I claimed that Jensen’s views are relatively uncontroversial, not that they are entirely so. In making that claim, I wasn’t thinking only of Jensen’s views about the genetic component of the Black-White gap in IQ scores, but also about his views on the existence of such a gap and on the degree to which such scores measure genuine differences in intellectual ability. Perhaps it was confusing on my part to use Jensen’s name to refer to the cluster of views I had in mind. The point I wished to make was that the various views about race and IQ that taw might have had in mind in writing the sentence quoted above are not significantly more controversial today than they were in the past, and are shared by a sizeable portion of the relevant community of experts. As Snyderman and Rothman write (quoted by Gottfredson, p. 54),
On the whole, scholars with any expertise in the area of intelligence and intelligence testing … share a common view of [what constitute] the most important components of intelligence, and are convinced that [intelligence] can be measured
with some degree of accuracy. An overwhelming majority also believe that individual genetic inheritance contributes to variations in IQ within the white community, and a smaller majority express the same view about the black-white and SES [socioeconomic] differences in IQ.
Anecdotally, I myself have become an agnostic about the source of the Black-White differences in IQ, after reading Richard Nisbett’s Intelligence and How to Get It.
IIRC Jensen’s original argument was based on very high estimates for IQ heritability (>.8). When within-group heritability is so high, a simple statistical argument makes it very likely that large between-group differences contain at least a genetic component. The only alternative would be that some unknown environmental factor would depress all blacks equally (a varying effect would reduce within-group heritability), which is not very plausible.
Now that estimates of IQ heritability have been revised down to .5, the argument loses much of its power.
The Dickens-Flynn model, with high gene-environment correlations (the effects of genetic differences seem large because those genetic differences lead to assortment into different environments, but broad environmental change can still have major effects, as in the Flynn Effect) seems a very powerful indicator that environmental explanations are possible.
Hi Carl,
I claimed that Jensen’s views are relatively uncontroversial, not that they are entirely so. In making that claim, I wasn’t thinking only of Jensen’s views about the genetic component of the Black-White gap in IQ scores, but also about his views on the existence of such a gap and on the degree to which such scores measure genuine differences in intellectual ability. Perhaps it was confusing on my part to use Jensen’s name to refer to the cluster of views I had in mind. The point I wished to make was that the various views about race and IQ that taw might have had in mind in writing the sentence quoted above are not significantly more controversial today than they were in the past, and are shared by a sizeable portion of the relevant community of experts. As Snyderman and Rothman write (quoted by Gottfredson, p. 54),
Anecdotally, I myself have become an agnostic about the source of the Black-White differences in IQ, after reading Richard Nisbett’s Intelligence and How to Get It.
IIRC Jensen’s original argument was based on very high estimates for IQ heritability (>.8). When within-group heritability is so high, a simple statistical argument makes it very likely that large between-group differences contain at least a genetic component. The only alternative would be that some unknown environmental factor would depress all blacks equally (a varying effect would reduce within-group heritability), which is not very plausible.
Now that estimates of IQ heritability have been revised down to .5, the argument loses much of its power.
Bouchard’s recent meta-analysis upholds such high estimates, at least for adulthood. These are the figures listed on Table 1 (p. 150):
Did you type the number for Age 16 correctly? I can think of no sensible reason why there should be a divot there.
I uploaded Bouchard’s paper here. I also uploaded Snyderman and Rothman’s study here.
Yes, the figure is correct.
The Dickens-Flynn model, with high gene-environment correlations (the effects of genetic differences seem large because those genetic differences lead to assortment into different environments, but broad environmental change can still have major effects, as in the Flynn Effect) seems a very powerful indicator that environmental explanations are possible.