Universities and other institutions are watering down requirements in order to attract more women and minorities. Identity politics has engulfed the humanities and social sciences on American campuses; now it is taking over the hard sciences. The STEM fields—science, technology, engineering, and math—are under attack for being insufficiently “diverse.” The pressure to increase the representation of females, blacks, and Hispanics comes from the federal government, university administrators, and scientific societies themselves. That pressure is changing how science is taught and how scientific qualifications are evaluated. The results will be disastrous for scientific innovation and for American competitiveness. A scientist at...