The Bell Curve: Intelligence and Class Structure in American Life (7 page)

Given these different ways of understanding intelligence, you will naturally ask where our sympathies lie and how they shape this book.

We will be drawing most heavily from the classical tradition. That body of scholarship represents an immense and rigorously analyzed body of knowledge. By accepted standards of what constitutes scientific evidence and scientific proof, the classical tradition has in our view given the world a treasure of information that has been largely ignored in trying to understand contemporary policy issues. Moreover, because our topic is the relationship of human abilities to public policy, we will be dealing in relationships that are based on aggregated data, which is where the classical tradition has the most to offer. Perhaps an example will illustrate what we mean.

Suppose that the question at issue regards individuals: “Given two 11 year olds, one with an IQ of 110 and one with an IQ of 90, what can you tell us about the differences between those two children?” The answer must be phrased very tentatively. On many important topics, the answer must be, “We can tell you nothing with any confidence.” It is well worth a guidance counselor’s time to know what these individual scores are, but only in combination with a variety of other information about the child’s personality, talents, and background. The individual’s IQ score all by itself is a useful tool but a limited one.

Suppose instead that the question at issue is: “Given two sixth-grade classes, one for which the average IQ is 110 and the other for which it is 90, what can you tell us about the difference between those two classes and their average prospects for the future?” Now there is a great deal to
be said, and it can be said with considerable confidence—not about any one person in either class but about average outcomes that are important to the school, educational policy in general, and society writ large. The data accumulated under the classical tradition are extremely rich in this regard, as will become evident in subsequent chapters.

If instead we were more concerned with the development of cognitive processes than with aggregate social and economic outcomes, we would correspondingly spend more time discussing the work of the revisionists. That we do not reflects our focus, not a dismissal of their work.

With regard to the radicals and the theory of multiple intelligences, we share some common ground. Socially significant individual differences include a wide range of human talents that do not fit within the classical conception of intelligence. For certain spheres of life, they matter profoundly. And even beyond intelligence and talents, people vary temperamentally, in personality, style, and character. But we confess to reservations about using the word
intelligence
to describe such factors as musical abilities, kinesthetic abilities, or personal skills. It is easy to understand how intelligence (ordinarily understood) is part of some aspects of each of those human qualities—obviously, Bach was engaging in intelligent activity, and so was Ted Williams, and so is a good used-car salesman—but the part intelligence plays in these activities is captured fairly well by intelligence as the classicists and revisionists conceive of it. In the case of music and kinesthetics,
talent
is a word with a domain and weight of its own, and we are unclear why we gain anything by discarding it in favor of another word,
intelligence,
that has had another domain and weight. In the case of intrapersonal and interpersonal skills, conventional intelligence may play some role, and, to the extent that other human qualities matter, words like
sensitivity, charm, persuasiveness, insight—
the list could go on and on—have accumulated over the centuries to describe them. We lose precision by using the word
intelligence
to cover them all. Similarly, the effect that an artist or an athlete or a salesman creates is complex, with some aspects that may be dominated by specific endowments or capacities, others that may be the product of learned technique, others that may be linked to desires and drives, and still others that are characteristic of the kind of cognitive ability denoted by intelligence. Why try to make
intelligence
do triple or quadruple duty?

We agree emphatically with Howard Gardner, however, that the concept of intelligence has taken on a much higher place in the pantheon
of human virtues than it deserves. One of the most insidious but also widespread errors regarding IQ, especially among people who have high IQs, is the assumption that another person’s intelligence can be inferred from casual interactions. Many people conclude that if they see someone who is sensitive, humorous, and talks fluently, the person must surely have an above-average IQ.

This identification of IQ with attractive human qualities in general is unfortunate and wrong. Statistically, there is often a modest correlation with such qualities. But modest correlations are of little use in sizing up other individuals one by one. For example, a person can have a terrific sense of humor without giving you a clue about where he is within thirty points on the IQ scale. Or a plumber with a measured IQ of 100—only an average IQ—can know a great deal about the functioning of plumbing systems. He may be able to diagnose problems, discuss them articulately, make shrewd decisions about how to fix them, and, while he is working, make some pithy remarks about the president’s recent speech.

At the same time, high intelligence has earmarks that correspond to a first approximation to the commonly understood meaning of smart. In our experience, people do not use
smart
to mean (necessarily) that a person is prudent or knowledgeable but rather to refer to qualities of mental quickness and complexity that do in fact show up in high test scores. To return to our examples: Many witty people do not have unusually high test scores, but someone who regularly tosses off impromptu complex puns probably does (which does not necessarily mean that such puns are very funny, we hasten to add). If the plumber runs into a problem he has never seen before and diagnoses its source through inferences from what he does know, he probably has an IQ of more than 100 after all. In this, language tends to reflect real differences: In everyday language, people who are called very smart tend to have high IQs.

All of this is another way of making a point so important that we will italicize it now and repeat elsewhere:
Measures of intelligence have reliable statistical relationships with important social phenomena, but they are a limited tool for deciding what to make of any given individual.
Repeat it we must, for one of the problems of writing about intelligence is how to remind readers often enough how little an IQ score tells about whether the human being next to you is someone whom you will admire or cherish. This thing we know as IQ is important but not a synonym for human excellence.

