Kripke says that physicalists like me can't explain the 'apparent contingency' of mind-brain identities. He maintains that, if I really believed that pains are C-fibres, then I ought no longer to have any room for the thought that 'they' might come apart. His argument is that, since pains aren't identified via some contingent description, but in terms of how they feel, I have no good way of constructing a possible world, so to speak, where C-fibres are present yet pains absent.

I don't think that we are capable of anything like this many possible colour responses. Instead I argue that the perception of colour differences between two surfaces viewed side-by-side is a gestalt phenomenon.

The relevant features of scientific practice often have mundane explanations which don't point to any deep metaphysical moral. (Thus it would simply be messy and pointless for the chemists to essay physical reductions, or for the biologists to offer number-free explanations. It's a weird kind of science-worship that views these practical considerations as clues to the nature of reality.)

I rather incline towards 'conceptualism', in line with my view of colour perception - I don't think that we can represent objects and properties for which we have no concepts, not even in perceptual experience. In this sense I differ from those who defend 'non-conceptual content' like Michael Tye and Chris Peacocke.

There is a brain mechanism that works to identify colour differences directly, without first identifying the absolute colour of each surface. So on my view there is no reason to suppose anything like ten million colour responses to surface viewed singly.

After all, in supporting phenomenal concepts I am in a sense siding with introspection against the more behaviourist Wittgensteinians. But even so I don't think that introspection is powerful enough to resolve the specific issue about how many colours you can see.

This doesn't show that there is anything wrong with our theoretical understanding, any more than the intuition that the Earth is at rest shows that there must be something theoretically wrong with Copernicanism, or the intuition that time is moving shows that there is something theoretically wrong with the block universe 'B series' view of change.