et al. (2009), Ferrarelli
et al. (2010), and Casali et al. (2013).

11 Barrett (2014) suggests how Tononi’s information integration theory of
consciousness can be interpreted as a physical c-theory.

12 Tononi (2008) suggests that his algorithm could be applied to all possible
levels of the brain—the level at which it reaches a maximum would be the
one that is correlated with consciousness.

13 It might be objected that if information is subjective, then surely it must
be present in the brain? Where else can subjective things be? However, the
neural mechanisms (and electromagnetic fields etc.) that are active when
our brain applies an interface to a physical system are purely physical
processes—they do not have special informational properties that are
absent from the rest of the physical world. These physical mechanisms are
associated with bubbles of experience in which colours, abstract concepts
and 1s and 0s appear. The presence of 1s and 0s in consciousness does not
prove that there are 1s and 0s in our physical brains, any more than the
presence of red in consciousness proves that there is red in our physical
brains.

14 It could be argued that an observer has to exchange physically conserved
quantities with a system to read its state. This issue can be avoided if the
observer applies an interface to emissions from the system, such as light
patterns from a screen.

15 An information c-theorist might argue that a material implementation
of information has e-causal powers. The material holds the pattern of
Endnotes 187

information and this pattern affects future states of the physical system.
However, in this case the material must be considered to be implementing
every possible information set that can be read from the system. Some
of these are contradictory or have no relationship with each other. It is
implausible to claim that a potentially infinite collection of disparate
information sets are present in the material and lead to its state transitions.

16 The system could also extract information about an earlier state of itself.

17 I have discussed this experiment elsewhere (Gamez 2016). It would only
work if the problems with custom-designed interfaces could be addressed.

18 For example, Tononi’s information integration algorithms might be able
to identify neuron firing patterns that are linked to consciousness. If this
was a physical c-theory, these patterns would not be associated with
consciousness when they occurred in other materials.

8. Computation Theories of Consciousness
1 Kentridge (1994, p. 442).

2 The MONIAC was a water computer that was developed by Bill Phillips to
model the UK economy.

3 The solution is not necessarily optimal. A video can be found here: www.
youtube.com/watch?v=dAyDi1aa40E

4 This discussion sets aside issues about time slicing and parallel processing,
which do not affect the central argument. When a general-purpose
computer is parallel processing it is executing multiple special-purpose
computers simultaneously. When a general-purpose computer is time
slicing it is working as a particular special-purpose computer for short
periods of time.

5 This used to be a common practice—see Grier (2005).

6 Some of the computations that might be members of CC sets are
discussed by Cleeremans (2005). Jackendof (1987) and Bor (2012) set
out computational c-theories and Metzinger (2003) gives informational-
computational interpretations of his constraints on conscious experience.

7 Computation c-theories are similar to a philosophical position known as
functionalism, which claims that functions are the sole members of CC
sets. Putnam (1975) was one of the key advocates of this position, which
he later abandoned; Shagrir (2005) gives a good overview.
188 Human and Machine Consciousness

8 Standard orreries do not include the date—this could easily be added.

9 Strictly speaking, information cannot be stored in the physical world. To
store information we make changes to the physical world that are defined
by an interface. At a later point in time we access the same part of the
physical world through the same interface and the information reappears.

10 Horsman et al. (2014) give a good description of this interpretation of
computing.

11 This is based on the first example in Section 7.1.

12 This is true of any physical system because an interface can be custom-
designed to extract a given sequence of information states from any
sequence of physical states (Putnam 1988). The simplest method would
be to map unique states onto the required information, or a clock could
be used to handle repeated physical states. This mapping can only be
done retrospectively unless one has a good predictive model of how the
system’s physical states will change.

13 For example, it has been claimed that everything is a cellular automata
(Wolfram 2002; Zuse 1970) or that physical reality arises from the posing
of yes-no questions—Wheeler’s (1990) ‘It from bit’ hypothesis.

14 This theory of implementation will have to map spatiotemporal physical
structures onto computations. It cannot be based on information, which
only exists relative to a human-defined interface.

15 Putnam (1988) and Bishop (2002; 2009) discuss the problems with finite
state automata.

16 I have described the problems with combinatorial state automata in a
paper (Gamez 2014a) that raises more general problems with theories of
implementation.

