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Return of The Bell Curve January 19, 2007

Posted by David Bookstaber in Education, Social Politics.

12 years ago Charles Murray and the late Richard Herrnstein published the landmark book The Bell Curve, which documents the existence of an innate and largely immutable intellectual ability (formally called g, but corresponding to what is popularly called “IQ”), which is distributed across the human population with a non-zero standard deviation.1

This week Charles Murray published an important series of essays in the Wall Street Journal expounding on this simple observation of the distribution of human ability in order to challenge our institutionalized assumptions about how people should be educated and how they can best achieve their potential.  For anyone interested in maximizing both human productivity and the efficiency of our education institutions, these are essential reads.  Highlights:

In his first essay he points out, “Half of all children are below average, and teachers can do only so much for them.” The assumption that even in elementary school every child can attain an arbitrary level of proficiency is both absurd and counterproductive.  We know that there is an upper bound to the intellectual capacity of every individual, and in a large population we can readily estimate its distribution.

For example, in the 2005 round of the National Assessment of Educational Progress (NAEP), 36% of all fourth-graders were below the NAEP’s “basic achievement” score in reading. It sounds like a terrible record. But we know from the mathematics of the normal distribution that 36% of fourth-graders also have IQs lower than 95.

What IQ is necessary to give a child a reasonable chance to meet the NAEP’s basic achievement score? Remarkably, it appears that no one has tried to answer that question. We only know for sure that if the bar for basic achievement is meaningfully defined, some substantial proportion of students will be unable to meet it no matter how well they are taught. As it happens, the NAEP’s definition of basic achievement is said to be on the tough side. That substantial proportion of fourth-graders who cannot reasonably be expected to meet it could well be close to 36%.

This is not to say that American public schools cannot be improved. Many of them, especially in large cities, are dreadful. But even the best schools under the best conditions cannot repeal the limits on achievement set by limits on intelligence.

To say that even a perfect education system is not going to make much difference in the performance of children in the lower half of the distribution understandably grates. But the easy retorts do not work. It’s no use coming up with the example of a child who was getting Ds in school, met an inspiring teacher, and went on to become an astrophysicist. That is an underachievement story, not the story of someone at the 49th percentile of intelligence. It’s no use to cite the differences in test scores between public schools and private ones–for students in the bottom half of the distribution, the differences are real but modest. It’s no use to say that IQ scores can be wrong. I am not talking about scores on specific tests, but about a student’s underlying intellectual ability, g, whether or not it has been measured with a test. And it’s no use to say that there’s no such thing as g.

While concepts such as “emotional intelligence” and “multiple intelligences” have their uses, a century of psychometric evidence has been augmented over the last decade by a growing body of neuroscientific evidence. Like it or not, g exists, is grounded in the architecture and neural functioning of the brain, and is the raw material for academic performance. If you do not have a lot of g when you enter kindergarten, you are never going to have a lot of it. No change in the educational system will change that hard fact.

That says nothing about the quality of the lives that should be open to everyone across the range of ability. I am among the most emphatic of those who think that the importance of IQ in living a good life is vastly overrated. My point is just this: It is true that many social and economic problems are disproportionately found among people with little education, but the culprit for their educational deficit is often low intelligence. Refusing to come to grips with that reality has produced policies that have been ineffectual at best and damaging at worst.

We will make enormous gains as a society if our education system can incorporate the fact that there will always be some significant fraction of the population, at the bottom end of the bell curve, that simply lacks the capacity to function at the level of the majority.

Murray’s second essay considers the middle segment of the bell curve, which encompasses the majority of the population.  The problem here, as he puts it, “Too many Americans are going to college.”  Unfortunately today’s society maintains that a 4-year college degree is the price of admission to a successful life.  Murray makes a compelling argument that, “It makes sense for only about 15% of the population, 25% if one stretches it, to get a college education. And yet more than 45% of recent high school graduates enroll in four-year colleges.”

They are in college to improve their chances of making a good living. What they really need is vocational training. But nobody will say so, because “vocational training” is second class. “College” is first class.

Combine those who are unqualified with those who are qualified but not interested, and some large proportion of students on today’s college campuses–probably a majority of them–are looking for something that the four-year college was not designed to provide. Once there, they create a demand for practical courses, taught at an intellectual level that can be handled by someone with a mildly above-average IQ and/or mild motivation. The nation’s colleges try to accommodate these new demands. But most of the practical specialties do not really require four years of training, and the best way to teach those specialties is not through a residential institution with the staff and infrastructure of a college. It amounts to a system that tries to turn out televisions on an assembly line that also makes pottery. It can be done, but it’s ridiculously inefficient.

The fault lies in the false premium that our culture has put on a college degree. For a few occupations, a college degree still certifies a qualification. For example, employers appropriately treat a bachelor’s degree in engineering as a requirement for hiring engineers. But a bachelor’s degree in a field such as sociology, psychology, economics, history or literature certifies nothing. It is a screening device for employers. The college you got into says a lot about your ability, and that you stuck it out for four years says something about your perseverance. But the degree itself does not qualify the graduate for anything. There are better, faster and more efficient ways for young people to acquire credentials to provide to employers.

In his third essay Murray considers the individuals at the top of the bell curve: the gifted.  Society should acknowledge that some people are gifted with above-average intellectual potential.  Society should both develop this potential and demand that it be reinvested in society’s welfare.  “I am calling for a revival of the classical definition of a liberal education, serving its classic purpose: to prepare an elite to do its duty.”

[T]he top 10% of the intelligence distribution has a huge influence on whether our economy is vital or stagnant, our culture healthy or sick, our institutions secure or endangered. Of the simple truths about intelligence and its relationship to education, this is the most important and least acknowledged: Our future depends crucially on how we educate the next generation of people gifted with unusually high intelligence. 

1 They also provided ample evidence that g, like most human traits, is normally distributed and that its mean value has a significant genetic component. Though this should be obvious to any social scientist, it generated an enormous and unwarranted backlash in both academia and the media that somewhat overwhelmed the more pertinent points of the book.


1. federalist - August 26, 2007

See Bucking the Bell Curve for a salient example.

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