It's a given in many conservative circles that the rise of single-parent families is the biggest cause of increasing economic inequality and that liberals are to blame. The first "given" is correct. The second "given" is entirely in conservative heads — though a means to play politics without doing the heavy lifting.

More than 40 percent of births in the United States are to single women, mostly poor or working-class. Their families often suffer a poverty of time and money, for which their children pay the price. By contrast, the great majority of college-educated whites have children within the confines of marriage, conferring an extra set of privileges to their offspring.

Many conservatives want to pin this imbalance on a sexual revolution promoted by their fantasy hippie-baby-boomer-everyone-in-the-hot-tub liberals. These "elitist snobs" — author Charles Murray's favorite phrase — push free love to impressionable working-class kids, the story goes, while they themselves insist on marriage before children. Murray and company rarely furnish names. The villains are simply "liberals" or "they."

Conservative writer Jonathan V. Last recently complained in The Weekly Standard that a New York Times article on the widening class divide linked to marital status neglected to provide an underlying cause. "It's a complicated question," he admitted, but it has something to do with sexual freedom in ways that "readers of The New York Times will not like."

Last hinted at what he was talking about in an earlier piece. "The pill created the possibility of a world where sex would have no dire consequences," he wrote. And he quoted former colleague David Frum as follows: "The central dogma of the baby boomers is the belief that sex, so long as it's consensual, ought never be subject to moral scrutiny at all."

Where to start.

First off, the pharmaceutical industry invented the pill, not liberals. Secondly, if baby boomers were libertines not heeding the consequences of sex, how come they didn't have children out of wedlock? Thirdly, isn't it time to stop beating up the '60s for what's happening 50 years later? (Only 30 years separated the licentious 1920s from the puritanical '50s.)

Women giving birth out of wedlock are obviously not taking the pill. The pill prevents pregnancies rather than causes them. That makes conservative attacks on contraception rather inconsistent with their condemnations of single motherhood. Unless this is really about liberals ... er, I mean ... sex.

According to my moral compass, children should be protected from sexuality they can't responsibly handle, but what consenting adults do in their bedroom is no business of mine. If conservatives want to analyze the morality of such couplings, that's their right. While we may agree that children are best raised in two-parent families, this moralizing about sex has zero to do with the fact that most of these unmarried women are having children on purpose.

As for the politics, it bears reminding that the states reporting the lowest incidences of births out of wedlock, with the exceptions of Utah and Idaho, tend to be liberal. In Washington state, only 34 percent of births are to unmarried women. In Oregon and Massachusetts, it's 35 percent. In conservative Oklahoma, however, 42 percent of births are to single mothers, and in Georgia and Tennessee, it's 45 percent.

Nonetheless, conservative columnist David Brooks writes, "Liberals are going to have to be willing to champion norms that say marriage should come before childrearing and be morally tough about it." Is that an assignment?

Perhaps conservative intellectuals should be making their pitch to conservative America rather than outsourcing the job. The danger, of course, is that the folks they meet might not know one elite from the other.