Columnist Han van der Maas recently collaborated on a podcast (‘Forbidden territory’ by Maarten Boudry) about group disparities in IQ, a dangerous topic. Charles Murray, one of the authors of a notorious bestseller on the subject, can be admired on YouTube as a champion of free speech and the scientific method.
Charles Murray, together with several dozen researchers, defends the proposition that differences in average intelligence between the white and black populations of the U.S. are partly genetic. I advocate a cautious use of the term racism, but this thesis is also explicitly racist by my definition.
How should this be dealt with? I see three options: ignore, cancel or refute. Ignoring doesn't seem to work; the far right is on the rise worldwide. There is much to be said for canceling or de-platforming, but I was shocked to see how Murray's popularity soared after he was prevented from speaking at American universities.
Since intelligence is one of the subjects of our research group, we have made attempts at rebuttal. For example, we have shown that the IQ measurements in Africa, which they invariably quote, are unreliable and that the so-called Jensen effect, which we will leave aside for the moment, actually underscores the importance of environment. We also attempted to replace the g-theory of intelligence with a less biologically oriented alternative.
This soon becomes quite technical. Refuting it is not so simple because the science of intelligence is still in its infancy. Every link in Murray's reasoning is debatable but they are not all equally weak. For example, the IQ test is quite reliable and valid in the sense that it predicts success in education and employment reasonably well. Compared to instruments in the natural sciences, the IQ test is a joke, but in the humanities, it is one of the best tests we have.
Murray thinks attacks on the IQ test are wonderful. He thinks so even when critics dispute that there are group differences in average IQ scores between black and white populations in the U.S., for example. These may be decreasing, but they are there and they are quite large. Given the huge differences in living conditions, including access to good education, this is also not surprising.
Racist IQ researchers
The next step in the reasoning of racist IQ researchers is that individual differences in intelligence are largely hereditary. Again, this is not the weak link, although the debate about the roles of heredity and environment of intelligence and many other psychological traits is very complex. Modern genetic research in this area is undergoing major developments, but it is fairly certain that some of the differences in intelligence between people are related to a large number of genes, each of which explains only a very small part of the variance.
So what is the problem with Murray's argument? The first real problem is the concept of race. The genetic biological basis of this concept is very shaky. At best, it is about statistical clusters of traits in which variation within groups is enormous and the boundaries between groups are quickly diluted. A practical justification for this concept is that people identify with races and mention them in all kinds of questionnaires. But this does not take the sting out of it, because Murray usually talks about white and black populations without calling them races.
I think the racist reasoning goes wrong when Murray and others claim that because individual differences in intelligence are partly hereditary, average group differences must be, too. They call this the default assumption or the simplest hypothesis that opponents just have to refute. But the assumption that effects within and between individuals or between individuals and between groups are of the same nature is a fallacy also known as Simpson’s paradox. A simple example concerns typing skills. If I type faster I make more mistakes. But when I compare people with different typing skills, I discover that people who type faster actually make fewer mistakes. So the relationship reverses. Statistical effects at one level of aggregation (for example, between people), cannot be generalized to other levels (between groups).
This is an important point because there is not much more these researchers have to offer on this issue. There is no known genetic mechanism for differences in IQ scores between populations. On the contrary, several very well-documented environment-based causal mechanisms do explain these differences (poor education, poverty, and racism). It is up to Murray to show that these differences also have a genetic source: Extraordinary claims require extraordinary evidence. And that extraordinary evidence is lacking.
Racist IQ researchers are not looking for evidence that contradicts their position. They stand in one of the darkest traditions of science in which, in addition to racism, eugenics is a notorious theme. The main question I asked at the beginning is whether this attempt at refutation is futile. With this attempt, am I not merely legitimizing the work of these researchers? I think that clear rebuttal matters, poorly argued rebuttals are counterproductive, and de-platforming is misguided. But perhaps I am naïve.
Han van der Maas is professor of psychological methods theory.