I just noticed that the Stanford Encyclopedia of Philosophy entry on Zombies was recently updated (authored by Robert Kirk, who’s book I reviewed for phil. psych). I was pleased to see that my JCS paper was mentioned in the “anti-zombie argument for physicalism” section. But Kirk cites my paper as arguing that “we should reject the inference from conceivability to possibility”. It is true that others that have pressed versions of the ‘anti-zombie’ argument for this conclusion, I am not one of them. I want to grant the link between conceivability and possibility. It is true that I harbor empiricist leanings but if I were a rationalist I would find Chalmers’ CP thesis very attractive; but even so the zombie argument is inconclusive because we cannot simply assert that zombies are conceivable.
My complaint against the zombie argument has always been that the move from (1) ‘zombies seem conceivable to me’ to (2) ‘zombies are ideally conceivable’ is question begging. The only thing we really have evidence for is (1) but it is (2) that is actually used in the zombie argument. That this move is illegitimate is shown by the fact that shombies and zoombies seem conceivable to me (and others it turns out) but if I were to then say that they were ideally conceivable I would be accused of begging the question. Both zombies and shombies seem conceivable but only one of them can actually be ideally conceivable and importantly we have no a priori reasons that can decide which is which. Rather what seems to be happening is that one’s intuitions are tracking the theory that one accepts, perhaps implicitly. Thus we don’t know if zombies are ideally conceivable at this point. Nor do we know if shombies are. Both seem to be conceivable to various people but we don’t have enough empirical knowledge of the brain to decide. From this I draw the meta-lesson that we should deprioritize the a priori arguments for and against physicalism. What we need to do now is focus on specific theories of consciousness (like higher-order theories, say 🙂 ) and brain science. Even if we can in principle know a priori that the mind is just the brain, or that it isn’t, the way that we will come to know is empirical (just like water and H2O: even if it is in principle knowable a priori that water is H2O (because on can deduce one set of facts from the other) we discovered it empirically. A priori arguments played no positive role in the discovery).