Will someone please explain to me how permitting gays and lesbians to marry threatens the institution of marriage? Now that the Massachusetts Supreme Court has declared gay marriage a constitutional right, opponents really have to get their arguments in line. The most popular theory, advanced by David Blankenhorn, Jean Bethke Elshtain and other social conservatives is that under the tulle and orange blossom, marriage is all about procreation. There’s some truth to this as a practical matter–couples often live together and tie the knot only when baby’s on the way. But whether or not marriage is the best framework for child-rearing, having children isn’t a marital requirement. As many have pointed out, the law permits marriage to the infertile, the elderly, the impotent and those with no wish to procreate; it allows married couples to use birth control, to get sterilized, to be celibate. There’s something creepily authoritarian and insulting about reducing marriage to procreation, as if intimacy mattered less than biological fitness. It’s not a view that anyone outside a right-wing think tank, a Catholic marriage tribunal or an ultra-Orthodox rabbi’s court is likely to find persuasive.

So scratch procreation. How about: Marriage is the way women domesticate men. This theory, a favorite of right-wing writer George Gilder, has some statistical support–married men are much less likely than singles to kill people, crash the car, take drugs, commit suicide–although it overlooks such husbandly failings as domestic violence, child abuse, infidelity and abandonment. If a man rapes his wife instead of his date, it probably won’t show up on a police blotter, but has civilization moved forward? Of course, this view of marriage as a barbarian-adoption program doesn’t explain why women should undertake it–as is obvious from the state of the world, they haven’t been too successful at it, anyway. (Maybe men should civilize men–bring on the Fab Five!) Nor does it explain why marriage should be restricted to heterosexual couples. The gay men and lesbians who want to marry don’t impinge on the male-improvement project one way or the other. Surely not even Gilder believes that a heterosexual pothead with plans for murder and suicide would be reformed by marrying a lesbian?

What about the argument from history? According to this, marriage has been around forever and has stood the test of time. Actually, though, marriage as we understand it–voluntary, monogamous, legally egalitarian, based on love, involving adults only–is a pretty recent phenomenon. For much of human history, polygyny was the rule–read your Old Testament–and in much of Africa and the Muslim world, it still is. Arranged marriages, forced marriages, child marriages, marriages predicated on the subjugation of women–gay marriage is like a fairy tale romance compared with most chapters of the history of wedlock.

The trouble with these and other arguments against gay marriage is that they overlook how loose, flexible, individualized and easily dissolved the bonds of marriage already are. Virtually any man and woman can marry, no matter how ill assorted or little acquainted. An 80-year-old can marry an 18-year-old; a john can marry a prostitute; two terminally ill patients can marry each other from their hospital beds. You can get married by proxy, like medieval royalty, and not see each other in the flesh for years. Whatever may have been the case in the past, what undergirds marriage in most people’s minds today is not some sociobiological theory about reproduction or male socialization. Nor is it the enormous bundle of privileges society awards to married people. It’s love, commitment, stability. Speaking just for myself, I don’t like marriage. I prefer the old-fashioned ideal of monogamous free love, not that it worked out particularly well in my case. As a social mechanism, moreover, marriage seems to me a deeply unfair way of distributing social goods like health insurance and retirement checks, things everyone needs. Why should one’s marital status determine how much you pay the doctor, or whether you eat cat food in old age, or whether a child gets a government check if a parent dies? It’s outrageous that, for example, a working wife who pays Social Security all her life gets no more back from the system than if she had married a male worker earning the same amount and stayed home. Still, as long as marriage is here, how can it be right to deny it to those who want it? In fact, you would think that, given how many heterosexuals are happy to live in sin, social conservatives would welcome maritally minded gays with open arms. Gays already have the baby–they can adopt in many states, and lesbians can give birth in all of them–so why deprive them of the marital bathwater?

At bottom, the objections to gay marriage are based on religious prejudice: The marriage of man and woman is “sacred” and opening it to same-sexers violates its sacral nature. That is why so many people can live with civil unions but draw the line at marriage–spiritual union. In fact, polls show a striking correlation of religiosity, especially evangelical Protestantism, with opposition to gay marriage and with belief in homosexuality as a choice, the famous “gay lifestyle.” For these people gay marriage is wrong because it lets gays and lesbians avoid turning themselves into the straights God wants them to be. As a matter of law, however, marriage is not about Adam and Eve versus Adam and Steve. It’s not about what God blesses, it’s about what the government permits. People may think “marriage” is a word wholly owned by religion, but actually it’s wholly owned by the state. No matter how big your church wedding, you still have to get a marriage license from City Hall. And just as divorced people can marry even if the Catholic Church considers it bigamy, and Muslim and Mormon men can only marry one woman even if their holy books tell them they can wed all the girls in Apartment 3G, two men or two women should be able to marry, even if religions oppose it and it makes some heterosexuals, raised in those religions, uncomfortable.

Gay marriage–it’s not about sex, it’s about separation of church and state.