And it isn't that, either.

An eye-catching letter from the June issue of Scientific American, which has been giving economics its due lately:

"License to Work" [News Scan], by Rodger Doyle, suggests that the reason the number of dentists in the U.S. has not grown substantially compared with other professions is restrictive licensing practices. Doyle has the cart before the horse. The license to practice dentistry is obtained after the completion of educational requirements and is typically passed by most dentists, although it sometimes calls for more than one attempt. The restriction on numbers is at the beginning of the road, where the educational system has not changed the number of dentists it is capable of training on average since the 1970s.

Fair enough; dental licensing is not the barrier to entry that most trade licensing turns out to be.

But the author goes on:

This restriction is not caused by the licensing board but by the cutting of direct and indirect federal and state support for dental education (number of schools, class size, faculty members, student loans, and so on).

Keith J. Lemmerman
Graduate Periodontics
University of Kentucky
College of Dentistry

So there is something about dentistry--which doesn't apply to, say, auto mechanics, computer programmers, nurses, and the like--which requires the government, not the market, to provide the impetus to start or expand training programs? What is that?

Or is there something wrong with professional education?

Mr. Lemmerman thinks the trouble is with public policy, perhaps he needs a shovel. Dig deeper. If you find yourself saying "well, the government isn't driving the economy...", that you'd even find yourself thinking that the government should drive the economy in a particular sector is a symptom of much deeper structural problems.