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Epiphenomenal Qualia

Author(s): Frank Jackson

Source: The Philosophical Quarterly, Vol. 32, No. 127 (Apr., 1982), pp. 127-136

Published by: Blackwell Publishing for The Philosophical Quarterly

Stable URL: http://www.jstor.org/stable/2960077

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127

EPIPHENOMENAL QUALIA

BY FRANK JACKSON

It is undeniable that the physical, chemical and biological sciences have

provided a great deal of information about the world we live in and about

ourselves. I will use the label 'physical information' for this kind of informa-

tion, and also for information that automatically comes along with it. For

example, if a medical scientist tells me enough about the processes that go

on in my nervous system, and about how they relate to happenings in the

world around me, to what has happened in the past and is likely to happen

in the future, to what happens to other similar and dissimilar organisms,

and the like, he or she tells me - if I am clever enough to fit it together

appropriately - about what is often called the functional role of those states

in me (and in organisms in general in similar cases). This information, and

its kin, I also label 'physical'.

I do not mean these sketchy remarksto constitute a definition of 'physical

information', and of the correlative notions of physical property, process,

and so on, but to indicate what I have in mind here. It is well known that

there are problems with giving a precise definition of these notions, and so

of the thesis of Physicalism that all (correct) information is physical informa-

tion.1 But - unlike some - I take the question of definition to cut across

the central problems I want to discuss in this paper.

I am what is sometimes known as a "qualia freak". I think that there

are certain features of the bodily sensations especially, but also of certain

perceptual experiences, which no amount of purely physical information

includes. Tell me everything physical there is to tell about what is going

on in a living brain, the kind of states, their functional role, their relation

to what goes on at other times and in other brains, and so on and so forth,

and be I as clever as can be in fitting it all together, you won't have told me

about the hurtfulness of pains, the itchiness of itches, pangs of jealousy, or

about the characteristic experience of tasting a lemon, smelling a rose,

hearing a loud noise or seeing the sky.

There are many qualia freaks, and some of them say that their rejection

of Physicalism is an unargued intuition.2 I think that they are being unfair

to themselves. They have the following argument. Nothing you could tell

of a physical sort captures the smell of a rose, for instance. Therefore,

Physicalism is false. By our lights this is a perfectly good argument. It is

1See, e.g., D. H. Mellor, "Materialism and Phenomenal Qualities", Aristotelian Society

Supp. Vol. 47 (1973), 107-19; and J. W. Cornman, Materialism and Sensations (New

Haven and London, 1971).

2Particularly in discussion, but see, e.g., Keith Campbell, Metaphysics (Belmont,

1976), p. 67.

128

FRANKJACKSON

obviously not to the point to question its validity, and the premise is

intuitively obviously true both to them and to me.

I must, however, admit that it is weak from a polemical point of view.

There are, unfortunately for us, many who do not find the premise intuitively

obvious. The task then is to present an argument whose premises are obvious

to all, or at least to as many as possible. This I try to do in ?1 with what I

will call "the Knowledge argument". In ?II I contrast the Knowledge argu-

ment with the Modal argument and in ?11 with the "What is it like to be"

argument. In ?IV I tackle the question of the causal role of qualia. The

major factor in stopping people from admitting qualia is the belief that they

would have to be given a causal role with respect to the physical world and

especially the brain;3 and it is hard to do this without sounding like someone

who believes in fairies. I seek in ?IV to turn this objection by arguing that

the view that qualia are epiphenomenal is a perfectly possible one.

I. THE KNOWLEDGE ARGUMENT FOR QUALIA

People vary considerably in their ability to discriminate colours. Sup-

pose that in an experiment to catalogue this variation Fred is discovered.

Fred has better colour vision than anyone else on record; he makes every

discrimination that anyone has ever made, and moreover he makes one that

we cannot even begin to make. Show him a batch of ripe tomatoes and he

sorts them into two roughly equal groups and does so with complete con-

sistency. That is, if you blindfold him, shuffle the tomatoes up, and then

remove the blindfold and ask him to sort them out again, he sorts them

into exactly the same two groups.

We ask Fred how he does it. He explains that all ripe tomatoes do not

look the same colour to him, and in fact that this is true of a great many

objects that we classify together as red. He sees two colours where we see

one, and he has in consequence developed for his own use two words 'redl'

and 'red2' to mark the difference. Perhaps he tells us that he has often

tried to teach the difference between red, and red2 to his friends but has

got nowhere and has concluded that the rest of the world is redl-red2 colour-

blind - or perhaps he has had partial success with his children, it doesn't

matter. In any case he explains to us that it would be quite wrong to think

that because 'red' appears in both 'redl' and 'red2' that the two colours are

shades of the one colour. He only uses the common term 'red' to fit more

easily into our restricted usage. To him red1 and red2 are as different from

each other and all the other colours as yellow is from blue. And his dis-

criminatory behaviour bears this out: he sorts red1 from red2 tomatoes with

the greatest of ease in a wide variety of viewing circumstances. Moreover,

an investigation of the physiological basis of Fred's exceptional ability re-

veals that Fred's optical system is able to separate out two groups of wave-

8See, e.g., D. C. Dennett, "Current Issues in the Philosophy of Mind", American

Philosophical Quarterly, 15 (1978), 249-61.

