↑ comment by satt ·
2013-10-28T02:18:53.806Z · LW(p) · GW(p)
We can keep putting data back and forth, but the very fact that a reasonable argument can be made for either case is my evidence for the claim that uncertainty is warranted.
Look at this from a different perspective; how much evidence of climate change would I have to reject as "just indicative," how many discipline's consensus's would I have to ignore, how much special pleading and goalpost-moving would I have to do before you gave up on reasonable argument and called me a climate kook?
As far as I can tell, the implied analogy here between Ishaan's position and climate kookery is an unfair one. I am not aware of a consensus on the aetiology of between-race IQ differences comparable to the consensus on global warming.
Of course, even if there aren't synthesis reports written by hundreds of scientists, or statements from national scientific societies, there are smaller-scale reports & surveys on the IQ controversy. But what Ishaan wrote turns out to broadly agree with those.
The two obvious examples here are the research summaries published in the wake of the commotion around The Bell Curve. One is "Intelligence: Knowns and Unknowns", a report by an 11-member panel approved by the American Psychological Association.
For IQ's heritability the panel reports values "of the order of .45" in childhood and "around .75" "by late adolescence" (p. 85). On the possibility of environmental factors entering into the white-black IQ gap it suggests that socioeconomic status "cannot be the whole explanation", but pays respectful attention to other cultural explanations of the gap (pp. 94-95) while acknowledging that they "have little direct empirical support" (p. 97). As for genetic factors: "There is certainly no such support for a genetic interpretation. At present, no one knows what causes this differential." (p. 97); "There is not much direct evidence on this point, but what little there is fails to support the genetic hypothesis." (p. 95). These conclusions are compatible with Ishaan's, except for the review's estimate of adult IQ heritability being higher than Ishaan's 60%.
The other research summary is Linda S. Gottfredson's "Mainstream Science on Intelligence: An Editorial With 52 Signatories, History, and Bibliography". It goes into less detail on IQ's heritability, but where it gets quantitative it says "estimates range from 0.4 to 0.8" (p. 14), which brackets Ishaan's 60% estimate nicely. As for the cause of lower black IQ, it says:
22. There is no definitive answer to why IQ bell curves differ across racial-ethnic groups. The reasons for these IQ differences between groups may be markedly different from the reasons for why individuals differ among themselves within any particular group (whites or blacks or Asians). [...] Most experts believe that environment is important in pushing the bell curves apart, but that genetics could be involved too.
23. Racial-ethnic differences are somewhat smaller but still substantial for individuals from the same socioeconomic backgrounds. To illustrate, black students from prosperous families tend to score higher in IQ than blacks from poor families, but they score no higher, on average, than whites from poor families.
This too is consistent with what Ishaan wrote.
(A shorter petition, "Behavior and Heredity", appeared in American Psychologist in 1972 over the names of 50 researchers. But it doesn't make any claims specific enough to compare to Ishaan's.)
I also know of a couple of surveys. The more recent is Charlie Reeve & Jennifer Charles's "Survey of opinions on the primacy of g and social consequences of ability testing: A comparison of expert and non-expert views", but that didn't ask its respondents about heritability or causes of interracial IQ differences. The older survey is Mark Snyderman & Stanley Rothman's "Survey of Expert Opinion on Intelligence and Aptitude Testing", which did ask.
In fact, it broke the heritability question down further, by asking about IQ's heritability among American whites and American blacks, considered separately:
7. White heritability estimate. Despite a consensus that there is a significant heritability to IQ in the American white population, experts disagree on the issue of whether there is sufficient evidence to arrive at a reasonable estimate of this heritability. Thirty-nine percent feel that there is sufficient evidence, compared to 40% who do not. Twenty-one percent do not feel qualified to answer. Only those respondents who feel there is sufficient evidence were asked to provide a heritability estimate. The mean estimate for the 214 received is 0.596 (SD = 0.166), meaning that these experts believe, on the average, that 60% of the variation in IQ within the American white population is associated with genetic variation.
8. Black heritability estimate. Experts are much less inclined to believe that sufficient evidence exists for an estimate of IQ heritability among the American black population. Twenty percent feel there is sufficient evidence, and 54% feel there is not. The mean heritability estimate for 101 received is 0.571 (SD = 0.178).
Those averages are very close to Ishaan's. As for the black-white IQ difference:
12. The source of the black-white difference in IQ. [...] Forty-five percent believe the difference to be a product of both genetic and environmental variation, compared to only 15% who feel the difference is entirely due to environmental variation. Twenty-four percent of experts do not believe there are sufficient data to support any reasonable opinion, and 14% did not respond to the question. Eight experts (1%) indicate a belief in an entirely genetic determination.
There was no majority opinion in the survey. Even after cutting out the non-responses, only a bare majority (about 53%) felt confident in saying the IQ difference had a genetic component. Meanwhile, about 45% of those who responded took either the same position as Ishaan (insufficient data) or a more environmentalist one.
All in all, Ishaan's views are about as hereditarian as the expert consensus, where that consensus exists. I don't understand which "discipline's consensus's" Ishaan's meant to be ignoring. (I'm leery of the suggestion of "goalpost-moving", too, since I can't spot any substantial drift in the claims Ishaan made over time.)