17 Piccinini (2007) puts forward a theory of implementation based on string
processing.

18 Theories of implementation based on cellular automata have been put
forward by Zuse (1970), Wolfram (2002) and Schule (2014). Piccinini (2012)
gives a good overview of different theories of implementation and their
problems.

19 Computational and functional concepts can be useful ways of describing
physical correlates of consciousness. Suppose someone claims that
consciousness is linked to a global workspace in the brain (Baars 1988). If
this was interpreted as a physical c-theory, the global workspace would
Endnotes 189

just be a convenient way of describing a pattern in spiking neurons. The
global workspace would not form a CC set by itself and it would not be
correlated with consciousness if it was implemented in a different physical
system.

9. Predictions and Deductions about Consciousness
1 Popper (2002, p. 18).

2 Research on change blindness suggests that we cannot accurately recall
earlier conscious states. See, for example, Simons and Rensink (2005).

3 I am indebted to Ron Chrisley for this suggestion. To convert a c-description
into a virtual reality file (for example, an X3D XML file) it is necessary
to model the connection between virtual environments and states of
consciousness. This will have to take the limited resolution of the senses
and the active nature of the visual system into account. There will also
be a one-to-many mapping between a c-description of a conscious state
and virtual environments that could produce this state. This method of
validating consciousness is limited to online consciousness that is evoked
by sensory input. Many aspects of consciousness, such as body states and
emotions, are difficult to control with virtual reality technology.

4 This is similar to the approach that is used in experiments on brain
reading. For example, in one set of experiments by Nishimoto et al. (2011)
the subjects watched a video while their brains were measured. The
scientists used this data to build a model of the spatiotemporal structures
in their brains that were activated by the video. This model was then used
to reconstruct the video that the subjects were watching from their brain
activity. The subjects could compare the consciousness that they had when
they watched the reconstructed videos with the consciousness that they
had when they watched the original video.

5 This testing method is easier if there is a 1:1 relationship between conscious
states and physical states. Otherwise, the c-theory will map each conscious
state onto multiple potential physical states.

6 There has been much speculation about whether a head remains conscious
after it has been cut off. Dash (2011) discusses some of the early experiments
that were carried out on humans. One study on rats suggests that they
retain consciousness for several seconds after decapitation, and a wave of
potentially conscious activity occurs approximately 50 seconds later (van
Rijn et al. 2011). The EEG traces of dying humans show a similar pattern
on a longer time scale (Chawla et al. 2009).
190 Human and Machine Consciousness

7 This is the classic problem raised by Nagel (1974) about what it is like
to be a bat. From the perspective of this book, this is not a problem with
the irreducibility of subjective experience, but with our limited ability to
transform our bubble of experience into a different bubble of experience.
There is no philosophical problem about deducing a c-description of
a bat’s consciousness from a p-description of its physical state—just a
problem with our ability to imaginatively comprehend the c-description
we have generated.

8 One potential solution would be to create virtual reality environments
that enable us to experience aspects of a bat’s consciousness. Alternatively
Chrisley (1995a) has suggested how we could use robotic systems
to specify the non-conceptual contents of a bat’s consciousness. This
approach has been demonstrated by Chrisley and Parthemore (2007), who
used a SEER-3 robot to specify the non-conceptual content of a model of
perception based on O’Regan and Noë’s (2001) sensorimotor theory.

9 This will only be possible if we have a flexible and general c-description
format (see Section 4.9).

10 For example, deductions could help us to breed or genetically engineer
food animals that are not conscious.

11 D could also be a constant pattern or a partially correlated pattern (see
Section 6.4).

12 The concept of similar physical contexts needs to be worked out in detail.
Normally functioning adult human brains have a great deal of variability
in their patterns and materials, so a statistical definition of the normal
variability in their patterns and materials is required to precisely define a
physical context.

