The standard social conservative argument against gay marriage is that it undermines and trivializes traditional forms of marriage and the family, by incorporating into them relationships that lack the same level of solemn responsibility and commitment. Two prominent moderate conservatives, Ross Douthat and David Frum, have finally managed to identify the main problem with this argument: it gets the flow of causation backwards. It's not that acceptance of gay marriage undermines traditional marriage, but rather that gay marriage couldn't possibly have reached today's levels of popular approval, were it not for the fact that the ideal of marriage as a socially enforced rock-solid commitment to fidelity and family is already, for all intents and purposes, moribund in the Western world. In an era when ordinary heterosexuals routinely enter into--and drift out of--"relationships" of greater or lesser length that can include sex, cohabitation or even reproduction, more or less irrespective of whether or not they choose to add a marriage ceremony into the mix, it's hard to see why anyone would bother to take a stand on the minor detail of whether the redundant formalism that is modern marriage might also be stretched to include yet another category of indeterminately casual or serious liaison.

In another respect, though, both Frum and Douthat hew to the standard conservative line about traditional marriage, by fretting about the effects on society of its collapse. In their characterization, disdain for the traditional family is a kind of pernicious cultural fashion, rather like uneconomical recycling programs or ugly, annoying "transgressive" art, that affluent Westerners have affected as a form of social snobbery, and that has by now percolated down to--and wrought havoc upon--the masses. The middle and lower classes, according to their theory, have embraced the elite's lack of sexual and domestic discipline, thereby ruining their prospects for social and economic stability, let alone advancement.

To be frank, I once subscribed to this view myself. But the stubborn failure of traditional marriage to revive itself, despite all the supposed incentives it offers, has led me to rethink this analysis. And I've arrived at a very different conclusion: the feminist and sexual revolutions of the 1960s, far from being mere elite cultural fads, were in fact fundamental, historic breaks with the past, of which the collapse of the traditional family is just one facet.

Although it is rarely stated explicitly, the traditional family rests on a basic assumption: that in the vast majority of cases, a woman needs (or at least benefits greatly from having) a man to provide for her. And for most of human history, that was simply true, because much of the business of survival involved physically strenuous activities--first hunting, later agriculture, and even, fairly recently, heavy industry--to which men were significantly more suited, and which were incompatible with maternal care of infants.

By the late twentieth century, however, technology and its attendant prosperity together allowed women to be more or less fully competitive with men at the majority of reasonably well-paying occupations. Meanwhile, medical advances have vastly reduced the amount of time a woman has to spend caring for infants in order to be confident of raising a small number of them to adulthood. Thus, for the first time in history, a critical mass of women have truly come to need men, as the old feminist saying goes, "like a fish needs a bicycle".

And it is this newfound independence that has brought about the destruction of the traditional family, not vice versa. While the conventional wisdom characterizes men as reveling in their sexual freedom while women still pine for a stable marriage and family, it is in fact women who have shifted their position on marriage most dramatically. Well over half of divorces, for example, are instigated by women, and the surge in extramarital sexual partnerships, from casual relationships to long-term unmarried cohabitations, would be impossible without women's consent to them--something that would have been simply unheard-of fifty years ago, when most women's economic stability was dependent on marital stability. Today's women, freed by the prospect of financial independence, can now structure their personal relationships the way men have long preferred to: based on emotional preference, rather than material need. And as it turns out--for many of them, though certainly not all of them--emotional preference is less conducive to stable, lifelong marital commitment than material need used to be.

Now, it's quite possible that social conservatives are correct in warning that this shift has had, and will continue to have, deleterious effects on society. In particular, there's the whole matter of childrearing: now that women are no longer bound by economic need to the role of wife and mother, they are having, on average, far fewer children, and caring for them less. The effects of this new family profile on society are only beginning to make their impact, and we don't know for sure that they will be even tolerably benign in the longer term.

But neither are we likely to be able to put the genie back into the bottle. If I'm correct that today's radically altered options and incentives for women are a result of prosperity and technology--two things we probably can't give up even in the unlikely event that we wanted to--then it's surely far more productive to consider how society can best adapt to the new reality of domestic instability, than to pine for a not-so-happy past era in which economic and technological backwardness made it less of a problem.