This movement’s primary political weapon is not persuasion but intimidation. Starting in the universities and spreading to politics and the private sector, progressivism uses social media platforms to assert: Fall in line with our views or we will isolate and discredit you with moralistic shaming.

It was working. Hark back to the first Democratic presidential debate, in June, when the contestants included the likes of Kamala Harris, Cory Booker, Kirsten Gillibrand and Julián Castro.

It was striking to see these Democratic politicians pay obeisance in varying degrees to wokeness—to Mr. Sanders’s Medicare for All or Alexandria Ocasio-Cortez’s Green New Deal or the idea that police racism was rampant across the U.S. The high point of Ms. Harris’s campaign was her attack on Joe Biden that night for working with segregationist Southern senators in the 1970s: “I do not believe you are a racist,” she allowed.