To avoid issues of polygamy and bisexuality, proponents of gay marriage implicitly assert that the number "2" is the magical element of marriage, beyond which one need look little further. For example, David Brooks would define marriage as an "exclusive commitment" of 2 persons without regard to the partners' sex.

That definition, an "exclusive commitment of 2 persons," is incomplete. For there is nothing about the number 2, in and of itself, that makes an "exclusive commitment" of 2 persons deserving of special social status not accorded to an "exclusive commitment" involving three or more persons of whatever sex for whatever purpose. Society's granting the special social status of "marriage" to exclusive commitments of 2 persons, while denying that special status to exclusive commitments of more than 2 persons, can be justified only to the extent that the limitation serves some social good that is not served by arrangements involving a greater number. So one must ask, "Exclusive commitment for what purpose? What is the social purpose served by society's granting special status to exclusive commitments of two persons that is not as well served by exclusive commitments of three or more persons?"

In the Western tradition, the answer has been that the social good served by the institution of marriage is the procreation and well-rearing of children. Indeed, this is the only social good sufficient to distinguish marriage from other formal and informal social arrangements such as loyal friendships, monogamous sexual relationships, business partnerships, intellectual collaborations, or exclusive social clubs. Thus, marriage--as a social institution--deserves its special status apart from other "exclusive commitments" only so long as it remains grounded in the procreation and rearing of children.

To preserve the special status of the number 2 with regard to the "exclusive commitment" of marriage, society must take children into account. Children are a naturally cohering end of marriage. As the fruit, the focus, and the beneficiaries of a couple's joined efforts, children secure the bonds of marriage. And marriage in turn serves and protects children. Society must resist the complacent inclination to formally accept as "marriage" whatever arrangement two (or more) persons of whatever sex happen to want to receive that designation, beginning with the vague notion that marriage is "an exclusive commitment of 2 persons."

As a husband who is father to a stepchild only, I happily admit that a childless couple can have a successful marriage. Yet the prospect of the shared blood relationship created through generation of children is the only distinctly sustainable reference point for marriage generally. That is why it still strikes most of us as odd and even unnatural when a married couple announces they don't ever want to have children. If marriage is to remain a social institution deserving of special status, the example of the heterosexual couple with naturally conceived children must remain directly accessible to view as the reference point for all marriage. Homosexual marriage, because by nature it cannot produce offspring, weakens marriage by severing it radically from its fundamental social and natural grounding.

And yet the centrality of children to the question of gay marriage has been largely ignored in the current debate: For several years, Stanley Kurtz has been making strong and sensible arguments against gay marriage. Yet too often even Kurtz fails to emphasize the essential connection between marriage and children. For example, in an article last year, The Libertarian Question, though Kurtz does mention children and procreation, he does not say much about the symbiosis between marriage and children. His discussion of how homosexuality undermines the traditional taboo against non-procreative sex touches on this central issue, but approaches the central question via a circuitous route that emphasizes a tenuous negative argument (i.e., that the taboo on non-procreative sex protects marriage by discouraging adultery) while overlooking the positive, direct and obvious arguments (e.g., that procreative sex is at the core of the social status of marriage; that child-bearing strengthens marriage; that marriage protects children, etc.). I am pleased to see that in his most recent writing, Kurtz has returned children to the center of the argument:

Marriage is not meant solely, or even mainly, for husbands and wives. Marriage exists as a public institution because children need mothers and fathers.

Not surprisingly, in his article advocating gay marriage, David Brooks barely mentions children. The one time he does get around to mentioning children, Brooks writes dismissively of heterosexual relationships: "Men and women shack up for a while, produce children and then float off to shack up with someone else." Brooks seems to think that, because too many couples no longer perceive the link between child-bearing and marriage, we should accept gay marriage, which even further weakens that link. Other than that strange statement, Brooks has nothing to say about how children fit into his concept of gay marriage--because they don't fit into it.

Without resort to adoption or artificial methods of reproduction (which raise a host of other issues), homosexual unions must, by their nature, remain childless, and therefore are inconsistent with the natural and social grounding of marriage. Many, such as David Brooks, want to dismiss arguments about nature as "biological determinism." They would point to the example of a faithful yet barren heterosexual couple that adopts children and ask, "Is the bond between this barren couple who have adopted children less strong than one between a now-divorced couple with children they naturally conceived together? Cannot homosexual marriages with adopted children produce equally strong bonds?" As to a particular couple, one cannot say, but speaking generally (and putting aside terribly difficult problems created if the decision to have children becomes more commonly a process of selecting and manufacturing rather than begetting) it seems clear that the arrival of a child a couple conceived together strengthens the marriage bond more immediately and more naturally than the arrival of an adopted child. Now this might strike some as a harsh conclusion, but society should not ignore or minimize these problems of "flesh and blood."

Yes, "flesh and blood" can be transcended, and when "flesh and blood" is transcended, then you have something beautiful and rare. Yes, barren couples with adopted children can transcend the absence of a flesh and blood connection with their children, forming bonds with each other based on something deeper than "mere" shared flesh and blood. But such transcendence of nature's "mere" flesh and blood can readily occur only if society maintains the grounding of marriage in nature, rather than if society dismisses nature as "biological determinism." Nature provides the beginning point, the stable ground, and the support above and from which one elevates the ordinary human experience. In that sense, transcendence of nature never requires one to lose sight of the natural reference point. A barren heterosexual couple that adopts is reaching for a result toward which nature points them, but fails to complete. A barren heterosexual couple adopts children because they want what nature points them toward, what a fruitful heterosexual couple has naturally. The heterosexual couple that procreates naturally still supplies the reference point by which a barren heterosexual couple orients itself when adopting children. But no homosexual couple will ever bear children naturally, and it would be ludicrous (in more ways than one) to suggest that procreative heterosexual marriage could ever be a natural reference point for homosexual unions.

If homosexual marriage--which cannot generate children naturally--becomes more commonly accepted, the status of the procreative heterosexual marriage as the natural and social reference point for marriage becomes less accessible to view. If, to accommodate homosexual couples, an "exclusive commitment between two persons" is accepted as the vague reference point for marriage, then children will lose their status as the special end sought and served by marriage generally. When children lose that status, then the number 2 does indeed become an arbitrary limit. As it degenerates into "an exclusive commitment" for whatever purpose, duration, and number of persons of whatever sex the contracting parties happen to choose, marriage begins to lose its meaning.