the mit press consciousness and persons unity and identity nov 2003

some-Tye begins his account by proposing an account of the unity of perceptual experience at a single time; this account is extended over the succeeding chapters to cover bodily sensatio

Consciousness and Persons

Consciousness and Persons

Unity and Identity Michael Tye

In Consciousness and Persons: Unity and Identity Michael Tye takes on the thorny issue of the unity of conscious- ness and answers these important questions: What exactly is the unity of consciousness? Can a single person have a divided consciousness? What is a single person? Tye argues that unity is a fundamental part of human consciousness—something so basic to everyday experi- ence that it is easy to overlook For example, when we hear the sound of waves crashing on a beach and at the same time see a red warning flag, there is an overall unity to our experience; the sound and the red shape are presented together in our consciousness Similarly, when

we undergo a succession of thoughts as we think thing through, there is an experience of succession that unifies the thoughts into a conscious whole But, Tye shows, consciousness is not always unified Split-brain subjects, whose corpus callosum has been severed, are usually taken to have a divided or disunified conscious- ness Their behavior in certain situations implies that they have lost the unity normal human subjects take for grant- ed; it is sometimes even supposed that a split-brain sub- ject is really two persons.

some-Tye begins his account by proposing an account of the unity of perceptual experience at a single time; this account is extended over the succeeding chapters to cover bodily sensations at a single time and perceptual experiences, bodily sensations, conscious thoughts, and felt moods at a single time Tye follows these chapters with a discussion of the unity of experience through time Turning to the split-brain phenomenon, he proposes an account of the mental life of split-brain subjects and argues that certain facts about these subjects offer fur- ther support for his theory of unity Finally, addressing

“It would be impossible not to learn from this outstanding book Michael Tye displays real insight into the problems of unity and identity, and an intimidating

mastery of the relevant philosophical and psychological literature But almost

as important, its brevity and clarity make the book a pleasure to read.”

—Frank Jackson, The Australian National University

“Not just another book on consciousness! This one is about various kinds of unity (and a few disunities) in phenomenal experience Provocative claims are

defended, and the presentation is lucid and engaging throughout I especially recommend Tye’s chapter on the specious present.”

—William G Lycan, William Rand Kenan, Jr Professor of Philosophy, University

of North Carolina

“Tye presents a compelling, original, philosophically sophisticated theory of the unity of phenomenal consciousness without ever getting bogged down in philo-

sophical trench warfare.”

—Brian P McLaughlin, Department of Philosophy, Rutgers University

“This short volume is full of good philosophy Michael Tye raises new questions about the unity of experience, and his answers cast important light on personal identity All philosophers working on consciousness or personhood should read

this book.”

—David Papineau, Department of Philosophy, King’s College London Cover image: Salvador Dalí, Apparition of the Visage of Aphrodite © 2003 Salvadore Dalí,

Gala-Salvadore Dalí, Foundation/Artists Rights Society (ARS), New York

The MIT Press Massachusetts Institute of Technology

Cambridge, Massachusetts 02142 http://mitpress.mit.edu

tationalism to the theory of unity being advanced.

Michael Tye is Professor of Philosophy at the University

Consciousness and Persons

Representation and Mind

Hilary Putnam and Ned Block, editors

Representation and Reality Hilary Putnam

Explaining Behavior: Reasons in a World of Causes Fred Dretske

The Metaphysics of Meaning Jerrold J Katz

A Theory of Content and Other Essays Jerry A Fodor

The Realistic Spirit: Wittgenstein, Philosophy, and the Mind Cora Diamond The Unity of the Self Stephen L White

The Imagery Debate Michael Tye

A Study of Concepts Christopher Peacocke

The Rediscovery of the Mind John R Searle

Past, Space, and Self John Campbell

Mental Reality Galen Strawson

Ten Problems of Consciousness: A Representational Theory of the Phenomenal Mind Michael Tye

Representations, Targets, and Attitudes Robert Cummins

Starmaking: Realism, Anti-Realism, and Irrealism Peter J McCormick (ed.)

A Logical Journey: From Gödel to Philosophy Hao Wang

Brainchildren: Essays on Designing Minds

Daniel C Dennett

Realistic Rationalism Jerrold J Katz

The Paradox of Self-Consciousness José Luis Bermúdez

In Critical Condition: Polemical Essays on Cognitive Science and the Philosophy

of Mind Jerry Fodor

Mind in a Physical World: An Essay on the Mind-Body Problem and Mental Causation Jaegwon Kim

Oratio Obliqua, Oratio Recta: An Essay on Metarepresentation François

Recanati

The Mind Doesn’t Work That Way Jerry Fodor

Consciousness, Color, and Content Michael Tye

New Essays on Semantic Externalism and Self-Knowledge Susana Nuccetelli Consciousness and Persons: Unity and Identity Michael Tye

Consciousness and Persons

Unity and Identity

Michael Tye

A Bradford Book

The MIT Press

Cambridge, MassachusettsLondon, England

© 2003 Massachusetts Institute of Technology

All rights reserved No part of this book may be reproduced in any form by any electronic or mechanical means (including photocopying, recording, or information storage and retrieval) without permission in writing from the publisher.

This book was set in Sabon by UG / GGS Information Services, Inc and was printed and bound in the United States of America.

Library of Congress Cataloging-in-Publication Data

Tye, Michael.

Consciousness and persons: unity and identity / Michael Tye.

p cm.—(Representation and mind)

“A Bradford book.”

