Significance and policy relevance
IQ and social outcomes
Reviewing the literature on the effects of intelligence (1996), the American Psychological Association concluded that the characteristics measured by IQ tests predict many socially important outcomes, including: educational performance, job performance and income, and lawful conduct. While these are not the only factors influencing social outcomes, they may be the strongest relative to school performance.[1] Regarding job performance, Frank Schmidt and John Hunter have stated that the validity of IQ as a predictor of job performance is above zero for all work studied to date, but varies with the type of job and across different studies, ranging from 0.2 to 0.6.[2] Regarding academic achievement, Treena Eileen Rohde and Lee Anne Thompson write that general cognitive ability, not specific ability, scores predict academic achievement, with the exception that processing speed and spatial ability predict SAT math performance over the effect of general cognitive ability.[3]
On the basis of this relationship, several scholars have concluded that the racial disparities in these areas are partly the result of the IQ gap.[4][5][6] Some have also argued that the causal relationship between these variables and IQ points in the opposite direction, meaning that high income and social status cause high IQ rather than the reverse,[7] or that IQ and social status both influence one another.[8]
In The Bell Curve, Murray and Herrnstein conclude that when Blacks and Whites are compared while adjusting for IQ, the difference in many social and economic variables shrinks or disappears. For example, controlling for IQ shrinks the income gap from thousands to a few hundred dollars, cuts differential poverty by about three-quarters and unemployment differences by half. At a given IQ level, the odds of having a college degree and working in a high-level occupation are higher for blacks than for whites.[9] Studies outside of The Bell Curve that have produced similar results are Nyborg and Jensen (2001)[10] and Kanazawa (2005).[11] Another study by Bowles and Gintis concluded that wealth, race and schooling are important to the inheritance of economic status, but IQ is not a major contributor.[12]
Minority groups whose IQs are above the white average are often over-represented in high-paying professions. Examining this relationship, Nathanial Wehl has concluded that this over-representation is a consequence of their above-average IQ.[13][14] Cochran and Harpending have also made this proposal about Ashkenazi Jews, which make up on 3% of the United States population but have won 27% of its Nobel prizes, which these authors attribute to them having an average IQ somewhere between one-half and one standard deviation above the White average.[15] (See "Ashkenazi intelligence".) The professions in which Asians and Ashkenazi Jews tend to be over-represented differ, and Richard Lynn has proposed that this difference is directly related to the fact that Ashkenazim tend to have above-average verbal and mathematical scores but below-average visuospatial scores, while for East Asians the opposite is the case.[16] While acknowledging that East Asians have average IQs above the white average, the APA states that this group’s over-representation in high-paying professions is considerably greater than what could be predicted on the basis of IQ scores alone, so culture and temperament are likely to also be factors.[1]
Policy implications
Because of the real-world effects associated with IQ, some scholars believe that addressing the racial IQ gap is a pressing social concern.[17] One effort to address the IQ gap often advocated by educators is more equitable funding for education.[18][19] Compensatory education programs have also been aimed at reducing achievement gaps between races, the most recent of which is the No Child Left Behind Act,[20] whose stated goal is to eliminate all racial achievement gaps by 2014.[21] Arthur Jensen has argued that compensatory education programs as traditionally structured have a poor success rate,[22] and that in order to adequately address differences in educational outcomes, it is necessary to provide educational services that are tailored to each person's individual ability regardless of race.[23]
As a result of the existence of racial gaps in average IQ, the US Supreme Court has ruled in the 1971 case Griggs v. Duke Power Co. that the use of IQ tests as a criteria for employment qualification was discriminatory even if no intentional discrimination was present.[24] This case defined the U.S. policy of disparate impact, by which corporate policies which adversely affect one gender or ethnic or religious group can be considered discriminatory even if they do not discriminate on the basis of gender, race or religion itself, unless such policies can be shown to be specifically related to job performance. This policy has been further defined by several additional laws and court cases, including the Civil Rights Act of 1991 and the 2009 supreme court case Ricci v. DeStefano, which ruled that disparate treatment on the basis for race was not permissible unless there was a strong basis of evidence that disparate impact would otherwise result.[25]
The social and scientific value of research about race and intelligence has also been questioned. Critics of research in this area have asserted that research in race and intelligence can never escape its association with the eugenics movement and scientific racism of the early 20th century, as well as that even modern research in this area is likely to be ideologically motivated.[26] In response to this and similar criticisms, Linda Gottfredson has argued that a genetic contribution to the IQ gap does not in itself demand any particular policy response: while a conservative/libertarian commentator may feel the results justify, for example, reductions in affirmative action, a liberal commentator may argue from a Rawlsian point of view (that genetic advantages are undeserved and unjust) for substantial affirmative action.[27] Jensen and Rushton have also argued that their research in this area is necessary to answer the question of how much racism should be held responsible for ethnic groups' unequal performance in certain areas:
[T]he view that one segment of the population is largely to blame for the problems of another segment can be even more harmful to racial harmony, by first producing demands for compensation and thereby inviting a backlash. Equating group disparities in success with racism on the part of the more successful group guarantees mutual resentment. As overt discrimination fades, still large racial disparities in success lead Blacks to conclude that racism is not only pervasive but also insidious because it is so unobservable and "unconscious." Whites resent that nonfalsifiable accusation and the demands to compensate blacks for harm they do not believe they caused.[28]
The APA concludes their 1995 report Intelligence: Knowns and Unknowns with a statement that further research in this area is necessary because of its social and scientific importance, as well as a warning against considering the debate over this topic fully resolved:
In a field where so many issues are unresolved and so many questions unanswered, the confident tone that has characterized most of the debate on these topics is clearly out of place. The study of intelligence does not need politicized assertions and recriminations; it needs self-restraint, reflection, and a great deal more research. The questions that remain are socially as well as scientifically important. There is no reason to think them unanswerable, but finding the answers will require a shared and sustained effort as well as the commitment of substantial scientific resources. Just such a commitment is what we strongly recommend.[1]