Can one really reconcile biological differences with a concept of social justice? Absolutely. In his famous theory of justice, the philosopher John Rawls asks us to imagine a social contract drawn up by self-interested agents negotiating under a veil of ignorance, unaware of the talents or status they will inherit at birth—ghosts ignorant of the machines they will haunt. He argues that a just society is one that these disembodied souls would agree to be born into, knowing that they might be dealt a lousy social or genetic hand.22 If you agree that this is a reasonable conception of justice, and that the agents would insist on a broad social safety net and redistributive taxation (short of eliminating incentives that make everyone better off), then you can justify compensatory social policies even if you think differences in social status are 100percent genetic. The policies would be, quite literally, a matter of justice, not a consequence of the indistinguishability of individuals.

  Indeed, the existence of innate differences in ability makes Rawls’s conception of social justice especially acute and eternally relevant. If we were blank slates, and if a society ever did eliminate discrimination, the poorest could be said to deserve their station because they must have chosen to do less with their standard-issue talents. But if people differ in talents, people might find themselves in poverty in a nonprejudiced society even if they applied themselves to the fullest. That is an injustice that, a Rawlsian would argue, ought to be rectified, and it would be overlooked if we didn’t recognize that people differ in their abilities.

  SOME PEOPLE HAVE suggested to me that these grandiloquent arguments are just too fancy for the dangerous world we live in. Granted, there is evidence that people are different, but since data in the social sciences are never perfect, and since a conclusion of inequality might be used to the worst ends by bigots or Social Darwinists, shouldn’t we err on the side of caution and stick with the null hypothesis that people are identical? Some believe that even if we were certain that people differ genetically, we might still want to promulgate the fiction that they are the same, because it is less open to abuse.

  This argument is based on the fallacy that the Blank Slate has nothing but good moral implications and a theory of human nature nothing but bad ones. In the case of human differences, as in the case of human universals, the dangers go both ways. If people in different stations are mistakenly thought to differ in their inherent ability, we might overlook discrimination and unequal opportunity. In Darwin’s words, “If the misery of the poor be caused not by the laws of nature, but by our institutions, great is our sin.” But if people in different stations are mistakenly thought to be the same, then we might envy them the rewards they’ve earned fair and square and might implement coercive policies to hammer down the nails that stick up. The economist Friedrich Hayek wrote, “It is just not true that humans are born equal;… if we treat them equally, the result must be inequality in their actual position;… [thus] the only way to place them in an equal position would be to treat them differently. Equality before the law and material equality are, therefore, not only different but in conflict with each other.”23 The philosophers Isaiah Berlin, Karl Popper, and Robert Nozick have made similar points.

  Unequal treatment in the name of equality can take many forms. Some forms have both defenders and detractors, such as soak-the-rich taxation, heavy estate taxes, streaming by age rather than ability in schools, quotas and preferences that favor certain races or regions, and prohibitions against private medical care or other voluntary transactions. But some can be downright dangerous. If people are assumed to start out identical but some end up wealthier than others, observers may conclude that the wealthier ones must be more rapacious. And as the diagnosis slides from talent to sin, the remedy can shift from redistribution to vengeance. Many atrocities of the twentieth century were committed in the name of egalitarianism, targeting people whose success was taken as evidence of their criminality. The kulaks (“bourgeois peasants”) were exterminated by Lenin and Stalin in the Soviet Union; teachers, former landlords, and “rich peasants” were humiliated, tortured, and murdered during Chinas Cultural Revolution; city dwellers and literate professionals were worked to death or executed during the reign of the Khmer Rouge in Cambodia.24 Educated and entrepreneurial minorities who have prospered in their adopted regions, such as the Indians in East Africa and Oceania, the Ibos in Nigeria, the Armenians in Turkey, the Chinese in Indonesia and Malaysia, and the Jews almost everywhere, have been expelled from their homes or killed in pogroms because their visibly successful members were seen as parasites and exploiters.25

  A nonblank slate means that a tradeoff between freedom and material equality is inherent to all political systems. The major political philosophies can be defined by how they deal with the tradeoff. The Social Darwinist right places no value on equality; the totalitarian left places no value on freedom. The Rawlsian left sacrifices some freedom for equality; the libertarian right sacrifices some equality for freedom. While reasonable people may disagree about the best tradeoff, it is unreasonable to pretend there is no tradeoff. And that in turn means that any discovery of innate differences among individuals is not forbidden knowledge to be suppressed but information that might help us decide on these tradeoffs in an intelligent and humane manner.

  THE SPECTER OF eugenics can be disposed of as easily as the specters of discrimination and Social Darwinism. Once again, the key is to distinguish biological facts from human values.