Includes bibliographical references and index.

ISBN 0-262-20147-X (hc.: alk paper)

1 Consciousness 2 Whole and parts (Philosophy) I Title II Series B808.9.T935 2003

126—dc21

2002040999

10 9 8 7 6 5 4 3 2 1

For Lauretta, Cecily, and Claudia

Preface xi

Introduction: Kinds of Unity and Kinds of

Consciousness 1

I.1 Preliminary Remarks 1

I.2 Cases of Consciousness (or Its Absence) 2

I.3 Kinds of Consciousness 5

I.4 Kinds of Unity 11

1 The Unity of Perceptual Experience at a Time 17

1.1 Multiple Experiences and the Problem of Unity 171.2 Undermining the Problem as Standardly

Conceived 21

1.3 The One Experience View 25

1.4 An Account of Synchronic Phenomenal Unity 36

2 The Body Image and the Unity of Bodily

Experience 43

2.1 The Body Image 43

2.2 A Theory of Bodily Sensations 49

2.3 The Problem of Bodily Unity 62

3 The Unity of Perceptual and Bodily Experiences, Occurrent Thoughts, and Moods 67

3.1 Opening Remarks 67

3.2 Perceptual Consciousness and Experience of theBody 68

3.3 Unity and Conscious Thoughts 78

3.4 Unity and Felt Moods 81

4 The Unity of Experience through Time 85

4.1 Examples of Unity through Time 85

4.2 The Specious Present and the Problem of DiachronicUnity 86

4.3 An Account of Unity through Time 95

4.4 Some Mistakes, Historical and Contemporary 1024.5 Carnap and the Stream of Consciousness 106

5 Split Brains 109

5.1 Results of Splitting the Brain 109

5.2 Multiple Personality Disorder, Split Brains, andUnconscious Automata 113

5.3 Indeterminacy in the Number of Persons 1175.4 Disunified Access Consciousness 121

5.5 Disunified Phenomenal Consciousness: Two

Alternatives 126

5.6 The Nontransitivity of Phenomenal Unity 129

6 Persons and Personal Identity 133

6.1 The Ego Theory and the Bundle Theory QuicklySummarized 133

6.2 Objections to the Ego Theory 134

6.3 Objections to the Bundle Theory 138

6.4 A New Proposal 140

6.5 Problem Cases 143

6.6 Vagueness in Personal Identity 154

viii Contents

Some philosophers like to publish large, dense books I donot The simple fact is that large philosophy books are rarelyread carefully This is especially true if the books are hardgoing, as more often than not they are Philosophers usuallytake great care in stating their positions; but, in my experi-ence, they have less patience when they read others I am nodifferent in this regard My attention span is limited I don’tlike having to work hard at trying to understand what thebook or article I am reading is saying I want clarity and,where possible, brevity

The present book is written for those who share my erences Its chapters are divided into numbered sections,typically only a paragraph or two long The book is clear, Ihope, both in structure and content And it is relativelyshort There are even a few cartoons and illustrations to pro-vide some light relief The issues the book addresses, how-ever, are not light or easy They have taxed some of thegreatest philosophers of the past, and they are slippery andconfusing

pref-This is the third book I have written at least partly on sciousness and it may well be asked how many is enough

con-I concede that three seems excessive, especially given the

veritable explosion of books on consciousness in the last tenyears But excess is not always a bad thing, even if we agreethat Oscar Wilde and William Blake went a little over thetop when they commented (respectively), “Nothing suc-ceeds like excess” and “The road of excess leads to thepalace of wisdom.” Still, it was an epiphany, rather than aqualified respect for excess, that led to the present work.The epiphany occurred a couple of years ago, as I was sit-ting in my garden, having a drink late in the afternoon (Thedrink, as I recall, was not alcoholic, as some have supposed.)The air was heavy, there were sounds of birds calling to oneanother, bees buzzing around nearby flowers, the smell ofdamp grass, a profusion of colors What struck me withgreat intensity was the unity in my experience, the way inwhich my experience presented all these things to me

together What also struck me was that remarkably this unity

hadn’t really struck me before, that it was as if I had failed tonotice it!

Unity is a fundamental part of our experience, somethingthat is crucial to its phenomenology It is so fundamental, somuch a part of our everyday consciousness, that it is easy tooverlook And this, I speculate, is why more has not beenwritten about it in the recent vigorous debate about phe-nomenal consciousness Be that as it may, unity is an impor-tant topic that connects both with empirical studies inpsychology of people with split brains and with the theoret-ical, philosophical issue of personal identity

The book begins with an introduction to the topics ofunity and consciousness Different kinds of unity and con-sciousness are distinguished, largely to help avoid misun-derstanding as to the scope of the theory that follows.Chapter 1 is concerned to undercut one standard way ofthinking about unity for the case of perceptual experience at

xii Preface

a single time and to offer an alternative account Chapter 2extends this account to the case of bodily sensations at a sin-gle time; in the course of so doing, it provides a theory ofthese sensations This theory is compatible with my pastproposals on bodily sensations (e.g., in Tye 1995a) but itgoes beyond them in important ways Chapter 3 extends theaccount of unity still further to cover unity for perceptualexperiences, bodily sensations, conscious thoughts, and feltmoods, again at a single time.

