The Bell Curve - Content

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The Bell Curve, published in 1994, was written by Richard Herrnstein and Charles Murray as a work designed to explain, using empirical statistical analysis, the variations in intelligence in American society, raise some warnings regarding the consequences of this intelligence gap, and propose national social policy with the goal of mitigating the worst of the consequences attributed to this intelligence gap. Many of the assertions put forth and conclusions reached by the authors are very controversial, ranging from the relationships between low measured intelligence and anti-social behavior, to the observed relationship between low African-American test scores (compared to whites and East Asians) and genetic factors in intelligence abilities. The book was released and received with a large public response. In the first several months of its release, 400,000 copies of the book were sold around the world. Several thousand reviews and commentaries have been written in the short time since the book's publication. The Bell Curve argues that:

1. Intelligence exists and is accurately measurable across racial, language, and national boundaries.
2. Intelligence is one of, if not the most, important factors correlated to economic, social, and overall success in the United States, and its importance is increasing.
3. Intelligence is largely (40% to 80%) heritable.
4. No one has so far been able to manipulate IQ to a significant degree through changes in environmental factors—except for child adoption and that they conclude is not large in the long term—and in light of these failures, such approaches are becoming less promising.
5. The USA has been in denial of these facts. A better public understanding of the nature of intelligence and its social correlates is necessary to guide future policy decisions.

Their evidence comes from an analysis of data compiled in the National Longitudinal Study of Youth (NLSY), a study conducted by the United States Department of Labor's Bureau of Labor Statistics tracking thousands of Americans starting in the 1980s. All participants in the NLSY took the Armed Services Vocational Aptitude Battery (ASVAB), a battery of ten tests taken by all who apply for entry into the armed services. (Some had taken an IQ test in high school, and the median correlation of the AFQT and those tests was .81.) Participants were later evaluated for social and economic outcomes. In general, IQ/AFQT scores were a better predictor of life outcomes than social class background. Similarly, after statistically controlling for differences in IQ, many outcome differences between racial-ethnic groups disappeared.

They also stated that the average IQ of African Americans is 85; Latinos 89; Whites 103; Asians 106.