As Jillian Keenan reiterated last week at Slate, gay marriage opponents often assert that allowing same-sex marriages will lead us to polygamy and other perversions. It's an odd rhetorical move, inasmuch as, in terms of chronology, the slippery slope from gay marriage to polygamy appears to run in the wrong direction. The major American experiment with multiple wives in one marriage, occurred, after all, in the 19th century with the early Mormon Church. To talk about polygamy, then, doesn't raise the specter of a dystopic future. It points instead to the past. And it also underlines the extent to which marriage experimentation in the U.S. goes back a long, long way.
As far as the history of that experimentation goes, the Mormons were not even the most radical. That distinction goes to the Oneida community, several hundred strong, founded in upstate New York in 1848 by John Humphrey Noyes. Noyes was a graduate of Yale Theological Seminary and a preacher—though his license had been revoked after he began to develop his own shocking social and theological doctrines.
Those doctrines are still shocking today. Reading through the account of Oneida in Louis J. Kern's 1981 monograph An Ordered Love is an exercise in feeling your jaw drop. Among his followers, Noyes devised a system called complex marriage, which meant that everyone was married to everyone else. Thus, every man could have sex with every woman—in private, by appointment, and with length of encounter regulated by community norms (at first, all night—but that was eventually decided to be too exhausting).