To: Melvin F.
From: Geoffrey Klempner
Subject: Zombies in philosophy and Wittgenstein's Blue Book
Date: 18 January 2008 12:46

Dear Mel,

Thank you for your email of 8 January, with your first essay for the Philosophy of Mind program, in response to the question, 'What is the philosophical significance of the idea of a zombie?' and your notes on Wittgenstein's 'Blue Book' in lieu of comments on unit 3.

Idea of a zombie

As you point out, there is a problem here about the question of onus: is the onus on the zombie supporter to prove the logical possibility of a zombie, or is the onus on the zombie detractor to prove its logical impossibility?

Let's take your invisible pink elephants. If someone believes that pink elephants exist then the onus is clearly on them to establish their existence. On the other hand if they merely believe that invisible pink elephants are logically possible, where does the onus lie?

Surely in this case, with the detractor. If I say, 'There is an invisible pink elephant on the streets of Sheffield,' this statement, although neither verifiable nor falsifiable is made up of words which have a meaning. Some things are invisible, some things are pink and some things are elephants. The only difficulty is how something can be pink and invisible at the same time. But we can stipulate an answer. E.g. 'pink on occasions when the elephant becomes visible.' No contradiction there.

On the other hand, 'There is a philosopher in Sheffield who writes emails to his students, but who does not have any thoughts or experiences,' is prima facie self-contradictory. To 'write' or to 'philosophise' implies thought of some kind. So according to this the onus is on the zombie supporter to establish logical possibility.

What turns the debate is the idea of qualia. The zombie supporter claims that the words 'think' and 'experience' have two meanings, a behavioural (3rd person) meaning and a 1st person meaning accessible only to the subject. Hence the idea of a subject who behaves normally but for whom there is 'darkness inside'.

If you say, 'There might be something non-physical which ultimately explains consciousness' this isn't a possible defence for the zombie supporter, so long as the 'non-physical something' is conceived merely as an entity which escapes the net of physical law. Maybe there are such entities, and maybe that is what makes me conscious. But now I can perform exactly the same thought experiment as before. I can imagine someone like me physically and 'non-physically' for whom there is darkness inside. Why is that not logically possible?

One other point I wanted to make is that there is some unclarity about the claim that physical facts 'explain' consciousness.

In order to be a material monist, it is not necessary to hold out the possibility of any kind of reductive explanation of consciousness. Maybe there are things which are intrinsically inexplicable. Davidson's argument in 'Mental Events' claims to establish material monism on the basis of a denial of reducibility. Connectionists deny that the brain works by 'running a program'. And so on. The minimum required for material monism is supervenience, and it is this claim that the zombie argument must refute.

My own argument against zombie supporters is simply, 'A zombie would say what you are saying' which at the very least poses a difficult paradox even if this is not an outright self-contradiction.

Blue Book

Wittgenstein was unhappy about publishing Philosophical Investigations, which we now regard as his major work, because he thought it was unfinished. And most commentators agree that the first third or so is more tightly argued than the rest.

The Blue Book, although only intended for circulation amongst his students, nevertheless represents a stage in the development of his thought (as the Brown Book, which is composed in a style much more reminiscent of the Investigations). Therefore, I would read the Blue Book with the working assumption that this was Wittgenstein's best attempt to express his views at the time. Having a particular audience in mind (as I have found, with Pathways) is a great way to help one focus one's thoughts.

You have picked up on two strands of Wittgenstein's thought, one concerning the metaphysics of solipsism/ idealism/ realism and one concerning epistemological scepticism. Wittgenstein does distinguish these, although in discussing 'solipsism' his focus is very much on the metaphysical variety.

The best book to read for Wittgenstein's epistemological views is 'On Certainty', his last book and one of the most accessible. Wittgenstein's response to scepticism argued for on the basis of the kinds of thought experiment you cite (I might be alone in a world populated by robots, I might be a brain in a vat) is not to deny the 'logical possibility' of the hypothesis but rather to point out that more is needed. At one point, in the Investigations, in response to the question, 'Aren't you shutting your eyes to scepticism?' Wittgenstein answers simply, 'They are shut.' Circumstances could arise which would prompt us to raise meaningful sceptical questions (e.g. the appearance of strange anomalies, as in the Matrix). But they haven't, so we don't. This is a point about meaning, not merely an observation of fact.

Wittgenstein's standard argument against the solipsist or idealist is that none of the words that the solipsist or idealist uses succeeds in expressing what they 'mean'. For example, the solipsist wants to say that only my pains are real pains. OK, says Wittgenstein, so now instead of saying 'I am in pain' I can say, 'There is a real pain'. So what?

In the Metaphysics program, I develop an extended dialectic in which what the solipsist and idealist 'mean' can be expressed, and argued against. So I am not in full agreement with Wittgenstein here, although I do take the point that (once again) we are dealing with a question of onus. Mere statements like, 'I believe XYZ' are not enough to 'prove' that you are -- or 'make' you -- a solipsist or idealist.

All the best,

Geoffrey