Jesse Prinz's Mistaken Account of the IQ Debate

In my course on "Biopolitics and Human Nature" this semester, we have begun with the debate over human nature, or we might call it the nature-nurture debate.  The two main readings for this debate are my Darwinian Natural Right: The Biological Ethics of Human Nature, which advocates an appeal to biological human nature as a moral and political standard, and Jesse Prinz's Beyond Human Nature: How Culture and Experience Shape the Human Mind, which criticizes any such appeal to biological human nature.  One might think that we are on opposite sides of this debate; but I can't be sure about this, because Prinz often contradicts himself, and sometimes he seems to be in complete agreement with me.

I argue that the nature-nurture dichotomy is a false dichotomy, because there's always a complex interaction between nature and nurture; and almost no one argues either for the extreme of genetic determinism or the extreme of cultural determinism.  Prinz agrees when he says that the biological determinist and the blank slate are straw men, because almost no one argues for such extreme positions (6).

But then Prinz affirms a naturist/nurturist dichotomy.  Although naturists and nurturists are not absolutely opposed to one another, they are different, but their difference is just a matter of emphasis.  Naturists do not say that biology is everything, and culture is nothing.  But they do say that biology is more important than culture.  Nurturists do not say biology is nothing, and culture is everything.  But they do say that culture is more important than nature (6-8).

And yet, as Prinz takes up various issues in this debate, he often ends up agreeing totally with the conclusions of the naturists.  For example, Prinz concludes that in the gene-environment interactions that explain schizophrenia, personality traits, and IQ the split is probably about 50% genes and 50% environment (26, 41, 50).  But that's exactly the conclusion reached by those naturists that Prinz the nurturist is supposed to be debating!  So now it seems there no real opposition between the naturists and the nurturists.

This point is sometimes obscured, however, because Prinz often suggests that the naturists really are genetic determinists, despite his claim that this is a straw man.  This becomes evident in his mistaken account of the debate over Richard Herrnstein and Charles Murray's book The Bell Curve.

Prinz says that Herrnstein and Murray claim that "difference in IQ cannot be affected by education," because "IQ differences are biologically fixed."  Thus, he identifies Herrnstein and Murray as biological determinists, and he rejects their position as "patently false" (71).

This is not true.  Herrnstein and Murray emphasize that IQ is not biologically fixed, because the genetic component of IQ is unlikely to be higher than 60%, and the rest is environmental (Bell Curve, 105-106).  They have a long section in their book on raising IQ through education (393-402, 414).  "Moving a child from an environment that is the very worst to the very best may make a big difference."  Unfortunately, however, in the United States, "what most interventions accomplish is to move children from awful environments to ones that are merely below average" (109).

Prinz points to the fact that students can increase their scores on the Scholastic Aptitude Test by taking preparatory courses, and he presents this as a refutation of Herrnstein and Murray's biological determinism.  But he doesn't tell his readers that Herrnstein and Murray acknowledge this improvement in SAT scores from coaching (Bell Curve, 400-402).

Prinz says that Herrnstein and Murray "argue that we disband affirmative action programmes" (62).  But he doesn't tell his readers that Herrnstein and Murray argue for returning "to the original intentions of affirmative action: to cast a wider net, to give preference to the members of disadvantaged groups, whatever their skin color, when qualifications are similar," as a way to achieve "progress toward a healthy multiracial society" (Bell Curve, 448).

Prinz cites a study finding that "infants transferred from poor homes into affluent homes increase scores by 12 to 16 points" (64).  But he doesn't tell his readers that Herrnstein and Murray recommend adoption and equalizing environments as a way to raise IQ scores (Bell Curve, 410-416).

Prinz illustrates the importance of environment by asking us to imagine having some genetically identical seeds, half of which we plant in "nutrient soil" and half in "bad soil."  The seeds planted in the bad soil will grow into plants much shorter than the plants in the good soil.  We can then explain the black/while IQ gap by saying that "black Americans are raised in bad soil" (64-67).  But he doesn't tell his readers that Herrnstein and Murray use exactly the same analogy: they suggest imagining two handfuls of genetically identical seed corn with one handful planted in the Mojave Desert and the other in Iowa.  "The seeds will grow in Iowa, not in the Mojave, and the result will have nothing to do with genetic differences" (298).

Prinz claims that the white/black IQ gap is explained by the effects of racist black stereotypes.  He cites one study to support this: "a group of good black and white students were asked to take a test, and half the students were asked to write down their race.  White students who specified their race did just as well as white students who did not specify their race.  Black students who did not specify their race performed just as well as whites, but black students who specified their race dramatically underperformed. . . . When black students are made aware of their race, their performance declines" (66-67).  He thus conveys the impression that this study showed that when black students are not afraid of confirming racist stereotypes about their race, the white/black IQ gap disappears.

But Prinz does not tell his readers that this impression is false, although it has been widely reported in psychology textbooks.  Anyone who reads the original article by Claude Steele and Joshua Aronson--"Stereotype Threat and the Intellectual Test Performance of African Americans," Journal of Personality and Social Psychology 69 (1995): 797-811--will see that it does not show that eliminating the stereotype threat eliminates the black/white IQ gap.  In the experiments by Steele and Aronson, black and white students were statistically equated on the basis of prior SAT scores, so that high-scoring blacks were matched with high-scoring whites.  In the sample studied, therefore, there were no differences between the groups in prior SAT scores.  Introducing a stereotype threat induced the black students to perform below the white students.  Removing the stereotype threat returned the scores to the prior level of no difference.  It is a misrepresentation of this experiment to conclude that eliminating stereotype threat eliminates the black/white IQ gap.  This has been pointed out by Paul Sackett, Chaitra Hardison, and Michael Cullen in "On Interpreting Stereotype Threat as Accounting for African-American-White Differences on Cognitive Tests," American Psychologist 59 (January 2004): 7-13.  This article is followed by an article by Steele and Aronson who agree that this is a good correction of a popular misrepresentation of their 1995 article.  Prinz does not bring any of this to the attention of his readers.

Some of my posts on The Bell Curve debate can be found here, here, here, here, and here.

I will be writing some more posts on Prinz.