Myth: IQ best predicts if you will succeed or fail in life.

Fact: IQ, although important, is only one of countless factors that predict success.


Using data from a long-term survey, The Bell Curve purports to show that IQ is a far better predictor of adult success than childhood socioeconomic status. But the authors used an extremely limited number of social factors as the basis for their calculations. By taking into consideration a greater number of social factors (to make the study resemble a more complete picture of real life), sociologists have been able to show that social factors, not IQ, are a much better predictor of future success.


In The Bell Curve, authors Herrnstein and Murray claim that a child's IQ is a far better predictor of future success than a child's initial socioeconomic status (or SES). For example, a white child raised in the bottom 5 percent of SES is eight times more likely to become poor than a child from the top 5 percent. But a white child whose IQ is in the bottom 5 percent is fifteen times more likely to become poor than a child whose IQ is in the top 5 percent. (1)

Is this true? (Well, no -- but more on this below.) It does seems obvious that intelligence is important to succeed in life, but it also seems obvious that social factors play a large, if not larger, role. For example, the crushing economic disparity between North and South Korea has nothing to do with IQ differences, and everything to do with different social and economic policies. Even on a personal level, intelligence is only one of countless factors that contribute to success. Others include:

And these are just the adult factors -- there's a whole host of childhood factors as well, which follow below. How the rules of the game are constructed determines which of these factors becomes most important for winning and losing, and therefore which individuals have the most "merit." For example, we might think that those who play professional baseball have the most merit -- that is, they are the best players in the game. But the rules of the game determine which group of players is "best." In 1893, the pitching distance was increased, and the need for heavier pitchers increased as well. By 1908, pitchers weighed a whopping 12 pounds more than they did in 1894, and they were an inch taller. Similar tinkering with the rules -- lowering the pitching mound, tightening the strike zone -- have produced similar changes in the pitching constituency. (2)

Social scientists have long studied how these countless factors -- including intelligence -- promote success. The authors of Inequality by Design write: The problem with Herrnstein and Murray's analysis was that they left many things out of their definition of socioeconomic status (SES). To determine how important childhood SES was in predicting later success, they reviewed data from the National Longitudinal Survey of Youth (NLSY), which has been tracking the lives of 12,000 young adults since 1979. From this data, Herrnstein and Murray selected only three factors to describe the social backgrounds of the survey subjects. Murray defended their limited selection this way: Academics wasted no time debunking Murray's challenge. Linda Datcher Loury of Tufts University responded: The next step was for sociologists to assemble a more complete SES index and reanalyze the very survey data that Herrnstein and Murray used. Many have been already doing this, but a team of Berkeley sociologists led by Claude Fischer has conducted perhaps the best known effort, for the book Inequality by Design. They added family size, the presence of two parents in the home, geographical residence and other social factors to the list, and then recalculated the NLSY data. They found that social factors predicted future success far better than IQ did. In fact, based on their results, the authors conclude: "If we could magically give everyone identical IQs, we would still see 90 to 95 percent of the inequality we see today." (6)

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1. Richard Herrnstein and Charles Murray, The Bell Curve (New York: Simon & Schuster, 1994), p. 127.

2. Benjamin Rader, Baseball: A History of America's Game (Urbana: University of Illinois Press, 1994), pp. 87, 89, 114-16, 169, cited in Claude Fischer et al., Inequality by Design, (Princeton: Princeton University Press, 1996), p. 130.

3. Fischer, pp. 71-2.

4. Charles Murray, "'The Bell Curve' and its critics," Commentary, May 1995, vol. 99, no. 5, p. 23.

5. Linda Datcher Loury, letter to the editor, Commentary, August 1995, vol. 100, no. 2.

6. Fischer, p. 70-101, 14.