Chapter 4 takes up the knotty issue of the unity of ence through time Some historical proposals are consideredhere and a new theory developed Chapter 5 turns to thecase of people whose corpus callosum has been severed,thereby splitting the two hemispheres of the brain On thebasis of the anomalous behavior such individuals exhibit inspecial experimental settings, they are usually taken to have

experi-a divided or disunified consciousness Sometimes, it is gested that they are really two persons An account is pro-posed and defended of the consciousness of split-brainpatients, and it is argued that certain facts about these patientssupply further support for the theory of unity on offer.Finally, in chapter 6, the nature of persons and personalidentity is discussed Some connections are drawn betweenthe issue of identity and that of unity; the discussion alsoprovides further theoretical underpinning for some of theclaims about persons in chapter 5 The two great historicaltheories of the nature of persons—the ego theory and thebundle theory—are found lacking for various reasons, and anew proposal is made The last part of the chapter takes upthe difficult question of whether there can be indeterminacy

sug-in personal identity Here it proves necessary to dangle a toe

or two into the quicksand of vagueness; but, given the focus

of the book, I resist the temptation to go any deeper

Preface xiii

In my last two books, I laid out and defended the sentationalist view of phenomenal character That view isdirectly relevant to the proposals made in this book.However, it is not necessary to endorse the specific theory Itake of the phenomenal character of experience in order tofind my ideas on unity agreeable Representationalism is avery general theory For example, it involves no direct com-mitment to physicalism and it takes no direct stand on thenature of content Those who finds themselves attracted tothe representationalist view of phenomenal consciousness,even if they are unpersuaded by the specific form of theview I endorse, should still find the current proposals aboutunity of value Those who are disinclined to accept even anonreductive form of representationalism may nonethelessfind food for thought in the book; for the simple and appeal-ing way in which representationalism comes to grips withunity provides further reason to take the theory seriously.Since it may not be fully clear just what the commitments

repre-of representationalism are, I have included an appendix onrepresentationalism This appendix locates my version ofrepresentationalism within the space of alternative possibleaccounts of the theory and it reminds the reader that repre-sentationalism comes in many varieties

I have given talks on chapters from the book at manyplaces in the United States and the U.K., and I am indebted to

a large number of people for helpful comments I recall inparticular remarks by Bob Adams, Kati Balog, Alex Byrne,David Chalmers, Jim Dye, Bob Hale, Shelley Kagan, SeanKelly, Bob Kuehns, Fiona Macpherson, David Pitt, JosephRaz, Stephen Read, Mark Sainsbury, Sydney Shoemaker,Susanna Siegel, Charles Spence, Leslie Stevens, DanielStoljar, Scott Sturgeon, Jerry Vision, and Crispin Wright

I am also indebted to Jim Gibbs for drawing the cartoons

xiv Preface

The material in the book is new with the exception of part of the introduction, which incorporates (with revi-

sions) some of my “The Burning House,” in Conscious

Experience (1996), edited by T Metzinger, and most of

section 5 in chapter 6, which draws on my “Vagueness and

Reality,” Philosophical Topics 28 (2001).

Preface xv

Introduction: Kinds of Unity and Kinds of Consciousness

I.1 Preliminary Remarks

The thesis that consciousness is necessarily or essentiallyunified plays a central role in Descartes’s writings and also

in those of Kant Descartes took this to have significantimplications for whether the mind is a material thing; for,according to Descartes, consciousness is the essence of themind and any material entity is separable into distinct parts.Kant wisely resisted any such inference In his view, it is noless puzzling how an immaterial entity without parts couldhave a unified consciousness than a material entity withparts or components acting together

Recent work in neuropsychology on subjects whose brainshave been bisected seems to undercut the thesis that Descartesand Kant shared These subjects behave in ways that are oftentaken to show that their consciousness is disunified Somecontemporary philosophers (Dennett, for example) even holdthat consciousness is frequently disunified What makes theevaluation of claims such as these difficult is that there is noone kind of consciousness and there is no one kind of unity

I shall not attempt here to draw up an exhaustive list

of kinds of consciousness or unity But it will be useful to

distinguish some common kinds, if the main focus of thisbook is to be properly grasped I begin by presenting a num-ber of ordinary, everyday cases, in some of which we nor-mally suppose that consciousness is present while in others

we deny it The purpose of these cases is to distinguishbetween several different kinds of consciousness The dis-tinctions I draw reflect how we ordinarily think about con-

sciousness In this way, they are conceptual distinctions.

I.2 Cases of Consciousness (or Its Absence)

Case 1: The Distracted Philosopher

Walking along the road, I find myself lost in thought for eral hundred yards, as I make my way home During thistime I manage to keep myself on the sidewalk, but I am notconscious of how things look to me as I walk along Later on,

sev-I “come to” and realize that sev-I have been walking for sometime without any real consciousness of my perceptions.1

Case 2: The Bird-watcher

You and I are both bird-watchers There is a bird singing in atree nearby We both hear it, but only you initially are con-scious of it by sight You tell me exactly where to look, and Istare at the right part of the right branch My retinal image

is, let us suppose, just the same as yours when I stand in thespot you are located and look in the same direction But

I report to you that I am not visually conscious of any bird.2

Case 3: The Wine Taster

Apprentice wine tasters are much less discriminating thanexperts Through training they come to discriminate flavors

2 Introduction

that initially seemed to them to be the same They becomeconscious of subtle differences in wines of which they werenot previously conscious.

