Policy wonks on the left are sometimes willing to concede that particular ideas they supported for micromanaging the economy haven’t worked out as planned. But they are rarely willing to admit that there are deeper problems with central planning in general.

Consider this op-ed in the Washington Post from education scholar Diane Ravitch, which argues that the nation needs to change course on the K-12 schools. Ravitch was a supporter of the No Child Left Behind Act, but now she says “we wasted eight years with the ‘measure and punish’ strategy of NCLB.”

Central planning of the schools from Washington didn’t work under George W. Bush, but now Ravitch has a bunch of new central planning ideas. She uses the phrases “we need” and “we must” repeatedly, implying that we should impose new national rules of her choosing on all the schools.

She says: ”Everyone agrees that good education requires good teachers. To get good teachers, states should insist — and the federal government should demand — that all new teachers have a major in the subject they expect to teach…”

In the column, Ravitch laments the unexpected negative consequences of NCLB, but she seems not to realize that the new policies she advocates may also have negative consequences. Wouldn’t demands that teachers have certain degrees push up teaching costs at a time when schools are complaining that their budgets are stretched tight? Wouldn’t her mandate cause schools to substitute teachers with paper qualifications but poor teaching skills for other teachers who have better teaching skills? Is having a degree in a specific subject more important than teachers having qualities such as empathy, patience, and love of learning?

I don’t know the answer to those questions, and I’m not an education expert. But I do know that experts often disagree on the best teaching methods and that the established educational wisdom is always evolving. For that reason, one-size-fits-all decrees from Washington make absolutely no sense. So why should Ravitch impose her judgment regarding teacher qualifications on all 100,000 or so public schools in America?

Let’s let the nation’s schools in their local communities try new approaches, learn from each other, and move the ball forward as they see fit. And let’s encourage folks like Ravitch to run for her local school board if she has ideas about schooling that she wants to experiment with.