What I find somewhat surprising in the gay-marriage discussion is this: By the evidence of most polls, nearly half of Americans favor gay marriage, even though only 3-5 percent of Americans are gay. That is, only a very small minority of the population has any personal interest in the matter; so why does nearly half the population favor the matter? Suppose athletic directors in high schools proposed some special tax benefit for themselves. Would half of the population support giving that small minority such a tax benefit, merely because they wished to have it? I doubt it. So what accounts for such widespread support for a public policy that would only benefit a very small portion of the population? I believe the answer has two parts.

First, for many people, to oppose gay marriage is to be bigoted; it is to oppose homosexuals themselves. For such people, not to approve gay marriage is to be bigoted (an “enemy of humanity,” as Justice Kennedy so breezily put it), and in our pluralistic and relativistic culture, the only value that is commonly shared is non-bigotry. The last thing we wish to appear is bigoted.

The reason I believe this is what motivates many people is that, whenever I raise the question of the hypothetical public interest in gay marriage, I get blank stares. Whenever I mention that I am open to being persuaded that the public has an interest in protecting homosexual unions, and open to hearing, therefore, arguments to that effect, I get no reply. Indeed, some of my friends and acquaintances appear to be almost shocked when I ask, “Why does the public have an interest in gay marriage? What public good does it serve?” If I had framed the question differently, and inserted “tax benefit for athletic directors” instead of “gay marriage,” the question would be regarded as a perfectly legitimate, ordinary question of public policy. But in this case, if I raise the question of the public interest or the public good, I get embarrassed, indignant, or horrified looks, rather than reasoned opinion. Why? Because for many people, anything associated with homosexuality is merely a litmus test for bigotry. The first and most ordinary question of public policy – how does this proposal serve the public good? – is not even germane.

Second, for many people, human sexuality is completely disconnected from procreation. The widespread availability of birth-control has disconnected human sexuality from its biological purpose, at least in the minds of many people (though not in their reproductive organs). For them, human sexuality no longer serves the public good of producing other generations of mature and responsible citizens; human sexuality is merely a private good, something that brings pleasure to individuals. And for some people such sexual activity is even more enjoyable for those who are married; thus, to deprive them of marital status is to deprive them of some of the private pleasure of human sexuality.

I hardly know where to begin in responding to such a belief, a belief that effectively reduces public policy to a sexual aid. I might timidly suggest to such individuals that the government and its policies are not obliged to enhance the pleasure individuals derive from sexual activity; government is designed to promote the public welfare. If government’s purpose were to enhance sexual pleasure … well, just think where that might lead. But if we were to grant that government exists to promote the public welfare, then Justice Kennedy would have to grant not only that there are “two tiers” of union, but four: Committed and reproductive (i.e. traditional marriage between a man and a woman), casual and reproductive (e.g., unwed mothers), committed and non-reproductive (e.g. same-sex unions), and casual and non-reproductive (Hugh Hefner). Curiously enough, then, one might argue that the state has more interest in the second than in the third or fourth, because the state does have an interest in the extension of the human race. On the other hand, the children of the second category often require substantial government assistance, and so, perhaps, this category is a “wash,” financially. If this were so, we would indeed be right back to Justice Kennedy’s “two tiers” of committed sexual unions: those that ordinarily produce offspring, and those that do not and cannot do so.

So, once we get over all the emotion, hand-wringing, and fear of bigotry, the question is merely this: Does human reproduction serve the public good?

By the government’s own calculations, it cost my wife and I $225,000 to rear each of our two daughters until they were 21, nearly half a million dollars total. The public now benefits from these two adult, independent, gainfully employed, tax-paying citizens. If the public does not benefit from such citizens, then Cass Sunstein is right, and the state should stop recognizing any unions of any sort (cf. “Privatizing Marriage,” chapter 15 of Sunstein’s Nudge: Improving Decisions about Health, Wealth, and Happiness, co-authored with Richard H. Thaler). But if human reproduction does serve the public good (e.g. Who will pay for my Medicaid when I retire?), then it is perfectly reasonable to consider protecting those unions that ordinarily foster such human reproduction. Every other union, by this consideration, is “second tier,” as Justice Kennedy said, but justifiably so.

T. David Gordon, Ph.D., is a professor of religion and Greek at Grove City College and a contributing scholar with The Center for Vision & Values.