Three lines of reasoning are discussed which have been put forward by A. R. Jensen in support of the hypothesis of genetic racial differences in IQ. These are the probabilistic connection of heritability to between-group genetic differences, the theoretical or formal relationship of within-group heritability to between-group heritability, and the regression of the IQ scores of blacks and whites to different population means. The first is shown to be a purely empirical claim that has no value as evidence in the absence of substantial confirming data, which are not available. The second and third are shown to be purely formal implications of the statistical models used to describe between-group heritability and linear regression, with no implications for the validity of the hypothesis. The attempted use of all three to support the hypothesis of genetic racial differences in IQ is discussed as an example of the fallacious reification of abstract methodology.
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Mackenzie, B. Hypothesized genetic racial differences in IQ: A criticism of three proposed lines of evidence. Behav Genet 10, 225–234 (1980). https://doi.org/10.1007/BF01066273
- A. R. Jensen
- race differences