For the past six and a half years, that post has regularly had more pageviews than any other post that I have ever written. Apparently, people are Googling "What is wrong with incest?" and my post pops up. A lot of people are struggling with their incestuous thoughts and looking for some way to overcome the taboo against incest. Unfortunately, my post has even turned up on a porno website!
Of course, sex is interesting, and prohibited sex is especially interesting. But what is notable about the incest taboo is that it's a universal prohibition of a sexual activity that most human beings in every human society never consider as a possibility. Most human beings have no sexual interest in their parents, their siblings, or their children.
So why do we need a social rule to prohibit what no one wants to do? Well, actually, as the popularity of my post on incest indicates, some people are troubled by incestuous thoughts. After all, incest is a serious social problem, particularly with fathers sexually abusing their daughters. Even here, however, there's an interesting pattern: the most common form of incest is actually child abuse. Daughters who have been sexually abused by their fathers usually break away from this as adults. Incest between consenting adults within the nuclear family is extremely rare. But once we move to more distant kinship relationships--such as cousins--the strength of the inhibition weakens, because depending upon the circumstances of rearing and kinship rules, cousin marriage might be allowed or even preferred.
As I have argued in various posts, I find Edward Westermarck's Darwinian explanation of incest avoidance and the incest taboo to be the best account of this. Elaborating on some suggestions coming from Darwin himself, Westermarck laid out the reasoning for explaining our human reaction to incest as a biological adaptation. If close inbreeding tends to create high risks for the offspring--death or mental and physical defects--then we might predict that evolution by natural selection would favor a propensity to feel no sexual interest in those with whom one has been reared from early infancy. Consequently, as people are reared together with siblings and parents, they will tend to have no sexual interest in their parents, their siblings, or their children. This emotional aversion to incest might then be expressed as a general social disapproval of incest that could become an incest taboo. How far this taboo extends beyond the nuclear family will depend upon social conditions and kinship rules.
The evidence for the Westermarck hypothesis has increased over the past sixty years as biologists and social scientists have studied some natural experiments among human beings--particularly, the history of the kibbutzim in Israel and Chinese "minor" marriages--and incest avoidance among primates and other non-human animals. This evidence has been well surveyed by people like Arthur Wolf of Stanford University.
The leading opponent of Westermarck's theory was Sigmund Freud, who assumed that far from having a natural inclination to avoid incest, human beings were naturally inclined to it (the Oedipus Complex), and therefore the incest taboo must be understood as a purely cultural invention of human beings to repress their natural animal desires for incestuous relations.
Many cultural anthropologists have adopted the Freudian position. For example, Claude Levi-Strauss declares:
"It will never be sufficiently emphasized that, if social organization had a beginning, this could only have consisted in the incest prohibition since . . . the prohibition is, in fact, a kind of remodelling of the biological conditions of mating and procreation (which know no rule, as can be seen from observing animal life) compelling them to become perpetuated only in an artificial framework of taboos and obligations. It is there, and only there, that we find a passage from nature to culture, from animal life to human life, and that we are in a position to understand the very essence of their articulation."This remarkably dramatic language--"from nature to culture, from animal life to human life"--suggests something like a Creation story of human origins, except that in this case the elevation from animal life to human life comes not through God's creative power, but from the power of human beings to create themselves through culture.
As Wolf has indicated, cultural anthropologists often see human culture as having a kind of redemptive or transcendent quality to it, because it preserves human dignity through an elevated image of the human species that cannot be explained in Darwinian terms. Westermarck's Darwinian explanation of incest avoidance and the incest taboo is rejected by them because it presents a morally degrading view of human beings as merely highly evolved animals.
This might explain why debates between biological anthropologists and cultural anthropologists become so emotional. Wolf has seen this at Stanford. In 1998, the split in the Department of Anthropology had become so combative that the Department was officially separated into two distinct departments--a Department of Cultural and Social Anthropology and a Department of Anthropological Sciences. As these titles indicate, the split was between culture and science--between those who think that culture transcends biological science and those who think that culture can be explained by biological science. (In 2007, the central administration of Stanford forced these two departments to be reunited as a Department of Anthropology, but many of the faculty members were angry about this.)
The radical separation of nature and culture that one sees in the work of many cultural anthropologists arose first in the thought of Thomas Hobbes and Immanuel Kant. Despite the monism of Hobbes's materialism, his political teaching presupposes a dualistic opposition between animal nature and human will or reason: in creating political order, human beings transcend and conquer nature. This dualism was explicitly developed by Kant, who originally formulated the modern concept of culture (Kultur). For Kant, culture is that uniquely human realm of artifice in which human beings escape their natural animality to express their rational humanity as the only beings who have a "supersensible faculty" for moral freedom. Through culture, human beings free themselves from the laws of nature.
Although culture has become a vague concept in the social sciences, it retains the four central features prescribed by Kant. (1) Culture is uniquely human. (2) It is uniquely human because only human beings have the understanding and the will to set purposes for themselves by free choice. (3) Culture is an autonomous human artifice that transcends nature. (4) Culture is the necessary condition for forming moral values.
Oddly enough, although Friedrich Nietzsche generally rejects Kantian dualism, the Nietzsche of the early and later writings actually embraces something like Kantian dualism in depicting human beings as capable of redeeming themselves from their animality by creating themselves through culture, allowing them to create what is "beyond" themselves. Only in the Darwinian writings of his middle period does Nietzsche escape from this "need for redemption" by accepting the animal nature of human beings.