Wednesday, December 05, 2007

The ongoing IQ debate

 
Vitriolic and anti-conservative cultural commentator Stephen Metcalf has apparently put a bit of work into his recent article in Slate in which he attempts to rebut Saletan's article on IQ research. Metcalf actually appears to have read stuff on the subject! Predictably for a Leftist, though, most of what he says is ad hominem -- attempted character assassination of those with whom he disagrees. Vdare has however highlighted the shallowness of Metcalf's claims in that department rather well so I will just focus on a few of the substantive points that Metcalf raises.
 
...My interest in this debate springs from the fact that I am a psychometrician (specialist in the measurement of psychological variables) by trade. See here. <http://ray-dox.blogspot.com/2006/08/all-published-papers-by-j.html>
 
I think it is about time that I pointed out the obvious about the "seed" analogy to black/white IQ differences. Metcalf puts it as follows:
 
[[Imagine two wheat fields. Now imagine two genetically identical sets of seeds. (The analogy was first made famous by the Harvard evolutionary biologist and geneticist Richard Lewontin.) Now imagine each field is planted with these two identical seed stocks. Field No. 1 is given the best possible inputs: sunshine intensity, rain, soil nitrates, etc. Field No. 2 is given much less of all of the above. Within each field, inputs are kept uniform. Inevitably, the first field grows a healthier supply of grain than the second. But here is the rub: Within each field, the variation in outcomes is entirely hereditary. Between the two fields, the variation in outcomes in entirely environmental.]]
 
The argument simply assumes what it has to prove. It assumes that the two lots of seeds (genetic inheritance) are identical to start with. So the argument comes back immediately to the problem of sorting out whether black and white IQ is genetically different. And it is precisely that question which has been the subject of decades of research. Environmental differences do have SOME effect on IQ so it is perfectly possible that the UNDERLYING differences between blacks and whites are nil. But there is NOTHING that has ever been found which suggests that -- only a lot of wishful thinking.

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