zelazo - the cambridge handbook of consciousness (cambridge, 2007)

These include the infamous interactionist dualism of Descartes and a host of dual-ist alternatives forced by the intractable problem of mind-matter interaction; a vari-ety of idealist po

The Cambridge Handbook of Consciousness

The Cambridge Handbook of Consciousness is the

first of its kind in the field, and its appearance

marks a unique time in the history of intellectual

inquiry on the topic After decades during which

consciousness was considered beyond the scope

of legitimate scientific investigation,

conscious-ness re-emerged as a popular focus of research

toward the end of the last century, and it has

remained so for nearly 20 years There are now

so many different lines of investigation on

con-sciousness that the time has come when the field

may finally benefit from a book that pulls them

together and, by juxtaposing them, provides a

comprehensive survey of this exciting field

Philip David Zelazo is Professor of Psychology

at the University of Toronto, where he holds

a Canada Research Chair in Developmental

Neuroscience He is also Co-Director of the

Sino-Canadian Centre for Research in Child

Development, Southwest University, China He

was Founding Editor of the Journal of

Cogni-tion and Development His research, which is

funded by the Natural Sciences and

Engineer-ing Research Council (NSERC) of Canada, the

Canadian Institutes of Health Research (CIHR),

and the Canadian Foundation for Innovation

(CFI), focuses on the mechanisms ing typical and atypical development of exec-utive function – the conscious self-regulation

underly-of thought, action, and emotion In September

2 0 0 7, he will assume the Nancy M and John

L Lindhal Professorship at the Institute of ChildDevelopment, University of Minnesota

Morris Moscovitch is the Max and Gianna man Chair in Neuropsychology and Aging inthe Department of Psychology at the University

Glass-of Toronto He is also a Senior Scientist at theRotman Research Institute of Baycrest Centrefor Geriatric Care His research focuses on theneuropsychology of memory in humans but alsoaddresses attention, face recognition, and hemi-spheric specialization in young and older adults,and in people with brain damage

Evan Thompson is Professor of Philosophy at the

University of Toronto He is the author of Mind

in Life: Biology, Phenomenoloy, and the Sciences of Mind and Colour Vision: A Study in Cognitive Sci- ence and the Philosophy of Perception He is also the co-author of The Embodied Mind: Cognitive Science and Human Experience He is a former

holder of a Canada Research Chair

i

ii

The Cambridge Handbook

of Consciousness

Edited by

Philip David Zelazo, Morris Moscovitch

and Evan Thompson

University of Toronto

iii

First published in print format

Information on this title: www.cambridge.org/9780521857437

This publication is in copyright Subject to statutory exception and to the provision of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press.

Published in the United States of America by Cambridge University Press, New York www.cambridge.org

hardback paperback paperback

eBook (EBL) eBook (EBL) hardback

To the memory of Francisco J Varela (7 September 1946–28 May 2001)

– ET

To my growing family: Jill, Elana, David, Leora, and Ezra Meir

– MM For Sam, and the next iteration

– PDZ And a special dedication to Joseph E Bogen (13 July 1926–22 April 2005 )

v

vi

Evan Thompson and Dan Zahavi

5 Asian Perspectives: Indian Theories

Ron Sun and Stan Franklin

Daniel J Simons, Deborah E.

Hannula, David E Warren, and Steven W Day

vii

1 0 Three Forms of Consciousness in

Henry L Roediger III, Suparna

Rajaram, and Lisa Geraci

1 1 Metacognition and Consciousness 2 8 9

Philip David Zelazo, Helena Hong

Gao, and Rebecca Todd

f alternative states of

consciousness

1 6 States of Consciousness: Normal

Approaches and Impaired

Subjective States of Awareness

2 8 The Cognitive Neuroscience of

Memory and Consciousness 8 0 9

Scott D Slotnick and Daniel

x

The Neurosciences Institute

10 6 4 0John Jay Hopkins Drive

San Diego, CA 92121 USA

Institute of Cognition and Culture

Queen’s University, Belfast

Florida Atlantic University

Boca Raton, FL 3 3 43 1-0091 USA

E-mail: dbjorklund@fau.edu

Joseph E Bogen, MD (Deceased)Formerly of University of Southern Californiaand the University of California, Los AngelesRebekah Bradley

Department of Psychiatry and BehavioralSciences

Emory University

14 6 2 Clifton RoadAtlanta, GA 3 03 22 USAE-mail: rbradl2@emory.eduWallace Chafe, PhDDepartment of LinguisticsUniversity of California, Santa BarbaraSanta Barbara, CA 93 106 USAE-mail: chafe@linguistics.ucsb.eduMichael C Corballis, PhDDepartment of PsychologyUniversity of AucklandPrivate Bag 92019Auckland 1020 NEW ZEALANDE-mail: m.corballis@auckland.ac.nzDiego Cosmelli, PhD

Centro de Estudios Neurobiol ´ogicosDepartomento de Psiquiatr ´oa

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Santiago, Chile

xi

(Also: Laboratoire de neurosciences Cognitives

et Imagerie C´er´ebrale (LENA)

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E-mail: jean-marie.danion@chru strasbourg.fr

Richard J Davidson, PhD

W M Keck Laboratory for Functional Brain

Imaging and Behavior

Institute for Intelligent Systems

The University of Memphis

Memphis, TN 3 815 2 USA

E-mail: franklin@memphis.edu

Helena Hong Gao, PhD

School of Humanities and Social Sciences

Nanyang Technological University

Psychology DepartmentUniversity of Illinois

6 0 3E Daniel Street, Room 807Champaign, IL 61820 USAE-mail: hannula@uiuc.edu

J Allan Hobson, MDMassachusetts Mental Health CenterPsychiatry, S12

7 4Fenwood RoadBoston, MA 02115 USAE-mail: allan hobson@hms.harvard.eduCaroline Huron, MD, PhD

INSERM 0117Service Hopitalo-Universitaire de Sant´e Mentale

et Th´erapeuthique

H ˆopital Sainte-AnneUniversit´e Paris VPavillon Broca

2ter rue d’Al´esia

7 5 0 14Paris FRANCEE-mail: huron@broca.inserm.frJohn F Kihlstrom, PhDDepartment of Psychology, MC 165 0University of California, BerkeleyTolman Hall 3 210

Berkeley, CA 94720-165 0 USAE-mail: kihlstrm@socrates.berkeley.eduAsher Koriat, PhD

Department of PsychologyUniversity of HaifaHaifa 3 1905 ISRAELE-mail: akoriat@research.haifa.ac.ilUriah Kriegel, PhD

Department of PhilosophySocial Science Bldg Rm 213P.O Box 210027

Tucson, AZ 85 721-0027 USAE-mail: kriegel@email.arizona.eduJean-Philippe Lachaux

INSERM – Unit´e 280Centre Hospitalier Le VinatierBˆatiment 45 2

9 5Boulevard Pinel

6 9 5 0 0BRON, FRANCEE-mail: lachaux@lyon.inserm.fr

W M Keck Laboratory for Functional Brain

Imaging and BehaviorWaisman Center

SUNY at Stony Brook

Stony Brook, NY 11794-25 00 USA

E-mail: suparna.rajaram@sunysb.edu

Henry L Roediger III, PhD

Department of Psychology, Box 1125

Department of Experimental Psychology

South Parks Road

Oxford OX1 3 UD ENGLAND

E-mail: Edmund.Rolls@psy.ox.ac.uk

Daniel L Schachter, PhDDepartment of PsychologyHarvard UniversityCambridge, MA 0213 8 USAE-mail: dls@wjh.harvard.eduWilliam Seager, PhDDepartment of PhilosophyUniversity of Toronto at Scarborough

2 6 5 Military TrailScarborough, ON M1C 1A4 CANADAE-mail: seager@utsc.utoronto.caDaniel J Simons, PhD

Psychology DepartmentUniversity of Illinois

6 0 3 E Daniel Street, Room 807Champaign, IL 61820 USAE-mail: dsimons@uiuc.eduScott D SlotnickDepartment of PsychologyBoston College

McGuinn HallChestnut Hill, MA 02467 USAE-mail: sd.slotnick@bc.eduHenry Stapp, PhD

Lawrence Berkeley National LabPhysics Division

1Cyclotron Road Mail Stop 5 0A-5 101Berkeley, CA 94720-815 3 USAE-mail: hpstapp@lbl.govPetra Stoerig, PhDInstitute of Physiological PsychologyHeinrich-Heine-University

