Lately I’ve had a lot to say about Scandinavian gay marriage–and the relationship between marriage and parenthood. For years, though, I’ve been arguing that gay marriage is likely to roll us down the slippery slope to polygamy/polyamory. Almost every time I’ve published a piece on the polygamy/polyamory issue, a howling chorus of (largely libertarian) critics has angrily dismissed the argument as absurd. After my comprehensive treatment of the issue in “Beyond Gay Marriage,” though, the baying chorus fell silent. As far as I know, no one has offered a sustained (much less effective) critique of that piece. Now, an influential libertarian who favors gay marriage has acknowledged the power of the slippery-slope argument. In “Opening Marriage,” (Reason, March 2004) Cathy Young asks whether same-sex unions pave the way for polygamy. Her answer seems to be, “Quite possibly.”

Cathy Young begins her piece on gay marriage and polygamy by noting that prominent pro-gay marriage scholars like Richard Posner and Eugene Volokh take the slippery-slope argument seriously. She points out that supposedly “hysterical” warnings that gay marriage would follow from laws banning discrimination by gender or sexual orientation were ultimately vindicated. (Massachusetts referred to just such provisions in authorizing same-sex marriage.) Young also demolishes attempts by gay marriage proponents to differentiate same-sex marriage and polygamy. Then she points out that proponents of same-sex marriage “have offered no substantive arguments to show that the reasoning used to assert the right to same-sex marriage could not be extended to plural marriage as well.” Young even grants that polygamy could destabilize both existing marriages, and the larger ethos of marital monogamy. Having granted the power of the slippery-slope argument, Young offers no rebuttal. Instead she reflects on the complicated options for avoiding the problem. Young considers abolishing state-sanctioned marriage altogether, for example, but dismisses this as politically unworkable.

In short, although Cathy Young certainly doesn’t repudiate her advocacy of same-sex marriage, she does acknowledge the power and legitimacy of the slippery-slope argument. Young never mentions my work, yet there are certainly signs in the piece that she’s read it. Young, in fact, has criticized my arguments on gay marriage in the past–-yet always thoughtfully and respectfully. I don’t doubt that Young still favors same-sex marriage. And no doubt, she is not endorsing every point that I, or others, have made in the course of presenting the slippery-slope argument. But hat’s off to Cathy Young for honestly exploring an important argument against gay marriage. In this case, at least, a thoughtful libertarian in the traditional medium of print has put a chorus of yelping, “Fisking,” bloggers to shame.