It's controversial. Don't say I didn't warn you.

See The Bell Curve.

That the word intelligence describes something real and that it varies from person to person is as universal and ancient as the understanding about the state of being human. Literate cultures everywhere and throughout history have had words for saying that some people are smarter than others. Given the survival value of intelligence, the concept must be still older than that. Gossip about who in the tribe is cleverest has probably been a topic of conversation around the fire since fires, and conversation, were invented.

Yet for the last thirty years, the concept of intelligence has been a pariah in the world of ideas. The attempt to measure it with tests has been variously dismissed as an artifact of racism, political reaction, statistical bungling, and scholarly fraud.

I don't think so.

We are at a very precarious time now. More and more the intrinsic nature of IQ is making a resoundingly strong case for intelligence as a strong predictor of individual -- and societal -- success.

For example, white youths in the top ten percent of IQ and with parents in the lowest income bracket still had better than 75% chance of attaining a college degree. Among those in the highest of income brackets -- with parents making 250,000 + -- but with marginal IQs, only 16% completed college.

This gives credence to the theory that intelligence is a relatively fixed enterprise, as those most affluent would necessarily have access to top schools and programs. Current estimates put IQ variance coming from environment at between 20 and 40 percent.

This says nothing of the dysgenic affect stifling IQ in the United States. Gone are the days of the self-made immigrant -- the dedicated, intelligent, assiduous working-man or woman immigrating to the United States for religious or economic freedom.

The experiences of different immigrants at different times (especially now) have varied drastically. Consider the conditions under which immigrants will be self-selective from the upper and lower tails of the ability distribution. Suppose you are living in a foreign country, considering whether to immigrate to America. Presumably a major consideration is your potential income in the United States versus your current country.

It makes sense for high-ability people to emigrate when they can reasonably think that they are being under-rewarded in their home country, relative to their ability, and that the United States rewards the same level of ability more generously.

Conversely, it makes sense for low-ability people to come to the United States when they can reasonably think that the U.S not only pays better for the same work but protects them against poor labor market outcomes (relative to their birth country) with welfare payments and other entitlements.

In other words, the United States may be expected to draw high-ability workers from countries that have more extensive welfare states and less income inequality than the United States (such as Western and Northern Europe), and will draw low-ability workers from countries that have less extensive welfare states and higher income inequality (such as the poorer countries of the third world).

In the 1960s the United States became much more of a welfare state, causing the nature of immigrants to change considerably. Further, the increased immigration of people from third world nations carries with it the effect of higher fertility and a faster generational cycle among an immigrant population below the native-born population in comparative intelligence. (Credit: Murphy, The Bell Curve)

Putting the pieces together, the case is strong that something worth worrying about is happening to the cognitive capital of the country. How big is the rift?

“If we were to put it in IQ points per generation, the usual metric for such analyses, it would be nearly impossible to make the total come out to less than one point per generation. It might be twice that.” (Murphy, 365, The Bell Curve)

This leads to another issue worth worrying about. So what if the mean IQ is dropping by a point or two per generation? One reason to worry is that the drop may be enlarging ethnic differences in cognitive ability at a time when the nation – especially those enacting its programs – badly need narrowing differences. Another reason for worry is when the mean shirts a little, the size of the tails of the distribution changes considerably.

“For example, assuming a normal distribution, a three-point drop at the average would reduce the proportion with IQ above 120 (currently the top ten percent) by 31 percent and the proportion with IQ above 135 (currently the top 1 percent) by 42 percent. The proportion of the population with IQ below 80 (currently the bottom ten percent) would rise by 41 percent and the proportion with IQ below 65 (currently the bottom 1 percent) would rise by 68 percent. Given the predictive power of IQ scores, particularly in the extremes of the distribution, changes this large would profoundly alter many aspects of American life, none that we can think of to the good.” (The Bell Curve)

Given this seemingly harmless IQ decrease of 3 points what happens to the social fabric of the United States?

Credit this data on the 1992 NLSY sample of over 20,000 randomly selected individuals.

So what changes? Marriage rates do not change. With the three point decline in the average, divorce, unemployment, and dropout from the labor force rise only marginally. But the overall poverty rate rises by 11 percent and the proportion of children living in poverty throughout the first three years of their lives rises by 13 percent. The proportion of men interviewed in jail rises by 13 percent. The proportion of children living with non-parental custodians, of women ever on welfare, and of people dropping out of high school all rise by 14 percent.

This exercise assumed that everything else but IQ remained constant. In the real world, things would no doubt be more complicated. A cascade of secondary effects may make social conditions worse than is here suggested or perhaps not as bad. But the overall effect is that an apparently minor shirt in IQ could produce devastating social outcomes. Three points in IQ seem to be nothing (and indeed, are nothing in terms of understanding an individual’s ability), but a population with an IQ mean that has slipped three points is likely to be measurably worse off.

Furthermore, a three-point slide in the near future is well within the realm of possibility. The social phenomena that have been so worrisome in the last few decades (I shall return to this later) may in some degree already reflect an ongoing dysgenic effect in aggregate intelligence.

I contend that cognitive partitioning through education and occupation will continue (indeed, must continue) and there is not much that the government or anyone else can do about it. Economics dictates this fact. At the same time that elite colleges and professional schools are turning out brighter graduates, the value of higher education in the marketplace is rising. Wages earned by people in high-IQ occupations (i.e. Professors, Engineers, Doctors, Lawyers, etc) have pulled away from wages in low-IQ occupations, and differences in education cannot explain all of this change.

Another force for cognitive partitioning is the increased physical segregation of the cognitive elite from the rest of society. Members of this elite typically work in jobs that usually keep them off the shop floor, away from the construction site, and close to others who tend to be smart. The isolation of this elite is compounded by its choices of where to live, shop, play, worship, and send its children to school.

Add to this the phenomenon known as “assertive mating”. (Hernnstein, 91 The Bell Curve)

Likes attract when it comes to marriage, and intelligence is one of the most important of likes. When this propensity to mate by IQ is combined with increasingly efficient educational and occupational stratification, mating by IQ has more powerful effects on the next generation than it had on the previous one. This process too seems to be getting stronger, eliminating the middle class, and is part of the brew creating a more delineated American class system.

What’s more, if those in high-IQ jobs necessarily make more than their counterparts, and are increasingly segregated, what would result if they became more like-minded politically?

Imagine the consequences.

This nation is at a fork in the road, with those in power coming to realize that they must make fundamental choices when it comes to whom our educational system should be geared toward. There is not only a “dumbing down” of American schools taking place – with those most gifted being passed over or not recognized – there is also a “dumbing down” of America, due in large part to the educational establishment and the inundation of third-world immigrants.

As the educational establishment allies with the media in providing an environment dedicated not to knowledge, but to entertainment, the American IQ isn’t the only casualty. As the examples above have borne out, with the reduction in IQ comes inexorably the loosening of morality, the profusion of illegitimacy, and the anarchy that follows.

The truth is a harsh mistress.