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The Pros and Cons of Polygamy – Would legalizing polygamy increase people’s freedom, or limit it?


Source: Hermin/Shutterstock

With gay marriage now legal nationwide, many (like William Baude in the New York Times) are now wondering if legalized polygamy may be next, and some (like Fredrik Deboer in Politico) are suggesting that it should be.

Should it?

As Baude points out in his op-ed, polygamy should remain illegal because it would increase genderinequality and social instability:

“Judge Richard A. Posner of the United States Court of Appeals for the Seventh Circuit rejected a right to plural marriage because it would lead to gender imbalances if ‘the five wealthiest men have a total of 50 wives.’ Similarly, the same-sex marriage advocate Jonathan Rauch has argued that polygamy allows ‘high-status men to hoard wives’ and destabilizes society.”

Note that Posner and Rauch are assuming that the most common type of legal polygamous marriage would be one husband with multiple wives (polygyny), as opposed to one wife with multiple husbands (polyandry). They’re also not considering more complex types of plural marriage (e.g. multi-male multi-female), or homosexual plural marriage. (Nor will I consider these two latter types here; they’re relevant but beyond the scope of this post.)

Is it safe to assume that most polygamous heterosexual marriage would indeed involve one husband with multiple wives? Probably, as this chimes with the evidence about how people tend to mate cross-culturally. Historically, polygamy was permitted in the vast majority of cultures; in these cultures, polygyny was far more common than polyandry. Still, even within cultures that permit polygyny, it is much less common than monogamous marriage, in part because it can be difficult to attract more than one spouse, even if you’d want to. (Note also that polyandry rates may be underestimated in the anthropological record.)

Because our minds were designed by these evolutionary environments, men—cross-culturally and on average—are more motivated to acquire multiple mates [3], and seem more averse to sharing a spouse, compared to women. That said, forms of polyandry are certainly observed anthropologically, and are quite common in some societies, so it would be misguided to suggest that it is “contrary to human nature.” It would be more accurate to say that the evolved psychological mechanisms in men and women that lead to polygyny are activated under a wider range of environments than are the mechanisms that lead to polyandry.

So it seems reasonable to assume that if polygamy were legal, most polygamous marriage would indeed take the form of polygyny. We can also assume that given roughly equal sex ratios, polygyny could lead to the kinds of gender imbalances described above, with some men who were more attractive (in terms of overall mate value) having multiple wives, and some less-attractive males going wife-less or having to share a mate with other men.

Would such outcomes be a problem? Possibly. Many people would regard them as being unfair or exploitive of women in polygynous marriages, or to men unable to attract a wife of their own. Another convincing argument is that societies with too many unmated men tend to suffer from social instability due to intensified male-male mating competition. Given these potential problems, why would it be a good idea to legalize polygamy?

So it does seem that by prohibiting polygamy between consenting adults, we restrict people’s ability to choose their own mate(s). However this doesn’t mean making it legal is a good idea. Personal freedom is not the only value we should strive to maximize, of course, and there may be a greater social good served by keeping polygamy illegal. Would the potential costs of legalizing polygamy—such as reduced gender equality, increased numbers of low-status unmarried men, decreased social stability, or some other unmentioned problem—exceed the potential benefits?

Wikimedia Commons

Source: Wikimedia Commons

Copyright Michael E. Price 2015. All rights reserved.


  1. Trivers, R. L.  1972.  Parental investment and sexual selection.  In B. Campbell, ed. Sexual Selection and the Descent of Man, 1871-1971, Aldine-Atherton, Chicago, pp. 136-179. 
  2. Marlowe, F. W., & Berbesque, J. C. (2012). The human operational sex ratio: effects of marriage, concealed ovulation, and menopause on mate competition. Journal of Human Evolution, 63, 834-842.
  3. Schmitt, D. P. (2005). Sociosexuality from Argentina to Zimbabwe: A 48-nation study of sex, culture, and strategies of human mating. Behavioral and Brain Sciences, 28, 247-275.