According to Andrew Brown of the Guardian, the Supreme Court of British Columbia will consider whether to strike down a law banning polygamy in the province, spurred by protests from a Mormon commune. But anthropologist Joe Heinrich is in favor of keeping the ban in place — for the good of men, women, and children alike. You can read Heinrich's argument in full here, but Brown sums up some of his main points:
— Almost all polygamy is polygyny. Heinrich writes, "Only 1% of societies have ever been considered "polyandrous," and even this is deceptive as in most (but not all) of these societies, polyandry co-occurs with both monogamy and polygyny." So practically speaking, allowing multiple spouses means allowing multiple wives.
— Polygamy encourages poor treatment of women. Brown summarizes:
Because the competition for women is so fierce, making them valuable objects rather than loveable people, men, whether fathers, husbands, or brother, must control them more carefully. The same dynamic places pressure on the recruitment of younger and younger brides into the marriage market, because in a polygynous society you can never have enough of them. Finally, the men will reduce their investment in any particular wives and children, partly because their resources will be much more widely spread; partly because they will increasingly spend their efforts on getting more wives rather than looking after the ones they have.
— Men suffer too, especially if they have low social standing:
There is good data to show that unmarried men are more violent and more generally criminal than married ones, other things being equal. The worst affected are the poor and uneducated who are also the least likely to prosper in a free market in women where the winners can collect as many women as they can handle.
— Society collapses. Heinrich cites higher murder, rape, and robbery rates in polygynous cultures, as well as higher infant mortality. He also argues that these factors, along with gender equality, lead to economic depression.
The troubling thing about the last two arguments is that they treat women like a resource, which must be spread around equally for the good of civilization. We've heard before about the plight of men denied "access" to women, and the contention that pussy is an inalienable right is frankly disturbing. That said, Heinrich's first two points are pretty convincing. There's every reason to believe that legalizing polygamy, rather than creating a free society where everyone could marry whoever (and however many) they want, would just allow a few already powerful men to amass women like, well, a resource. It's kind of like women can't win.