Is it time to grant polygamous marriages the same legal recognition as monogamous marriages? I think it is and here’s why: all of the standard objections to polygamous marriage can apply to heterosexual monogamous marriage as well.

One important objection is that polygamous marriages tend to reinforce traditional, inegalitarian gender norms. This strikes me as a compelling worry but, as Martha Nussbaum and Cheshire Calhoun have pointed out, it also applies to heterosexual monogamous marriages. But we still grant these sorts of marriages legal recognition.

You might reply that polygamous marriages are simply more likely to reinforce inegalitarian gender norms. That seems pretty reasonable. But imagine that a new club pops up: the Society for Traditional Gender Hierarchies (STGH). Thousands of men and women nationwide sign up and pledge their commitment to the notion that a wife must always be the primary caregiver and a husband must always be the primary breadwinner. Needless to say, this is a bad club. You shouldn’t join and, indeed, you should morally oppose the principles of the club. However, even if marriages between STGH members are very likely to reinforce inegalitarian gender norms, they would still receive legal recognition. Part of liberalism is tolerating illiberality.

A related objection alleges that children and women involved in polygamous marriages tend to end up in worse psychological condition than those in monogamous marriages. Part of the explanation is that children are less likely to receive care from their father given that his attention is divided across multiple families and thus lots of children. Fair enough–but would this justify withdrawing legal recognition from monogamous marriages that result in lots of kids? Or suppose that the Smith family has a history of producing dysfunctional (monogamous) marriages. Smiths tend to be self-centered, emotionally distant, and neglectful, so people who marry Smiths tend to end up worse off than those who don’t marry Smiths. We still wouldn’t deny legal recognition to a marriage with a Smith.

Lastly, as Calhoun argues, failing to recognize polygamous marriages results in a kind of black market that comes with all of the familiar problems of black markets in other domains. If a woman informally enters a polygamous marriage and then gets a divorce she can be left without any legal rights to financial support, etc. By analogy, drugs aren’t a good thing but a world with legalized drug markets is better than one with black markets in drugs. Similarly, polygamy might not be a good thing but a world with above-board polygamy is probably better than one where it is driven underground.

I don’t know if polygamous marriages are, on average, worse for those involved than monogamous marriages. But my arguments suggest that this is largely irrelevant: we don’t want to put the state in the business of deciding which kinds of marriages it likes best.