D ¨usseldorf D-40225 GERMANYE-mail: petra.stoerig@uni-duesseldorf.deRon Sun, PhD

Cognitive Science DepartmentRensselaer Polytechnic Institute

110Eighth Street, Carnegie 3 02ATroy, NY 12180 USA

E-mail: rsun@rpi.eduEvan Thompson, PhDDepartment of PhilosophyUniversity of Toronto

15King’s College CircleToronto, ON M5 S 3 H7 CANADAE-mail: evan.thompson@utoronto.ca

C Jason Throop, PhDDepartment of AnthropologyUniversity of California, Los Angeles

3 4 1Haines HallLos Angeles, CA 90095 USAE-mail: jthroop@ucla.edu

2 5 2Bloor Street West

Toronto, Ontario M5 S 1V6 CANADA

5 3 2N Kilgo CircleAtlanta, GA 3 03 22 USAE-mail: dwesten@emory.edu

Dan Zahavi, PhDDanish National Research FoundationCenter for Subjectivity ResearchKobmagergade 46

DK-115 0 Copenhagen K DENMARKE-mail: zahavi@cfs.ku.dk

Philip David Zelazo, PhDDepartment of PsychologyUniversity of Toronto

10 0St George StreetToronto, ON M5 S 3 G3 CANADAE-mail: zelazo@psych.utoronto.ca(After September 2007:

Institute of Child DevelopmentUniversity of Minnesota

5 1East River RoadMinneapolis, MN 5 5 45 5 USAE-mail: zelazo@umn.edu)

The Cambridge Handbook of Consciousness

xv

xvi

C H A P T E R 1

Consciousness: An Introduction

Philip David Zelazo, Morris Moscovitch, and Evan Thompson

The Cambridge Handbook of Consciousness

brings together leading scholars from around

the world who address the topic of

con-sciousness from a wide variety of

perspec-tives, ranging from philosophical to

anthro-pological to neuroscientific This handbook

is the first of its kind in the field, and its

appearance marks a unique time in the

his-tory of intellectual inquiry on the topic

After decades during which consciousness

was considered beyond the scope of

legiti-mate scientific investigation, consciousness

re-emerged as a popular focus of research

during the latter part of the last century and

it has remained so for more than 20 years

Indeed, there are now so many different lines

of investigation on consciousness that the

time has come when the field may finally

benefit from a book that pulls them together

and, by juxtaposing them, provides a

com-prehensive survey of this exciting field

By the mid-1990s, if not earlier, it waswidely agreed that one could not get a full

appreciation of psychological phenomena –

for example, of perception or memory –

without distinguishing between conscious

and unconscious processes The antecedents

of this agreement are many, and it would

be beyond the scope of this Introduction to

do more than highlight a few (for furtherdiscussion, see Umilt`a & Moscovitch, 1994).One of the most obvious is the so-called cog-nitive revolution in psychology and the sub-sequent emergence of cognitive science as aninterdisciplinary enterprise Whereas previ-ously psychologists sought to describe law-ful relations between environmental stimuliand behavioral responses, in the mid-195 0s

or so they began to trace the flow of mation through a cognitive system, viewingthe mind as a kind of computer program

infor-It eventually became clear, however, that byfocusing on the processing of information –the kind of thing a computer can do –psychology left out most of what reallymatters to us as human beings; as conscioussubjects, it left us cold The cognitive revo-lution opened the door to the study of suchtopics as attention and memory, and sometime later, consciousness came on through.The pre-1990s tendency to avoid discus-sions of consciousness, except in certain con-texts (e.g., in phenomenological philoso-phy and psychoanalytic circles), may have

been due, in part, to the belief that

con-sciousness necessarily was a kind of ghost in

the machine – one that inevitably courted

the awful specter of dualism Since then,

however, our ontological suppositions have

evolved, and this evolution may be a

conse-quence of the growing trend toward

interdis-ciplinary investigation – seen, for example, in

the emergence of cognitive science and

neu-roscience as coherent fields The

transdisci-plinary perspective afforded by new fields

may have engendered an increased

open-ness and willingopen-ness to explore problems

that earlier were deemed too difficult to

address Certainly, it provided the means

that made these problems seem soluble

Indeed, precisely because consciousness is

such a difficult problem, progress in

solv-ing it probably depends on a convergence of

ideas and methodologies: We are unlikely to

arrive at an adequate understanding of

con-sciousness in the absence of a

transdiscipli-nary perspective

Clinical sciences, and in particular

neu-ropsychology, also played a prominent role

in helping usher in a new willingness to

tackle the problem of consciousness

Vari-ous unusual syndromes came to light in the

latter half of the 20th century, and these

syndromes seemed to demand an

explana-tion in terms of consciousness Blindsight is

a good example: In this syndrome, patients

with lesions to the occipital lobe of the

brain are phenomenologically blind, but can

nonetheless perform normally on a number

of visual tasks Another example is

amne-sia, in which people who are

phenomeno-logically amnesic as a result of damage to

medial temporal lobes or the diencephalon

can acquire, retain, and recover

informa-tion without awareness Similar examples

emerged in other domains, and it soon

became clear that processes under

con-scious control complement, or compete

with, unconscious processes in the control

of cognition and behavior These issues are

also beginning to play a major role in the

rigorous, scientific analysis of

psychopathol-ogy, the one field in which concerns with the

role of conscious and unconscious processes

have played a steady role since Freud

More-over, some of these same atypical ena (e.g., blindsight) have also been demon-strated in non-human animals, raising thepossibility that consciousness is not associ-ated exclusively with human beings

phenom-A third prominent contribution to thecurrent state of affairs is the development

of new techniques that have made it sible to treat consciousness in a more rig-orous and scientifically respectable fashion.Foremost among these is the development

pos-of neuroimaging techniques that allow us tocorrelate performance and subjective expe-rience with brain function These techniquesinclude electrophysiological methods, such

as magneto-encephalography (MEG), andvarious types of functional neuroimaging,including functional magnetic resonanceimaging (fMRI) The analytic sophistication

of these technologies is growing rapidly, as

is the creation of new technologies that willexpand our capabilities to look into the brainmore closely and seek answers to questionsthat now seem impossible to address

There is currently considerable interest inexploring the neural correlates of conscious-ness There is also a growing realization,however, that it will not be possible tomake serious headway in understanding con-sciousness without confronting the issue ofhow to acquire more precise descriptivefirst-person reports about subjective expe-rience (Jack & Roepstorff, 2003 , 2004).Psychologists, especially clinical psycholo-gists and psychotherapists, have grappledwith this issue for a long time, but it hasgained new prominence thanks to the use

of neuroimaging techniques Here one ing idea is that it may be possible to recoverinformation about the highly variable neu-ral processes associated with conscious-ness by collecting more precise, trial-by-trial first-person reports from experimentalparticipants

guid-If ever it was possible to do so, tainly serious students of the mind can

cer-no longer igcer-nore the topic of ness This volume attempts to survey themajor developments in a wide range ofintellectual domains to give the reader anappreciation of the state of the field and

conscious-where it is heading Despite our efforts to

provide a comprehensive overview of the

field, however, there were several

unavoid-able omissions Though we had hoped to

include chapters on psychedelic drugs and

on split-brain research, in the end we were

unable to obtain these chapters in time

Readers interested in the latest scientific

writing on drugs and consciousness may

wish to see Benny Shanon’s (2002) book

on ayahuasca Michael Gazzaniga’s (1998)

book, The Mind’s Past, provides an

accessi-ble overview of work on split-brain research

and its implications for subjective

experi-ence We note, too, that although we were

able to cover philosophical approaches to

consciousness from a variety of cultural

perspectives, including Continental

phe-nomenology and Asian philosophy

(particu-larly Buddhism), there were inevitably

oth-ers that we omitted We apologize for these

unfortunate gaps

The volume is organized mainly around

a broad (sometimes untenable) distinction

between cognitive scientific approaches and

neuroscientific approaches Although we are

mindful of the truly transdisiplinary nature

of contemporary work on consciousness, we

believe this distinction may be useful for

readers who wish to use this handbook as

an advanced textbook For example, readers

who want a course in consciousness from a

cognitive science perspective might

concen-trate on Chapters 2–24 Readers

approach-ing the topic from the perspective of

neu-roscience might emphasize Chapters 25 –3 1

A more sociocultural course could include

Chapters 2–4, 13 –15 , 19–24, and 3 1 More

focused topical treatments are also possible

For example, a course on memory might

include Chapters 6–8, 10, 18, and 29

The topic of consciousness is relevant toall intellectual inquiry – indeed, it is the

foundation of this inquiry As the

chap-ters collected here show, individually and

together, by ignoring consciousness, one

places unnecessary constraints on our

under-standing of a wide range of phenomena –

and risks grossly distorting them Many

mys-teries remain (e.g., what are the neural

sub-strates of consciousness? are there varieties

or levels of consciousness within domains offunctioning, across domains, across species,and/or across the lifespan?), but there hasalso been considerable progress We hopethis collection serves a useful function byhelping readers see both how far we havecome in understanding consciousness andhow far we have to go