13 Conservative deductions could be made about unreportable consciousness
in a platinum standard system during an experiment on consciousness.
Suppose a brain contains two identical structures, one connected to
c-reports and one not. If these structures were always present together,
pilot studies would identify their union as the correlate. However,
if the structure that was disconnected from c-reports came and went
intermittently, then we could exclude it as the correlate. At a later point in
time when both structures were present we might deduce that there are
two consciousnesses in the platinum standard system, only one of which
is reportable. This would violate assumptions A1, A2 and A6. However,
we would still need A1, A2 and A6 to identify the correlate that was
used to make the deduction. An example of this type of reasoning can be
found in Lamme (2006; 2010), who uses paradigmatic cases of reportable
Endnotes 191

consciousness to establish the link between consciousness and recurrent
processing, and then makes inferences about the presence of inaccessible
phenomenal consciousness.

14 In previous work I proposed that indeterminacy envelopes could be used
to make liberal deductions about consciousness (Gamez 2012a). I have
replaced this with the framework that is described in this book.

15
The conservative/liberal distinction is based on a binary opposition
between similar and different physical contexts. The differences between
physical contexts could also be expressed as a continuous value, which
would correspond to the degree of liberality of the deduction.

10. Modification and Enhancement of
Consciousness
1 James (1985, p. 388).

2 A fused consciousness would be separately created in my brain and your
brain—there would not be any merging of our actual consciousnesses.

3 As explained in Section 2.5, the overall level of consciousness is something
like the average level of intensity of the properties and objects in a bubble
of experience. This can be reduced with anaesthetics, such as propofol, or
by a blow to the head. Chemicals, such as caffeine or LSD, can increase the
overall level of intensity. It can also be increased by emotionally intense
situations, such as a car crash.

4 Sensory input is the main method that we use to change the contents of
our consciousness. If I want an elephant in my bubble of experience, then I
go to the zoo and look at an elephant. Hallucinogenic drugs have a strong
effect on contents and we have some control over contents in lucid dreams
and imagination.

5 This type of experience is well documented (Crookall 1972) and it can be
induced through body trauma, mental exercises (Harary and Weintraub
1989; Ophiel 1970), or chemicals, such as ketamine (Wilkins et al. 2011).
Out-of-body experiences can also occur in brain-damaged patients (Blanke
and Arzy 2005) and psychology experiments can induce the illusion that
part or all of our bodies are in a different location (Ehrsson 2007). There
is no compelling evidence to suggest that people who are having an out-
of-body experience can report information about the physical world that
has not been obtained through the senses of their physical body (Alvarado
1982; Blackmore 2010).
192 Human and Machine Consciousness

6 Sensory manipulation can alter the perceived size of our body in relation
to our environment (van der Hoort et al. 2011). Muscimol (found in the
mushroom Amanita Muscaria) is reported to be capable of this.

7 Castaneda (1968) describes how he used a combination of mental
control and hallucinogens to transform his conscious experience of his
body into a crow (the truth of his account has been disputed). Phantom
limbs demonstrate that our experiences of our bodies are linked to brain
activity and are distinct from our actual physical bodies (Gamez 2007, pp.
57-60; Melzack 1990; Melzack 1992). This suggests that the shape of our
consciously experienced bodies can be altered by modifying our brains.

8 Sensory input, such as looking at fearful or beloved objects, changes our
emotional states. Chemicals, such as cocaine or Prozac, alter the intensity
of our emotional states on short or long time scales.

9 The current size of our bubbles of experience is probably linked to the
size of our brains. More brain tissue is likely to be required to expand our
bubbles of experience without loss of resolution.

10 Chakravarthi and VanRullen (2012) describe experimental evidence for
the discrete nature of conscious perception. VanRullen and Koch (2003)
have a more general discussion of this issue. There are well-documented
examples of people with expanded long term memories—a condition
known as hyperthymesia (Parker et al. 2006). Borges’ (1970) Funes the
Memorious is a fictional example.

11
Animals with different senses (for example, bats and fish) are likely to have
different sensations. I have suggested elsewhere that conscious sensations
might be linked to the neural patterns caused by sensory input, and that
our conscious perception of a three-dimensional world could be linked to
a combination of sensory and sensorimotor patterns (Gamez 2014b). If this
is the case, then a novel sensory pattern would be associated with a novel
sensation.
Attempts have been made to create novel sensations. For example,
the feelSpace belt gives subjects information about the location of North
(Nagel et al. 2005) and magnetic fingertip implants enable people to feel
magnetic fields. However, it is not clear whether these devices give people
new conscious sensations. This is probably because the novel sensory
input is processed through the existing senses, instead of being directly
fed into the cortex.

