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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
Accessed: 30/10/2008 07:01
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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.
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.
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.
lengths in the red spectrum as sharply as we are able to sort out yellow from
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.).
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.
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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