There is always something new, as my students understood, that you aren’t supposed to say. And worst of all, you often don’t find out about it until after you have said it. The term political correctness, which originated in the 1970s as a form of self-mockery among progressive college students, was a deliberately ironic invocation of Stalinism. By now we’ve lost the irony but kept the Stalinism—and it was a feature of Stalinism that you could be convicted for an act that was not a crime at the time you committed it. So you were always already guilty, or could be made to be guilty, and therefore were always controllable.
–William Deresiewicz, On Political Correctness