In the 19th century, institutionalized American racism—notably slavery and Jim Crow—was rooted in the idea that some human beings were inferior.

In the 20th century, a new form emerged, this one rooted in the fear that some minorities might give the Anglo-Saxon ascendancy a run for its money if judged solely on merit. Harvard President A. Lawrence Lowell infamously took this approach to Jews after their numbers jumped to nearly 22% of the student body in 1922 from roughly 7% in 1900. In one letter, he likened his university...