In the animal kingdom, polygamy is not uncommon. But society tends to frown on polygamy among people, and laws have spurred raids to root out the behavior. But aside from legal questions, some ethicists ponder whether polygamy ever be morally permissible.

In the new issue of the journal Ethics, a researcher argues that traditional forms of polygamy — defined as a marriage with more than two partners— are inherently unequal and therefore morally objectionable.

"In traditional polygamy, only one person may marry multiple spouses. This central spouse divides him or herself among multiple spouses, but each peripheral spouse remains exclusively devoted to the central spouse," writes Gregg Strauss, a Ph.D. candidate at the University of Illinois, Champaign-Urbana. "With this hub-and-spoke structure, even a perfectly virtuous central spouse has more rights and fewer obligations than each peripheral spouse. Moreover, a central spouse has more control over the family than each peripheral spouse."

Significant modifications to traditional polygamy would be necessary, Strauss argues, to alleviate these inherent inequalities.

One potentially equalizing variation is polyfidelity, an arrangement in which each spouse marries every other spouse. This is unlike traditional polygamy, in which the peripheral spouses aren't married to each other, only to the central spouse. Polyfidelity eliminates the central spouse and allows equal sharing of the rights, responsibilities, and benefits of marriage by each spouse.

Another equalizer would be what Strauss terms "molecular marriage." In this arrangement, peripheral spouses are able to enter additional marriages. This permits any peripheral spouse to become a central spouse of another polygamous family, which again, breaks down the unequal hub-and-spoke structure.

There would of course be practical difficulties in these arrangements, and they would "significantly revise the traditional conception of polygamy and challenge our understanding of marriage," Strauss writes. However they would "at least eliminate the inequalities that will otherwise pervade polygamous marriages."

The full article is available here.