In November 2016, Mark Lilla, the humanities scholar, published an essay, “The End of Identity Liberalism,” in the New York Times. “In recent years,” he wrote, “American liberalism has slipped into a kind of moral panic about racial, gender and sexual identity that has distorted liberalism’s message and prevented it from becoming a unifying force capable of governing.”

The reaction of many liberals to Lilla’s piece was disheartening. Writing in The Los Angeles Review of Books, Columbia law professor Katherine Franke compared Lilla to David Duke: Both were pledged “to the same ideological project, the [one] cloaked in a KKK hood, …