The two bell curves

Critiques of The Bell Curve, compared to subsequent rebuttals by Murray, suggest that two books are being discussed: the one that Herrnstein and Murray claim to have written and the one that most readers believe we have read. Extensive debate about what is actually printed in The Bell Curve can be traced to the authors' use of a disclaimer/ignore disclaimer strategy. Unfortunately, illogical juxtapositions of disclaimers and conclusions often demand specialized knowledge to detect, such as familiarity with the heritability coefficient. This essay begins by illustrating the disclaimer/ignore disclaimer strategy with selected quotes from Chapter 13 (“Ethnic Differences in Cognitive Ability”). A primer of heritability follows to familiarize readers with the technical limitations of that concept. Finally, Herrnstein and Murray's disclaimers about heritability are contrasted with their conclusions based upon that concept.