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August 30, 2005

The "Cognitive Elite"

Matthew Yglesias writes:

TPMCafe || Holds Up Well?: For all I know, the uncontroversial parts of [Herrnstein and Murray's The Bell Curve book] (which I understand to have been the clear majority of the text) hold up just find, but the controversial stuff about race and IQ doesn't hold up at all...

Ummm... No.

The "uncontroversial" parts of the book are a set of claims that:

  1. Genetically-inherited intelligence is the really important driver of socioeconomic success or failure in America.
  2. American society is or is about to become highly stratified by genetically-inherited intelligence.
  3. An important consequence of this is that there is nothing we can do to prevent the children of the rich and powerful from being rich and powerful themselves.
  4. Because the reason they are rich and powerful is because they are members of a genetic cognitive elite.

These are all wrong too. As Bowles and Gintis report:

Brad DeLong's Semi-Daily Journal: Why Oh Why Can't We Have a Better Press Corps? (Michael Barone: Intellectual Garbage Scow Edition): If the heritability of IQ were 0.5 and the degree of assortation, m, were 0.2 (both reasonable, if only ball park estimates) and the genetic inheritance of IQ were the only mechanism accounting for intergenerational income transmission, then the intergenerational correlation [of lifetime income] would be 0.01, or roughly two percent [of] the observed intergenerational correlation [of lifetime income between parents and children].

Yes, America is an increasingly stratified society. Yes, a huge amount of inequality is inherited. No, differences in IQ--acting both directly on job performance and indirectly because higher IQ people get more education--is not a terribly important source of income inequality. No, inheritance of genetic factors shaping IQ is not more than a trivial source of the intergenerational transmission of income inequality.

Posted by DeLong at August 30, 2005 03:33 PM