Reading: Lewis 'What Experience Teaches' in Lycan (ed.) Mind and Cognition
Jackson 'Epiphenomenal Qualia' in Lycan (ed.) Mind and Cognition and Philosophy Quarterly (1982)
Nagel 'What is it Like to be a Bat' in Mortal Questions
I will argue that physicalism about the world cannot be true because it cannot capture what Nagel calls the 'subjective character of experience'. Physicalism, or materialism, is the theory that holds that everything we know can be explained in purely physical terms. That is to say, a physicalist believes that we can give an account of everything that goes on in our brain (ie. the movement of neurons etc.) and we will be able to learn everything there is to know about a person's experience. I will argue that mental states cannot be reduced to physical states and that consciousness cannot be explained by a physicalist. The crux of the question we are investigating is whether we can devise an objective phenomenology that would "describe the subjective character of experiences in a form comprehensible to beings incapable of having those experiences"1 . I would argue, with Jackson and Nagel, that we cannot.
In this essay I will first of all consider three main arguments for the existence of phenomenal information (what Jackson terms 'qualia'). I will then look at a physicalist response to these arguments and assess the plausibility of the Ability Hypothesis. Finally I will look briefly at arguments that physicalists and non-physicalists give for qualia being epiphenomenal (that is, causally impotent with regards to the physical world) and will hopefully show that it is nonsensical to think of qualia as anything other than epiphenomenal.
The principal argument for the existence of qualia, put forward by Jackson and others, is the knowledge argument. In my view, this is the most effective attack on physicalism that can be made and it shows that a physicalist account of the world leaves something crucial out. We are asked to imagine a scientist, Mary, who has never experiences colour. She conducts all her research from a black and white room, using a black and white television monitor. She is an expert on colour perception and knows exactly what takes place in the brain when someone experiences, say, the colour blue. So she has all the physical information about someone's experience of the colour blue, but imagine that she is released from the room and she looks up at the sky and sees blue for the first time. It just seems obvious that she is gaining new information, namely what it is like to experience the colour blue, and this undermines physicalism, as Jackson shows:
"It is inescapable that her previous knowledge was incomplete. But she had all the physical information. Ergo there is more to have than that, and physicalism is false."2
A physicalist would have to deny that Mary is finding out anything new on her release, and come up with an alternative explanation. I will return to the physicalist response to the knowledge argument a bit later.
Another argument that can be used against physicalism is the modal argument, whereby appeal is made to a possible world where there are creatures exactly physically alike to us, but lacking consciousness. This argument is less effective than the knowledge argument, because a physicalist can simply reject the fact that there is such a possible world. It seems that this argument only carries weight if we have already accepted the knowledge argument.
The third argument put forward by non-physicalists is that which Nagel adopts in his paper 'What is it like to be a Bat?'. The crux of his argument seems to be that no amount of physical information can illuminate for us the unique nature of the subjective experience that a bat (or indeed another person) undergoes. Nagel argues that physicalism (which is essentially objective) cannot account for conscious experience because it cannot explain the phenomenological features of experience that are essentially subjective. Her even questions whether experiences have an objective character at all:
"Does it make sense...to ask what my experiences are really like, as opposed to how they appear to me?"3
So, on this view, a certain brain state doesn't necessarily entail a corresponding subjective character, and thus, yet again, physicalism leaves something out.
I will now consider how a physicalist might respond to these arguments and look in particular at Lewis' criticisms of the Hypothesis of Phenomenal Information and his arguments for the alternative Ability Hypothesis. Lewis admits that if the Hypothesis of Phenomenal Information is correct then the knowledge argument undermines physicalism and so, as a physicalist, he must deny the Hypothesis of Phenomenal Information (ie deny the existence of qualia). The Hypothesis of Phenomenal Information holds that, besides physical information, there is another quite different kind of information, namely phenomenal information, and this can not be reduced to, or explained in terms of, physical information. It follows from this that two cases can be exactly alike physically, yet differ phenomenologically (this explains why a non-physicalist would be able to accept the modal argument, and why a physicalist like Lewis would dispute it). Obviously, physicalism stands in stark contrast to this because it holds that there is no difference without physical difference. Lewis suggests that the idea of phenomenal information does not make sense because it treats information in terms of eliminated possibilities, and he cannot see, in the case of tasting Vegemite, what the alternative open possibilities are. He states that:
"I cannot present to myself in thought a range of alternative possibilities about what it might be like to taste Vegemite".4
But is this so? It seems to me that we can imagine a range of different possibilities of what an experience might be like, and it is only by undergoing that experience that we are able to eliminate those which do not accurately reflect the character of the experience. So it does not seem as though Lewis can show exactly what is wrong with the Hypothesis of Phenomenal Information. He presents an alternative hypothesis, namely the Ability Hypothesis which holds that:
"Knowing what an experience is like just is the possession of these abilities to remember, imagine, and recognise. It isn't the possession of any kind of information. It isn't knowing that certain possibilities aren't actualised. It isn't knowing-that. It's knowing-how.".5
Whilst I would agree that having a certain experience does endow you with new abilities, I would argue that these abilities are gained in virtue of the fact that you now have new information. You are able to remember and recognise the colour blue because, having experienced seeing the colour blue, you now have the information of what it is like to see the colour blue at your disposal. I would dispute Lewis' claim that knowing what an experience is like is not knowing that certain possibilities are not actualised. Before you have had an experience of, say, tasting Vegemite, you can only speculate about what it is like (call this expectation A). Having tasted it, it would be quite natural to comment, 'It doesn't taste like I expected it to'. It seems that what you expected it possibly tasted like is not, in actual fact, what it tastes like. So you are gaining the information that possibility A has not been actualised. So it seems that the Hypothesis of Phenomenal Information captures more accurately than the Ability Hypothesis what goes on when we find out what it is like to undergo a certain experience.
Finally I will look briefly at why, if qualia exist, they must be epiphenomenal (ie. they must be causally impotent to the physical world). It could be argued that it is just obvious that qualia are not epiphenomenal, but, as Jackson argues, what happens is simply that physical happenings in the brain cause both the hurtfulness of pain and the interjection 'It hurts!'. It can also be argued that since qualia are not conducive to survival, their existence goes against Darwin's theory of natural selection. But it can be argued in response that qualia are a necessary by-product of something which is conducive to survival, namely certain brain processes. A third criticism of the view that qualia are epiphenomenal is that, if they were causally impotent and made no impact on behaviour, we would be able to make no inferences about the existence of other minds. But, as Jackson points out,
"The epiphenomenalist can argue from the behaviour of others to the qualia of others by arguing from the behaviour of others back to the causes in the brains of others and out again to their qualia".6
Even a physicalist like Lewis can argue that if qualia exist, then they must be epiphenomenal, whilst denying that qualia do exist. Lewis states that,
"If something non-physical sometimes makes a difference to the motions of physical particles, then physics as we know it is wrong...(so) a friend of the phenomenological aspect would be safer to join Jackson in defence of epiphenomenal qualia".7
As we have seen, physicalism can be rejected convincingly by way of the knowledge argument, which rests on the Hypothesis of Phenomenal Information. I do not think that the Ability Hypothesis forwarded by Lewis is a plausible alternative, and therefore a physicalist cannot show that qualia do not exist. The physicalist still needs to explain how, in Mary's case, her seeing red for the first time not only seems to give her new abilities, but also new information, which can only be phenomenal. I would argue that qualia can be persuasively argued for and that they must be epiphenomenal for the reasons discussed above, that both non-physicalists and physicalists give.
© Anne Witton 1996. No part of this article may be copied without my permission.
