It sure seems like he did. The following piece, on the "PISA Rankings and the Role of Schools in Student Performance on Standardized Tests," was posted by Posner on January 1, 2011, at his and Gary Becker's law and economics blog.
International comparisons are tricky, as Becker points out, but the PISA (Programme for International Student Assessment), which tests 15-year-olds for proficiency in reading, math, and science by well designed standard tests conducted in thousands of schools all over the world, is a careful and responsible program, the results of which deserve to be taken seriously. The latest results (which are for 2009) reveal among other things that although the United States spends more money per student on secondary school education than any other country except Switzerland and Austria, Americans’ performance on the PISA tests is mediocre. In the latest tests Americans ranked 17 in reading, 24 in science, and 30 in math. 15-year-old kids in East Asian nations (including Australia and New Zealand), along with Finland, Switzerland, the Netherlands, Belgium, and Canada, outperform the United States in all three subjects. Since 2000, when the PISA tests were first given, the United States has fallen in rank in reading and science, and is unchanged in math.
The rankings tend to be interpreted as measures of the quality of a nation’s pre-collegiate school system (primary and secondary education, since primary education influences performance in secondary schools). But this may be a mistake. Schooling is only one, though doubtless an important, input into performance on the PISA tests. Another is IQ. There have been some efforts to compare IQ across countries, notably by Richard Lynn and Tatu Vanhanen; see their 2006 book IQ and Global Inequality. Their results cannot be regarded as definitive, given significant limitations in the data, but they are suggestive. The authors find that the East Asian countries, which generally rank highest on the PISA tests (including reading—not just math and sciene), have the highest average IQs; the average IQ of Americans is lower because of our large black and Hispanic populations, which have lower average IQs than whites and Asians.
IQ is understood to reflect both genetic endowment and environmental factors, particularly factors operative very early in a child’s life, including prenatal care, maternal health, the educational level of the parents, family stability, and poverty (all these are correlated, and could of course reflect low IQs of parents as well as causing low IQs in their children). The case for very early intervention in children’s development, powerfully urged by the distinguished University of Chicago economist James Heckman, can be understood as an effort to lift IQs in the black and Hispanic communities and by doing so improve the educational performance of black and Hispanic children, including performance on the PISA tests. It is true that Heckman emphasizes noncognitive skills that facilitate learning, but these skills could also increase performance on IQ tests, indicating a positive effect on IQ.
The 2009 PISA test scores reveal that in American schools in which only a small percentage (no more than 10 percent) of the students receive free lunches or reduced-cost lunches, which are benefits provided to students from poor families, the PISA reading test scores are the highest in the world. But in the many American schools in which 75 percent or more of the students are from poor families, the scores are the second lowest among the 34 countries of the OECD; and the OECD includes such countries as Mexico, Turkey, Portugal, and Slovakia.
If IQ is playing a significant role in America’s mediocre showing on the PISA tests, improvements in secondary school education are unlikely to have dramatic effects. The white and Asian kids in American schools are already doing fine, for the most part; the black and Hispanic kids may not do much better until their early childhood environment is improved to the point at which black and Hispanic IQs are raised significantly.
Richard Posner is, by one estimate, the most frequently cited legal scholar of the 20th century; however one might view his jurisprudence, his willingness to quote approvingly from Richard Lynn and Tatu Vanhanen carries immeasurable weight.