Acknowledgments

The editors would like to thank Phil lin, formerly of CUP, who encouraged us toprepare this volume, and Armi Macaballugand Mary Cadette, who helped us during thefinal production phases Dana Liebermannprovided valuable assistance as we plannedthe volume, and Helena Hong Gao helped uspull the many chapters together; we are verygrateful to them both We would also like

Laugh-to thank the contribuLaugh-tors for their patienceduring the editorial process (the scope of thisvolume threatened, at times, to turn this pro-cess into an editorial nightmare ) Finally,

we note with sadness the death of JosephBogen, one of the pioneers in research onconsciousness We regret that he was unable

to see his chapter in print

References

Gazzaniga, M S (1998) The mind’s past

Berke-ley, CA: University of California Press

Jack, A & Roepstorff, A (Eds.) (2003 ) Trusting the subject? The use of introspective evidence in cognitive science Vol 1.Thorverton, UK: Imprint

Academic

Jack, A & Roepstorff, A (Eds.) (2004) ing the subject? The use of introspective evi- dence in cognitive science Vol 2 Thorverton,

Trust-UK: Imprint Academic

Shanon, B (2002) The antipodes of the mind: Charting the phenomenology of the ayahuasca experience New York: Oxford University Press Umilt`a, C & Moscovitch, M (Eds.) (1994) Con- scious and nonconscious information processing: Attention and Performance XV: Conscious and nonconscious processes in cognition Cambridge,

MA: MIT/Bradford Press

P a r t I

THE COGNITIVE SCIENCE

OF CONSCIOUSNESS

A Philosophy

The problem of consciousness, generally

referred to as the mind-body problem

although this characterization is

unfortu-nately narrow, has been the subject of

philo-sophical reflection for thousands of years

This chapter traces the development of this

problem in Western philosophy from the

time of the ancient Greeks to the

mid-dle of the 20th century The birth of

sci-ence in the 17th century and its

subse-quent astounding success made the problem

of mind particularly acute, and produced a

host of philosophical positions in response

These include the infamous interactionist

dualism of Descartes and a host of

dual-ist alternatives forced by the intractable

problem of mind-matter interaction; a

vari-ety of idealist positions which regard mind

as ontologically fundamental; emergentist

theories which posit entirely novel

enti-ties, events, and laws which ‘grow’ out of

the material substrate; panpsychist, double

aspect, and ‘neutral monist’ views in which

both mind and matter are somehow

reflec-tions of some underlying, barely knowable

ur-material; and increasingly sophisticatedforms of materialism which, despite fail-ing to resolve the problem of consciousness,seemed to fit best with the scientific view ofthe world and eventually came to dominatethinking about the mind in the 20th century

I Forms of Consciousness

The term ‘consciousness’ possesses a hugeand diverse set of meanings It is not evenobvious that there is any one ‘thing’ thatall uses of the term have in common whichcould stand as its core referent (see Wilkes

19 8 8) When we think about ness we may have in mind highly complex

conscious-mental activities, such as reflective

self-consciousness or introspective ness, of which perhaps only human beingsare capable Or we may be thinking about

conscious-something more purely phenomenal, perhaps

something as apparently simple and tary as a momentary stab of pain Paradig-matic examples of consciousness are the per-ceptual states of seeing and hearing, butthe nature of the consciousness involved is

uni-actually complex and far from clear Are

the conscious elements of perception made

up only of raw sensations from which we

construct objects of perception in a

quasi-intellectual operation? Or is perceptual

con-sciousness always of ‘completed’ objects

with their worldly properties?

The realm of consciousness is hardly

exhausted by its reflective, introspective, or

perceptual forms There is distinctively

emo-tional consciousness, which seems to

nec-essarily involve both bodily feelings and

some kind of cognitive assessment of them

Emotional states require a kind of

evalua-tion of a situaevalua-tion Does consciousness thus

include distinctive evaluative states, so that,

for example, consciousness of pain would

involve both bodily sensations and a

con-scious sense of aversion? Linked closely with

emotional states are familiar, but

nonethe-less rather peculiar, states of consciousness

that are essentially other directed, notably

empathy and sympathy We visibly wince

when others are hurt and almost seem to

feel pain ourselves as we undergo this unique

kind of experience

Philosophers argue about whether all

thinking is accompanied by or perhaps even

constituted out of sensory materials (images

have been the traditional favorite candidate

material), and some champion the idea of

a pure thought-consciousness independent

of sensory components In any event, there

is no doubt that thought is something that

often happens consciously and is in some

way different from perception, sensation, or

other forms of consciousness

Another sort of conscious experience is

closely associated with the idea of conscious

thought but not identical to it:

epistemolog-ical consciousness, or the sense of certainty

or doubt we have when consciously

enter-taining a proposition (such as ‘2 + 3 = 5’

or ‘the word ‘eat’ consists of three letters’)

Descartes famously appealed to such states

of consciousness in the ‘method of doubt’

(see his Meditations 1641/1985 ).

Still another significant if subtle form

of consciousness has sometimes been given

the name ‘fringe’ consciousness (see Mangan

2 0 0 1, following James 1890/195 0, ch 9),which refers to the background of aware-ness which sets the context for experience

An example is our sense of orientation orrightness in a familiar environment (considerthe change in your state of consciousnesswhen you recognize someone’s face who

at first appeared to be a stranger) Moodspresent another form of fringe conscious-ness, with clear links to the more overtlyconscious emotional states but also clearlydistinct from them

But I think there is a fundamental monality to all these different forms of con-sciousness Consciousness is distinctive forits subjectivity or its first-person character.There is ‘something it is like’ to be in a con-scious state, and only the conscious subjecthas direct access to this way of being (seeNagel 1974) In contrast, there is nothing it

com-is like to be a rock, no subjective aspect to anashtray But conscious beings are essentiallydifferent in this respect The huge variety inthe forms of consciousness makes the prob-lem very complex, but the core problem ofconsciousness focuses on the nature of sub-jectivity

A further source of complexity arisesfrom the range of possible explanatory tar-gets associated with the study of conscious-ness One might, for instance, primarilyfocus on the structure or contents of con-sciousness These would provide a validanswer to one legitimate sense of the ques-tion, What is consciousness? But then again,one might be more interested in how con-sciousness comes into being, either in adeveloping individual or in the universe atlarge Or one might wonder how conscious-ness, seemingly so different from the purelyobjective properties of the material worldstudied by physics or chemistry, fits in withthe overall scientific view of the world Toaddress all these aspects of the problem ofconsciousness would require volumes uponvolumes The history presented in this chap-ter focuses on what has become perhaps thecentral issue in consciousness studies, which

is the problem of integrating subjectivityinto the scientific view of the world

II The Nature of the Problem

Despite the huge range of diverse opinion,

I think it is fair to say that there is now

something of a consensus view about the

ori-gin of consciousness, which I call here the

mainstream view It is something like the

fol-lowing The world is a purely physical

sys-tem created some 13 billion years ago in the

prodigious event that Fred Hoyle labeled the

big bang Very shortly after the big bang

the world was in a primitive, ultra-hot, and

chaotic state in which normal matter could

not exist, but as the system cooled the

famil-iar elements of hydrogen and helium, as

well as some traces of a few heavier

ele-ments, began to form Then very interesting

things started to happen, as stars and

galax-ies quickly evolved, burned through their

hydrogen fuel, and went nova, in the process

creating and spewing forth most of the

ele-ments of the periodic table into the

increas-ingly rich galactic environments

There was not a trace of life, mind, orconsciousness throughout any of this pro-

cess That was to come later The mainstream

view continues with the creation of

plan-etary systems At first these systems were

poor in heavier elements, but after just a

few generations of star creation and

destruc-tion there were many Earth-like planets

scat-tered through the vast – perhaps infinite –

expanse of galaxies, and indeed some

7 or 8 billion years after the big bang, the

Earth itself formed along with our solar

system

We do not yet understand it very well,but whether in a warm little pond, around

a deeply submerged hydrothermal vent,

amongst the complex interstices of some

clay-like matrix, as a pre-packaged gift from

another world, or in some other way of

which we have no inkling, conditions on the

early Earth somehow enabled the special –

though entirely in accord with physical

law – chemistry necessary for the beginnings

of life

But even with the presence of life orproto-life, consciousness still did not grace