Case 4: The Brief Encounter

You are looking at a shelf on which there are eighteen books.Your eyes quickly pass over the entire contents of the shelf You see more than you consciously notice Indeed,you see all the books (let us suppose) But you are not con-scious of how each of the books looks

Case 5: The Headache That Won’t Go Away

You have a bad headache, which lasts all afternoon Fromtime to time during the afternoon, there are distractions.You think of other things, you forget for a few moments Inshort, you are not always conscious of your headache.When this happens, we do not infer that really you had oneheadache that ceased at the first distraction, then anotherquite different headache until the next distraction, so thatyou were really subject to a sequence of discontinuousheadaches.3

Case 6: The Pain in the Night

I am fast asleep During the night I am awoken by a pain ofwhich, before awakening, I was not conscious.4

Case 7: What It Is Like

I smell a cigar smoldering; I feel a burning pain in my ache; I taste some smoked salmon; I seem to see bright yel-low In each of these cases, I undergo a different feeling or

stom-Kinds of Unity and stom-Kinds of Consciousness 3

experience For feelings and perceptual experiences, there is

always something it is like to undergo them, some

phenom-enal or subjective aspects to these mental states They areinherently conscious mental states

Case 8: The Boring Shade of Blue

I am staring at a wall that has been painted deep blue Mymind wanders for a few moments, and I am not consciousthat I am undergoing a visual experience of blue But thewall continues to look blue to me even when my mind iswandering

Case 9: The Party Animal

I am at a party, and I have been drinking all night.Eventually, not long before dawn, I leave Upon arrivinghome, I make my weary way to the kitchen and pass out onthe kitchen floor I lose all consciousness

Case 10: The Dreamer

I am asleep, dreaming that I am being pursued by a dactyl that is swooping down on me with evil intent Eventhough I am not awake, I am having conscious experiences.These experiences are real to me, so much so that I wake up

ptero-in a panic

Case 11: The Sleeping Dog

My dog is asleep Her eyes are moving rapidly As they do

so, her nose twitches and she growls and shudders She ishaving conscious experiences

4 Introduction

Case 12: The “Haunted” Graveyard

One night I take a shortcut home and cross an old yard I suddenly feel very afraid I seem to smell a strangesweet odor in the air and to see a shape floating over a grave.Although I do not know it, I am hallucinating I am fully con-scious, but the conscious states I am in are delusive

grave-What are the kinds of consciousness that these cases illustrate?

I.3 Kinds of Consciousness

In case 1, I certainly see the sidewalk ahead as I walk home,and I react accordingly If this were not the case, I wouldbump into things or end up in the street But I am not con-scious of my perceptions I am not aware of how things look

to me on the sidewalk and road I am distracted

The kind of consciousness the absence of which this caseillustrates is that of introspective awareness It is sometimesheld that this sort of consciousness is solely a matter of itssubject having a higher-order thought that he or she isundergoing a certain mental state, where this thought is notbased on inference or observation (Rosenthal 1997) Anotherview is that introspective awareness, at least in the case ofexperiences and feelings, is a kind of secondary seeing-that

or displaced perception (Dretske 1995; Tye 1995a, 2000) Ishall have more to say about this view in chapter 1 A thirdview is that introspective awareness is a kind of monitoring

of mental states much like perception via the senses butinwardly directed (Lycan 1997) For present purposes, it isnot necessary to adjudicate between these accounts

Let us call the above kind of consciousness “introspective

consciousness” or “I-consciousness” for short, however it is

Kinds of Unity and Kinds of Consciousness 5

further analyzed A distracted walker, then, has no

I-consciousness of his visual perceptions.

The cases of the bird-watcher and the wine taster (cases 2

and 3) illustrate what I shall call “discriminatory (or D-)

consciousness.” The bird-watcher who is conscious of thebird has successfully picked it out cognitively from thebranches and foliage in its immediate vicinity Likewise, thewine taster who becomes conscious of certain differences inwines of which he was, earlier in his training, unconscious has

noticed those differences D-consciousness is a form of

percep-tual consciousness—a form that involves recognition of what

is perceived

The party animal (case 9) lacks discriminatory ness with respect to anything external He is not processinginformation about the external world and responding to it

conscious-in a rational manner Let us say that the general sort of sciousness lacked by the party animal is “responsive con-

con-sciousness,” or “R-consciousness” for short This sort of

consciousness, I might add, can be partial: A person who islimited in his reactions upon opening his eyes in the morn-ing after taking a heavy sleeping draught the night before is

not fully R-conscious There is much around him that he does not notice R-consciousness, then, is a generalized ver- sion of D-consciousness.

In case 4—the brief encounter—you see eighteen books,but, for some of the books, you are not conscious of your see-

ing them This is an absence of I-consciousness You also lack

D-consciousness with respect to some of the books, since

there are books you do not notice

In case 5, you have a headache of which you sometimes

are not conscious This again is the absence of I-consciousness,

as is the following case of the pain that wakes you in thenight These two cases, however, strongly suggest another

6 Introduction

kind of consciousness not yet distinguished If you have aheadache then you have a pain And, intuitively, to have apain is to undergo a certain sort of feeling In case 5, then,

there is a feeling without I-consciousness, and likewise in

case 6 (the pain in the night) at least prior to waking up But

if there is a feeling, then there must be consciousness, in

some sense of the term For how could a feeling be a feeling

and yet not be conscious at all?