12 We understand the link between changes in sensory input and changes
in consciousness, but we do not understand how changes in sensory
input lead to changes in the brain that are associated with an altered
Endnotes 193

consciousness. The same is true for imagination and the ingestion of
consciousness-modifying chemicals.

13 We would be unlikely to remember some of the conscious states that
could be induced in us. Episodic memories regenerate earlier states of our
brains. This might not be possible if a CC set is not the consequence of the
brain’s own activity.

14 This technology is dramatized in the 1995 film Strange Days. It is different
from a virtual reality system, which only mimics the sensory input
produced by an environment and has little effect on our conscious
experience of our body.

15
Patterns in electromagnetic fields, glia and blood can be indirectly
manipulated by changing the neuron activity.

16 See Legon et al. (2014).

17 For example, electrodes have been used to modify the memories of mice
(de Lavilleon et al. 2015; Ramirez et al. 2013).

18 For example, see Nikolenko et al. (2007). Electrodes and optogenetics are
unlikely to be able to increase a neuron’s firing rate beyond a certain point
because of metabolic constraints.

19 Chen et al. (2015) have developed a method for brain stimulation that
uses magnetic nanoparticles. Seo et al. (2013) have outlined a design
for a wireless brain interface that uses thousands of biologically neutral
microsensors to convert electrical signals into ultrasound that can be read
outside the brain. This could potentially be extended to deliver signals to
the brain.

20 This might be required if we want to expand our spatial and temporal
consciousness.

21 Whether a synthetic neuron is a valid member of a CC set will depend on
how neurons are p-described (see Section 5.1).

22 Additional neurons would only alter consciousness if CC sets consist of
neuron activity patterns or if the additional neurons altered CC sets in
some other way—for example, by changing the electromagnetic fields.

23 For example, Yin et al. (2013) have developed a wireless electrode interface
that is implanted below the skin.

24 A further problem is that invasive technologies are only allowed under
very specific conditions on human subjects. This may change if the safety
194 Human and Machine Consciousness

of these techniques is demonstrated and there is demand or demonstrable
benefits. A workable technology will also be appropriated by the public at
large regardless of the safety issues or legal constraints. For example, you
can buy tDCS kits on the Internet.

25 Huxley (1965, pp. 71-2).

11. Machine Consciousness
1 Metzinger (2003, p. 618).

2 Searle (1980, p. 424).

3 Machine consciousness is also called artificial consciousness. I have
presented a version of these types of machine consciousness elsewhere
(Gamez 2008b). They overlap with Seth’s (2009) distinction between
strong and weak artificial consciousness and have some similarity with
Searle’s (1980) distinction between strong and weak artificial intelligence.
More information about previous work on machine consciousness is given
by Holland (2003), Chella and Manzotti (2007), Gamez (2008b) and Reggia
(2013). The International Journal of Machine Consciousness has published
many papers on this topic.

4 This is sometimes known as artificial general intelligence (AGI).

5 Arrabales’ (2010) ConsScale ranks systems according to their MC1
consciousness. The Turing test and Harnad’s (1994) variations of it are
designed to test whether a system exhibits the full spectrum of human
behaviour. There has been a large amount of work on MC1 systems—
virtually any computer capable of perception and learning can be
interpreted as a MC1 machine.

6 For example, computer models of global workspaces have been built
(Franklin 2003; Gamez et al. 2013; Shanahan 2008; Zylberberg et al. 2010).

7 A number of people have used internal models that are updated with
sensory data to control robots—for example, Chella, Liotta and Macaluso
(2007). Computer models have also been built of imagination (Gravato
Marques and Holland 2009) and of sensorimotor theories of consciousness
(Chrisley and Parthemore 2007).

8 For example, I have collaborated on a global workspace model implemented
in spiking neurons (MC2), which produced human-like behaviour (MC1)
in the Unreal Tournament computer game (Gamez et al. 2013).
Endnotes 195

9 Digital computers that are simulating neurons produce very different
electromagnetic fields from biological neurons. Neuromorphic chips use
the flow of electrons to model the movement of ions in biological neurons
(Indiveri et al. 2011). This type of chip is more likely to produce similar
electromagnetic fields to biological neurons.

