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.
Summary
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.
Argument
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:
- Access to education
- Training opportunities
- Personality type
- Physical attractiveness
- Athletic ability
- Inheritance
- Nepotism
- Prejudice
- Social and business connections
- Knowing someone who is successful
- Lobbying Congress
- Business cycle trends
- Fads
- Inventions
- Discoveries
- Wars
- Speculation
- Gambling
- Miserliness
- Insider trading
- Unfair market practices
- And, last but not least, dumb luck -- being at the right place
at the right time
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:
"Since the late 1950s an entire school of research has devoted
itself to explaining economic outcomes. The 1972 book Inequality
by Christopher Jencks and his associates is a well-known example
of such studies… These researchers have typically found that
conventional measures of intelligence… are correlated
with important outcomes, especially education and earnings. But
the effects are not large… This extensive and well-known
research literature made us very skeptical of the claims that
were emanating from press coverage of The Bell Curve. Years
of accumulated research, not ideology, lies behind the academic
community's chilly reception of The Bell Curve. On close
examination of the book itself, our skepticism turned out to be
well-founded." (3)
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:
"To avoid controversy, we deliberately constructed an SES
index that uses the same elements everybody else uses: income,
occupation, and education. What Herrnstein and I have done, in
effect, is to throw down a challenge: if you don't like the way
IQ dominates this thing we call 'socioeconomic status' in producing
important social outcomes, come up with another means of measuring
the environment that produces results you like better." (4)
Academics wasted no time debunking Murray's challenge. Linda Datcher
Loury of Tufts University responded:
"Contrary to Mr. Murray's claim that the book uses the same
SES index that everyone uses, the literature of the effects of
social background on children's academic achievement has identified
a long list of factors which significantly influence the outcomes
for children.
"These factors include: (1) peer influences in the form of
perceived peer education plans; (2) parental expectations and
aspirations for their children's schooling; (3) the income and
racial composition of the community of origin; (4) the amount
of time mothers spend in the labor market; (5) family structure--two
parents versus a single parent, and whether parents are separated
or divorced; (6) number of siblings and birth order; (7) religious
denomination and church attendance; (8) grandparents' schooling;
(9) age of the mother at birth; (10) measures of the quality of
stimulation found in the home environment, including emotional
and verbal responsivity of the mother, provision of appropriate
play materials, time and quality of maternal involvement with
the child .... parental instigation of and participation in intellectual
activities, parental affection, rejection, and nurturance ...
etc.; (11) language spoken at home; (12) discussions about college
plans with teachers and other school officials; (13) parental
emphasis on self-direction versus conformity; (14) ethnicity and
immigrant status; (15) parental involvement in school activities;
and (16) parental wealth and receipt of welfare income.
"This long list is hardly exhaustive. I enumerate at such
length only to stress how grossly inaccurate is Mr. Murray's assertion
that, by including their simple index of parents' education, occupation,
and income, he and Herrnstein were using 'what everybody else
uses.'" (5)
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)
Return to Overview
Endnotes:
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.