the Earth The long, slow processes of

evolu-tion by natural selecevolu-tion took hold and mately led at some time, somewhere to the

ulti-first living beings that could feel – pain and

pleasure, want and fear – and could rience sensations of light, sound, or odors.The mainstream view sees this radical devel-opment as being conditioned by the evolu-tion of neurological behavior control systems

expe-in co-evolutionary development with morecapable sensory systems Consciousness thus

emerged as a product of increasing biological

complexity, from non-conscious precursorscomposed of non-conscious components.Here we can raise many of the cen-tral questions within the problem of con-sciousness Imagine we were alien exo-biologists observing the Earth around thetime of the emergence of consciousness.How would we know that certain organ-isms were conscious, while other organismswere not? What is it about the consciousorganisms that explains why they areconscious? Furthermore, the appearance ofconscious beings looks to be a developmentthat sharply distinguishes them from theirprecursors, but the material processes ofevolution are not marked by such radicaldiscontinuities To be sure, we do find strik-ing differences among extant organisms Theunique human use of language is perhapsthe best example of such a difference, but

of course the apes exhibit a host of related,potentially precursor abilities, as do humanbeings who lack full language use Thus

we have possible models of at least someaspects of our prelinguistic ancestors whichsuggest the evolutionary path that led tolanguage

But the slightest, most fleeting spark offeeling is a full-fledged instance of conscious-ness which entirely differentiates its posses-sor from the realm of the non-conscious.Note here a dissimilarity to other biologi-cal features Some creatures have wings andothers do not, and we would expect that

in the evolution from wingless to wingedthere would be a hazy region where it justwould not be clear whether or not a cer-tain creature’s appendages would count aswings or not Similarly, as we consider the

evolutionary advance from non-conscious to

conscious creatures, there would be a range

of creatures about which we would be

unclear whether they were conscious or not

But in this latter case, there is a fact whether

or not the creatures in that range are feeling

anything, however dimly or weakly, whereas

we do not think there must be a fact about

whether a certain appendage is or is not a

wing (a dim or faint feeling is 100% a kind of

consciousness, but a few feathers on a

fore-limb is not a kind of wing) It is up to us

whether to count a certain sort of appendage

as a wing or not – it makes no difference, so

to speak, to the organism what we call it

But it is not up to us to decide whether or

not organism X does or does not enjoy some

smidgen of consciousness – it either does or

it does not

Lurking behind these relatively

empiri-cal questions is a more basic theoretiempiri-cal,

or metaphysical, issue Given that

crea-tures capable of fairly complex behavior

were evolving without consciousness, why

is consciousness necessary for the

contin-ued evolution of more complex behavior?

Just as wings are an excellent solution to

the problem of evolving flight, brains (or

more generally nervous systems) are

won-derful at implementing richly capable

sen-sory systems and coordinated behavior

con-trol systems But why should these brains

be conscious? Although perhaps of

doubt-ful coherence, it is usedoubt-ful to try to

imag-ine our alien biologists as non-conscious

beings Perhaps they are advanced machines

well programmed in deduction, induction,

and abduction Now, why would they ever

posit consciousness in addition to, or as a

feature of, complex sensory and behavioral

control systems? As Thomas Huxley said,

‘How it is that anything so remarkable as

a state of consciousness comes about as a

result of irritating nervous tissue, is just as

unaccountable as the appearance of Djin

when Aladdin rubbed his lamp’ (1866, 8,

2 10) We might, rather fancifully, describe

this core philosophical question about

con-sciousness as how the genie of

conscious-ness gets into the lamp of the brain, or

why, to use Thomas Nagel’s (1974) famous

phrase, there is ‘something it is like’ to be a

conscious entity?

III Ancient Hints

Of course, the mainstream view has notlong been mainstream, for the problem ofconsciousness cannot strike one at all until

a fairly advanced scientific understanding

of the world permits development of thematerialism presupposed by the mainstreamview A second necessary condition is sim-ply the self-recognition that we are con-scious beings possessing a host of mental

attributes And that conception has been

around for a long time Our ancestors tiated a spectacular leap in conceptual tech-nology by devising what is nowadays calledfolk psychology The development of theconcepts of behavior explaining states such

ini-as belief and desire, motivating states ofpleasure and pain, and information-ladenstates of perceptual sensation, as well asthe complex links amongst these concepts,

is perhaps the greatest piece of theorizingever produced by human beings The powerand age of folk psychology are attested bythe universal animism of preliterate peo-ples and the seemingly innate tendencies

of very young children to regard variousnatural or artificial processes as exemplify-ing agency (see, among many others, Bloom

2 0 0 4; Gergeley et al 1995 ; Perner 1991) Thepersistence of the core mentalistic notions

of goal and purpose in Aristotle’s scientific but highly sophisticated theoriz-ing also reveals the powerful hold these con-cepts had, and have, on human thought But

proto-to the extent that mentalistic attributes areregarded as ubiquitous, no special problem

of relating the mental to the non-mentalrealm can arise, for there simply is no suchrealm

But interesting hints of this problem ariseearly on in philosophy, as the first glim-merings of a naturalistic world view occur

A fruitful way to present this history is

in terms of a fundamental divergence inthought that arose early and has not yet diedout in current debate This is the contrast

between emergence and panpsychism The

mainstream view accepts emergence: mind

or consciousness appeared out of

non-conscious precursors and non-non-conscious

components (note there is both a synchronic

and diachronic sense of emergence)

Panpsy-chism is the alternative view that emergence

is impossible and mind must be already and

always present, in some sense, throughout

the universe (a panpsychist might allow that

mind emerges in the trivial sense that the

universe may have been created out of

noth-ing and hence out of ‘non-consciousness’;

the characteristically panpsychist position

here would be that consciousness must have

been created along with whatever other

fundamental features of the world were

put in place at the beginning) Of course,

this divergence transcends the mind-body

problem and reflects a fundamental

differ-ence in thinking about how the world is

structured

The Presocratic philosophers who ished some 2,5 00 years ago in the Mediter-

flour-ranean basin were the first in the West

to conceive of something like a scientific

approach to nature, and it was their

con-ception that eventually led to what we call

science Although their particular theories

were understandably crude and often very

fanciful, they were able to grasp the idea that

the world could be viewed as composed out

of elemental features, whose essential

char-acterization might be hidden from human

senses and which acted according to constant

and universal principles or laws

The Presocratics immediately recognizedthe basic dilemma: either mind (or, more

generally, whatever apparently macroscopic,

high-level, or non-fundamental property is

at issue) is an elemental feature of the world,

or it somehow emerges from, or is

condi-tioned by, such features If one opts for

emer-gence, it is incumbent upon one to at least

sketch the means by which new features

emerge If one opts for panpsychism (thus

broadly construed), then one must account

for the all too obviously apparent total lack

of certain features at the fundamental level

For example, Anaxagoras (c 5 00–425 bce)

flatly denied that emergence was possible

and instead advanced the view that thing is in everything’ Anaxagoras explainedthe obvious contrary appearance by a

‘every-‘principle of dominance and latency’ (seeMourelatos 1986), which asserted that somequalities were dominant in their contri-bution to the behaviour and appearance

of things However, Anaxagoras’s views onmind are complex because he apparentlyregarded it as uniquely not containing anymeasure of other things and thus not fully

in accord with his mixing principles haps this can be interpreted as the asser-tion that mind is ontologically fundamen-tal in a special way; Anaxagoras did seem

Per-to believe that everything has some tion of mind in it while refraining fromthe assertion that everything has a mind(even this is controversial; see Barnes 1982,

por-4 0 5 ff.)

