Last month the Supreme Court of British Columbia in Canada rejected an attempt by breakaway Mormons to recognise polygamous marriage.

Pressure is growing across the Western world to no longer restrict marriage to one man and one woman. The biggest and most successful source of that pressure is the gay rights movement, but increasingly Muslims and certain religious sects are demanding that more than two people should be allowed to marry one another.

Here in Ireland, for example, a Lebanese man recently tried, without success, to have his two wives recognised under Irish law.

The Green party in parts of Scandinavia have come out in support of polygamy. After all, if choice is king, then why shouldn’t a man have more than one wife, or a woman more than one husband?

But of course the traditional definition of marriage should be preserved if it serves some social good. The Supreme Court of British Columbia ruled that monogamous marriage does indeed serve a social good.

Among the reasons Chief Justice Bauman gave for rejecting polygamous marriage were the following: “Women in polygamous relationships are at an elevated risk of physical and psychological harm”; “They face higher rates of domestic violence and abuse, including sexual abuse”;   “Early marriage for girls is common, frequently to significantly older men. The resultant early sexual activity, pregnancies and childbirth have negative implications for girls, and also significantly limit their socio-economic development.”

But suppose it could be shown that these effects are a by-product of the sorts of societies in which polygamous marriage is relatively common, e.g. Pakistan, and the experience would be different in Western societies?

In any event, Bauman’s general principle is correct, namely if monogamous marriage serves a wider good, then it should be maintained.

What of the other crucial component of traditional marriage, namely that it be restricted to opposite-sex couples?

That, too, serves a social good, namely to encourage men and women to marry before they have children. It is true, of course, that not all married couples have children. But a far more important truth is that all children have a mother and a father, and we should therefore encourage men and women to marry before they have children. This is why marriage has its particular character.

Finally, here is a further reflection on the Canadian decision, this time from British lawyer, Neil Addison, who has previously addressed The Iona Institute.