Call this sort of consciousness “phenomenal (or P-) sciousness.” A mental state may be said to be P-conscious if,

con-and only if, it has a phenomenal character (or a subjective

“feel”) Thus, a pain of which its subject is not I-conscious is nonetheless P-conscious Via I-consciousness, the subject comes to know what it is like to have the pain, but what the

pain itself is like—its phenomenal “feel”—is not a matter of

experience of blue And if I am having a visual experience of

blue, then I am in a conscious state representing blue There issome phenomenal character to my visual state as I view theblue wall Of course, if my mind is wandering, I will not beconscious (in the introspective sense) of this phenomenal char-acter But the wall, by hypothesis, continues to look blue Had

I introspected at the time at which my mind was wandering,

I would have been aware that I was continuing to have avisual experience of blue But I did not, in fact, then intro-

spect There is P-consciousness without I-consciousness.

Suppose that on the wall in the center of my field of viewthere is an insect Initially I notice the insect, but, as my

Kinds of Unity and Kinds of Consciousness 7

mind wanders, for a moment or two I fail to notice it.

Intuitively, I still see it, even though briefly I do not see that

it is on the wall before me But if I see the insect, it must looksome way to me;6and if it looks some way to me, it pro-

duces in me a conscious state This state is P-conscious, but

I am not D-conscious of the insect.

P-consciousness is integral to experiences and feelings

generally, as is noted in case 7 Wherever there is a feeling or

experience, there must be P-consciousness, some

phenome-nology that the relevant state has

P-consciousness is often illustrated further by reference to

the famous inverted and absent qualia hypotheses.7The mer of these hypotheses, for the case of color, is the claimthat there might be someone whose color experiences arephenomenally inverted relative to those of others eventhough she uses color words and functions in color tests inall the standard ways Here there is a phenomenal differ-ence, that is, a difference in phenomenal consciousness, that

for-is not manifested in any behavioral or functional ences The latter hypothesis is the claim that there might besomeone who felt or experienced nothing at all, someone

differ-who altogether lacked P-conscious states, but differ-who

func-tioned in just the same manner as someone who underwentsuch states

It is also in connection with P-consciousness that the

sug-gestion arises that there is a huge explanatory gap Physicalchanges in the gray and white matter composing our brainsproduce states that can be fully understood only by crea-tures that share our experiential perspective, states thathave a “technicolor phenomenology” (as McGinn puts it inhis 1991) There seems an immense gap here, something thatcries out for explanation Why does a given firing patterngenerate a given feeling instead of a different one? Why

8 Introduction

does that firing pattern produce any felt quality or tive phenomenology at all? How can a state like pain, whosenature cannot be fully comprehended by someone who hasnever experienced it, be generated by objective, physicalprocesses in the brain—processes whose nature is accessiblefrom many points of view?

subjec-P-consciousness, it should be noted, is a feature of mental

states I-, D-, and R-consciousness are different: they are properties of creatures They are all forms of creature con-

sciousness Are they also forms of consciousness that could

be present in a zombie, that is, a being who functionally is

just like a sentient creature but who lacks any phenomenal

consciousness? That depends On one natural view of and R-consciousness, they are purely cognitive activities that are normally based on P-consciousness without inher- ently requiring it In the case of I-consciousness, the relevant

D-issue is whether introspection is necessarily accompanied

by an inner phenomenology However this is settled, a ture cannot be conscious in any of the three ways distin-guished unless it undergoes mental states having conceptualcontents that play a role in reasoning and the intentional con-

crea-trol of behavior Such states are sometimes said to be access

conscious (Block 1993; also this vol., chap 5, p 123) If

zom-bies are conceivable, then access consciousness can ably occur without phenomenal consciousness

conceiv-Returning now to the adumbrated cases, we should note

that P-consciousness is also present indirectly in case 4 Ex hypothesi, you see all the books So, each book (briefly)

looks some way to you as your eyes move along the shelf Inhaving visual experiences of books that you do not notice,you are subject to a kind of visual consciousness There isthus something it is like for you at each moment as youreyes scan the contents of the shelf What it is like changes,

Kinds of Unity and Kinds of Consciousness 9

even if you are not introspecting and you are not cognizant

of all the changes Your visual experiences are nally conscious.8

phenome-There is one complication worth mentioning here.Perhaps in some cases the act of introspection itself causallyimpacts the phenomenal character of the introspected state,

so that what it is like to undergo the state then changes withthe act of introspection For example, suppose I have atoothache that persists all evening There are times at which

I am not conscious of it At other times, I am conscious of itand I attend carefully to how it feels Perhaps the act ofattention changes to some extent the phenomenal character

of the toothache That at least seems conceivable If so, thenthe attended phenomenal character is different from theunattended one

In case 10 (the dreamer), my experiences are P-conscious.

