Human Universals

The blank slate theory holds that human beings do not have a fixed nature. Instead we have a general ability to learn and form moral beliefs. The lesson of the blank slate is that there is no “best way” to do things because different human cultures have found radically different ways to work. However, the evidence contradicts the blank slate theory. Anthropologists have documented human traits that are true of every human culture, which means that human nature is at least partially fixed by genetics. Donald Brown has compiled a list of hundreds in his book Human Universals. Here are some of the highlights:

Belief in the supernatural, baby talk, body adornment, the division of labor by age and sex, envy, ethnocentrism, etiquette, females do more direct child care, forming kin groups and distinguishing between close and distant kin, males and females are seen as having different natures, males are more aggressive, prone to violence, and dominate the political realm, marriage, materialism, preferences for own children and close kin (nepotism), prestige inequalities, rape and laws against rape, self as neither wholly passive or wholly autonomous, sexual jealousy, sexual modesty, and sexual regulation including incest prevention, a preference for sweets, dominance/submission, husband older than wife on average, pride, and sex differences in spatial cognition and behavior.

Brown’s list of human universals is powerful evidence against the blank slate theory. On the other hand, the human universals still leave a lot of room for variation so Pojman is correct that you can’t derive an objective system of morality based on human nature. Besides, many of these human universals are clearly immoral, such as rape, male violence, and envy. If we based morality on human nature then we’d have to endorse a lot of immoral acts. This is an important point. A lot of political debates commit the logical fallacy of the appeal to nature, which is basing morality on nature. For example, people who are opposed to same-sex marriage may argue that love and sex between a man and a woman is biologically natural. Conversely, many defenders of samesex marriage point to widespread practice of homosexuality throughout different human cultures to argue that homosexuality really is natural after all. Both arguments miss the point. Rape and murder are common throughout human societies but that does not make rape or murder good. The moral status of homosexuality, and everything else, has nothing to do with how common or widespread it is. Mothers know this, “If every other human culture jumped off a cliff would you jump off a cliff too?”