The Anatomy of a Minimal Mind - Angelfire

480 Pages·2007·2.15 MB·English

The Anatomy of a Minimal Mind

Vincent Joseph Torley

Submitted in total fulfilment of the requirements
of the degree of Doctor of Philosophy
February 2007

Philosophy Department
The University of Melbourne

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Abstract
This thesis is entitled “The Anatomy of a Minimal Mind”. By a “minimal mind” I mean the simplest
kind of mind that could exist. As there is widespread philosophical disagreement about what a
mind is, or what mental states are, I refrain from assuming at the outset that a minimal mind has
to be phenomenally conscious, or subjectively aware of events in its surroundings. My objective
is to identify the requirements that an organism would have to satisfy, before it could be credited
with possessing a mind of any sort, however rudimentary. I then attempt to develop a detailed
model of this minimal mind, using a conservative methodological approach: we should not
interpret an organism's behaviour as a manifestation of underlying mental states unless doing so
enables us to make better scientific predictions about its behaviour and/or explain its behaviour
more fully.

In section A, chapter one, I discuss the philosophical background to the contemporary discussion
of minds and mental states. I defend the controversial claim that only living things can be said to
have minds or mental states, and I argue that there are no convincing grounds for rejecting the
common view that mental states are real phenomena. This in no way implies the more
controversial view that all mental phenomena share some distinguishing feature that
characterises them as mental. If, however, there is some distinguishing property which is
common to all mental states, and only those states, then the two most promising philosophical
candidates for this property would surely be consciousness and intentionality. I argue that the
different varieties of consciousness distinguished by philosophers fail to “carve nature at the
joints”. I then analyse the strengths and weaknesses of three common definitions of intentionality.
Lastly, I examine Dennett’s intentional stance and argue that the two ways in which it can be
formulated are in fact quite distinct. I propose that one of these formulations, which I refer to as
the agent-centred intentional stance, can be used to help us identify creatures with minimal
minds.

In section B (chapters two to eight), I attempt to identify the necessary conditions for intentional
agency in creatures, by examining several broad categories of behavioural and biological
properties that have been proposed in the philosophical and scientific literature as relevant to
having a mind, and sifting through them, all the while attempting to put together a constructive
definition of a "minimal mind". In particular, I discuss sensory capacities (including discriminatory
ability and perception); memory; flexible behaviour patterns; the ability to learn; self-directed
movement and control; the ability to correct one's mistakes; and the ability to form concepts.
Within each category of "mind-relevant" properties, I examine the different ways in which these
properties are realised by different kinds of organisms, at various levels of complexity. The
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biological case studies that I discuss range from the relatively simple (viruses) to the most
complex (vertebrates, especially birds and mammals).

In section C, I list about a dozen detailed conditions that an animal has to meet before it can be
said to possess this kind of "minimal mind", which, I argue, is the most basic kind of mind
anything can have. Perhaps the most crucial condition is that the animal possess an internal
“minimal map" by which it represents the means it has to adopt to achieve its ends, enabling it to
steer itself around its environment. I argue that animals whose maps are of the right sort can be
said to have beliefs, desires and intentions.

Finally, I claim that these "minimal minds" come in no less than four different varieties. Operant
agency, navigation using visual landmarks, tool use and the social practice of following a guide
are all behaviours that manifest mental states. Although these states are not phenomenally
conscious states, I argue that the intentionality they possess is fundamentally the same as that
found in conscious mental states. In the end, I conclude that many insects and spiders, as well
as octopuses and squid, and of course fish, qualify as having minimal minds.

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Declaration
This is to certify that:
(i) the thesis comprises only my original work toward the PhD except where indicated in the
Preface;
(ii) due acknowledgement has been made in the text to all other material used;
(iii) the thesis is less than 100,000 words in length, exclusive of tables, maps, bibliographies and
appendices.

Vincent Torley

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Acknowledgements
It is with a sense of humility that I offer my thanks to all those who have assisted me in the
preparation of this thesis. First and foremost, I would like to acknowledge a deep debt of
gratitude to my dearest wife, Futaba, for her encouragement, faith and selfless acts of kindness,
which enabled me to see this project through to the end. Without her generosity of spirit, this
thesis would not have been possible. Above all others, it was the presence of my wife and our
baby son Ken that sustained me in the final stages of this thesis, and gave me the determination
to finish it.

I would also like to thank my mother, Mrs Jill Torley, for taking an ongoing personal interest in the
direction of my thesis, for assisting me with my research on animals and for regularly sending me
clippings of topical articles through the mail. My mother's ideas and thoughtful comments helped
shape the content of this work.

I wish to thank my mother-in-law, Mrs Ayako Soshi, for her moral support and patience with me
during the last four years, as she generously provided me with a room and a phone line for
Internet access.

My brother-in-law Tatsundo also deserves special thanks for letting me use his personal
computer to do online research and to edit my thesis online.