There is something it is like for me in dreaming of the

ptero-dactyl But I am not R-conscious I am not processing

infor-mation about the external world and responding to it in arational manner So, there is nothing real with respect to

which I am D-conscious Need there be I-consciousness? If

I wake up in a panic, to some significant degree I mustbelieve that I am in a situation that is dangerous to me But Ineed not believe or think that I am having a visual experi-ence as of a pterodactyl, even if I do believe that I am beingpursued by a pterodactyl So long as the latter belief is pre-sent, it will cause in me fright The former belief or thought,which is higher-order and hence more complicated content-wise, is not necessary So, at least on accounts of introspec-

tion that require such a higher-order state, I-consciousness

need not be present

This conclusion is reinforced by case 11 It seems to meplausible to suppose that dogs that growl during REM sleep

10 Introduction

are subject to P-conscious states that cause beliefs about

things in the world or people (for example, a coveted bone or

a postman) But it seems much less plausible to suppose that

in each and every such case, a higher-order belief or thought

must be present Surely, one important difference between

humans and other animals is that the former are much more

reflective than the latter There is certainly P-consciousness,

however It would be absurd to suppose that there is nothing

it is like for a dog that chews a favorite bone or preferschopped liver for its dinner over anything else it is offered.Case 12 is similar to case 11 Although I am hallucinating,

I am still undergoing sensations and perceptual experiences

My experiential states are P-conscious: there is something it

is like for me as I feel afraid, as I seem to smell a strangeodor, and as I seem to see a white shape But in this case I am

also R-conscious For I am awake and cognitively

process-ing information from my surroundprocess-ings

Of the kinds of consciousness illustrated by the above

exam-ples, by far and away the most problematic is P-consciousness; for it is in connection with P-consciousness that the really

difficult philosophical puzzles and conundrums arise It is

also in connection with P-consciousness that the sort of

unity that will concern us in this book is found

I.4 Kinds of Unity

One important issue of investigation recently in cognitivepsychology and neurophysiology has been how the visualsystem brings together information about shape and color If

I view a green, circular object, the greenness and roundness Iexperience are represented in different parts of my visual sys-tem In my experience, however, the color and shape are uni-

fied I experience a single green, circular object I notice and

Kinds of Unity and Kinds of Consciousness 11

report on only one such object How can this be? How are thecolor and shape unified as belonging to a single object in myconsciousness? This is often called “the binding problem” and

the kind of unity it concerns is object unity.9

Object unity is not a necessary feature of P-consciousness.

We frequently experience colors and shapes without encing them as belonging to the same object, as when, forexample, I see a green object next to a round one withoutseeing a green, round object So, colors and shapes need not be object-unified in my consciousness as I undergo a

experi-P-conscious state.

A second kind of unity is neurophysiological unity.

Conscious states may be said to be neurophysiologicallyunified if and only if they are realized in a single neuralregion or via a single neurological mechanism

A third sort of unity is spatial unity Consciousness is

spa-tially unified for a given subject if and only if everythingexperienced by that subject is experienced as belonging to asingle, common space Spatial unity can obtain at a time orthrough time; it can obtain for consciousness of one sortwhile failing for consciousness of another The view thatperceptual consciousness is necessarily spatially unified isquite plausible; and it has had some distinguished advo-cates (most notably Kant)

A fourth kind of unity is subject unity Two different states

of consciousness may be said to be subject unified if andonly if they are undergone by the same mental subject.These states could be higher-order ones, involved in

I-consciousness, or they could be first-order states Whatever

the states, the thesis that, for any given subject, all his or herstates of consciousness are subject unified is trivially true.Kant held that the unity of consciousness involves havingexperiences that the subject of the experiences can self-ascribe

12 Introduction

in thought This ties the unity of experience to the subject

via order consciousness Let us call this unity

higher-order subject unity Consciousness is higher-higher-order

subject-unified for a given subject (at a given time or for a givenperiod of time) if and only if that subject can self-ascribeeach of her conscious states in thought (at that time or forthat period) Higher-order subject unity is thus much moredemanding than subject unity

Another related thesis is that two states of consciousnessare unified if and only if the subject can introspect both

states in a single act of introspective awareness This is

intro-spective unity.

Gestalt unity is the sort of unity that obtains if and only if

the experience of a whole is such that had one salient part ofthe whole been removed from consciousness, the experiencewould have had a radically different phenomenal character.For example, on one natural way of seeing figure I.1, theviewer has an experience of a vase; but if the right half isremoved, the experience becomes one of a face, in profile,turned to the right

Gestalt unity is an interesting phenomenon, the principles

of which have been studied in detail by psychologists It ismore the exception than the rule, however For example,removing a part of figure I.2—the left half, say—does notproduce an experience of a whole with a radically differentcharacter And with intermodal cases, there are few Gestalteffects.10

The final kind of unity I shall distinguish is phenomenal

unity Phenomenal unity is present in all normal cases of

phenomenal consciousness It is usually taken to be a

prop-erty of experiences or P-conscious states; in my view, it is

different from object unity, neurophysiological unity, spatialunity, subject unity, higher-order subject unity, introspective

Kinds of Unity and Kinds of Consciousness 13

14 Introduction

Figure I.1

Figure I.2

unity, and Gestalt unity Phenomenal unity is the kind ofunity with which this book is concerned In chapter 1, anumber of examples of phenomenal unity are adduced,with the aim of clarifying what is involved for the case ofperceptual experience at a single time, and a theory isoffered of synchronic, perceptual, phenomenal unity.

