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.

Philosophers sometimes also use 'reductionist' more strictly, to mean 'type-identities' between mental and physical categories, and to exclude 'non-reductive physicalisms' like metaphysical functionalism.

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.

A certain kind of methodologically-minded philosopher of science is quick to read off metaphysical conclusions from features of scientific practice. Chemists don't derive their laws from fundamental physics, so reductive physicalism must be false. Biologists refer to natural numbers in some of their explanations, so numbers must exist. I think that this kind of thing makes for bad philosophy.

I think that there are non-physical laws all right: genuine (if not strict) laws written in the language of biology, economics, and so on. But I don't regard that as a contentious issue. Even reductionists about chemistry will think that there are special chemical laws whose formulation makes essential use of chemical terminology.

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 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.