On the other hand, Empedocles, analmost exact contemporary of Anaxagoras,favoured an emergentist account based uponthe famous doctrine of the four elements:earth, air, fire and water All qualities were

to be explicated in terms of ratios of theseelements The overall distribution of theelements, which were themselves eternaland unchangeable, was controlled by ‘loveand strife’, whose operations are curiouslyreminiscent of some doctrines of mod-ern thermodynamics, in a grand cyclicallydynamic universe It is true that Empedo-cles is sometimes regarded as a panpsy-chist because of the universal role of loveand strife (see Edwards 1967, for exam-ple), but there seems little of the mental inEmpedocles’s conceptions, which are rathermore like forces of aggregation and dis-aggregation, respectively (see Barnes 1982,

3 0 8 ff.)

The purest form of emergentism was pounded by the famed atomist Democritus(c 460–3 70 bce) His principle of emer-gence was based upon the possibility ofmulti-shaped, invisibly tiny atoms interlock-ing to form an infinity of more complexstructures But Democritus, in a way echo-ing Anaxagoras and perhaps hinting at thelater distinction between primary and sec-ondary properties, had to admit that the

pro-qualities of experience (what philosophers

nowadays call qualia, the subjective

fea-tures of conscious experience) could not be

accounted for in this way and chose,

ulti-mately unsatisfactorily, to relegate them to

non-existence: ‘sweet exists by convention,

bitter by convention, in truth only atoms

and the void’ Sorely missed is Democritus’s

account of how conventions themselves –

the consciously agreed upon means of

com-mon reference to our subjective responses –

emerge from the dancing atoms (thus, the

ideas of Democritus anticipate the

reflex-ive problem of modern eliminativist

mate-rialists [e.g., Churchland 1981] who would

enjoin us to consciously accept a view which

evidently entails that there is no such thing

as conscious acceptance of views – see

Chapter 3 )

What is striking about these early

strug-gles about the proper form of a scientific

understanding of the world is that the mind

and particularly consciousness keep rising as

special problems It is sometimes said that

the mind-body problem is not an ancient

philosophical issue on the basis that

sensa-tions were complacently regarded as

bod-ily phenomena (see Matson 1966), but it

does seem that the problem of

conscious-ness was vexing philosophers 2,5 00 years

ago, and in a form redolent of

contem-porary worries Also critically important is

the way that the problem of

conscious-ness inescapably arises within the context of

developing an integrated scientific view of

the world

The reductionist strain in the Presocratics

was not favoured by the two giants of Greek

philosophy, Plato and Aristotle, despite their

own radical disagreements about how the

world should be understood Plato utterly

lacked the naturalizing temperament of the

Presocratic philosophers, although he was

well aware of their efforts He explicitly

criti-cizes Anaxagoras’s efforts to provide

natural-istic, causal explanations of human behavior

(see Phaedo, Plato 1961).

Of course, Plato nonetheless has a

signifi-cant role in the debate because he advances

positive arguments in favour of the thesis

that mind and body are distinct He also

provides a basic, and perpetually tial, tri-component-based psychological the-

influen-ory (see Republic, Book 4, Plato 1961) These

facets of his thought illustrate the two basicaspects of the problem of consciousness: theontological question and the issue of howmind is structured Plato’s primary motiva-tion for accepting a dualist account of mindand body presumably stems from the doc-

trine of the forms These are entities which

in some way express the intrinsic essence

of things The form of circle is that which

our imperfect drawings of circles imitate andpoint to The mind can grasp this form, eventhough we have never perceived a true cir-cle, but only more or less imperfect approx-imations The ability of the mind to com-mune with the radically non-physical formssuggests that mind itself cannot be physical

In the Phaedo, Plato (putting words in the

mouth of Socrates) ridicules the ist account of Anaxogoras which sees humanaction as caused by local physical events Inits place, the mind is proposed as the final(i.e., teleological) cause of action, merelyconditioned or constrained by the physical:

reduction-‘if it were said that without such bones andsinews and all the rest of them I should not

be able to do what I think is right, it would

be true But to say that is because of themthat I do what I am doing, and not throughchoice of what is best – although my actionsare controlled by mind – would be a very lax

and inaccurate form of expression’ (Phaedo,

9 8b ff.)

In general, Plato’s arguments for dualismare not very convincing Here’s one Lifemust come from death, because otherwise,

as all living things eventually die, everythingwould eventually be dead Life can comefrom death only if there is a distinct ‘compo-nent’, responsible for something being alive,that persists through the life-death-life cycle.That persistent component is soul or mind

(Phaedo 72c-d) Another argument which

Plato frequently invokes (or presupposes inother argumentation) is based on reincarna-tion If we grant that reincarnation occurs,

it is a reasonable inference that somethingpersists which is what is reincarnated This

is a big ‘if’ to modern readers of a scientific

bent, but the doctrine of reincarnation was

widespread throughout ancient times and

is still taken seriously by large numbers

of people The kernel of a more powerful

argument for dualism lurks here as well,

which was deployed by Descartes much later

(see below)

Aristotle is famously more

naturalisti-cally inclined than Plato (Raphael’s School of

Athens shows Plato pointing upward to the

heavens while Aristotle gestures downward

to Earth as they stare determinedly at each

other) But Aristotle’s views on mind are

complex and obscure; they are certainly not

straightforwardly reductionist (the soul is

not, for example, a particularly subtle kind of

matter, such as fire) Aristotle’s metaphysics

deployed a fundamental distinction between

matter and form, and any object

necessar-ily instantiates both A statue of a horse

has its matter, bronze, and its form, horse

Aristotle is not using Plato’s conception of

form here The form of something is not an

other-world separate entity, but something

more like the way in which the matter of

something is organized or structured Nor by

matter does Aristotle mean the fundamental

physical stuff we refer to by that word;

mat-ter is whatever relatively unstructured stuff

is ‘enformed’ to make an object (English

retains something of this notion in its use

of matter to mean topic), so bronze is the

matter of a statue, but soldiers would be the

matter of an army Objects can differ in

mat-ter, but agree in form (two identical pictures,

one on paper and another on a computer

screen) or vice versa More abstractly,

Aris-totle regarded life as the form of plants and

animals and named the form of living things

soul (‘the form of a natural body having life

potentially within it’ 1984, De Anima, bk 2,

ch 1) Aristotle’s views have some affinity

both with modern biology’s conception of

life and the doctrine of psychophysical

func-tionalism insofar as he stresses that soul is

not a separate thing requiring another

onto-logical realm, but also cannot be reduced to

mere matter because its essential attribute is

function and organization (for a close and

skeptical look at the link between

Aristo-tle’s philosophy and modern functionalism

see Nelson 1990; see also Nussbaum andPutnam 1992)

Yet there are elements of Aristotle’saccount that are not very naturalistic Early

in the De Anima Aristotle raises the

pos-sibility that the relation between the bodyand the mind is analogous to that betweensailor and ship, which would imply thatmind is independent of body Later Aristotleapparently endorses this possibility when hediscusses, notoriously obscurely, the ‘activeintellect’ – the ‘part’ of the soul capable of

rational thought (De Anima, bk 3 , chs 4–

5) Aristotle clearly states that the activeintellect is separable from body and canexist without it For Aristotle, like Plato, theproblematic feature of mind was its capac-ity for abstract thought and not conscious-ness per se, although of course these thinkers

were implicitly discussing conscious thought

and had no conception of mind apart fromconsciousness

Discussion of one particular, and highlyinteresting if perennially controversial, fea-ture of consciousness can perhaps be traced

to Aristotle This is the self-intimating orself-representing nature of all consciousstates Many thinkers have regarded it asaxiomatic that one could not be in a con-scious state without being aware of thatstate, and Aristotle makes some remarks thatsuggest he may belong to this school of

thought For example, in Book Three of De Anima Aristotle presents, rather swiftly, the

following regress argument:

Since we perceive that we see and hear,

it is necessarily either by means of the seeing that one perceives that one sees

or by another [perception] But the same [perception] will be both of the seeing and of the colour that underlies it, with the result that either two [perceptions] will be of the same thing, or it [the perception] will be of itself Further, if the perception of seeing is

a different [perception], either this will ceed to infinity or some [perception] will be

pro-of itself; so that we ought to posit this in the first instance.

