I’ve been thinking of the best way to answer Ross Douthat’s column calling for “magnanimity in victory” from the liberal side of the same-sex marriage debate.

Douthat’s point, basically, is that the marriage norm has continued to erode, across the West, even as the movement for same-sex marriage has burgeoned. Hence, one might plausibly argue that the movement for same-sex marriage, which, in his words, “press[ed] the case that modern marriage has nothing to do with the way human beings reproduce themselves, that the procreative understanding of the institution was founded entirely on prejudice, and that the shift away from a male-female marital ideal is analogous to the end of segregation” was a contributor to that trend away from a marital norm, or at least had a common cause with whatever forces were driving that trend. As such, he calls for liberals to be magnanimous, recognize trade-offs, and say that this trade-off was worth it.

I’m all in favor of recognizing trade-offs, and that all good things don’t go together, but I think to do it right you need to look deeper, and not pick one (still somewhat) controversial proposition and highlight it for that kind of analysis. The deep causes of the decline of the marriage norm are the rise of the equality of women and the yawning wage gap between the working classes and the profession and upper-middle classes. Marriage has become aspirational rather than normative because men are less-desireable than they used to be, both because women need them less and because men can offer less than they used to. It is certainly true that the best way to fall off the path to bourgeois stability, for yourself and your children, is to have those children before marrying, but everyone plays the odds, as best they can, consciously or unconsciously, and if falling off the path looks less-horrible (because one will not starve) and staying on the path looks less-probable (because the men look more like burdens than supports and bourgeois stability looks like a very distant aspiration), then it takes considerably more strength of will to stay on the path. And once a bunch of people fall off the path more or less voluntarily, cultural norms change. They take time to change, but eventually they reach a tipping point where they can no longer be called norms.

So the trade-off is not “was gay marriage worth the cost to the marriage norm” but “was giving women the vote worth the eventual cost to the marriage norm.”

And that’s a question that’s almost impossible to grapple with, because it’s impossible for us to look at the question in other than historical terms. As Matt Yglesias points out, the counter-factual with respect to gay marriage is not “what if this movement had never happened” but “what if the balance of power had tipped the other way for longer.” I suspect he is correct that what that would mean is that liberal enclaves would do more and more to undermine the marriage norm by “thickening” alternatives to marriage – domestic partnerships and the like – and that these, in turn, would become preferable to marriage for the rising generation of young urbanites – again, assuming that these liberal enclaves continued to exist, and exhibit high tolerance for homosexuality. That being the case, the question – as Andrew Sullivan posed it repeatedly to David Frum over the years, Frum being well-aware of these alternative approaches to the marriage “problem” and their potential normative costs – is: what, in your worldview, are you offering to gay people, if not marriage? And there was never a good answer to that. And, there being no good answer – good in the sense of being something that would be readily accepted as an answer – the marriage movement grew, and burgeoned.

I understand the anti-same-sex-marriage argument. I used to adhere to one version of it, though I abandoned it within a couple of years of my articulation. It is rooted in a conviction that men and women are fundamentally different and that the law needs to be deeply cognizant of that difference. That last part is essential to the argument, and is the part that is hard to defend in a liberal democracy.

It’s not so hard to defend in a context where liberal democracy has no formal purchase, such as a religious institution (though a religion whose sacred text includes Galatians 3:28 stands on tricky ground to defend the fundamentality of male-female complementarity). So Daniel McCarthy’s conclusion is correct: the question for those who hold to the fundamentality of distinctions between men and women is how to defend it within their own social spheres. Without articulating the argument in full (that will have to wait until another time), I think the preferable grounds is not individual liberty but collective autonomy. That is to say: the question should not be my individual negative freedom to believe and practice as I wish, free of social constraint, but the positive value to society as a whole of incubating social entities that, as a matter of collective constitution, do not conform to the social norms of the wider society. Those are the terms under which my people needed to justify their sometimes radical dissent from the norms of the societies in which they resided, whether Hellenistic or Roman or Zoroastrian or Christian or Muslim, and notwithstanding periodic and horrific ructions the Jewish story as a whole is filled more with triumph than with tragedy. There might be something to learn from it.

Regardless, the first point for conservatives to recognize is that an argument cannot be unmade. History has no endpoint, but it does proceed dialectically, at least within a society: one argument, whether articulated intellectually or embodied in social “forces,” is resolved, and thereby engenders another. And you cannot proceed in reverse; time’s arrow points in one direction only. The Counter-Reformation Church was necessarily a different thing from the pre-Reformation Church, and one must even ask, by way of counterfactuals, how the hegemonic Church was changed not merely by the challenge posed by the Cathars, but by the Church’s determination to meet that challenge by obliterating them. The challenge of the modern understanding of homosexuality, and political the self-consciousness of gay men and lesbians, is a reality. It can’t be wished away. It can only be responded to, and any response, whether accommodative or repressive, will have consequences, for both sides.