10 Neurons cultured in a Petri dish have been used to control a virtual animal
(Demarse et al. 2001) and a robot (Warwick et al. 2010).

11 I have carried out preliminary experiments that illustrate how deductions
can be made about the consciousness of an artificial system (Gamez 2008a;
Gamez 2010).

12 The implantation of non-conscious chips that modify CC sets in the brain is
covered in Section 10.4. The implantation of chips to study the relationship
between consciousness and the physical world is covered in Section 5.4.

13 See Footnote 9.

14 The connections between neurons have traditionally been identified by the
laborious method of injecting tracers (Zingg et al. 2014). More promising
techniques are starting to emerge that might be able to automatically scan
dead human brains. For example, knife-edge scanning microscopes can
automatically slice and photograph brain tissue, which enables some
of the neurons and connections to be discovered (Mayerich et al. 2008).
However, this technique can only identify a limited number of neurons and
it cannot reveal the direction of connections. A more promising direction
is the automation of electron microscopy to mill and scan blocks of brain
tissue. With further development this approach might be able to identify
all of the neurons and connections in an adult human brain (Knott et al.
2008). There has also been research into techniques for making dead tissue
transparent, which could help us to map the neurons and connections
(Yang et al. 2014).
When the neurons and connections have been identified the next
challenge is to simulate them on a computer. The adult human brain has
approximately 100 billion neurons and 1014 connections. Networks with
around a billion point neurons and 1013 connections have been simulated
much slower than real time (Ananthanarayanan et al. 2009) and the
SpiNNaker project is working towards the goal of simulating a billion
neurons in real time (Furber and Temple 2007; Rast et al. 2011). One critical
question is how much of the neurons’ structure will need to be simulated
to reproduce the brain’s large-scale behaviour. If it is a large amount,
then it is going to take a lot longer to reach the point at which it can be
done in real time. It is also unlikely that we will be able to realize CC
196 Human and Machine Consciousness

sets in artificial systems by simulating neurons. Neuromorphic chips have
a greater chance of reproducing the electromagnetic fields of biological
neurons, and it should soon be possible to run a million of these in real
time (Benjamin et al. 2014).

15
This possibility has been dramatized in the 2014 film Transcendence.
Carbon Copies is a non-profit organization that promotes the scanning
and uploading of brains (www.carboncopies.org).

16 Imagine a scenario in which an artificial implant (made from appropriate
materials) was added to your brain and the pattern associated with 1% of
your consciousness was on the implant, with the rest of the pattern in your
brain. The proportion on the implant could be progressively increased
until the entire pattern was on the implant. This would still be a process of
copying in which the original is progressively lost. At the beginning of this
process there would be a consciousness associated with your brain and
no consciousness associated with the implant. At the end, a copy of your
consciousness would be associated with the implant and your brain would
have lost consciousness. In the intermediate cases, there would be some
of the original consciousness and some of the copy. This type of gradual
replacement of materials happens all the time in the brain as it exchanges
atoms with its surroundings. So in practice we cannot avoid the gradual
replacement of our consciousness as the material in our brains changes.
At best we can minimize such changes—for example, by not agreeing to
copies of our consciousness that destroy the original.
The identity of bubbles of experience over time is similar to the identity
of physical objects over time. Some changes to a motorbike have minimal
impact on our sense of its continuity—for example, replacing the spark
plugs. Other changes, such as swapping the chassis or making an atom-
for-atom copy have a bigger effect. When large changes are made, I
might prefer the original because of its history—it is my motorbike, the
motorbike that I rode around the world, and so on. Other people might
not care whether they have the original or an atom-for-atom copy. In a
similar way, some people might believe that the arrangement of their
bubble of experience is what is important—these people are happy as long
as this arrangement exists somewhere. This is equivalent to the atom-for-
atom copy of the motorbike. Other people prefer the consciousness that is
linked to their brain and believe that they will die when this consciousness
ceases, regardless of whether a copy has been made somewhere. This is
equivalent to preferring the original motorbike with none of its parts
replaced.

