The Dickens-Flynn model of IQ, part 3: The social multiplier, and race.

We’ve established than a one-time intervention for a single person can’t permanently change their IQ, because once their environment returns to normal, so will their IQ.


But what if the “normal” environment changes? That’s what Flynn believes has happened over time – average levels of education have increased, more jobs require abstract reasoning, and so on. The sum of all these changes adds up to something vastly more powerful than a one-time intervention, which Flynn calls the “social multiplier.” This is his explanation for the effect that bears his name; it’s why average IQ scores have increased all over the world. And it’s an effect that builds on itself – the more time you spend around people who have developed their ability to reason abstractly, the better you get at reasoning abstractly – and then you become part of the social environment that raises other peoples’ IQs.

Simple enough. But we haven’t yet dealt with the most controversial aspect of IQ research: racial differences.
It’s not clear to me whether Flynn sees racial IQ differences as part of the individual multiplier or the social multiplier, because he says relatively little about race in his recent writings. But he wrote fairly extensively about it in the much earlier Race, Jensen, and IQ. At that point, he may not have fully appreciated the importance of the Flynn effect, so he focused on several other lines of evidence that racial IQ differences are not genetic:

  • Racial IQ differences have narrowed over time, even though genetic differences have not.
  • Biracial children with a black father have higher IQs than biracial children with a black mother, for no obvious genetic reason.
  • To the extent that we can measure racial ancestry of black people, it does not seem that black people with more “white genes” have consistently higher IQs.
  • Black people of American descent raised in certain other countries have IQs similar to white people of American descent raised in those countries.
  • The evidence is a bit mixed on this, but it seems that black women might have higher IQs on average than black men – a pattern we don’t see among white people, and thus another reason to suspect environmental influence.

So what environmental factors does Flynn think cause racial differences in IQ? Before I get to that, I need to clarify why this question is considered so difficult – because a lot of people seem to think the answer is obvious: black people are poorer than white people and go to worse schools, so they score lower on IQ tests.
But we can be pretty sure that’s not it, at least on the individual level. Studies have shown the following:

  • Parents have only a modest influence on the IQs of their children, and that influence fades to nothing as those children grow up and move away.
  • That includes parents’ socio-economic status: Identical twins have very similar IQs, even when one is raised in a wealthier home than the other.
  • School and teacher quality, including interventions like Head Start, has some influence on the IQ scores of schoolchildren, but that influence also fades as children grow up.

Parents, schools, and poverty are often the go-to environmental explanations for IQ, so once we’ve proven that they’re not the reason for racial differences in IQ scores, what’s left?

Possibly quite a lot. Flynn seems to more or less endorse the conclusions of the controversial Moynihan Report – that the legacy of slavery had left American black culture with a variety of maladaptive tendencies. He also cites Thomas Sowell extensively, and I get the sense that he would rather let Sowell do most of the talking rather than risk saying anything too controversial himself.
So I read Sowell. And I discovered that Sowell’s arguments against a genetic basis for racial IQ differences are thorough and persuasive, by far the best case I’ve seen made.


Which raises a question – why, when Vox wants to make a case against genetic IQ differences, do they rustle up three white people to do it?  I suspect that it’s because Vox’s readers would find Thomas Sowell unpalatable – he’s a socially conservative, black libertarian, and black conservatives seem to get an extra measure of scorn from liberals.
Also, Sowell’s views on racial IQ differences sometimes overlap with his “black rednecks” critique of what he claims are the pathologies of black culture – he claims, for example, that black culture in the United States devalues education, and that the cause of this is not discrimination or the legacy of slavery, but the influence of rural Southern and Appalachian culture (basically, the Borderers from Albion’s Seed.)

If you asked Sowell to explain racial IQ differences in one word, he would probably say “culture”; Flynn frames things differently and assigns much more blame to slavery and discrimination, and he would probably call it the “social multiplier”, but the general idea is the same – the usual suspects like parents, schools, neighborhoods, and poverty do influence IQ after all, as do many other things in the environment, but they work their magic on social groups, not on individuals. Blacks in the United States are culturally segregated to a large extent from whites, regardless of who their individual parents are or which school they went to, and (in Flynn and probably Sowell’s view) this segregated culture has a certain average IQ that exerts a pull on all its members.


My brain has a hard time deciding whether this is completely obvious or the most counterintuitive thing ever. Our society’s way of thinking tends to analyze people as individuals, in terms of their distinct life experiences; to think that parents exert a strong influence on their children; and that early experiences can alter the overall trajectory of a child’s life. Flynn and Sowell say that instead we should pay more attention to cultures, environments, and social categories. This reminds me in many ways of the case Judith Harris makes in The Nurture Assumption – a book that, not coincidentally, upsets a lot of people.


I should point out that it’s not necessary to think there’s anything wrong with black culture in order to accept this argument – white American culture in the 1950s apparently had an average IQ lower than that of today’s black culture, but we don’t think of that culture as promoting laziness or devaluing education. Notably, if a white American from the 1950s somehow showed up in our world today, we wouldn’t think they were stupid or unqualified to work a job. In some ways, this could be considered a theory of “cultural bias” – but of a kind much subtler than the “What SPF lotion would you use if your were going down to the polo grounds, fellow Klan member?” variety.


Conclusions in Part 4.

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