With more free time on my hands, I’ve been reading an excellent book by the linguist Steven Pinker entitled The Blank Slate: The Modern Denial of Human Nature. This fascinating book covers a wide range of topics, but his thesis is that twentieth century intellectuals wrongly persisted in denying the biological basis of human behavior. As a society, he argues we must examine the evolutionary origins and physiological structure of the human brain in order to understand human nature for the construction of better public policy, social relations, etc.

One particularly interesting topic is his examination of how the political Left will respond to what he calls the new sciences of human nature (neuroscience, evolutionary psychology, etc). As Pinker examines, the twentieth century political Left was committed to Locke’s vision of human beings containing a tabla rasa at birth and believed that culture and society were the supreme determinates of human behavior. This theory of human nature fit neatly into the Left’s political agenda because it implied that we could improve the human condition by reforming society. The blank slate doctrine, however, has lost all scientific credibility: the human brain has been forged by millions of years of natural selection. Human behavior and individual character traits are undeniably influenced by a person’s genetic endowments. Studies that compare identical twins, fraternal twins, and siblings all show that intelligence is at least partly heritable. The Left commonly argues that people become violent criminals because they come from broken families and/or communities, but violence has infected all human societies throughout history. Pinker in fact convincingly shows that violence was far more prevalent in pre-historical societies than in our own.

I believe the Left has no choice but to accept these scientific discoveries about human nature and incorporate them into its ideological vision. Along this line of thinking, the philosopher Peter Singer argues in his book A Darwinian Left that ideological liberals must use a scientifically-informed view of human nature to argue for their policies or they risk disaster. To take one example, the argument for Rawlsian justice will very likely be strengthened by a greater appreciation of the powerful role genetics has in determining a person’s intelligence and talents. The genetic variation among human beings means that even in a hypothetical system of perfectly fair economic competition, some will succeed more than others. For Rawls, the importance of this genetic lottery in shaping human destiny demands strong redistributive socioeconomic justice because people’s natural endowments are morally irrelevant (we do not deserve to be born smart or stupid). Recognizing innate differences in human intelligence does not need to be the property of the Right, it should make the Left more adamant at insisting on a strong welfare state to help those with the misfortune of bad genetic luck.

Liberals will no doubt struggle to accept some of the forthcoming scientific discoveries about human nature. For example, the goals of feminism will need to be more carefully articulated as researchers discover more of the innate cognitive differences between the sexes. Nonetheless, I sincerely believe the Left is in a far more comfortable position to incorporate scientific discoveries about human nature than the Right. Many members of the Religious Right continue to deny the validity of evolution, scientific discoveries about the human brain seem to leave no room for an immortal soul created by God, and the Right’s insistence that homosexuals are choosing sin will seem even more ridiculous when neuroscientists pinpoint the genetic sources of homosexuality. The Left’s internal divisions over the implications of scientific discoveries about human nature will most likely be overshadowed by the fierce disagreements between secular conservatives who want to use the new sciences to vindicate their politics and the religious conservatives that will bitterly resist accepting these scientific developments.