I don’t agree. Of course, it depends on what you mean by “intelligence.” This is hypothetical, but – if brain size were correlated with scores on a test – and moreover, this correlation existed even when you narrowed your study to people raised in the same environment, for example, siblings – then the simplest explanation would be to posit the existence of some quality related to brain function which explains the ability of people to solve the sort of problems found on that test efficiently. And furthermore, we’d have to conclude that this test is a measure of that quantity.

Now if the test contained a collection of logical, verbal, spatial, mathematical puzzles, then that would bring us pretty close to what people normally mean when they say “intelligence.”

They don’t mention race, do they? The Abiola Lapite post I linked quoted Cernovsky criticizing Rushton specifically on the brain size-race link:

Rushton implied that Beals et al. presented large-scale evidence for racial inferiority of the Blacks with respect to cranial size. De facto, extensive statistical analyses by Beals et al. showed that cranial size varies primarily with climatic zones (e.g., distance from the equator), not race. According to Beals et al., the correlations of brain size to race are spurious: smaller crania are found in warmer climates, irrespective of race.

And, although Rushton misleadingly reported Tobias’s (1970) and Herskovits’ s (1930) surveys of cranial data as confirming his theory, their data are more consistent with the model presented by Beals et al. As already mentioned, in their reviews, cranial size and number of excess neurons of North American Blacks compared favorably to those of Caucasoids. It is only by pooling their data with data for Negroids from countries in hot climatic zones (notorious for famine and infant malnutrition) that Rushton obtained an illusory support for his postulates.

So even if the papers you link are right, reliance on Rushton is still a bad idea.

Also, I don’t think it follows that if there’s a link between brain size and performance on a test, that the test measures something fundamental about the brain—at least not something fundamental about intelligence.

Yes, if there was a link between brain size and performance on a test, I’d be forced to concede that this test at least in part measures something fundamental about the brain. However, this link is far from established: for example these two papers dispute it, and this one casts doubts on the causation mechanism. Sullivan & Saletan present only one side of the story, neglecting to mention criticisms and counterexamples. What does their eagerness to believe say about them?

Some commenters have called into question the reputability of J.P. Rushton, who published some papers on these correlations. I want to point out it isn’t just J.P. Rushton publishing correlations between head-size and intelligence – see here, here, and here for examples of peer-reviewed research by others with the same punchline.

Through willful ignorance.

Sickle Cell Disease
“Is sickle cell a “black” disease? No. Contrary to popular perception, the gene variant that causes sickle cell disease evolved as a result of its surprising upside – malaria resistance. In the malaria belt regions of Africa, the Middle East, southern Europe and South Asia, this gene variant flourished because the benefits of malaria resistance outweighed the negative impact of sickle cell disease.”

Moreover I have no data showing that the propensity to take the mickey out of psychologists who come bearing psychometric kits correlates with religious affiliation. But would Sir Cyril Burt have let that stop him?

Ah, well now I am happy to kick Sir Cyril with any foot of your choosing.

And (again, IIRC), musical ability and mathematical ability are supposed to be linked.

This is why I’ve come to the conclusion that there are no honest, informed Bell Curvists – because we can throw a vast quantity of contrary data at their thesis (group-level, changes in time, national and international, down to many replicable controlled experiments).

And in the end, they shrug off the data like a duck shrugging off water, and continue paddling their way, peddling their sh*t.

Posted by Matt Weiner: “Barry, that’s just not true—check this thread.”

Day-am. I’d seen some overposting by Steve, but I didn’t recall that one. And I read Yglesias’ blog.

Quite so, Mrs T. Obviously I am extending Ray’s theory in a way he might not endorse. Moreover I have no data showing that the propensity to take the mickey out of psychologists who come bearing psychometric kits correlates with religious affiliation. But would Sir Cyril Burt have let that stop him?

http://comm.colorado.edu/jjackson/chapt1.pdf

Note the echoes of Sullivan’s own conspiracy rhetoric.