Kinds of Unity and Kinds of Consciousness 15

1 The Unity of

Perceptual Experience

at a Time

1.1 Multiple Experiences and the Problem of Unity

(1) It is widely supposed in both philosophy and ogy that the senses function as largely separate channels ofinformation that generate different sense-specific impres-sions or experiences For example, I see some flowers, afence, and two squirrels, and in seeing them, I undergovisual experiences Listening to a nearby bird singing, I hearmelodious sounds, and in so doing, I am the subject of audi-tory experiences Finding a broken egg on the ground andsmelling its pungent odor, I experience olfactory experi-ences Placing a chocolate in my mouth and tasting itssweetness, I have gustatory experiences Running my fin-gers over the bark of a tree and feeling its roughness, I expe-rience tactual experiences

psychol-(2) So, according to the received view, if I am using all five

of my senses at a given time, I undergo five different taneous perceptual experiences at that time, each with itsown distinctive sense-specific phenomenal character Thisgenerates one version of the problem of the unity of con-scious experience How is it that if I am undergoing five

simul-different simultaneous perceptual experiences, it is nomenologically as if I were undergoing one? How is it thatthe five experiences are phenomenologically unified?(3) Suppose that at midday a wine taster is tasting aCabernet Sauvignon He sees the red wine in the wineglassbeneath his nose, as he brings the wine to his lips He smellsthe rich bouquet of the wine, as he tastes its fruity flavor inhis mouth; and in tasting it, he experiences the liquid touch-ing his tongue and the back of his mouth Perhaps, as hedoes this, he flicks a finger against the glass, thereby pro-ducing a high-pitched sound One way to describe the winetaster’s phenomenal state is to say that he has an experience

phe-of a certain colored shape and further he has an experience

of a certain smell and in addition he has an experience of a taste and etc But intuitively, this is unsatisfactory It

leaves something out: the unity of these experiences There

is something it is like for the wine taster overall at midday,

as he brings the wine to his lips and smells and tastes it.There is a unified phenomenology How can this be, if, inreality, he is undergoing five separate experiences? Ofcourse, for each of these experiences, there is something it islike to undergo the experience But there is also something it

is like to have these experiences together And that remains

to be accounted for

(4) Here is another example Holding a ripe apple in myhand, I experience a red surface and I experience a cold sur-face These experiences aren’t experienced in isolation, how-ever They are experienced together This is part of thephenomenology of my experience overall There is a unity

in my experience In what does this unity consist, given that

I am subject to two different token experiences, one visualand one tactual?

18 Chapter 1

(5) Phenomenal unity is not simply a matter of the relevantexperiences being directed on a single object in a spatiallylocalized region For one thing, in the wine taster case,although the wine he sees is in the glass, the wine he tastes is

in his mouth For another, the phenomenological unity ofexperiences to which I am referring can occur even withexperiences directed on widely separated objects Standing

by the railing of a ship and smelling the sea air, as I look at theship’s wake in the ocean, I may hear the sound of a tugboat

on my left some distance away Again, my overall experience

is unified It forms a seamless phenomenal whole withinwhich smell, sound, and various visual qualities are phenom-enologically present Phenomenal unity thus is to be distin-guished from object unity

(6) The phenomenal unity of simultaneous experiences isalso not a matter of their being actual or potential objects of

a single act of the subject’s attention Allowing for themoment that subjects can attend introspectively to theirexperiences,1intuitively the unity of simultaneous experi-ences can exist even without the introspective attention, just

as the experiences can Walking along a lane filled withleaves, you see many more leaves than you notice If yourinterest is held by one large, yellow and brown, star-shapedleaf, you do not cease to see the other leaves They do notvanish from your visual experiences They simply recedeinto the phenomenal background Likewise if some nestingbirds nearby take flight and you are struck by one shrillsound in particular The other sounds are still there in thephenomenal background of your auditory experience.Corresponding points apply to the phenomenal unity of

experiences Intuitively, this unity is not created by the act of

introspective attention Rather, it is revealed or disclosed

The Unity of Perceptual Experience at a Time 19

If this is so, then phenomenal unity is not the same as spective unity.2

intro-(7) This point also undermines the view, historically lar, that unity is imposed on the different sense experiences

popu-by thought, insofar as this view is supposed to account forphenomenal unity The Kantian suggestion that experiencesare unified by the capacity of their subjects to think of them

as their own fails to come to grips with the intuitive fact thatphenomenal unity is there in the experiences, whatevertheir subjects can or cannot think It is certainly true thatwithout the relevant concepts, a person cannot recognizethat there is phenomenal unity and thus, in these circum-stances, he or she is “blind” to it But the unity itself is not acognitive matter It is also worth noting that Kant’s pro-posal, insofar as it is applied to the case of phenomenalunity, is in trouble anyway with respect to the case of split-brain patients who are certainly able to self-ascribe theirperceptual experiences, but whose experiences, after thecommissurotomy, are phenomenally disunified in certainspecial experimental situations.3

(8) If there really is something it is like to undergo all thesense-specific experiences together at the same time—ifthere really is a phenomenological unity—then there must

be an encompassing experience, one that includes the otherexperiences within itself That experience is the bearer of thetotal, unified phenomenology

(9) Note that this experience cannot just be a conjunction ofthe five modality-specific experiences The conjunction oftwo experiences isn’t itself an experience at all The maximalexperience must be a new experience, one that unifies theother experiences into a single phenomenological whole AsBayne and Chalmers put the point in a recent discussion:

20 Chapter 1

At any given time, a subject has a multiplicity of experiences These experiences are distinct from each other But at the same time, they seem to be unified, by being aspects of a single encompassing state of consciousness (2003, p 23)

this encompassing state of consciousness can be thought of

as involving at least a conjunction of many more specific conscious states But what is important, on the unity thesis, is that this total state is not just a conjunction of conscious states It is also a conscious state in its own right (Ibid., p 27)

