Polygamy has always been against American custom and culture. Polygamy is against the law in the United States, though, due to the long struggle in the nineteenth century over Mormonism. As a result of this struggle, the Church of Jesus Christ of Latter Day Saints condemned polygamy, and, in the early years of the twentieth century, actually abolished it. Today the Mormons are so monogamous that the church’s Relief Society manual tried to portray Brigham Young with one wife – neglecting to mention the other 50+. Renegade Mormon sects do still practice polygamy, but without the blessing of either church or state. Utah could be admitted to the Union only after it condemned polygamy. Monogamy is settled law in the United States, from top to bottom.
There was another important effect of the struggle against Mormon polygamy: the Supreme Court based its rejection of polygamy on the claim that the United States is a Christian nation. In the nineteenth century, it was a legal commonplace to claim that Christianity was part of the common law of the United States. It was only in the past fifty years or so that this claim has been seriously challenged. Today, no court would declare that America is a Christian nation.
So, why, exactly, is polygamy illegal in the United States?
Something like the original Utah law would be rejected because it allowed men to have multiple wives, but not the reverse. Equal protection would take care of that statute. But suppose a neutral law were written, allowing both polygyny (multiple wives) and polyandry (multiple husbands)? William Galston, in Public Matters, notes that the Defense of Marriage Act, which was written to prohibit a federal recognition of same-sex marriages, specifies that legal marriage joins one man and one woman. If the law is challenged successfully, both the man and woman part, and the one and one part, could be rejected.
This is not a hypothetical case. There are already renegade Mormons practicing polygamy underground in the West. African immigrants bringing traditional tribal religions could argue for accommodation. Most importantly, the growing Muslim community in the USA could argue that their long-established recognition of limited polygamy, which is practiced by millions of Muslims worldwide, should be accepted under the “free exercise” clause of the first amendment. No such case has been filed yet, but it is only a matter of time.
I think polygamy is a bad idea for society. With a couple of exceptions, polygamy is really polygyny – one man, multiple women. What happens in polygynous societies is that low status men don’t get to marry at all. This, it seems to me, is just unfair and un-American. Moreover, in every case I have read about of polygyny, even in societies in which it was well established, the wives are never really ok with the fact that their husband has other wives and other children. Polygyny is one widely used way of settling the conflict between male and female strategies in mate selection and childrearing. It is not crazy, nor do I think it is barbarous. But I do think that it is unwise anywhere, and deeply unsuited to our culture and history.
It is not likely that American legislatures would ever legalize polygamy, no matter how many marriages and mistresses individual legislators have. But it is hard to see exactly how a court would now justify forbidding religions that do accept, even encourage, polygamy, from doing so here.
When we look at the numbers, there are many more polygamists in the world than there are people who want to have a same-sex marriage. It is not way out to imagine a polygamy crisis in America in, say, the 2030s, as there was in the 1830s. Polygamy, more than same-sex marriage, is, I think, more likely to result in a constitutional amendment defining marriage.