EPIPHENOMENAL QUALIA

129

lengths in the red spectrum as sharply as we are able to sort out yellow from

blue.4

I think that we should admit that Fred can see, really see, at least

one more colour than we can; red1is a different colour from red2. We are to

Fred as a totally red-green colour-blind person is to us. H. G. Wells' story

"The Country of the Blind" is about a sighted person in a totally blind

community.5 This person never manages to convince them that he can see,

that he has an extra sense. They ridicule this sense as quite inconceivable,

and treat his capacity to avoid falling into ditches, to win fights and so on

as precisely that capacity and nothing more. We would be making their

mistake if we refused to allow that Fred can see one more colour than we can.

What kind of experience does Fred have when he sees red, and red2?

What is the new colour or colours like? We would dearly like to know but

do not; and it seems that no amount of physical information about Fred's

brain and optical system tells us. We find out perhaps that Fred's cones

respond differentially to certain light waves in the red section of the spectrum

that make no difference to ours (or perhaps he has an extra cone) and that

this leads in Fred to a wider range of those brain states responsible for

visual discriminatory behaviour. But none of this tells us what we really

want to know about his colour experience. There is something about it we

don't know. But we know, we may suppose, everything about Fred's body,

his behaviour and dispositions to behaviour and about his internal physi-

ology, and everything about his history and relation to others that can be

given in physical accounts of persons. We have all the physical information.

Therefore, knowing all this is not knowing everything about Fred. It follows

that Physicalism leaves something out.

To reinforcethis conclusion, imagine that as a result of our investigations

into the internal workings of Fred we find out how to make everyone's

physiology like Fred's in the relevant respects; or perhaps Fred donates his

body to science and on his death we are able to transplant his optical system

into someone else - again the fine detail doesn't matter. The important

point is that such a happening would create enormous interest. People

would say, "At last we will know what it is like to see the extra colour, at

last we will know how Fred has differed from us in the way he has struggled

to tell us about for so long". Then it cannot be that we knew all along all

about Fred. But ex hypothesi we did know all along everything about Fred

that features in the physicalist scheme; hence the physicalist scheme leaves

something out.

Put it this way. After the operation, we will know moreabout Fred and

especially about his colour experiences. But beforehand we had all the

physical information we could desire about his body and brain, and indeed

4Put this, and similar simplifications below, in terms of Land's theory if you prefer.

See, e.g., Edwin H. Land, "Experiments in Color Vision", Scientific American, 200 (5

May 1959), 84-99.

5H. G. Wells, The Country of the Blind and Other Stories (London, n.d.).

130

FRANK JACKSON

everything that has ever featured in physicalist accounts of mind and

consciousness. Hence there is more to know than all that. Hence Physicalism

is incomplete.

Fred and the new colour(s) are of course essentially rhetorical devices.

The same point can be made with normal people and familiar colours. Mary

is a brilliant scientist who is, for whatever reason, forced to investigate the

world from a black and white room via a black and white television monitor.

She specialises in the neurophysiology of vision and acquires, let us suppose,

all the physical information there is to obtain about what goes on when we

see ripe tomatoes, or the sky, and use terms like 'red', 'blue', and so on. She

discovers, for example, just which wave-length combinations from the sky

stimulate the retina, and exactly how this produces via the central nervous

system the contraction of the vocal chords and expulsion of air from the

lungs that results in the uttering of the sentence 'The sky is blue'. (It can

hardly be denied that it is in principle possible to obtain all this physical

information from black and white television, otherwise the Open University

would of necessity need to use colour television.)

What will happen when Mary is released from her black and white room

or is given a colour television monitor? Will she learn anything or not? It

seems just obvious that she will learn something about the world and our

visual experience of it. But then it is inescapable that her previous know-

ledge was incomplete. But she had all the physical information. Ergo there

is more to have than that, and Physicalism is false.

Clearly the same style of Knowledge argument could be deployed for

taste, hearing, the bodily sensations and generally speaking for the various

mental states which are said to have (as it is variously put) raw feels, phen-

omenal features or qualia. The conclusion in each case is that the qualia

are left out of the physicalist story. And the polemical strength of the

Knowledge argument is that it is so hard to deny the central claim that one

can have all the physical information without having all the information

there is to have.

II. THE MODAL ARGUMENT

By the Modal Argument I mean an argument of the following style.6

Sceptics about other minds are not making a mistake in deductive logic,

whatever else may be wrong with their position. No amount of physical

information about another logically entails that he or she is conscious or

feels anything at all. Consequently there is a possible world with organisms

exactly like us in every physical respect (and remember that includes func-

tional states, physical history, et al.) but which differ from us profoundly

in that they have no conscious mental life at all. But then what is it that

we have and they lack? Not anything physical ex hypothesi. In all physical

6See, e.g., Keith Campbell, Body and Mind (New York, 1970); and Robert Kirk,

"Sentience and Behaviour", Mind, 83 (1974), 43-60.

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