Of course, there remains the question of why we should find mind-brain identities so persistently counter-intuitive, if they are true. But this is a simple psychological question, and there are a number of plausible explanations. Indeed this is a topic that is quite extensively discussed outside philosophy, by developmental psychologists and theorists of religion among others, under the heading of 'intuitive dualism'. It is rather shocking that so few of the many philosophers working on 'the explanatory gap' are familiar with this empirical literature.

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.)

If neuroscientific research shows that those mechanisms only contain comparative information about colour differences, and have 'thrown away' more fine-grained information about the absolute colours of single surfaces, then that would support my position, in a way that just introspecting our colour experiences can't.

Of course our genes will make some capacities very much easier to learn than others, and of course our genes themselves are not learned. But the point remains that genes themselves are not cognitive capacities, and that anything worth calling a cognitive capacity will depend to some degree on learning and so not be innate.

I think my view is rather more radical than Pete Mandik's. Both of us want to show that colour perception doesn't transcend what can be conceptualized, but I don't think he goes so far as to deny that it doesn't involve different responses to all the discriminable surfaces.

If there is such a simple argument for physicalism, how come everybody hasn't always been a physicalist? That's a good question, and there is a good answer. The 'causal completeness of physics' wasn't widely accepted until recently.

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.