Friday, March 17, 2006


Liam Lenten sent me this by Robert Frank on the economics of polygamy. The article examines who is harmed by polygamy.

A traditional argument is that it harms women, particularly younger women who may be coerced to enter such marriages. But that is an argument against forcing women into any marriage. What about women who accept polygamy? Some are harmed by facing more restricted choices - they may have to settle for polygamy as a second-best option if they seek a particular partner. But with fewer wives available women generally have greater bargaining power in selecting a mate thereby increasing their advantage.

Also, too, polygamy would benefit some men who would not only prefer multiple wives, but are able to attract them. But what about men who prefer monogamy? Permitting plural unions would create an imbalance of men over women among monogamists. With many formerly eligible women no longer available, male bargaining power would fall - as happened recently in China as a result of female infanticide - and many men would never marry. Thus the likely victims of polygamy are men

'This conclusion is reinforced if we take account of the costly, and mutually offsetting, jockeying for position associated with men's attempts to win the attention of scarce women'.
The wastefulness of such 'positional arms races' is clear from nonhuman animal species examples. Many species are polygynous, so some males take more than one mate and males battle ferociously for access to females. Size often decides these battles, so males tend to be considerably larger than females in polygynous species. For example, bull elephant seals weigh more than 6,000 pounds whereas females weigh 1,500 pounds. Natural selection favored larger males because the winners of the long and bloody battles between males often command nearly exclusive sexual access to harems of more than 50 females.

But being bigger increases vulnerabity to sharks and other predators. Relative not absolute size, governs the outcomes of fights, so it would clearly be better if each male were only half as large. All fights would be resolved yet all males would be less vulnerable to predators. But male seals have no way of curtailing the positional arms race that makes them so big.

Permitting plural marriage in human societies would unleash analogous competition. With women in short supply, men would face even more intense pressure than they do now to get ahead economically, to spend even longer hours honing their abs. Yet no matter how hard each man strove, the same number would be destined not to marry.

Unlike other animals, human societies can employ laws to constrain such positional arms races. Laws against polygamy function as positional arms control agreements that make life less stressful for men. This explains their appeal to the male legislatures that enact them.

A further thought: In Islamic societies women often cannot voluntarily contract marriage arrangements. From a male perspective, such restrictions are necessary if polygamy is to be widespread - otherwise the bidding up of female bargaining power that Frank describes will occur. It is crucial for the Frank argument to go through that women be free to contract. If they can't their bargaining power, both inside and outside marriage, will be reduced and hence they will be worse-off. Men without partners will still be worse off.


rabee said...

Polygamy is sustainable as if:
a) Households with many people of one sex match households with many people of the other sex. Or
b) There is population growth and people who decide to marry many partners wait till they are older and pick from the younger more numerous generation. Or
c) There is a declining population and people who decide to marry many partners do so when they are young and pick from the older more numerous generation.

Sam Ward said...

"With women in short supply, men would face even more intense pressure than they do now to get ahead economically, to spend even longer hours honing their abs."

Wouldn't this increased pressure result in higher productivity?

"b) There is population growth and people who decide to marry many partners wait till they are older and pick from the younger more numerous generation."

This describes both polygamous and monogomous (monotonous?) marriage for most of human history.

hc said...

Agree Rabee and Sam but not sure the effects of picking younger more numerrous females are strong enough. In Utah I've heard that young men can't get partners.

I've had further thoughts which I will post above.

conrad said...

Thats a big argument to buy for the restrictions of personal freedoms it entails -- I think consenting adults should be able marry whoever/whaterver they want, rather than put up with some puritan "The government knows better" definition. People do unofficially in any case. Should we penalize them if what they are really doing is so bad for society ? What happens if unnofficial polygamy becomes widespread ? Given that official marriage is going the way of the dodo, that is certainly a possiblity amongst some groups in the community.

I also fail to to see any use in the evolutionary comparison. People are people, not bonobos nor seals. Inferring things about complex behavior and economic consequences from such comparisons really fails to persuade me.

In addition, what evidence is there in the history of humanity that polygamy has really led to a deteriation in society ? Given its widespread nature throughout human history, the evidence that societies fall apart because of it is poor. Is there any evidence that it is even a weak factor with respect to negative societal consequences ?

hc said...

Conrad, I am sure Robert Frank is not presenting a moral argument against polygamy. He simply trying to work out why men - who dominate legislatures - make it illegal. His answer: In a society where women have choice it is men who are disadvantaged by polygamy because the bargaining power of women is enhanced by it.

conrad said...

I just find the sorts of evolutionary comparisons next to meaningless. They're even stranger in this case, because many species with huge male/female discrepancies seem to do just fine, including those mentioned. Most polygamous societies seem to do just fine also.

Another problem with such evolutionary arguements is that they're typically unfalsifiable, and when people do actually find data that goes against them, the arguments are simply changed to become yet more unfalsifiable.

A good example of this is the "evolutionary" preferance men have for feminine looking faces. When this was noted, everybody said "more fertile...etc.", and assumened women would like men with more masculine features too. When it turned out that the second of these wasn't actually true (it was the oppositie), the argument was simply changed "women now like men who are likely to be more caring", thereby providing an answer for any possible preferance that could be found.

Thats just an example from human evolutionary psychology looking at something a lot more concrete than the economic consequences of complex behavior, let alone cross-species comparisons of evolutionary behavior with respect to things that don't exist in other species, like complex economics.

I realize that these arguments are appealing to a lot of people (especially when they seem to provide confirmatory data), but in the end I often find them particularily poor examples of good science.

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