Why social conservatives should not argue — as Dennis Prager does — that a woman should have sex with her husband whether she's in the mood or not.

And by "social conservatives," I mean, specifically, persons who oppose homosexual relationships or, at least, same-sex marriage.

Here's Dennis Prager's much-mocked Townhall column. He says things like "Why would a loving, wise woman allow mood to determine whether or not she will give her husband one of the most important expressions of love she can show him?"

Prager's position throws away the most persuasive argument that marriage, limited to the relationship between a man and a woman, is the basis of civilization.

Do you see my point? I'll elaborate later, but I would like you to think about it on your own before I explain what, in my view, is obvious.

LATER: Okay, here's my point. Prager sees the differential sex drive of males and females as a problem that should be solved by wives going along with sex even when they are not in the mood. But why do social conservatives see heterosexual marriage as the foundation of civilization? I thought their idea was that various male urges were controlled and sublimated through marriage to females. There is a civilizing effect — I think the theory goes — as the natural impulses pressure a man to do what he can to impress and please the woman. This process is undermined if the woman simply accedes to his sexual impulses. The pressure must be kept up. The man should be required to understand the woman and figure out how to do things that will make her desire sex with him. Or he can sublimate his urges, and pour his energy into great architectural and scientific achievements and the like.

So Prager should not want sex to become more efficient and more in line with the male biological drive. If that is the goal, he ought also to favor sex between 2 men. Homosexual sex is a solution to the problem he identifies. It should be favored. To remain socially conservative, it is necessary to honor the female fussiness about sexual intercourse, because it inspires the male to work harder and to acquire greater self-control. This is the reason for thinking of heterosexual marriage as the foundation of civilization.

Note: I'm not a social conservative, and I support same-sex marriage. I just want to clear away some of the obfuscation about marriage and this often odd-sounding notion of "defending" it. Something important happens when men and women get together. I don't think that means same-sex couples should be disrespected any more than I think it's wrong to remain single.