My father Mr John Torley and my brothers Christopher, Philip and Paul all encouraged me to
finish this thesis, but Philip deserves special thanks for arranging the printing of the draft version
of this thesis with the University of Queensland printery, and for sending it to the School of
Graduate studies at the University of Melbourne.

I would especially like to thank my thesis supervisor, Professor Brian Scarlett, whose insightful
comments sharpened the presentation of my arguments, and whose generosity with his time
went far beyond the call of duty. I would also like to thank Dr Francois Schroeter for taking over
the supervision of this thesis during a brief period when my current supervisor had to go on leave.
Finally, I would like to thank Professor Barry Taylor, the Head of the Philosophy Department, for
encouraging me to finish this work.

I would also like to thank Mr Ryan Phinisee, my business partner, for his encouragement and
moral support during the final stages of this thesis, when he was kind enough to lend me his
computer after mine had given up the ghost. Mr James Bower also deserves special thanks for
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converting this thesis into a PDF document and for his technical assistance with images.

Many thanks are due to the academics who were kind enough to lend me their time and answer
my scientific queries - especially those relating to chapters one through four of this thesis. I would
like to thank Dr Charles Abramson, Dr Guenther Albrecht-Buehler, Dr Yehuda Ben-Shahar, Dr
Bjorn Brembs, Dr Michel Cabanac, Dr Eric Chudler, Dr Rodney Cotterill, Dr Josh Dubnau, Dr
David Edelman, Dr Randy Gallistel, Dr Bertram Gerber, Dr Martin Heisenberg, Dr Martin Giurfa,
Dr Robert Kentridge, Dr Steven Laureys, Dr Joseph LeDoux, Dr Bernd S. Muller, Dr Lauren
Myers, Dr Jennifer Mather, Dr Randolf Menzel, Dr Bill Nuttley, Dr Jaak Panksepp, Dr James
David Rose, Dr Dan Ryder, Dr Catharine Rankin, Dr George Stefano, Dr Giulio Tononi, Dr Kirk
Visscher and Dr David Wood.

I would also like to offer my deepest thanks to the staff at Atsugi Nishi high school, Ohara high
school, Hadano Minamigaoka high school and Shonan Gakuen in Japan, for allowing me to use
their computer facilities for my thesis research and writing. Without their generosity, this thesis
could not have been completed.

This thesis is dedicated to all creatures, great and small.

Beyond the shadow of the ship,
I watched the water-snakes:
They moved in tracks of shining white,
And when they reared, the elfish light
Fell off in hoary flakes.

Within the shadow of the ship
I watched their rich attire:
Blue, glossy green, and velvet black,
They coiled and swam; and every track
Was a flash of golden fire.

From The Rime of the Ancient Mariner by Samuel Taylor Coleridge.

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Table of Contents

Section A: Background to the Problem of Identifying Minds in Other Creatures 14
Introduction 15
0.0 What this thesis is about 15
0.1 Scope of this thesis 15
0.2 Assumptions I make regarding minds and mental states 16
0.2.1 Eliminative materialism and the reality of the mental 16
0.2.2 The unity of the mental 18
0.2.2.1 Consciousness as a hallmark of mental states 19
0.2.2.2 Intentionality as the mark of mental states 21
0.2.2.3 Dennett’s intentional stance 24
0.2.3 Biological assumptions about mental states 26
0.2.4 Necessary and Sufficient Conditions for the Occurrence of Mental States 28
0.3 How should we go about identifying the occurrence of mental states in other
organisms? 29
0.4 Appropriate Sources of Evidence 33
0.4.1 Thought experiments versus empirical observations 33
0.4.2 Singular versus replicable observations 33
0.4.3 Laboratory versus natural observations 34
0.5 How generous should we be in assessing claims for mental states? 35
0.6 What terminological conventions will I follow when describing minds and mental
states? 37
0.7 Preview of my conclusions 40