17 Kaczynski (1996) and Joy (2000) believe that we will increasingly pass
responsibility to intelligent machines until we are unable to do without
Endnotes 197

them—in the same way that we are increasingly unable to live without
the Internet today. This might eventually leave us at the mercy of super-
intelligent machines who could use their power against us. Kaczynski
killed three people and injured twenty-three others to raise awareness of
this issue.

18 Most people are concerned about machines that behave like conscious
human beings, so I am setting aside the possibility that machines could
produce non-conscious external behaviour that threatens humanity.

19 We might be able to produce a MC1 machine by scanning a human brain
and simulating it on a computer (see Footnote 14). This would not be
any more intelligent than us or any more of a threat to humanity than
an intelligent human. However, it would be easier to understand and
improve than a human brain, so it could be the starting point for more
advanced forms of intelligence. In the medium term it might become
possible to run simulations of brains faster than biological brains and
to run multiple simulated brains in parallel. Deep learning is another
promising method for producing MC1 machines. For example, Mnih et al.
(2015) used deep reinforcement learning to train a neural network to play
1980s video games with human-level performance.

20 For example, machines would have to have human level intelligence; they
would have to be capable of powering and maintaining themselves for
long periods of time; military computers would have to be connected to
the Internet and inadequately defended against hackers; etc. Machines
would also become a threat if they became good at manipulating human
behaviour.

21 Chalmers (2010) has a good discussion of the singularity. Eden et al. (2012)
have edited a collection of papers on this topic.

22 If we had a mathematical way of measuring intelligence, then genetic
algorithms could be used to create systems with a high value of this
measure. A number of universal intelligence measures have been put
forward (Hernández-Orallo and Dowe 2010; Hibbard 2011; Legg and
Hutter 2007), but I am not aware of any that would be suitable for this task.

23 The construction of a system that can produce something that is more
intelligent than itself is extremely challenging. It will not happen by
accident, but through many years of laborious trial and error. Papers
will be published on prototypes, there will be early versions that are
partly functional, and so on. Only when the technology has been tried
in many different ways is there any possibility that it could create a
super-intelligence.
198 Human and Machine Consciousness

24 One of the most dangerous computer errors was a malfunction in the Soviet
nuclear early warning system in 1983, which almost led to a third world
war. Asimov (1952) dramatizes some of the problems with malfunctioning
intelligent machines.

25 Sloman (2006).

26 This position is put forward by Moravec (1988) and Asimov (1952).

27
For example, murder entails the premature loss of the victim’s
consciousness and creates suffering in the bubbles of experience of the
bereaved. On the other hand, switching off the life support of a coma
patient is not generally considered wrong if the patient is not conscious
and if they have no chance of regaining consciousness.

28 This might be the only way in which consciousness and our cultural
traditions could survive the death of the sun in 5.4 billion years. It is
unlikely that humans will be able to physically travel beyond our solar
system to escape the dying sun. Machines can go much further because
they can accelerate faster, feed on light and shut down for thousands of
years while travelling.

29 Metzinger (2003, p. 621).

12. Conclusion
1 Popper (2002, p. 94).

2 Metzinger describes the current state of consciousness research as follows:
‘The interdisciplinary project of consciousness research, now experiencing
such an impressive renaissance with the turn of the century, faces two
fundamental problems. First, there is yet no single, unified and paradigmatic
theory of consciousness in existence which could serve as an object for
constructive criticism and as a backdrop against which new attempts could
be formulated. Consciousness research is still in a preparadigmatic stage.
Second, there is no systematic and comprehensive catalogue of explananda.
Although philosophers have done considerable work on the analysanda,
the interdisciplinary community has nothing remotely resembling an
agenda for research. We do not yet have a precisely formulated list of
explanatory targets which could be used in the construction of systematic
research programs.’ (Metzinger 2003, pp. 116-7).

3 For example, whether consciousness is a non-physical substance, the hard
problem, solipsism, zombies, colour inversion and the causal relationship
between consciousness and the physical world.
Endnotes 199

4 In the standard version of dualism there is a bidirectional e-causal
relationship between non-physical consciousness and the physical world.
This is ruled out by assumption A5.