The passage is somewhat difficult to pret, even in this translation from Vic-tor Caston (2002) which forms part of an

inter-intricate (and controversial) mixed

philo-sophical, exegetical, and linguistic argument

in favor of the view that Aristotle accepted

a self-representational account of conscious

states which possessed unique phenomenal

properties Aristotle’s argument appears to

be that if it is essential to a conscious state

that it be consciously apprehended then

con-scious states must be self-representing on

pain of an infinite regress of states, each

representing (and hence enabling conscious

apprehension of) the previous state in the

series The crucial premise that all mental

states must be conscious is formally

neces-sary for the regress Modern representational

accounts of consciousness which accept that

conscious states are self-intimating, such

as the Higher Order Thought theory, can

block the regress by positing non-conscious

thoughts which make lower order thoughts

conscious by being about them (see Seager

19 9 9, Chapter 3 , and see Chapters 3 and 4,

this volume)

IV The Scientific Revolution

Although the philosophy of the Middle Ages

was vigorous and compendious, the

prob-lem of fitting consciousness into the

natu-ral world did not figure prominently (for an

argument, following in the tradition of

Mat-son 1966, that the medievals’ views on the

nature of sensation precluded the

recogni-tion of at least some versions of the

mind-body problem, see King 2005 ) There were

many acute studies of human psychology

and innovative theoretical work on the

con-tent and structure of consciousness and

cog-nition Of special note is the 4th-century

philosopher and Church Father, St

Augus-tine (3 5 4–43 0 ce) His writings exhibit

important insights into the phenomenology

of consciousness, especially with regard to

the experience of time, will, and the self

(see especially Confessions and On Free Will;

4 0 0/1998, 426/1998) He was one of the first

philosophers to address the problem of other

minds, arguing on the basis of introspection

and analogy that because others behave as

he behaves when he is aware of being in a

certain mental state, they too have mentalstates In addition, he anticipated certain keyfeatures of Descartes’ dualistic account ofhuman beings, including Descartes’ famousargument from his conscious self-awareness

to the certainty of his own existence (City of God, Bk 11, Ch 21) and the idea that mind

and body, although ontologically entirelydistinct, somehow are united in the humanperson Here Augustine also broaches one ofthe key puzzles of Cartesian dualism where

he admits the ‘mode of union’ by whichbodies and spirits are bound together tobecome animals is ‘beyond the comprehen-

sion of man’ (City of God, Bk 21, Ch 10).

Although we see here that Augustine didnot agree with Descartes in denying minds

to animals, we can also note the completelack of any idea that this mystery poses anyspecial problem for our understanding of thenatural world (see O’Daly 1987 for a detaileddiscussion of Augustine’s philosophy ofmind)

In fact, the tenets of Christian dogma,eventually wedded to a fundamentally Aris-totelian outlook, conspired to suppress anyidea that consciousness or mind could be,should be, or needed to be explained in natu-ralistic terms It was the scientific revolution

of the 16th and 17th centuries that forced theproblem into prominence

Galileo’s distinction between primaryand secondary properties, crucial for thedevelopment of science insofar as it freed sci-ence from a hopelessly premature attempt

to explain complex sensible qualities inmechanical terms, explicitly set up an oppo-sition between matter and consciousness: ‘Ithink that tastes, odors, colors, and so on are

no more than mere names so far as the object

in which we place them is concerned, andthat they reside only in the consciousness.Hence if the living creature were removedall these qualities would be wiped away andannihilated’ (1623 /195 7, 274) The welcomeconsequence is that if there are therefore nocolors in the world then science is free toignore them That was perhaps good tactics

in Galileo’s time, but it was a strategic timebomb waiting to go off when science could

no longer delay investigating the mind itself

The mind-body problem in its modernform is essentially the work of a single genius,

Ren´e Descartes (15 96–165 0), who reformed

the way we think about mind and

conscious-ness, leaving us with a set of intuitions that

persist to this day To take just one

topi-cal example, the basic idea behind the

fic-tional technology of the Matrix films is

thor-oughly Cartesian: what we experience is not

directly related to the state of the

environ-ment, but is instead the result of a

com-plex function – involving essential sensory

and cognitive mediation based upon neural

systems – from the environment to our

cur-rent state of consciousness Thus two brains

that are in identical states ought to be in

the same state of consciousness, no matter

what differences there are in their

respec-tive environments It now seems intuirespec-tively

obvious that this is correct (so contemporary

philosophers make exotic and subtle

argu-ments against it) and that, to take another

stock philosophical example, a brain in a vat,

if kept alive in an appropriate chemical bath

and if fed proper input signals into its

sev-ered nerve endings (cleverly coupled to the

output of the brain’s motor output nerves),

would have experiences which could be

indistinguishable from, say, those you are

having at this very moment This thought

experiment reveals another of the

reforma-tions of philosophy instituted by Descartes:

the invention of modern epistemology, for

how could you know that you are not such a

brain in a vat

Descartes was of course also one of thecreators of the scientific revolution, pro-

viding seminal efforts in mathematics and

physics But he also saw with remarkable

prevision the outlines of neuropsychology

With no conception of how the nervous

system actually works and instead

deploy-ing a kind of hydraulic metaphor, Descartes

envisioned nerve-based sensory and

cogni-tive systems and a kind of network

struc-ture in the brain, even – anticipating Hebb –

suggesting that connections in the brain

are strengthened through associated

activa-tion His notorious discussion of animals as

machines can be seen as the precursor of a

materialist account of cognition

But Descartes is most remembered andreviled for his insistence upon the strictseparation of mind and body which, weare enjoined to believe, required sunder-ing the world itself into radically dis-tinct realms, thereby fundamentally splittinghuman beings from nature (including theirown), denigrated emotion in favour of rea-son, and inspired a lack of respect for animalsand nature in general Why was Descartes adualist? Some have suggested that Descarteslacked the courage to follow his science to itslogical and materialist conclusion (the fate ofGalileo is said to have had a strong effect onhim, or it may be that Descartes really had

no wish to harm the Catholic church) But

Descartes did have arguments for his

dual-ism, some of which still have supporters.These arguments also set out one of the basicstrategies of anti-materialism

To show that mind and body are distinct,

it will suffice to show that mind has someproperty that matter lacks The general prin-ciple here, which is that of the alibi, was cod-ified by another 17th-century philosopher,Gottfried Leibniz (1646–1716) and is nowknown as Leibniz’s Law: if x has a propertywhich y lacks, then x and y are not iden-tical Descartes argued, for example, thatalthough matter is extended in space, mindtakes up no space at all Thus, they couldnot be identical It certainly does seem odd

to ask how many cubic centimeters my mind

takes up (does a broad mind take up morespace than a narrow one?) But it is not obvi-ous that this question is anything more thanmerely a feature of the conventional way

we think about minds An analogy would

be an argument that machines cannot think

because they are not alive; there is no

par-ticular reason to think that the heretoforeconstant and evident link between life andthought represents anything more than akind of accident in the way minds happened

to be created In any event, this strategy is still

at the core of the problem of consciousness.One current line of argument, for example,contends that consciousness has a kind offirst-person subjectivity (the ‘what it is like’

to experience something), whereas matter

is purely third-person objective – hence

consciousness and matter must be

funda-mentally different phenomena

Descartes, in the sixth of his Meditations

(1641/1985 ), also invented an astonishingly

novel kind of argument for dualism The

argument is couched in theological terms,

but that was merely for purposes of clarity

and forcefulness (in the 17th century, using

God to explain one’s argument was

impec-cable rhetoric) Descartes asked us to

con-sider whether it was at least possible that God

could destroy one’s body while leaving one’s

mind intact If it was possible then of course

God could perform the feat if He wished

But nothing can be separated from itself! So

if it is merely possible that God could sunder

mind from body, then they must already be

different things So, anyone who thinks that,

say, a consciousness persisting after bodily

death is even so much as a bare

possibil-ity already thinks that consciousness is not

a physical phenomenon This argument is

valid, but it has a little flaw: how do we

know that what we think is possible is truly

so? Many are the mathematicians labouring

to prove theorems which will turn out to

be unprovable (think of the centuries-long

effort to square the circle) – what do they

think they are doing? Nonetheless, it is a

highly interesting revelation that the mere

possibility of dualism (in the sense

consid-ered here) entails that dualism is true

Cartesian dualism also included the

doc-trine of mind-body interaction This seems

like common sense: when someone kicks

me, that causes me to feel pain and anger,

and then it is my anger that makes me

kick them back Causation appears to run

from body to mind and back again But as

soon as Descartes propounded his theory of

mind, this interaction was seen to be deeply

problematic One of Descartes’ aristocratic

female correspondents, the Princess

Elisa-beth of Palatine, asked the crucial question:

“How can the soul of man determine the

spirits of the body, so as to produce voluntary

actions (given that the soul is only a thinking

substance)?” (from a letter of May 1643 ) It’s

a fair question and Descartes’ only answer

was that the mind-body union was instituted

and maintained by God and was humanly

incomprehensible The Princess allowed

her-self less than fully satisfied with this reply.

