...Those who do find jobs in the ivory tower can’t be too picky. In 1991, Diane Ravitch of the Teachers College at Columbia joined the Bush administration as an assistant secretary of education. She served for two years and then wrote a book on national standards for the Brookings Institution. With this project finished and her professional résumé sparkling, she assumed she would be welcomed back to her old school, where she had taught for 20 years. “I was told that my old colleagues didn’t want me back,” says Ravitch. She eventually wound up at New York University — not a horrible outcome, but also a case of a deserving scholar landing at a less prestigious school for committing a political offense. (Ravitch may not be a movement conservative, but as a school-choice supporter she falls well to the right of the education establishment.) Several universities have managed to poach talent by accepting conservatives rejected by more prestigious institutions. The law school at George Mason University, for example, has built an excellent faculty by spotting brainpower that others have overlooked...