5 Assumptions A7-A9 are more pragmatic and might not be needed by the
science of consciousness.

6 NeuroNexus sells electrodes that can record from 256 locations. It is
working to expand this to 1,000 electrodes (Marx 2014).

7 See Ahrens and Keller (2013).

8 For example, Shanahan and Wildie (2012) have proposed a ‘knotty
centrality’ measure that might be linked to consciousness.

9 An assumption that a mammalian brain is a platinum standard system
will have much less impact on the science of consciousness than a similar
assumption about an artificial system.

10 Wittgenstein (1969, remark 94).

11 For example, consider the assumption that all conscious states associated
with a platinum standard system are linked to c-reports (A2). We could
disprove this assumption if we could show that there are aspects of
consciousness that are not accessible through c-reports. But since these
aspects of consciousness cannot be accessed, we cannot prove that they do
or do not exist.

12 This is the position of Berkeley (1957). Husserl (1960) developed his
phenomenological program by suspending commitment to the reality of
the physical world.

13 Hume (1993, p. 114).

14 At present the most mathematical theories of consciousness are information
c-theories, which can be re-interpreted as physical c-theories. For example,
Tononi’s (2008) information integration theory of consciousness can be
re-interpreted as a theory about the relationship between neuron activity
and consciousness. Causal density (Seth et al. 2006), liveliness (Gamez
and Aleksander 2011) and Casali et al.’s (2013) perturbational complexity
index can also be reinterpreted as physical c-theories.
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Index

access consciousness. See phenomenal conscious behaviour 44, 170
and access consciousness consciousness, definition of.
anaesthetics 173 See definition of consciousness
animal consciousness 117, 121, 130, conservative deduction 121, 131
173 constraints on theories of
artificial consciousness. See machine consciousness 73
consciousness contents of consciousness 27, 126
artificial intelligence 83, 123, 142 context 71. See also physical context
assumptions for the measurement of correlates of consciousness 73, 74, 79.
consciousness 3, 48, 49, 52, 53, 55, See also CC set
58, 59, 60, 151 c-report 45, 48, 49, 56, 59, 73, 86, 101,
atomism 15, 18, 31 118, 141, 175, 176
c-theory 79, 82, 113, 115, 116, 119,
bat consciousness 117, 118, 122
129, 137, 139, 153
behaviour associated with
custom interface 95, 99
consciousness. See conscious
behaviour data 95
brain damage 126, 140, 173 deduction 118. See also conservative
brain in a vat 55 deduction, liberal deduction
brain measurement technology 152 definition of consciousness 26
brain modification technology 130 description of consciousness.
brute regularity 41, 81, 169 See c-description
bubble of experience 12, 126, 155 description of physical world.
bubble of perception 11 See p-description
dreams 11, 60
calculator 103, 108 drug-induced experiences 11, 126
Cartesian theatre 165 dualism 151
causation 56
CC set 54, 74, 80, 86, 89, 90, 108, 110, e-causation 57, 58, 73, 86, 99
116, 129, 130, 136, 137, 141 effective connectivity 60, 87, 153, 168
c-description 65, 115, 119, 129, 132, enhancement of consciousness 126,
137, 139 129
colour inversion 50 epiphenomenalism 151
coma patients 117, 126 ethical issues 119, 142, 144, 146
computational discovery of theories existential threat to humanity 142
of consciousness 83 experiments on consciousness 48, 49,
computation c-theory 106 61, 63, 74, 76, 88, 98, 100, 111, 113,
computer 93, 103, 104, 109 115, 119, 150, 170
concept of consciousness 26, 167, 176 eye movements 61
220 Human and Machine Consciousness

