Q. What do you call a conservative gay legislator who's in the closet?

A. A safe vote against gay rights.

As usual, a bunch of politicians have had sex scandals recently. As usual, a good helping of them have been family-values types. And as usual, progressive bloggers have been surprised and appalled that many of the scandalous are family-values types, and even more shocked because a bunch of the conservative family-values adulterers seem to be skating. How is it that Mark "Appalachian Trail" Sanford is still Governor of South Carolina, Swinging John Ensign is still Senator from Nevada, and David Vitter, who may have qualified for a loyalty rewards card at one or more houses of prostitution, is still Senator from Louisiana? How are some of these guys running for re-election while Eliot Spitzer is out of office and Bill Clinton got impeached? How is it that the far right wing, in the person of Glenn Beck, actually made an abortive attempt to recruit Eric Massa away from the Democrats after his sex scandal broke? There seems to be a double standard here, because in fact there is. And while that's repugnant, it's not illogical. If a voter genuinely wants the government to impose public restrictions on sexual liberties, voting for a creepy adulterous hypocrite is a sound strategy.

There are two bedrock political rules in play here. First, you should always vote for the candidate based on their policies. Second, political scandals become harmful when they resonate with some larger concern or anxiety about the candidate.

David Vitter may have repeatedly broken the law in order to break his marriage vows, but you can rely on him to make the law as sexually restrictive as he can possibly manage. Now, if you're like me you might take Vitter as an example of how difficult and impractical it is to enforce sexual morality through legislation. But family values voters do not. And Vitter is a rock-solid vote for them. He votes against gay marriage, for abortion restrictions, for abstinence-only education: the full family-values list. And now that he's publicly admitted being an adulterous whoremonger, Vitter is never going to deviate from the family-values platform again. If he does, even a little bit, he'll have a God-fearing primary challenger on his hands, and won't be able to defend himself. He knows he can be a libertine as long as there's no hint of liberalism, but his voters won't forgive him any compromise on legislation. An adulterous champion of family values is like a black opponent of affirmative action: voters respond to the policies first, and once the candidate depends upon those voters, his or her personal history and identity only make it harder to deviate from the party line.

On the other hand, Bill Clinton's adultery stuck to him, in part, because conservative voters were wary of his relative social liberalism, and most of all for his fairly egalitarian and therefore "non-traditional" marriage. (The widespread vilification of Hillary in the early 90s testifies to how frightened some cultural conservatives were by a marriage where the man and woman shared power as equals.) Voters who saw Bill and Hillary Clinton as dangerous modernists who were eroding the traditional Husband-Knows-Best marriage were completely rapt when Bill Clinton betrayed that marriage. If Clinton wanted to be unfaithful to his wife, but promote the old-school vision of marriage, he wouldn't have had much trouble. Because Clinton was seen in some quarters as promoting a new modern kind of marriage, marital traditionalists viewed his adultery as part of a larger public question.

In a similar way, Clinton was dogged in his earlier career by the false rumor that he'd fathered an illegitimate African-American child (a rumor Joe Klein chose to immortalize in Primary Colors). That rumor was held against Clinton because he was perceived as progressive on civil rights. Meanwhile, arch-segregationist Strom Thurmond could actually have an illegitimate African-American child without consequences. The difference was Clinton was perceived as being on African-Americans' side in important ways, while Thurmond was for maintaining as much white power as possible. The whisper of Clinton's love child resonated with racist fears about his policies; there was no worry that Thurmond would love African-Americans in general, even if he had loved an African-American.

This, while I'm on the topic, is why it's okay for proponents of reckless military policies to avoid Vietnam service, but not okay for politicians who want to moderate our military strategy (or our military spending) to have anything less than a Bronze Star. Bill Clinton, you'll recall, was reviled as a draft dodger, but George W. Bush, who is nobody's war hero, got the full backing of the "War Now!" crowd, even when he ran against a legitimate war hero.

To end where I began, the safest vote against gay marriage or repealing DADT is the closeted gay conservative, who has to experience his (or her, but generally his) orientation as a political vulnerability which must be guarded at all costs. The more open the secret of a gay politician's orientation, the harder "family values" line that politician will hew. That may be ugly. It may be morally suspect. It's certainly very sad. But it's not illogical. Alas.