From the debates in Wisconsin and elsewhere about public sector unions, you might get the impression that we’re going bust because teachers are overpaid.

That’s a pernicious fallacy. A basic educational challenge is not that teachers are raking it in, but that they are underpaid. If we want to compete with other countries, and chip away at poverty across America, then we need to pay teachers more so as to attract better people into the profession.

Until a few decades ago, employment discrimination perversely strengthened our teaching force. Brilliant women became elementary school teachers, because better jobs weren’t open to them. It was profoundly unfair, but the discrimination did benefit America’s children.

These days, brilliant women become surgeons and investment bankers  and 47 percent of America’s kindergarten through 12th-grade teachers come from the bottom one-third of their college classes (as measured by SAT scores). The figure is from a study by McKinsey & Company, “Closing the Talent Gap.”