> Granted, the questions are related, but they are distinct.
> The first one turns out to be the easier question: Twin and
> adoption research clearly supports the claim that variation
> in IQ performance is in part influenced by genetic variation
> (e.g., the correlation in IQ score between a biological parent
> and one of their offspring raised in an adoptive household is
> greater than 0: it's hard to cook up a nongenetic explanation
> for that.) Where our new friend drives me nuts is with the
> spiel about "genetic determinism" (Luke, what were you
> saying about people not being this naive about genetics?).
As I said, I don't want to get involved in adding anything substantive about these issues in this environment, since it would not be fruitful, but I would like to correct an misconception that my earlier words produced, which was entirely my own fault: I do not really believe the "spiel" about "genetic determinism" that you are referring to, not as it is stated, so bluntly. The main reason I gave that quote from Chomsky as if *I* had said it was to see if Chomsky would also be savaged as some kind of racist. It is only this sort of quick and easy dismissal that I was originally objecting to, whether it comes in the form that a single book written by an outsider who arguably has an ideological axe to grind says all that there is to say about intelligence, how to measure it, and how it (along with variations in its distribution) arises, or whether it comes in the form of dismissing everything a life-long researcher in the area has to say by characterizing him as a racist.
So to nuance Chonsky's statement somewhat, obviously both environment and heredity play some role in the particular distributions of many of qualities that individual people can possess, including many cognitive properties. But separating out the contributions of the two factors is clearly very difficult, and (like, I believe, probably every other lay person here considering the issue) I know very little about the mathematical models and the simplifications needed to make any kind of simple quantitative estimate. I do know, though, that the estimates of h given are for particular populations at particular times, and thus a high component for h does not mean that differing environmental conditions from those that actually obtain could not have made a great difference in the observed results. Moreover, as I understand it, the models assume that there is no environment/heredity interaction, which seems wildly implausible (a simple example could be that when parents discover that their child is "gifted" at a very early age, they might very well act differently toward it).
So, in fact, I am not at all sure that this is the "easier" of the two questions at all. Yes, it is indeed possible to take the most arbitrary of tests (that measures nothing of interest) and establish that there has to be some genetic factor, in the manner that you suggested (or, say, with twins raised apart, although in both of these cases it *is* possible to "cook up" nongenetic explanations that might account for a portion of this). The total meaningless of the attribute measured makes no difference, so that is not the issue.
But it seems to be very difficult to go from this sort of statement to statements about an entire population. I am not even aware of exactly how this is done, but I think it would be interesting to find out.
> The second question's the tricky one, hotly debated by
> research psychologists.
Yes, that's really my point: it *is* debated. It is an open question pursued by serious research psychologists, and I don't think we have reason to believe that all of them are either racists or strong disbelievers in a general component to intelligence which correlates to varying degrees with the results of various "IQ" tests. There is also research being done on attempts to "reify" this general intelligence in terms of some more proximal and direct cause than environment and heredity.
Incidentally, it is not necessary for either me or Chomsky to believe the "spiel" in order to attribute to others the fear of its being true. For example, suppose Chomsky had said instead that he was surprised that so many people were bothered by the fact that a dog might walk by their window at night and unbenowst to them, turn a silent somersault. That's a nutty thing, very unlikely, but why are people so concerned about it (assuming counterfactually that they were)? Just forget about it. It rationally should not matter.