Idiot Savants and Other Anomalies

To add one final complication, it is also known that some people with low measured IQ occasionally engage in highly developed, complex cognitive tasks. So-called idiot savants can (for example) tell you on what day Easter occurred in any of the past or future two thousand years.
⁴⁵
There are also many less exotic examples. For example, a study of successful track bettors revealed that some of them who used extremely complicated betting systems had below-average IQs and that IQ was not correlated with success.
⁴⁶
The trick in interpreting such results is to keep separate two questions: (1) If one selects people who have already demonstrated an obsession and success with racetrack betting systems, will one find a relationship with IQ (the topic of the study in question)? versus (2) if one selects a thousand people at random and asks them to develop racetrack betting systems, will there be a relationship with IQ (in broad terms, the topic of this book)?

Howard Gardner has also convinced us that the word
intelligence
carries with it undue affect and political baggage. It is still a useful word, but we shall subsequently employ the more neutral term
cognitive ability
as often as possible to refer to the concept that we have hitherto called
intelligence,
just as we will use IQ as a generic synonym for
intelligence test score.
Since
cognitive ability
is an uneuphonious phrase, we lapse often so as to make the text readable. But at least we hope that it will help you think of
intelligence
as just a noun, not an accolade.

We have said that we will be drawing most heavily on data from the classical tradition. That implies that we also accept certain conclusions undergirding that tradition. To draw the strands of our perspective together and to set the stage for the rest of the book, let us set them down explicitly. Here are six conclusions regarding tests of cognitive ability, drawn from the classical tradition, that are by now beyond significant technical dispute:

1. There is such a thing as a general factor of cognitive ability on which human beings differ.
   
2. All standardized tests of academic aptitude or achievement measure this general factor to some degree, but IQ tests expressly designed for that purpose measure it most accurately.
   
3. IQ scores match, to a first degree, whatever it is that people mean when they use the word
   intelligent
   or smart in ordinary language.
   
4. IQ scores are stable, although not perfectly so, over much of a person’s life.
   
5. Properly administered IQ tests are not demonstrably biased against social, economic, ethnic, or racial groups.
   
6. Cognitive ability is substantially heritable, apparently no less than 40 percent and no more than 80 percent.
   

All six points have an inverse worth noting. For example, some people’s scores change a lot; cognitive ability is not synonymous with test scores or with a single general mental factor, and so on. When we say that all are “beyond significant technical dispute,” we mean, in effect, that if you gathered the top experts on testing and cognitive ability, drawn from all points of view, to argue over these points, away from television cameras and reporters, it would quickly become apparent that a consensus already exists on all of the points, in some cases amounting to near unanimity. And although dispute would ensue about some of the points, one side—the side represented by the way the points are stated—would have a clear preponderance of evidence favoring it, and those of another viewpoint would be forced to lean heavily on isolated studies showing anomalous results.

This does not mean that the experts should leave the room with their differences resolved. All six points can be accurate as general rules and still leave room for differences in the theoretical and practical conclusions that people of different values and perspectives draw from them (and from the mass of material about cognitive ability and testing not incorporated in the six points). Radicals in the Gardner mold might still balk at all the attention being paid to intelligence as the tests measure it. But these points, in themselves, are squarely in the middle of the scientific road.

Having said this, however, we are left with a dilemma. The received wisdom in the media is roughly 180 degrees opposite from each of the six points. To prove our case, taking each point and amassing a full account of the evidence for and against, would lead us to write a book just about them. Such books have already been written. There is no point in our trying to duplicate them.
⁴⁷

We have taken two steps to help you form your own judgments within the limits of this book. First, we deal with specific issues involving the six points as they arise in the natural course of the discussion—cultural
bias when discussing differences in scores across ethnic groups, for example. Second, we try to provide a level of detail that will satisfy different levels of technical curiosity through the use of boxed material (you have already come across some examples), notes, and appendixes. Because we expect (and fear) that many readers will go directly to chapters that especially interest them rather than read the book from cover to cover, we also insert periodic reminders about where discussion of certain key topics may be found.

The twentieth century dawned on a world segregated into social classes defined in terms of money, power, and status. The ancient lines of separation based on hereditary rank were being erased, replaced by a more complicated set of overlapping lines. Social standing still played a major role, if less often accompanied by a sword or tiara, but so did out-and-out wealth, educational credentials, and, increasingly, talent.

Our thesis is that the twentieth century has continued the transformation, so that the twenty-first will open on a world in which cognitive ability is the decisive dividing force. The shift is more subtle than the previous one but more momentous. Social class remains the vehicle of social life, but intelligence now pulls the train.

Cognitive stratification takes different forms at the top and the bottom of the scale of intelligence. Part II will look at the bottom. In Part I, we look at the top. Its story line is that modern societies identify the brightest youths with ever increasing efficiency and then guide them into fairly narrow educational and occupational channels. These channels are increasingly lucrative and influential, leading to the development of a distinct stratum in the social hierarchy, which we hereby dub the Cognitive Elite. The isolation of the brightest from the rest of society is already extreme; the forces driving it are growing stronger rather than weaker. Governments can influence these forces but cannot neutralize them.

This does not mean that a member of the cognitive elite never crosses paths with a person with a low IQ, but the encounters that matter tend to be limited. The more intimate or more enduring the human relationship is, the more likely it is to be among people similar in intellectual level. That the brightest are identified has its benefits. That they become so isolated and inbred has its costs. Some of these costs are already visible in American society, while others lie over the horizon.