  If people differ genetically in intelligence and character, could we selectively breed for smarter and nicer people? Possibly, though the intricacies of genetics and development would make it far harder than the fans of eugenics imagined. Selective breeding is straightforward for genes with additive effects—that is, genes that have the same impact regardless of the other genes in the genome. But some traits, such as scientific genius, athletic virtuosity, and musical giftedness, are what behavioral geneticists call emergenic: they materialize only with certain combinations of genes and therefore don’t “breed true.”26 Moreover, a given gene can lead to different behavior in different environments. When the biochemist (and radical scientist) George Wald was solicited for a semen sample by William Shockley’s sperm bank for Nobel Prize-winning scientists, he replied, “If you want sperm that produces Nobel Prize winners you should be contacting people like my father, a poor immigrant tailor. What have my sperm given the world? Two guitarists!”27

  Whether or not we can breed for certain traits, should we do it? It would require a government wise enough to know which traits to select, knowledgeable enough to know how to implement the breeding, and intrusive enough to encourage or coerce people’s most intimate decisions. Few people in a democracy would grant their government that kind of power even if it did promise a better society in the future. The costs in freedom to individuals and in possible abuse by authorities are unacceptable.

  Contrary to the belief spread by the radical scientists, eugenics for much of the twentieth century was a favorite cause of the left, not the right.28 It was championed by many progressives, liberals, and socialists, including Theodore Roosevelt, H. G. Wells, Emma Goldman, George Bernard Shaw, Harold Laski, John Maynard Keynes, Sidney and Beatrice Webb, Margaret Sanger, and the Marxist biologists J. B. S. Haldane and Hermann Muller. It’s not hard to see why the sides lined up this way. Conservative Catholics and Bible Belt Protestants hated eugenics because it was an attempt by intellectual and scientific elites to play God. Progressives loved eugenics because it was on the side of reform rather than the status quo, activism rather than laissez-faire, and social responsibility rather than selfishness. Moreover, they were comfortable expanding state intervention in order to bring about a social goal. Most abandoned eugenics only when they saw how it led to forced sterilizations in the United States and Western Europe and, later, to the policies of Nazi Germany. The history of eugenics is one of many cases in which the moral problems posed by human nature cannot be folded into familiar left-right debates but have to be analyzed afre
sh in terms of the conflicting values at stake.

  THE MOST SICKENING associations of a biological conception of human nature are the ones to Nazism. Though the opposition to the idea of a human nature began decades earlier, historians agree that bitter memories of the Holocaust were the main reason that human nature became taboo in intellectual life after World War II.

  Hitler was undeniably influenced by the bastardized versions of Darwinism and genetics that were popular in the early decades of the twentieth century, and he specifically cited natural selection and the survival of the fittest in laying out his poisonous doctrine. He believed in an extreme Social Darwinism in which groups were the unit of selection and a struggle among groups was necessary for national strength and vigor. He believed that the groups were constitutionally distinct races, that their members shared a distinctive biological makeup, and that they differed from one another in strength, courage, honesty, intelligence, and civic-mindedness. He wrote that the extinction of inferior races was part of the wisdom of nature, that the superior races owed their vitality and virtue to their genetic purity, and that the superior races were in danger of being degraded by interbreeding with the inferior ones. He used these beliefs to justify his war of conquest and his genocide of Jews, Gypsies, Slavs, and homosexuals.29

  The misuse of biology by the Nazis is a reminder that perverted ideas can have horrifying consequences and that intellectuals have a responsibility to take reasonable care that their ideas not be misused for evil ends. But part of that responsibility is not to trivialize the horror of Nazism by exploiting it for rhetorical clout in academic catfights. Linking the people you disagree with to Nazism does nothing for the memory of Hitler’s victims or for the effort to prevent other genocides. It is precisely because these events are so grave that we have a special responsibility to identify their causes precisely.

  An idea is not false or evil because the Nazis misused it. As the historian Robert Richards wrote of an alleged connection between Nazism and evolutionary biology, “If such vague similarities suffice here, we should all be hustled to the gallows.”30 Indeed, if we censored ideas that the Nazis abused, we would have to give up far more than the application of evolution and genetics to human behavior. We would have to censor the study of evolution and genetics, period. And we would have to suppress many other ideas that Hitler twisted into the foundations of Nazism:

  • The germ theory of disease: The Nazis repeatedly cited Pasteur and Koch to argue that the Jews were like an infectious bacillus that had to be eradicated to control a contagious disease.

  • Romanticism, environmentalism, and the love of nature: The Nazis amplified a Romantic strain in German culture that believed the Volk were a people of destiny with a mystical bond to nature and the land. The Jews and other minorities, in contrast, took root in the degenerate cities.

  • Philology and linguistics: The concept of the Aryan race was based on a prehistoric tribe posited by linguists, the Indo-Europeans, who were thought to have spilled out of an ancient homeland thousands of years ago and to have conquered much of Europe and Asia.

