Last November, conservative commentator Ross Douthat penned a provocative column titled “How the Right Became the Left and the Left Became the Right.” “One of the master keys to understanding our era,” Douthat wrote in the opening paragraph, “is seeing all the ways in which conservatives and progressives have traded attitudes and impulses.”

The populist right’s attitude toward American institutions has the flavor of the 1970s — skeptical, pessimistic, paranoid — while the mainstream, MSNBC-watching left has a strange new respect for the F.B.I. and C.I.A. The online right likes transgression for its own sake, while cultural progressivism dabbles in censorship and worries that the First Amendment goes too far. Trumpian conservatism flirts with postmodernism and channels Michel Foucault; its progressive rivals are institutionalist, moralistic, confident in official narratives and establishment credentials.

Despite some terminological imprecision — Douthat often writes of “the Left” when he really means “liberals” — the argument speaks to something real.