Wednesday, March 04, 2015

Culture Is Part of Human Nature: Jesse Prinz and the Incest Taboo

According to Jesse Prinz, "every cultural trait is really a biocultural trait," because "every trait that we acquire through learning involves an interaction between biology and the environment."  Consequently, "there is no sharp contrast between nature and nurture."  "Nurture depends on nature, and nature exists in the service of nurture" (367). 

Oddly, in saying this, Prinz does not realize that he is endorsing E. O. Wilson's sociobiological argument that the necessary interaction of genes and culture constitutes human nature.  If human culture is part of human nature, then it's hard to see how Prinz's argument for the importance of human culture takes us "beyond human nature."  Strangely, only a few sentences after stating that "nurture depends on nature," Prinz concludes his book by declaring that through nurture, "we transcend nature" (368). 

Here we see the fundamental contradiction that runs throughout Prinz's book--first rejecting the nature/nurture dichotomy as a false dichotomy, but then embracing the dichotomy and insisting that nurture transcends nature.

In declaring that human beings transcend their human nature through human culture, Prinz shows his transcendentalist dualism, which he has inherited from Hobbes and Kant.  Despite the monism of Hobbesis materialism, his political teaching presupposes a dualistic opposition between animal nature and human will or reason: in creating political order, human beings use their rational will to transcend and conquer nature.  This Hobbesian dualism was explicitly developed by Kant, who originally formulated the modern concept of culture (Kultur) as 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.

In contrast to Prinz's transcendentalist dualism, one of the best illustrations of the gene-culture coevolution of human nature is the incest taboo as explained by Edward Westermarck's Darwinian theory.  Prinz's attempt to refute that theory shows the incoherence and deceptiveness of his reasoning.

Elaborating an idea first suggested by Darwin, Westermarck proposed that since inbreeding between close relatives tends to increase the risks of physical and mental defects that impede survival and reproduction, natural selection might have favored an emotional disposition to feel a sexual aversion to those with whom one has been raised in early childhood.  This natural aversion to incest could then create the moral disapproval that is expressed as an incest taboo.  Thus, Westermarck stood against Sigmund Freud's Oedipal theory of the incest taboo as a purely cultural construction that must repress the natural desires of human beings for incestuous sexual intercourse.

Since Prinz insists that the incest taboo is a purely cultural construction, we might think that he therefore agrees with Freud.  But Prinz is confusing on this point.  While he agrees with Freud that the incest taboo is cultural and not natural, he disagrees with Freud in that Prinz believes that there is a naturally evolved tendency for most people to avoid incest, because of the deleterious effects of close inbreeding (353, 355). 

Prinz criticizes the proponents of the Westermarck theory for failing to distinguish incest avoidance from incest taboos (353).  But he does not tell his readers that some of the proponents of the Westermarck theory have emphasized this distinction.  This is most clearly true for Arthur Wolf in his Sexual Attraction and Childhood Association (505-515) and in his Inbreeding, Incest, and the Incest Taboo (10-14).  Most recently, in a book published after the publication of Prinz's book, Wolf has elaborated his account of the relationship between incest avoidance and the incest taboos as two aspects of human nature.

There are at least six kinds of evidence for the Westermarck theory.  First is the evidence that the inbreeding of closely related relatives increases the risks of physical and mental deficiencies. 

Second is the research surveying how people react to incest with emotional disgust. 

Third is the evidence that other primates, including chimpanzees, avoid incest. 

Fourth is the anthropological evidence that incest taboos are a human universal. 

Fifth is Wolf's studies of Chinese "minor marriages."  In the first half of the 19th century, one form of marriage in China was for families to adopt infant girls who would marry their sons.  Wolf found that these minor marriages had higher divorce rates and lower fertility rates than the more common form of marriage.  It seemed that in being reared together as siblings, these couples had developed an aversion to sexual attraction, just as Westermarck predicted.

Sixth is the history of the kibbutzim in Israel.  The children of the kibbutz were reared together from infancy in the "children's house."  On reaching maturity, it was expected that they would find their marital partners among those with whom they had grown up.  But this did not happen, because this seemed like incest to them.

Prinz is silent about the evidence from the kibbutzim and the evidence of incest avoidance among other primates.  He seems to accept the evidence for the risks from inbreeding among close relatives.  But he rejects the other three lines of evidence.

If people find incest emotionally disgusting, Prinz argues, that's only because they were taught by their parents that incest is taboo.  But he provides no evidence for this--that people develop no revulsion against incest if they have not been explicitly instructed that this is wrong.  The evidence from Chinese minor marriages and the kibbutzim seems to contradict this claim.

Prinz dismisses the evidence from Chinese minor marriages by arguing that their high divorce rates and low fertility rates could be caused by the fact that such marriages do not arise from love affairs, and that they come from poor families, so that their poverty could be source of stress.  But Prinz does not tell his readers that Wolf has responded to this criticism by pointing out that the unsuccessful minor marriages tend to occur when the girls are less than three years old at adoption.  The Westermarck effect requires that the children are reared together from a very young age.  Prinz says nothing about this.

Prinz dismisses the evidence that the incest taboo is a human universal by pointing out that there is great cultural variation in the incest taboo, particularly in whether cousin marriage is considered incest.  Prinz does not notice, however, that Westermarck's theory predicts this.  The Westermarck effect arises only for those people who have been reared together from an early age, and thus it tends to arise most strongly for the nuclear family--parents and their children--and whether the incest taboo extends to cousins will be determined by variable kinship systems.  In the United States, cousin marriages are legal in some states but illegal in others.

And yet, Prinz argues, the cultural variation in the incest taboo goes beyond cousin marriage.  In Ptolemaic Egypt (around 300 BC), brother-sister marriage was common among the Greco-Roman citizens.  Among the ancient Zoroastrians in Persia (224-651 AD), there were no incest restrictions at all.  It was a religious obligation for fathers to marry daughters, mothers to marry sons, and brothers to marry sisters (353-56).

Prinz does not tell his readers that Wolf and others have pointed out the dubious character of the evidence from ancient Egypt and Persia.  The Westermarck effect arises when children are reared in their first few years with siblings and other family members.  Many of the sibling marriages in the data from ancient Egypt are between siblings with considerable age differences, which suggests that they were not reared together in their earliest years, and consequently the inhibitions to sexual intercourse and reproduction would not have been acquired.  Moreover, there is some evidence suggesting that some of the sibling marriages of people close in age were between people who could have been reared by wet nurses in their earliest years, which would have interfered with the Westermarck effect.  (The same is probably true for many of the patients that Freud saw in Vienna.)

Another problem with the data from Egypt is that it does not give us any evidence of the success or failure of these sibling marriages.  Did such marriages produce high rates of divorce, adultery, and infertility?  If they did, then they would follow the pattern that Wolf saw in Chinese minor marriages.

The same problems arise with the Persian evidence, which gives us no evidence that these marriages of nuclear family members were successful.  In fact, some of the documents quote remarks about such marriages being "difficult and hard."  Moreover, there is little evidence as to how frequent these marriages were.  There is some evidence, however, that many children of these marriages were born physically and mentally deformed.

Prinz is silent about all of this.

Some of my previous posts on the incest taboo can be found here, here, here, here, here, here, and here.

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