Chapter 1 – Two Approaches to Identifying Mental States in Other Creatures:
Consciousness and Intentionality 45
1.1 Why only living things can be said to have minds 45
1.1.1 Attributing minds to non-living systems leads to panpsychism 45
1.1.2 Non-living systems lack intrinsic finality 51
1.1.2.1 Intrinsic versus extrinsic finality: is the distinction a clear-cut one? 55
1.1.2.2 Do artifacts possess intrinsic finality? 56
1.2 A defence of mental states against eliminative materialism 59
1.2.1 Relevance for other animals 60
1.2.2 Eliminative materialism: arguments in favour 63
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1.2.3 Implications for animals 67
1.3 Do we need to unify the domain of the mental? 68
1.4 Consciousness as the hallmark of the mental: philosophical background 71
1.5 Problems associated with philosophical and scientific definitions of consciousness 77
1.5.1 Varieties of consciousness 77
1.5.2 Intransitive creature consciousness 79
1.5.3 Transitive creature consciousness 84
1.5.4 Varieties of state consciousness 85
1.5.4.1 Access consciousness 86
1.5.4.2 Phenomenal consciousness 89
1.5.4.2.1 Are primary and higher-order consciousness phenomenal? 90
1.5.4.2.2 Can there be phenomenal consciousness in the absence of primary
consciousness? 91
1.5.4.2.3 Criteria for primary consciousness and their relevance to the Distribution
Question 93
1.5.4.2.3.1 Behavioural criteria for primary consciousness 93
1.5.4.2.3.2 Neurological criteria for primary consciousness 101
1.5.5 Which varieties of consciousness should we distinguish? 109
1.6 Philosophical issues relating to intentionality 111
1.6.1 How should we define intentionality? 111
1.6.2 Common definitions of intentionality 112
1.6.3 An evaluation of philosophical accounts of intentionality 115
1.6.3.1 Fidelity to historical usage 115
1.6.3.2 Clarity 117
1.6.3.3 Ability to define and unify the domain of the mental 118
1.6.3.4 Biological scope 132
1.6.3.5 Ability to explain the relation between consciousness and intentionality 138
1.6.4 Dennett’s intentional stance 139
1.6.4.1 Is Dennett’s intentional stance tied to reductionism? 140
1.6.4.2 Two intentional stances? 143
1.6.4.3 A goal-centred versus an agent-centred intentional stance 144
1.6.4.4 Narrowing the search for mental states: the quest for the right kind of intentional
stance 145

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Section B: The Ingredients of Intentional Agency 148
A Biological Prelude 148
Chapter 2. Sensory Criteria for Identifying Mental States in Organisms 154
2.1 What is a sensor? 154
2.2 What grades of sensitivity are found among organisms? 157
2.3 Which organisms have true senses? 163
2.3.1 Only animals have senses: the Aristotelian perspective 164
2.3.2 Cotterill's arguments for denying true senses to bacteria 168
2.3.3 Eukaryotes vs. bacteria 171
2.3.4 The manner in which true senses bring about locomotion 172
2.4 Sensation and perception 173
2.5 The relation of the senses to different varieties of consciousness 176
2.6 The relevance of senses to the intentionality of mental states 178
2.7 Which intentional stance best describes the senses? 180

Chapter 3 – Memory 182
3.1 What is memory? 182
3.2 What kinds of memory exist in nature, and which creatures have them? 182
3.2.1 The simplest kind of memory: chemical memory 182
3.2.2 Procedural (Non-declarative) Memory 186
3.2.3 Perceptual Memory 189
3.2.4 Declarative Memory 189
3.3 Memory and Consciousness 191
3.4 The Intentionality of Memory 193
3.5 Does a creature need to exhibit memory before we can justifiably impute mental
states to it? 194
3.6 Which intentional stance is appropriate for describing the different kinds of memory
found in nature? 197

Chapter 4 - Flexible Behaviour and its Significance for Mental States 199
4.1 Fixed and flexible patterns of behaviour in organisms: an overview 199
4.1.1 What is flexible behaviour? A proposed definition 199
4.1.2 Different kinds of fixed behaviour distinguished by scientists 203
4.1.3 Examples of so-called "flexible" patterns of behaviour cited by philosophers, which
turn out to be fixed 205
4.1.4 Historical variables: even a pattern of behaviour that changes regularly over time 208
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can still be fixed
4.1.5 Gene-swapping in bacteria: a bona fide case of flexible behaviour 209
4.2 Philosophical evaluation 210
4.2.1 Do fixed patterns of behaviour warrant the ascription of mental states to
organisms? 210
4.2.2 Why memory matters for having a mind 213
4.2.3 Does flexible behaviour warrant the ascription of mental states to organisms? 213

Chapter 5 - Learning-related Criteria for Attributing Mental States to Organisms 217
5.1 A scientific overview of the most common varieties of learning found in organisms,
and their extent of distribution 217
5.1.1 Non-associative learning (habituation, sensitization and dishabituation) 217
5.1.1.1 Habituation 218
5.1.1.2 Sensitization 219
5.1.1.3 Dishabituation 220
5.1.2 Associative learning 221
5.1.2.1 Classical conditioning 221
5.1.2.2 Instrumental and operant conditioning 225
5.1.3 Other kinds of learning 226
5.2 Philosophical evaluation 227
5.2.1 Which of the above kinds of learning should count as true learning? 227
5.2.1.1 Reproducible learning effect 228
5.2.2 Flexible behaviour 229
5.2.3 Why the internally generated flexibility required for true learning is unique to
multicellular organisms 230
5.2.4 Associative learning 233
5.2.4.1 Why associative learning qualifies as true learning 233
5.2.4.2 Does associative learning involve mental states? 235
5.2.4.2.1 Dretske: instrumental/operant conditioning as a hallmark of belief and agency 235
5.2.4.2.2 An equivocation in Dretske’s account? 240
5.2.4.2.3 A critical evaluation of Dretske’s criteria for belief and agency 241
5.2.5 A richer notion of representation 248
5.2.5.1 How a minimal map encodes current position 250
5.2.5.2 Actions and their consequences: how associations can represent goals and
pathways on a minimal map 252
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