Well, that escalated quickly. The rise of “democratic socialism” has been one of the key developments in the Democratic Party in recent years, first with the popularity of Sen. Bernie Sanders, I-Vt., and more recently Alexandria Ocasio-Cortez’s primary win over party mainstay Rep. Joe Crowley in New York. One of the ways the movement is presented is with the claim that this is not your grandfather’s socialism -- or the socialism of the former Soviet Union, Venezuela or other failed states. It’s more “Scandinavian health care” than overthrowing the bourgeoisie. But now a democratic socialist writer is leveling with voters,...