It was also noticed that Descartes’ ism conflicted with the emerging under-standing of the conservation of certainphysical quantities Descartes himself onlyaccepted that the total amount, but notdirection, of motion was conserved Thusthe mind’s ability to wiggle the pineal gland(where Descartes posited the seat of thesoul) would redirect motion without vio-lating natural law But it was soon discov-ered that it was momentum – or directedmotion – that is conserved, and thus themind-induced motion of the pineal glandwould indeed contradict the laws of nature(one might try to regard this as a fea-ture rather than a bug, because at least itmakes Descartes’ theory empirically testable

dual-in prdual-inciple)

In addition to the ontological aspect ofhis views, Descartes had some interestinginsights into the phenomenological side ofconsciousness For Descartes, the elements

of conscious experience are what he called

‘ideas’ (Descartes pioneered the modern use

of this term to stand for mental items), andevery idea possesses two kinds of reality:formal and objective The formal reality

of something is simply what it is in itself,whereas the objective reality is what, if any-thing, it represents (so, the formal reality of apicture of a horse is paper and paint; a horse

is the objective reality) Though Descartes

is often pilloried as one who believed that

we are only ever conscious of our own ideas,

it is far from clear that this is Descartes’position It is possible to read him instead

as a precursor of modern representationaltheories of consciousness [see Chapter 3 ],

in which it is asserted that, although sciousness essentially involves mental rep-

con-resentation, what we are conscious of is

not the representations themselves but theircontent (rather in the way that although

we must use words to talk about things,

we are not thereby always talking about

words) Descartes says that ‘there cannot beany ideas which do not appear to represent

some things ’ (Meditation 3 ), and perhaps

this suggests that even in cases of illusion

Descartes’ view was that our experience is

of the representational content of the ideas

and that we do not, as it were, see our own

ideas

Finally, because Descartes is often resented as denigrating bodily feelings and

misrep-emotions in favour of pure reason, it is worth

pointing out that he developed a

sophisti-cated account of the emotions which stresses

both their importance and the importance

of the bodily feelings which accompany

them (1649/1985 ) Descartes – perhaps

con-tra Aristotle – strenuously denied that the

mind was ‘in’ the body the way a pilot is

in a ship, for the intimate connection to the

body and the host of functionally significant

feelings which the body arouses in the mind

in the appropriate circumstances meant that

the mind-body link was not a mere

commu-nication channel Descartes declared instead

that the mind and body formed a

‘substan-tial union’ and that emotional response was

essential to cognition

Despite the fact that if one is willing

to endorse a dualism of mind and body

then Descartes’ interactive version seems

to be the most intuitively reasonable, the

difficulties of understanding how two such

entirely distinct realms could causally

inter-act created an avid market for alternative

theories of the mind-body relation Two

broad streams of theory can be discerned,

which I label, not altogether happily,

ide-alist and materiide-alist Ideide-alists regard mind

or consciousness as the fundamental

exis-tent and deny the independent existence

of the material world; its apparent reality

is to be explained as a function of

mental-ity Materialists cannot follow such a direct

route, for they have great difficulty in

out-right denying the existence of mind and

generally content themselves with in some

way identifying it with features of matter

The asymmetry in these positions is

inter-esting Idealists can easily assert that the

material world is all illusory Materialists fall

into paradox if they attempt the same

strat-egy – for the assertion that mind is

illu-sory presupposes the existence of illusions,

which are themselves mental entities For

a long time (centuries, I mean) the idealist

position seemed dominant, but the rialists, like the early mammals scrabblingunder the mighty dinosaurs, were to havetheir day

mate-Early materialists had to face more than

an intellectual struggle, because their trine stood in clear contradiction with fun-damental beliefs endorsed by the Chris-tian church, and many thinkers have beencharged with softening their views to avoidecclesiastical censure One such is PierreGassendi (15 92–165 5 ), who espoused anupdated version of ancient Epicurean atom-ism, but who added immortal and immate-rial souls to the dance of the atoms The soulswere responsible, in a familiar refrain, for our

doc-higher intellectual abilities On the

material-ist core of such a view, nature is ultimatelycomposed of tiny, indivisible, and indestruc-tible physical particles whose interactionsaccount for all the complexity and behaviour

of organized matter Gassendi asserted thatthe ‘sentient soul’, as opposed to the imma-terial ‘sapient soul’, was a material compo-nent of animals and humans, composed of anespecially subtle, quick-moving type of mat-ter which is capable of forming the system

of images we call imagination and tion (Gassendi also endorsed the empiricistprinciple that all ideas are based on priorsensory experience) These are literally lit-tle images in the brain Of course, there

percep-is a problem here: who percep-is looking at theseimages? What good does it do to postu-late them? For Descartes, the experience ofsensory perception or imagination is simi-larly dependent upon corporeal imagery, butbecause the visual experience is a mentalact, there really is someone to appreciate thebrain’s artwork (Descartes in fact tried touse the imagistic quality of certain experi-ences as an argument for the existence ofmaterial objects, because real images need

a material substrate in which they are ized – but Descartes concluded that thisargument was far from conclusive.) A subtledistinction here may have directed philoso-phers’ thinking away from this worry This

real-is the difference between what are days called substance and property dualism.Descartes is a substance dualist (hence also

nowa-a property dunowa-alist, but thnowa-at is nowa-a rnowa-ather

triv-ial consequence of his view) Substance in

general was understood as that which could

exist independently (or perhaps requiring

only the concurrence of God) Matter was

thus a substance, but properties of matter

were not themselves substantial, for

proper-ties require substance in which to be

instan-tiated According to Descartes, mind is a

sec-ond kind of substance, with, naturally, its

own set of characteristically mental

prop-erties Thus one basic form of materialism

involves merely the denial of mental

sub-stance, and the early materialists were keen

to make this aspect of their views clear But

denial of substance dualism leaves open the

question of the nature of mental properties

or attributes (consciousness can be regarded

as a feature of the brain, but is no less

myste-rious for being labeled a property of a

phys-ical object)

The problem is clearer in the work of

another early materialist, Thomas Hobbes

(15 88–1679) who, entranced by the new

science inaugurated by Galileo, declared

that absolutely everything should be

expli-cable in terms of the motions of

mat-ter and the efficient causal inmat-teraction of

material contact Eventually coming to

con-sider the mind, Hobbes pursues motion

into the brain to account for sensory

phenomena: ‘the cause of sense is the

external body which presses the organ

proper to each sense which pressure, by

the mediation of the nerves continues

inwards to the brain ’ (165 1/1998, pt 1,

ch 1) Hobbes goes out of his way to stress

that there is nothing immaterial, occult, or

supernatural here; there is just the

vari-ous ways that physical events influence our

material sense organs: ‘neither in us that are

pressed are they anything else but divers

motions; for motion produceth nothing but

motion’ (165 1/1998, pt 1, ch 1) But then

Hobbes makes a curious remark: speaking

of these ‘divers motions’ in the brain he says,

‘but their appearance to us is fancy, the same

waking that dreaming’ However, he

else-where states that ‘all fancies are motions

within us’ (165 1/1998, pt 1, ch 3 )