(10) That experiences bundle together to form overarchingexperiences is a view that has counterparts, of course, withineach sense For there is phenomenal unity not just acrosssenses but within them too Thus, Wilfrid Sellars (1968,

p 27) remarks: “A sense-impression of a complex is a complex

of impressions.” Likewise, Sydney Shoemaker (1996, p 177)says: “ the visual experience of a spatially extended thing is

a synthesis of visual experiences of parts of that thing.”(11) Seen from this vantage point, the problem of the unity

of conscious experience, as it applies to the case of neous perceptual experiences, is, first and foremost, to give

simulta-an account of the nature of the unifying experience in tion to the other experiences

rela-1.2 Undermining the Problem as Standardly Conceived

(12) The problem, stated in this way, is threatened by aninfinite regress If what it is like to undergo the overall ormaximal experience is different from what it is like to

undergo the component sense-specific experiences, E1–E5,then there must be a unifying relation between the latterexperiences that is itself experienced The experience of theunifying relation is not itself a sense-specific experience But

The Unity of Perceptual Experience at a Time 21

it is an experience nonetheless; for if there were no ence of the unifying relation, then there would be nothing it

experi-is like to have the sense-specific experiences unified Thereare, then, it seems, six experiences: the five sense-specificones and the experience of unity However, the maximalexperience isn’t just a conjunction of experiences It is a gen-uinely new unified experience with its own phenomenol-ogy So, what unites the six experiences together? It seemsthat there must be a further unifying relation that binds theexperiences This relation, however, must itself be experi-enced For the unity is phenomenal And now a regress hasbegun to which there is no end

(13) There is also a real question as to whether there is amaximal, unifying experience in the first place For consider

three simultaneous unified experiences, e1, e2, and e3 If the

unity or experienced togetherness of any two experiencesrequires that there be a unifying experience, then the unity

of e1 and e2 requires a further experience E that includes them Since E is unified with e3, another experience E is

now required But E  is also unified with E; so a further experience, E , that includes E and E is needed And the unity of E  with E and E necessitates yet another experi-

ence; and so on, without end

(14) Another pressing difficulty is that we are not tively aware of our experiences as unified; for we are notaware of our experiences via introspection at all This needs

introspec-a little explintrospec-anintrospec-ation

Suppose that you have just entered a friend’s countryhouse for the first time and you are standing in the livingroom, looking out at a courtyard filled with flowers Itseems to you that the room is open, that you can walkstraight out into the courtyard You try to do so and, alas,

22 Chapter 1

you bang hard into a sheet of glass, which extends from ing to floor and separates the courtyard from the room Youbang into the glass because you do not see it You are notaware of it; nor are you aware of any of its qualities No mat-ter how hard you peer, you cannot discern the glass It istransparent to you You see right through it to the flowersbeyond You are aware of the flowers, not by being aware ofthe glass, but by being aware of the facing surfaces of theflowers And in being aware of these surfaces, you are alsoaware of a myriad of qualities that seem to you to belong tothese surfaces You may not be able to name or describethese qualities but they look to you to qualify the surfaces.You experience them as being qualities of the surfaces None

ceil-of the qualities ceil-of which you are directly aware in seeing thevarious surfaces looks to you to be a quality of your experi-ence You do not experience any of these qualities as quali-ties of your experience For example, if redness is one of thequalities and roundness another, you do not experienceyour experience as red or round

If your friend tells you that there are several floor sheets of glass in the house and that they all produce asubtle change in the light passing through them so thatthings seen the other side appear more vividly colored than

ceiling-to-is usually the case, as you walk gingerly into the next room,you may become aware that there is another partitioningsheet of glass before you by being aware of the qualities thatappear to belong to nonglass surfaces before your eyes Youare not aware of the second sheet of glass any more than youwere aware of the first; but you are now aware that there is asheet of glass in the room by being aware of qualities appar-ently possessed by nonglass surfaces before you

Visual experiences are like such sheets of glass Peer ashard as you like via introspection, focus your attention in

The Unity of Perceptual Experience at a Time 23

any way you please, and you will only come across surfaces,volumes, films, and their apparent qualities Visual experi-ences are transparent to their subjects We are not introspec-tively aware of our visual experiences any more than we areperceptually aware of transparent sheets of glass If we try

to focus on our experiences, we “see” right through them tothe world outside By being aware of the qualities apparentlypossessed by surfaces, volumes, etc., we become aware that

we are undergoing visual experiences But we are not aware

of the experiences themselves.4

This is true, even if we are hallucinating It is just that

in this case the qualities apparently possessed by surfaces,volumes, etc., before our eyes are not so possessed The surfaces, volumes, etc., do not exist

(15) Introspection, on the view just presented, is cantly like displaced perception or secondary seeing-that, asFred Dretske (1995) has observed When I see that the gastank is nearly empty by seeing the gas gauge or when I seethat the door has been forced by seeing the marks on thedoor, I do not see the gas tank or the forcing of the door Myseeing-that is secondary or displaced I am not aware—I amnot conscious—of either the gas tank or the forcing of thedoor I am aware of something else—the gas gauge or themarks on the door—and by being aware of this other thing,

signifi-I am aware that so-and-so is the case

Similarly, in the case of introspection of a visual ence, I am not aware or conscious of the experience itself

experi-I am aware that experi-I am having a certain sort of experience bybeing aware of something other than the experience—thesurfaces apparently outside and their apparent qualities.5

(16) What is true above for the case of vision is true for theother senses For example, we hear things by hearing thesounds they emit These sounds are publicly accessible

24 Chapter 1