The average American feels in his gut that something is not quite right with “homosexual marriage.”

But, typically, he can't back up his strong sensibility with an airtight argument. And he's silenced by the fear that, even if he were able to articulate his views with utmost reason and charity, he would be branded a “homophobe” just for trying.

When preparing testimony recently in favor of the Protection of Marriage Act before a joint sub-committee of the Massachusetts legislature, we came upon what seemed a simple and effective analogy for expressing the commonsense view that “homosexual marriage” is a pale imitation of — and a very real threat to — the real thing.

Last year, the U.S. Army created a public controversy when it announced a new policy designed to increase morale and win recruits. Black berets, previously reserved for the Rangers, an elite special-force unit, would now be handed out to every soldier as part of the standard-issue uniform. The idea was that ranks of enlisted soldiers would swell if every soldier could wear the coveted black beret.

As was reported in the national media, many Rangers objected strenuously to the new policy. Yet I am not aware of anyone asking these Rangers, “How are you harmed if we let every soldier in the Army wear a black beret like yours? Aren't you just being selfish and spiteful in wanting to reserve it for yourself?”

No one asked such questions because, whether we agreed with the angry reaction or not, it was easy enough to understand. Clearly, were we to give every soldier a black beret just for joining the service, the very meaning of the black beret would evaporate.

No longer would it identify an accomplished, specially prepared solider who has successfully completed a long and arduous training program; now it would signify nothing more than basic enlistment. And never mind what it would do to the morale of the real Rangers — or to the motivation for new recruits to aspire to become a Ranger.

In other words, if everyone gets a black beret, no one is honored by it. So why have black berets at all?

The reasons against “homosexual marriage” are exactly the same. The legal category of marriage, with various benefits and privileges attached, is a mark of honor. After all, there are many kinds of human relationships, and many different bonds of affection — friends, relatives, companions, co-workers and lovers.

In the past, society has selected out and honored just one of these in a special way, namely, the bond between a man and a woman who commit themselves to each other perpetually, and who aim to beget and raise children. In doing so, society has not been frivolous, since this bond by its nature requires unique sacrifices from which society benefits directly.

Let's carry through the analogy. Suppose now that, just as the Army decided to issue black berets universally, so we expand the definition of marriage to include homosexual partners and live-in sexual relationships. In that case we certainly do harm those heterosexual couples who are founding families, since we deprive them of an honor that was once theirs alone.

Moreover, we change the very meaning of the term marriage. The term can no longer at its core signify sacrifice of oneself for one's spouse and for the sake of one's offspring. Rather, now it signifies, merely, extended sexual intimacy. But, since extended sexual intimacy on its own does not imply any self-sacrifice, or any important benefits for society, it is not worthy of special honor.

Thus, the term marriage would lose whatever prestige and honor it still has. And the policy behind it, like black berets for all soldiers, would defeat the aim it sought to achieve.

If the analogy is indeed exact, then why are the Rangers’ objections against universal black berets so easy to grasp, while those against “homosexual marriage” are not? The reason is that society has already moved far in the direction of redefining marriage — through no-fault divorce, and through a social ethic which sees children as something burdensome and accidental in relation to sex. Clearly, many heterosexuals today become married with no purpose beyond emotional intimacy and sexual pleasure. So it can look unfair that homosexuals may not similarly be “married.”

The proper remedy lies not in expanding the definition of marriage, but rather in appropriately preserving it for permanently committed couples who aim to have children together.

We as a society are conflicted, and the question of gay marriage requires that we take a step toward resolving the conflict in one way or another. If we decide against “homosexual marriage,” we take a clear step toward restoring the ideal that a permanent relationship between a man and a woman, open to children, is the basic building block of society.

If we decide for “homosexual marriage,” we harm ourselves by removing one of the few remaining public witnesses to the bedrock of civilization.

Michael Pakaluk teaches philosophy at Clark University in Worcester, Mass. Catherine, his wife, is a doctoral student in economics at Harvard University. They reside in Worcester with eight children.