Com-pounding the confusion he also describes our

appetites or motivations as motions, but saysthat pleasure and pain are the appearances

of these motions (165 1/1998, pt 1, ch 6) Itwould seem that ‘appearance’ is Hobbes’sterm for something like phenomenal con-sciousness, and he seems to be saying that

such consciousness is caused by motions in

the brain but is not identical to them, which

of course flatly contradicts his claim thatmotion can only produce motion Thoughobviously Hobbes is not clear about thisproblem, we might anachronistically char-acterize him as a substance materialist who

is also a property dualist

In any case, materialism was very far fromthe generally favoured opinion, and the per-ceived difficulties of Descartes’ substancedualism led instead to a series of inventivealternatives to interactive substance dual-ism, the two most important being those ofBaruch de Spinoza (163 2–1677) and Leib-niz In an austerely beautiful if forbidding

work, the Ethics (1677/1985 ), Spinoza laid

out a theory which perhaps, logically, ought

to have been that of Descartes Spinoza notesthat substance is that which exists indepen-dently of all other things, and thus there can

be only one ‘maximal’ substance: God Ifthat is so, then matter and mind can only

be features of the God-substance (Spinozacalled them attributes and asserted therewere an infinite number of them, although

we are only aware of two) Spinoza’s theory

is an early form of what came to be called

‘dual aspect theory’, which asserts that mindand matter are mere aspects of some under-lying kind of thing of which we have no clearapprehension Particular material or men-tal individuals (as we would say) are meremodifications of their parent attributes (soyour mind is a kind of short-lived ripple inthe attribute of mind and your body a smalldisturbance in the material attribute) Theattributes are a perfect reflection of theirunderlying substance, but only in terms ofone aspect (very roughly like having both

a climatographic and topographic map ofthe same territory) Thus Spinoza believedthat the patterns within any attribute would

be mirrored in all the others; in lar, mind and body would be synchronized

particu-automatically and necessarily This explains

the apparent linkage between mind and

body – both are merely aspects of the same

underlying substance – while at the same

time preserving the causal completeness of

each realm In the illustrative scholium to

proposition seven of book two of the Ethics

(1677/1985 ) Spinoza writes, ‘A circle

ing in nature and the idea of the

exist-ing circle, which is also in God, are one

and the same thing therefore, whether

we conceive nature under the attribute

of Extension, or under the attribute of

Thought we shall find one and the same

order, or one and the same connection of

causes ’ On the downside, Spinoza does

have to assume that every physical event has

a corresponding mental event, and he is thus

a kind of panpsychist Even worse (from a

17th-century point of view) Spinoza’s view

is heretical, because it sees God as being

lit-erally in everything and thus as a material

thing not separate from the world

Leibniz never wrote down his physical system in extensive detail (he was

meta-doubtless too busy with a multitude of

other projects, such as inventing calculus,

rediscovering binary arithmetic, building the

first calculating machines, and writing

end-less correspondence and commentary, not

to mention his day job of legal counsel

and historian to the Hanoverian house of

Brunswick), but his views can be

recon-structed from the vast philosophical

writ-ings he left us They can be caricatured,

in part, as Spinoza’s with an infinite

num-ber of substances replacing the unique

God-substance These substances Leibniz called

monads (see Leibniz 1714/1989) Because

they are true substances, and hence can

exist independently of any other thing, and

because they are absolutely simple, they

can-not interact with each other in any way

(nonetheless they are created by God, who

is one of them – here Spinoza seems rather

more consistent than Leibniz) Yet each

monad carries within it complete

informa-tion about the entire universe What we call

space and time are in reality sets of

rela-tions amongst these monads (or, better, the

information which they contain), which are

in themselves radically non-spatial and haps even non-temporal (Leibniz’s vision ofspace and time emerging from some moreelementary systems of relations has alwaysbeen tempting, if hard to fathom, and nowfuels some of the most advanced physics onthe planet)

per-However, Leibniz does not see themonadic substances as having both men-tal and material aspects Leibniz’s mon-ads are fundamentally to be conceivedmentalistically; they are in a way mental-istic automatons moving from one percep-tual or apperceptual state to another, allexactly according to a God-imposed prede-fined rule The physical world is a kind of log-ical construction out of these mental states,one which meets various divinely insti-tuted constraints upon the relation betweenthose aspects matching what we call ‘mate-rial objects’ with those we call ‘states ofconsciousness’ – Leibniz called this the pre-established harmony, and it is his explana-tion for the appearance of mind-body inter-action So Leibniz’s view is one that favoursthe mental realm; that is, it is at bottom

a kind of idealism as opposed to Spinoza’smany aspect theory

As we shall see, Leibniz’s vision here had

a much greater immediate impact on quent philosophy than Spinoza’s An impor-tant difference between the two theories isthat, unlike Spinoza, Leibniz can maintain adistinction between things that have minds

subse-or mental attributes from those that do not,despite his panpsychism This crucial dis-tinction hinges on the difference between

a ‘mere aggregate’ and what Leibniz times calls an ‘organic unity’ or an organ-ism Each monad represents the world – inall its infinite detail – from a unique point

some-of view Consider a heap some-of sand It responds to a set of monads, but there is

cor-no monad which represents anything like apoint of view of the heap By contrast, yourbody also corresponds to a set of monads, butone of these monads – the so-called domi-nant monad – represents the point of view ofthe system which is your living body (Therepresumably are also sub-unities within you,corresponding to organized and functionally

unified physiological, and hence also

psycho-logical, subsystems.) Organisms correspond

to a hierarchically ordered set of monads;

mere aggregates do not This means that

there is no mental aspect to heaps of sand

as such, even though at the most

fundamen-tal level mind pervades the universe

One last point: you might wonder why

you, a monad that represents every detail

of the entire universe, seem so relatively

ignorant The answer depends upon another

important aspect of the conception of

men-tality Leibniz allows that there are

uncon-scious mental states In fact, almost all

men-tal states are unconscious, and low-level

monads never aspire to consciousness (or

what Leibniz calls apperception) You are

aware, of course, only of your conscious

mental states, and these represent a literally

infinitesimal fraction of the life of your mind,

most of which is composed of consciously

imperceptible petite perceptions (it is galling

to think that somewhere within each of our

minds lies the invisible answers to such

ques-tions as whether there are advanced

civiliza-tions in the Andromeda galaxy, but there

it is)

For Leibniz the material world is,

fun-damentally, a kind of illusion, but one of

a very special kind What Leibniz calls

‘well grounded’ phenomena are those that

are in some way directly represented in

every monad Imagine aerial photographs

of downtown Toronto taken from a

vari-ety of altitudes and angles The same

build-ings appear in each photograph, though their

appearance is more or less different But, for

example, sun flares caused by the camera

lens will not appear in every picture The

buildings would be termed well grounded,

the sun flare an illusion So Leibniz can

pro-vide a viable appearance-reality distinction

that holds in the world of matter (though it

is tricky, because presumably the illusions of

any one monad are actually reflected in all

monads – hence the weasel word ‘directly’

above) Nonetheless, it is the domain of

con-sciousness which is fundamental and, in the

end, the totality of reality, with the physical

world being merely a kind of construction

out of the mental

V The Idealist Turn

In some way, Leibniz represents the nation of the tradition of high metaphysics:the idea that reason could reveal the ulti-mate nature of things and that this nature

culmi-is radically different from that suggested bycommon sense But his model of the materialworld as mere appearance was taken to itslogical next step by the, at least superficially,anti-metaphysical Immanuel Kant (1724–

18 0 4) In Kant (see especially 1781/1929) wesee the beginning of the idealism which inone form or another dominated philosophyfor more than a century afterward

Once mind is established as the sole ity, the problem of consciousness and all theother traditional problems of relating matter

real-to mind, virtually disappear The problemthat now looks big and important is in a waythe inverse of the problem of consciousness:how exactly is the material world which

we evidently experience to be constructedout of pure and seemingly evanescent con-sciousness Two modes of response to thisproblem can be traced that roughly dividethe thinkers of the British Isles (forgive

me for including Ireland here) from those

of continental Europe, although the graphic categorization becomes increasinglymisleading as we enter the 20th century.Very crudely, these modes of idealism can

geo-be characterized respectively as nalism (material objects are ‘permanent pos-sibilities of sensation’) and transcendentalidealism (a system of material objects repre-sented in experience is a necessary conditionfor coherent experience and knowledge)

phenome-There were, of course, materialists ing about in this period, though they werenowhere near the heart of philosophicalprogress; in fact they were frequently notphilosophers at all, and quite a number camefrom the ranks of intellectually inclinedmedical doctors One such was Julien de LaMettrie (1709–175 1) who outraged Europe,

lurk-or at least enough of France to require a

retreat to Berlin, with his L’Homme machine

(1748/1987) (see also the slightly earlier

L’Histoire naturelle de l’ ˆame; 1745 ) In this

brisk polemical work, La Mettrie extends