In addition to the important procreative and child-raising purpose of marriage that David Blankenhorn and others opposed to gay marriage have emphasized, marriage has other functions arising from our history, tradition, and actual practice that are served by allowing people to marry even if they never have children.

So what does marriage do? What is it for? Marriage does at least six important things. I put these here in block text for ease of reference:

(1) Marriage is a legal contract. Marriage creates formal and legal obligations and rights between spouses. Public recognition of, and protection for, this marriage contract, whether in tax or divorce law, helps married couples succeed in creating a permanent bond.

(2) Marriage is a financial partnership. In marriage, "my money" typically becomes "our money," and this sharing of property creates its own kind of intimacy and mutuality that is difficult to achieve outside a legal marriage. Only lovers who make this legal vow typically acquire the confidence that allows them to share their bank accounts as well as their bed.

(3) Marriage is a sacred promise. Even people who are not part of any organized religion usually see marriage as a sacred union, with profound spiritual implications. "Whether it is the deep metaphors of covenant as in Judaism, Islam and Reformed Protestantism; sacrament as in Roman Catholicism or Eastern Orthodoxy; the yin and yang of Confucianism; the quasi-sacramentalism of Hinduism; or the mysticism often associated with allegedly modern romantic love," Don Browning writes, "humans tend to find values in marriage that call them beyond the mundane and everyday." Religious faith helps to deepen the meaning of marriage and provides a unique fountainhead of inspiration and support when troubles arise.

(4) Marriage is a sexual union. Marriage elevates sexual desire into a permanent sign of love, turning two lovers into "one flesh." Marriage indicates not only a private but a public understanding that two people have withdrawn themselves from the sexual marketplace. This public vow of fidelity also makes the married partners more likely to be faithful. Research shows, for example, that cohabiting men are four times more likely to cheat than husbands, and cohabiting women are eight times more likely to cheat than spouses.

(5) Marriage is a personal bond. Marriage is the ultimate avowal of caring, committed, and collaborative love. Marriage incorporates our desire to know and be known by another human being; it represents our dearest hopes that love is not a temporary condition, that we are not condemned to drift in and out of shifting relationships forever.

(6) Marriage is a family-making bond. Marriage takes two biological strangers and turns them into each other's next-of-kin. As a procreative bond, marriage also includes a commitment to care for any children produced by the married couple. It reinforces fathers' (and fathers' kin's) obligations to acknowledge children as part of the family system.

I suppose some people would dismiss these sentiments as the product of "adult-centered" thinking about marriage, with all the emphasis here on legal contracts, finances, sacred promises, sexual fulfillment, and private personal bonds. I suppose some would say I've missed the central importance of marriage as the place for child-rearing. After all, I've placed any procreative and child-rearing function at the very end. It doesn't even make the Top 5. I suppose others would say I've placed marriage in a largely private context and given little attention to the existence of marriage as a public institution with public purposes.

David Blankenhorn would not be among those people. He drafted these very claims about marriage as part of a "Statement of Principles" by the marriage movement in 2000, at a time when gay marriage was barely a blip on the radar. In the block text above, I have copied the statement word-for-word, except that in #4 I have substituted "the married partners" for "men and women." (The statement can be found here.)

Blankenhorn has also explicitly rejected the anachronistic and reductive view that the only public purpose of marriage is to encourage procreation and child-rearing. Marriage is a "multi-dimensional, multi-purpose institution," he acknowledges. "It is not true therefore to say that the state's only interest in marriage is marriage's generative role," he wrote a couple of years ago. "Instead, marriage's role as a pro-child social institution is only one, albeit the most important, of these legitimate state interests." (Emphasis original.)

Blankenhorn has been criticized for a "change of tune" -- for emphasizing procreation and biological parenthood in the context of the gay-marriage debate, while he did not emphasize these things before the debate took center stage. He has defended himself on this point by saying that it is only in the context of the gay-marriage debate that some people have insisted there's no connection between marriage and family-making. I suppose he could also say that the six dimensions of marriage are valuable only because they serve the family-making purpose of marriage by cementing the bond between two biological parents. But that is not how I read the statement and I don't think it fits the idea of marriage as a "multi-purpose" institution.

