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.

Natural selection has ensured that each species achieves the requisite effect somehow, but it doesn't care, so to speak, how the trick is done.

I do have quite a lot of sympathy for Fodor's picture of concepts as information-free atomic entities which get locked onto their referents causally, and to that extent they needn't involve anything much in the way of learning. But even so it seems perverse to call them 'innate'. Here we see again the oddity of treating 'not learned' as sufficient for innate.

The orthodox view of colour experience assumes that, when we see a colour difference between two surfaces viewed side-by-side, this is because we have different responses to each of the two surfaces viewed singly. Since we can detect colour differences between something like ten million different surfaces, this implies that we are capable of ten million colour responses to surfaces viewed singly.

I don't have much use for the concept of innateness. The everyday concept incorporates a number of different notions that can come apart in in many ways, and as a result encourages a range of dangerously fallacious inferences.

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.

Schrödinger's cat has a 50% quantum chance of coming out of the box alive and a 50% quantum chance of coming out dead. If you got in the box with it, the same would apply to you. So you really don't want to do that.