The argument that same-sex marriage may in the long-run lead to polygamous marriage is so often dismissed as “scare tactics” because we are told “no one is arguing for polygamous marriage.” And yet Jillian Keenan, a New York feminist writing in Slate, a mainstream online liberal magazine, is arguing for just that. She explains why supporting polygamous marriage must follow on from same-sex marriage.

“The definition of marriage is plastic. Just like heterosexual marriage is no better or worse than homosexual marriage, marriage between two consenting adults is not inherently more or less “correct” than marriage among three (or four, or six) consenting adults. Though polygamists are a minority—a tiny minority, in fact—freedom has no value unless it extends to even the smallest and most marginalized groups among us. So let’s fight for marriage equality until it extends to every same-sex couple in the United States—and then let’s keep fighting. We’re not done yet.”

Indeed, if the definition of marriage is in fact “plastic” it is very hard to oppose redefining marriage to include whatever anyone wants it to include. And that is a problem at the heart of the case for same-sex marriage.

Here is a podcast of the article

Blaise Joseph is a third-year commerce student at the University of New South Wales with a strong interest in social policy. Blaise is originally from Canberra, the centre of politics and the public...