Bell Curve

In generic usage, bell curve is a term describing the symmetrical shape of a normal distribution. It is more commonly referred to as the normal curve in statistics and measurement, where it serves as a model of relative frequencies or probabilities in a population. The Bell Curve is also the title of the 1994 book written by Richard J. Herrnstein and Charles Murray. Through reference to the assumptions of the normal curve, the authors contend that the distribution of intelligence scores in the United States has been undergoing significant change since the beginning of the 20th century. According to Herrnstein and Murray, this time period has witnessed a tremendous increase in the average IQ of students attending the top 12 universities. At the same time, a greater percentage of the population has been able to reap the benefits of a college education. In keeping with this upward shift, the tail of the curve below the mean represents a growing segment of the population whose intellect, educational attainment, and socioeconomic status have progressively declined.

The implications of this proposal have generated a great deal of debate. The Bell Curve describes a society where academic achievement and occupational prestige represent criteria by which class structure is partitioned. As proficiency in both realms relies on intellect, neither educational opportunity nor employee training is sufficient for those with lesser cognitive endowment to achieve parity with the best and brightest. A genetic basis for social stratification is explained, one whose genesis the authors trace to the feminist revolution. They claim that the resulting upsurge in career opportunities for gifted young women increased the likelihood of mate selection within the cognitive elite, thus augmenting the already substantial heritability of IQ.

Perhaps the most controversial topic broached in this book is that of disparate mean intelligence scores between ethnic groups. The authors maintain that the very definition of race relies on differentiation according to particular characteristics, and that intellectual fashion has prohibited inclusion of cognitive ability as a distinguishing biological trait. Moreover, after citing the results of various studies on ethnicity and intelligence, they postulate that genetic discrepancies not only exist, but also account for such social inequalities as poverty, unemployment, crime, family size, and single parenthood. The final chapters of the book explore solutions to various social and economic ills that the authors associate with a lower cognitive class, including “the leveling of education,” government assistance to low-income mothers, and immigration laws that fail to include standards of competency.

Scholarly opinion on the position explicated in The Bell Curve remains sharply divided. Richard Lynn and John Harvey report a worldwide trend toward cognitive decline due to the inverse relationship between intelligence and number of children, known as dysgenic fertility. They attribute the general increase in IQ scores over the latter half of the 20th century to the Flynn effect (increase in intelligence scores due to environmental factors), further maintaining that this progression has reached a plateau or reversed, and that cognitive degeneration on a global basis may ensue. These authors endorse such measures as screening embryos for intelligence and other desirable qualities, issuing parenthood licenses to those who meet established cognitive criteria, and additional means by which deterioration of the world's intelligence might be averted.

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