A report in the Times of London (click the link) claims that 1,000 men in Britain, more or less, are living with multiple wives. Unsurprisingly, most of them seem to be Muslims. Shariah permits polygamy, but British law does not. But it seems that immigration officials have been instructed to look the other way in questionable cases.
This will no doubt be dismissed, for a while, as an oddity. But in fact, it is food for thought.
First, we should recognize that this modest number of cases will increase, rapidly in European nations and more slowly in the United States, as the number of Muslims increases. Although most Muslim marriages involve one husband and one wife, exceptions -- especially among the affluent -- are not unheard of. So Western nations, largely unacquainted with plural marriage, will need to think hard about some of the questions that the practice raises.
For example, our laws generally prohibit the practice, mostly as a matter of habit rather than a matter of principle. Sooner or later we will need to ask whether there is in fact a principle at stake in this prohibition -- and whether it is a principle of law, of social policy, or of absolute morality. And in any of those cases, opponents will need to make a compelling argument that the principle at stake outweighs the apparent right of Muslims to a free exercise of their religion. (We went through this with Mormons, in the mid-1800s, but I'm not sure that the philosophical legwork of the era will stand up to rigorous scrutiny. it seems to have depended upon vague appeals to "decency," followed by a lot of gunplay).
In this conversation, those of us who have in recent years argued for an expansion of the legal definition of marriage, so that it can include same-sex couples, may find ourselves in an uncomfortable position. I already do. Can we in conscience maintain that position if it leads us logically to permit civil laws that recognize polygamy? And how will we respond when, in a generation or so, the Young Turks within the Church itself begin to argue for Christian solemnization of such marriages? And they will, if only because there is no idea so bad that some Christians will not give it a whirl.