  • Religious belief: Though Hitler disliked Christianity, he was not an atheist, and was emboldened by the conviction that he was carrying out a divinely ordained plan.31

  The danger that we might distort our own science as a reaction to the Nazis’ distortions is not hypothetical. The historian of science Robert Proctor has shown that American public health officials were slow to acknowledge that smoking causes cancer because it was the Nazis who had originally established the link.32 And some German scientists argue that biomedical research has been crippled in their country because of vague lingering associations to Nazism.33

  Hitler was evil because he caused the deaths of thirty million people and inconceivable suffering to countless others, not because his beliefs made reference to biology (or linguistics or nature or smoking or God). Smearing the guilt from his actions to every conceivable aspect of his factual beliefs can only backfire. Ideas are connected to other ideas, and should any of Hitler’s turn out to have some grain of truth—if races, for example, turn out to have any biological reality, or if the Indo-Europeans really were a conquering tribe—we would not want to concede that Nazism wasn’t so wrong after all.

  The Nazi Holocaust was a singular event that changed attitudes toward countless political and scientific topics. But it was not the only ideologically inspired holocaust in the twentieth century, and intellectuals are only beginning to assimilate the lessons of the others: the mass killings in the Soviet Union, China, Cambodia, and other totalitarian states carried out in the name of Marxism. The opening of Soviet archives and the release of data and memoirs on the Chinese and Cambodian revolutions are forcing a reevaluation of the consequences of ideology as wrenching as that following World War II. Historians are currently debating whether the Communists’ mass executions, forced marches, slave labor, and man-made famines led to one hundred million deaths or “only” twenty-five million. They are debating whether these atrocities are morally worse than the Nazi Holocaust or “only” the equivalent.34

  And here is the remarkable fact: though both Nazi and Marxist ideologies led to industrial-scale killing, their biological and psychological theories were opposites. Marxists had no use for the concept of race, were averse to the notion of genetic inheritance, and were hostile to the very idea of a human nature rooted in biology.35 Marx and Engels did not explicitly embrace the doctrine of the Blank Slate in their writings, but they were adamant that human nature has no enduring properties. It consists only in the interactions of groups of people with their material environments in a historical period, and constantly changes as people change their environment and are simultaneously changed by it.36 The mind therefore has no innate structure but emerges from the dialectical processes of history and social interaction. As Marx put it:

  All history is nothing but a continuous transformation of human nature.37

  Circumstances make men just as much as men make circumstances.38

  The mode of production of material life conditions the social, political, and intellectual life processes in general. It is not the consciousness of men that determines their being, but, on the contrary, their social being that determines their consciousness.39

  In a foreshadowing of Durkheim’s and Kroeber’s insistence that individual human minds are not worthy of attention, Marx wrote:

  Man is not an abstract being, squatting outside the world. Man is the world of men, the State and Society. The essence of man is not an abstraction inherent in each particular individual. The real nature of man is the totality of social relations.40

  Individuals are dealt with only in so far as they are the personifications of economic categories, embodiments of particular class-relations and class interests.41

  [Death] seems to be a harsh victory of the species over the particular individual and to contradict their unity. But the particular individual is only a particular species-being, and as such mortal.42

  Marx’s twentieth-century followers did embrace the Blank Slate, or at least the related metaphor of malleable material. Lenin endorsed Nikolai Bukharin’s ideal of “the manufacturing of Communist man out of the human material of the capitalist age.”43 Lenin’s admirer Maxim Gorky wrote, “The working classes are to Lenin what minerals are to the metallurgist”44 and “Human raw material is immeasurably more difficult to work with than wood” (the latter while admiring a canal built by slave labor).45 We come across the metaphor of the blank slate in the writings of a man who may have been responsible for sixty-five million deaths:

  A blank sheet of paper has no blotches, and so the newest and most beautiful words can be written on it, the newest and most beautiful pictures can be painted on it.

  —Mao Zedong46

  And we find it in a saying of a political movement that killed a quarter of its countrymen:

  Only the newborn baby is spotless.

  —Khmer Rouge slogan47

  The new
realization that government-sponsored mass murder can come from an anti-innatist belief system as easily as from an innatist one upends the postwar understanding that biological approaches to behavior are uniquely sinister. An accurate appraisal of the cause of state genocides must look for beliefs common to Nazism and Marxism that launched them on their parallel trajectories, and for the beliefs specific to Marxism that led to the unique atrocities committed in its name. A new wave of historians and philosophers is doing exactly that.48

  Nazism and Marxism shared a desire to reshape humanity. “The alteration of men on a mass scale is necessary,” wrote Marx; “the will to create mankind anew” is the core of National Socialism, wrote Hitler.49 They also shared a revolutionary idealism and a tyrannical certainty in pursuit of this dream, with no patience for incremental reform or adjustments guided by the human consequences of their policies. This alone was a recipe for disaster. As Aleksandr Solzhenitsyn wrote in The Gulag Archipelago, “ Macbeth’s self-justifications were feeble—and his conscience devoured him. Yes, even Iago was a little lamb too. The imagination and the spiritual strength of Shakespeare’s evildoers stopped short at a dozen corpses. Because they had no ideology.”