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.

I realize that I won't have quite enough time to understand everything - but that hasn't stopped me wanting to understand as much as I can.

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.

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.

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.

I favour an interpretation of quantum mechanics (the 'Everett interpretation') according to which reality branches in any chancy quantum situation. On this view, Schrödinger's set-up will give rise to in two future branches of reality, one with a live cat, and one with a dead cat - and the talk of '50% chances' just indicates that the two branches are both equally real futures of the cat that originally entered the box.

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.