first-person report 43, 50, 176. See measurement of consciousness 61.
also c-report See also c-report
functional connectivity 48, 55, 87, measurement of physical world 69,
168, 174 152
functionalism. See computation memory 62, 127
c-theory modification of consciousness 125,
129
general-purpose computer 104
mystical experience 127, 132
global workspace theory 87
naive realism 10, 11, 26
hallucination 13
natural experiment 76, 101, 131
hard problem of consciousness 36,
natural language 62, 65, 71, 80, 151
38, 41, 149
nc-report 46
imagination 34, 36, 38, 52, 81, 82, 118, neural correlates of consciousness
154 72, 87. See also correlates of
implantation of chip in brain 77, 101, consciousness
131, 140, 179 neuromorphic chips 138, 141
implementation of computation 110 neuron, definition of 71
information 93, 94
offline bubble of experience 13, 20,
information c-theory 97
29, 35
information entropy 96
online bubble of experience 12, 20,
information integration theory of 29, 35
consciousness 65, 87, 98
out-of-body experience 126
information processing 93, 109, 110
interface 94, 97, 109 panpsychism 50, 111, 151
intrinsic property 73, 86, 100, 178 p-description 72, 115, 119, 129, 137,
inverted qualia. See colour inversion 139, 152
invisible physical world 13, 16, 22, perception 11, 18, 87, 127, 165, 172,
26, 37, 69 192
phenomenal and access
language. See natural language consciousness 48, 171
level of consciousness 29, 126, 167 phenomenology 33, 64, 136, 155
liberal deduction 121, 132 philosophical problems with
limitations of this interpretation of consciousness 3, 151
consciousness 54, 64, 78, 117, 119, philosophy of science 181
140, 152, 153 physical context 121, 131
machine consciousness 72, 117, 121, physical c-theory 85, 98, 100, 113, 151
123, 135 physicalism 31, 33, 59, 151, 154
material 85, 86, 89, 101, 121, 140 physical world 81, 85
MC1 machine consciousness 136, platinum standard system 47, 53, 76,
142, 144 77, 116, 117, 140, 141, 154, 173
MC2 machine consciousness 136 prediction 80, 113, 115, 116
MC3 machine consciousness 136 primary qualities 17, 20, 22
MC4 machine consciousness 136,
qualia 9
139, 140, 144, 146
Index 221

reduction of consciousness to subjectivity of computation 108
physical world. See physicalism subjectivity of information 95, 98
robots 71, 117, 142, 143 supervenience 52, 55, 172
saccade. See eye movements testable prediction. See prediction
scientific experiments. theory of consciousness. See c-theory
See experiments on consciousness time 61, 127, 166
secondary qualities 17, 20, 22 Turing machine 104
sensorimotor theory 20, 166
simulation of brain 83, 141, 153, 195 unnatural experiment 76
singularity 143 uploading consciousness 141
solipsism 47 virtual reality 114
space 127, 166
special-purpose computer 103 wakefulness 167
specious present 176
zombies 47, 145
structural connectivity 168
Human and Machine Consciousness
DAVID GAMEZ
Consciousness is widely perceived as one of the most fundamental, interes�ng and diﬃcult
problems of our �me. However, we s�ll know next to nothing about the rela�onship
between consciousness and the brain and we can only speculate about the consciousness
of animals and machines.

Human and Machine Consciousness presents a new founda�on for the scien�ﬁc study
of consciousness. It sets out a bold interpreta�on of consciousness that neutralizes the
philosophical problems and explains how we can make scien�ﬁc predic�ons about the
consciousness of animals, brain-damaged pa�ents and machines.

Gamez interprets the scien�ﬁc study of consciousness as a search for mathema�cal
theories that map between measurements of consciousness and measurements of the
physical world. We can use ar�ﬁcial intelligence to discover these theories and they could
make accurate predic�ons about the consciousness of humans, animals and ar�ﬁcial
systems. Human and Machine Consciousness also provides original insights into unusual
conscious experiences, such as hallucina�ons, religious experiences and out-of-body states,
and demonstrates how ‘designer’ states of consciousness could be created in the future.

Gamez explains diﬃcult concepts in a clear way that closely engages with scien�ﬁc
research. His punchy, concise prose is packed with vivid examples, making it suitable for
the educated general reader as well as philosophers and scien�sts. Problems are brought
to life in colourful illustra�ons and a helpful summary is given at the end of each chapter.
The endnotes provide detailed discussions of individual points and full references to the
scien�ﬁc and philosophical literature.

As with all Open Book publica�ons, this en�re book is available to read for free on the
publisher’s website. Printed and digital edi�ons, together with supplementary digital
material, can also be found at www.openbookpublishers.com.

Cover image: Stereogram created by David Gamez with data from Anderson Winkler (CC BY-SA 3.0).

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