Blankenhorn, who has long been concerned about fathers leaving their families, is not necessarily being hypocritical by now emphasizing the role of marriage in bringing biological parents together. Nothing in the statement he endorsed seven years ago is inconsistent with the view that the central and important purpose of marriage is to encourage procreation and child-rearing within marriage. But that's the point: even if you erroneously thought gay marriage had nothing to do with benefiting children, and everything to do with, for example, a "personal bond" that "represents our dearest hopes that love is not a temporary condition," it would not be a threat to marriage.

Gay marriage can very clearly meet five of the six dimensions of marriage Blankenhorn himself has endorsed: it can benefit the couple with legal advantages that help "create a permanent bond"; it can facilitate the formation of a financial interdependence that "creates its own kind of intimacy and mutuality"; it helps the couple find values, including religious ones, that go beyond the mundane and everyday and that may be "a fountainhead of inspiration and support when troubles arise"; it can "elevate sexual desire into a permanent sign of love" and be more likely than cohabitation to lead the couple to withdraw themselves from the sexual marketplace; and of course it can be a deep personal bond between two people who share the common human desire for permanence and attachment to one other person.

Gay marriage can also serve the sixth, family-making, function identified by Blankenhorn seven years ago. A gay couple can't procreate as a couple, it's true. But they can fit and benefit from all of the dimensions listed above in the same way a sterile straight couple could. Marriage can turn gay couples, unrelated biologically, into next-of-kin, as it can for opposite-sex couples. It can reinforce parents' (and parents' kin's) "obligations to acknowledge children as part of the family system," just as it can for second-marriage couples and for sterile opposite-sex couples who adopt or use some method of assisted reproduction.

Even if they never have children, married gay couples will hardly be outside the bounds of marriage as it is actually practiced and as Blankenhorn described it in 2000. By choice or by necessity, lots of marriages never result in children. We do not think less of these marriages, do not think they transform marriage into something wholly adult-centered, and do not worry that they represent a threat to "the future of marriage" by making biological parents think family structure is unimportant. There are already far many more such childless opposite-sex marriages than there will be gay marriages. We recognize that these childless marriages fit the additional dimensions of marriage that Blankenhorn beautifully articulated seven years ago and that, in doing so, they do not undermine the important family-making purpose of marriage.

Many opponents of gay marriage would deny that homosexual couples can meet even the five companionate (non-generative) dimensions of marriage. But based on his public statements about homosexuality, I think Blankenhorn would have to agree that for gay Americans marriage would be "a personal bond," the "ultimate avowal of caring, committed, and collaborative love"; that gay persons equally share the deep human yearning "to know and be known by another human being"; and that they too possess "our dearest hopes that love is not a temporary condition."

If that's good enough reason to let childless straight couples marry, to let sterile couples adopt or reach outside their sexual union to produce a child, why is it not good enough for gay couples? The answer to that question might be found in moral or religious objections to homosexuality, in a desire to avoid placing society's imprimatur on homosexual relationships, or in ugly and unfounded stereotypes about gay people as hopelessly hyper-promiscuous or unstable. But it cannot easily be found in a world-view that affirms, as Blankenhorn recently did, "the equal dignity of homosexual love."

Blankenhorn is no flake. He's a serious scholar and thinker. He has thought long and hard about the needs of heterosexuals for marriage. He has challenged the idea that family structure is irrelevant. He has said that our ethical and moral traditions require that we place the needs of children above adult needs where they're in conflict. He has been right about all of this.

But for all his integrity and sincere opposition to anti-gay bigotry, I don't think he has thought very hard about the needs of gay families. That's why, for example, he and many others opposed to gay marriage could imagine that protecting gay families in law means placing the needs of adults ahead of children — as if we don't already have many childless marriages and as if thousands of gay families don't already include children whose welfare the gay parents place before their own.

Perhaps, just perhaps, Blankenhorn will one day see that marriage offers gay people and their families, at no cost to heterosexuals, the best hope that they too will not be "condemned to drift in and out of shifting relationships forever." They will have the prospects for permanence and stability enhanced but not guaranteed in their lives and in the lives of any children they may raise. That's all marriage can do.