David Brooks is one of the better columnists in the NYT (not of itself a great compliment). He does show respect for the facts most of the time. And his latest article on IQ is no exception (See also here). He does mention most of the salient findings from IQ research. Following his paper's real motto, however -- "all the news that's fit to slant" -- he exaggerates the uncertainties in that research. In so doing, he is following a long Leftist tradition that emerged in the '60s -- playing down the importance of IQ. There are few things more determinative of your success at achieving your goals in life than your IQ but that offends against the Leftist dogma that we are all equal and that we can all be "moulded" into whatever Leftists want us to be. And the fact that blacks have in general very low IQs (with some notable exceptions, of course) is "racist".

So a few comments on what he says: Firstly, he repeats the old saw that we don't really know what IQ is and that IQ is simply what IQ tests measure. Psychologists themselves sometimes say that but they do so mainly for PR reasons. It is perfectly plain what IQ tests measure: General problem solving ability -- or 'g', as it is mostly referred to in the academic literature. That the ability to solve one problem generalizes strongly (but not perfectly) to ability to solve many different sorts of problem is the basic finding underlying all IQ research.

Brooks also says: "A meta-analysis by Bernie Devlin of the University of Pittsburgh found that genes account for about 48 percent of the differences in I.Q. scores". I suppose one should be glad that the role of genetics in IQ gets a mention at all but Brooks seems to have picked the lowest estimate there is. An estimate of around 65% would be more representative of the findings over the last 100 years. I am not familiar with the Devlin study but the claim that it is a meta-analysis immediately induces cynicism in me. A meta-analyis is supposed to summarize ALL the available evidence on a question. In Leftist hands, however, a meta-analysis can summarize only that evidence which suits Leftists. See e.g. here.

Brooks then mentions the Flynn effect: That average IQs rose throughout the 20th centuary. This did puzzle psychologists for a while and it seems likely that many aspects of modernization played some role. Nutrition improved in most places over that period and nutrition can account for about 5 IQ points. Perinatal care improved (wider use of obstetricians etc.), thus avoiding damage to the fetal and newborn brain. But there is now fairly widespread agreement that improved test sophistication was the major factor. The 20th century saw a huge rise in the number of years that kids spent in the educational system and the educational system has generally featured a lot of testing. So good test-taking strategies were fostered and that helped with doing IQ tests too. But the rise in IQ scores now seems to have peaked in most Western countries so most of the barriers to people realizing their full genetic potential would now seem to have been removed and average levels of IQ should be fairly stable from now on. Interestingly, black IQ improved at roughly the same rate as white IQ but the black/white gap remains the same -- though there is some suggestion that it may have widened.

Brooks then goes on to mention the Turkheimer studies -- which found reduced heritability for IQ among poor U.S. blacks. The same result is not found in Britain but it would seem to show that genetic potential may be poorly realized under the very adverse environmental conditions that prevail in some black U.S. single-parent families. Brooks says that the Turkheimer studies show that "I.Q. can also be powerfully affected by environment". Indeed it can -- if the environment is adverse enough -- but it still remains that for most of us, it is our genetics that make us what we are.

Brooks then mentions the "multiple intelligences" theory. This is in fact a theory that goes back to the origins of IQ research about 100 years ago. And the finding then, as now, is that intelligence can indeed be divided into separate subject areas (mechanical ability, verbal ability, mathematical ability etc) but those "inteligences" still correlate highly. There are many cases where it is not so, of course, but people who are good in (say) verbal ability will also in general tend to do fairly well in mechanical ability. My skills, for instance, are predominantly verbal but I used to do my own mechanical repairs in my youth and I have taught statistics at university level. I actually rather hate anything mathematical but my general abilities got me where I needed to go in statistics. Interestingly enough, my son is a mathematician! The genetics were obviously there.

There are some psychologists, such as Gardner who claim to find a variety of different "intelligences" which do not correlate well with one-another. There is a very clear and simple demolition of the whole Gardner theory here -- which points out that the Gardner theory not only ignores the data but that its criteria for calling something "an intelligence" are so loose that sense of humour, sense of smell, musical ability, athletic ability etc could all be called "intelligences". By adopting similar rules I could say that all cats, dogs and horses are birds -- but that would still not make them so. See also my previous comments on the similar Sternberg theory.

Brooks concludes that scientists these days talk mostly about specific abilities rather than general ability and he is quite right about that. He forgets to mention, however, the fact that the vast political incorrectness of the IQ concept is the main reason behind that.

Finally, here is just one recent example of how widely helpful a high IQ can be. A toddler who has been reading since age 3 certainly has a very high IQ.


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