JAMES TARANTO: ‘Common’ Mistakes: When good people use bad logic.

Slate.com, you’re obviously trying to bait us with the headline of that Allison Benedikt post: “If You Send Your Kid to Private School, You Are a Bad Person.” Well, good job. You succeeded.

The attention-grabbing “bad person” formulation is presumably facetious, but the underlying argument–that all parents ought to enroll their children in public schools–is not. Conservatives frequently accuse elite liberals, including President Obama and his most recent Democratic predecessor, of hypocrisy for proclaiming their devotion to public education while shielding their own children from it. Benedikt’s argument is consistent with that criticism.

But that is not to say that it is logically sound. . . .

The assumption behind treating education as a public good is that in general, educating children makes them more successful adults, and successful people are more valuable to society than unsuccessful ones. If that is true, then consigning your child to a mediocre education is harmful to the common good, because it reduces his likelihood of success–which can mean everything from becoming a gainfully employed taxpayer to discovering a cure for cancer.

Benedikt’s view of what constitutes “the common good” seems to be limited to the institutions of government. It’s the flip side of the Dewey-Konczal theory that any “public” action–any action that affects anyone else–justifies government intervention. And like the Dewey-Konczal theory, the Benedikt argument leads in directions that liberals ought to find discomfiting. . . .

We have no children in public schools (that we know of), because we have no children. If we did have a child in a public school, we suspect we would indeed take a keen interest in the quality of education, and we just might be savvy and persistent enough to have an impact. By remaining single and childless, we are having exactly the same impact on the quality of public schools as we would have if we married, fathered a child, and sent him to a private school. Intelligent, successful people who choose to remain childless are therefore just as bad as parents who send their children to private schools.

No, actually we’re worse.

Education is not the only governmental function that is affected by the decision to have children or not. By depriving the future United States of taxpayers, we are hastening the insolvency of Social Security and Medicare and increasing their burden on other people’s children. At least most children who go to private schools eventually end up paying taxes.

So childless men are worse people than parents who send their children to private school. But by Benedikt’s logic, childless women are even worse people than childless men.

They told me if I voted for Mitt Romney, people would be trying to force women to breed. And they were right!