Why Not Allow Polygamy?

My last two posts, on gay marriage and polygamy and my religious skepticism betray a difficult contradiction. Viscerally, I don't feel we should legalize either gay marriage or polygamy, but without Christian teaching as an authoritative source for public morals, I have to resort to the reasonable but not entirely convincing argument that our mores have evolved over centuries, and radical tinkering with them is more likely to prove deleterious than positive. A change like legalizing gay marriage is thus a kind of social mutation, more likely to be harmful than not, much like biological mutations.

You can argue that gay marriage weakens a central function of legal marriage between a man and a woman -- providing a healthy environment for reproduction -- but that argument isn't very strong when it comes to polygamy. It's not totally off the mark, because one could surmise that polygamous (really, polygynous) households aren't as healthy for kids as monogamous ones, but who knows?

And of course, Jewish monogamy isn't even sanctioned biblically. It's a rabbinical innovation, going back to Rabbi Gershom, whose edict instituting monogamy for 1,000 years some think recently expired (others think it expired with the Jewish millenium years ago, and others regard it as eternal.)

If we're suitably multicultural and regard adults' sexual and reproductive choices as wholly private, and the legalization of homosexual monogamy as a matter of equal protection, in fact, legalized polygamy is at least logically on its way.

The idea of legally recognizing polygamy will meet great resistance in this country, but absent Christian cultural hegemony, if you support legally recognizing homosexual marriages, there's no principled basis for objecting to polygamy. Indeed, we can say polygamy has been tried over centuries, while gay marriage hasn't.

It's a puzzlement.

Update: revised "establishment of heterosexual monogamy" to read "legalization of homosexual monogamy." Also added "no" to form "no pinicipled basis." I need a copy editor.