Die Deutsche Version finden Sie hier.
In an earlier essay, I argued that intelligence is measurable, stable, and consequential. That was only half the truth. Here is the other half.
It lies in a testing room. A child sits over a matrix-reasoning task while the parents wait next door, and by the end of the afternoon a number appears in the record. That number will say more about the child’s future trajectory than almost anything else that could be measured that afternoon. And the child did nothing to obtain it.
Anyone who works in psychological assessment never quite gets used to this thought. One merely gets used to not saying it aloud.
The Best Predictor Psychology Has
The evidence is unremarkable precisely because it is so old. No other psychological variable predicts educational and occupational trajectories as reliably as general cognitive ability—more powerfully than personality, social background, or diligence alone.
Just how persistent these differences are is shown by a unique dataset. On June 1, 1932, Scotland had every eleven-year-old in the country take the same test—some 87,000 children on a single day. Decades later, Ian Deary tracked down some of them and gave them the same tasks again at age 77. The scores correlated at just over 0.6. An entire lifetime lay between the two tests—and the ranking remained largely intact.
The Influence of Genes Increases with Age
Robert Plomin, who has shaped behavioral genetics for decades, points to a counterintuitive finding: the heritability of intelligence increases with age. In early childhood, genetic differences account for roughly one-fifth of the variance; in adolescence, around 40 percent; in adulthood, depending on the study, between 50 and 70 percent.
One might expect the opposite. The explanation is not that genes somehow become more powerful with age, but that people increasingly choose their own environments. A child inherits his environment from his parents; an adult seeks it out for himself—friends, books, field of study, profession—and does so in accordance with his inclinations. The effect accumulates over a lifetime. The most striking evidence comes from adoption research: adopted siblings who grow up in the same household, attend the same school, and read the same books become, as adults, scarcely similar at all.
Potential Does Not Flourish in Poverty
Heritability is a statistic describing differences within a population under given conditions—not a destiny. Change the conditions, and the number changes. Eric Turkheimer found in American samples that heritability approaches zero among the poorest families: where people lack almost everything, predispositions do not unfold but are instead obscured. European replications have produced inconsistent results; the direction of the finding is sobering enough.
Heritability explains differences between people, but not the level at which those differences occur. Height is highly heritable—yet the Dutch grew by roughly twenty centimeters over the course of a century. Their genes did not change; their nutrition did. The same applies to intelligence. Throughout the twentieth century, test scores rose by roughly three points per decade—a phenomenon known as the Flynn effect. The genome of a population does not change in eighty years. Its environments do.
“Even what appears to be purely environmental—books in the home, parental attention, school choice—shows genetic influences.”
Nature and nurture are not separate accounts, either. Plomin coined the term “the nature of nurture” to describe the fact that even what appears to be purely environmental—books in the home, parental attention, school choice—shows genetic influences because children help shape the environments they inhabit. The child who loves to read gets more books. And parents pass on both: their predispositions and their bookshelves. If you measure only the bookshelf, you mistake a correlate for a cause.
For the political question, however, this dispute changes nothing. If intelligence is substantially influenced by genes, no one chose their genes. If it is the product of early environments, no one chose their parents or the bookshelf in the childhood bedroom. If it is the product of both interacting—as it is—then no one chose either. In none of these versions was the starting point a matter of merit. That applies to the person writing these words as well. I am examining a trait that happened to be given to me, and I make my living from it to boot.
A Dangerous Question
Arthur Jensen was one of the field’s most distinguished researchers. His work on the structure of general intelligence and on measuring cognitive ability through reaction times belongs to the discipline’s foundations.
In 1969, in the Harvard Educational Review, he asked how much intelligence and academic performance could actually be improved through remedial programs. What followed was not a debate but a firestorm: lectures were disrupted, and the Berkeley psychologist required personal protection for years. What provoked it were passages in which Jensen considered genetic explanations for differences between ethnic groups. I regard the freedom to ask such questions as a condition of science. The answer, however, remains open here—it is beside the point: how strongly a trait is heritable within a group tells us nothing about differences between groups.
The aftermath was different from what those involved had imagined. It was not Jensen’s controversial thesis that was buried, but discussion of the field itself. Ever since, there has been a strange division of labor: the empirical research knows how unevenly distributed our starting endowments are, while political language behaves as though the question had never been asked. In the short term, this suits liberalism: so long as no one asks about the prerequisites, the promise that anyone can make it if only they work hard enough can be repeated without challenge. But in the long run, liberalism pays a high price for this. A promise that is never tested is not disproved—it eventually ceases to be believed.
Hayek’s Uncomfortable Precision
Liberalism has had the answer all along—in Friedrich August von Hayek’s The Constitution of Liberty, in the chapter on merit and value. The book is more uncomfortable than its admirers would sometimes like to admit.
Hayek denies there that the market rewards moral merit. What it remunerates is the value of a person’s contribution to others—and that has nothing necessarily to do with effort, honesty, or sacrifice. The surgeon with the steady hand is not paid because he had it hard; he is paid because other people need what he can do. Someone who worked hard and failed may well deserve more in a moral sense and yet receive less.
For Hayek, this is not a malfunction but a condition of freedom. An order that sought to distribute rewards according to merit would require an authority capable of looking inside every person, separating effort from innate ability, and weighing both against circumstances. No such authority exists. And no one should wish for one. One might object that the argument leads to the opposite conclusion: if advantages are undeserved, they should be equalized. But the argument cuts both ways—if you cannot determine what someone deserves, you cannot determine what they are entitled to, either.
None of this turns biology into destiny. Nor does it reduce anyone to a test score. Anyone who knows the numbers knows how much they leave unexplained: 60 percent heritability means 40 percent something else; a genetic prediction that accounts for 15 percent of the differences in educational attainment misses 85 percent. Intelligence research describes distributions, not biographies—it tells us how the cards are dealt, not what someone does with the hand they are given. Responsibility does not become smaller because of this. What becomes smaller is the moral status the successful person is entitled to derive from his success: he has not earned a character certificate. He drew a hand and played it well.
Against Keeping Accounts on Individuals
Liberalism has grown accustomed to making a promise it cannot keep: that anyone can make it if they truly want to. It flatters the successful as confirmation and consoles everyone else with a deferred promise. And it is one reason so many people no longer believe it: when the numbers do not add up in your own life, you start to suspect the calculator is dishonest.
“Everyone is the architect of his own fortune,” as the saying goes. The sentence is even true. One should simply add that the hammer and anvil were handed out by lottery.
The alternative is not retreat but a smaller, harder promise: freedom applies regardless of what someone makes of it—even to the person who makes little of it. If freedom were contingent on the return it produces, someone would have to calculate that return. It is precisely this unconditional character that makes freedom immune to any accounting of the individual—even well-intentioned accounting.
I am not writing this out of contrition. Anyone who recognizes his own advantage need not surrender it—he need only name it correctly. Everyone is the architect of his own fortune, as the saying goes. The sentence is even true. One should simply add that the hammer and anvil were handed out by lottery.
Liberalism loses nothing by admitting this. It loses an illusion that never defended it in the first place, but merely made itself comfortable within it.
