In attempting to diagnose Americans’ sometimes-shoddy collective memory, the writer Gore Vidal once proposed renaming the nation “the United States of Amnesia.” Yet what ails much of our public conversation today is not so much a form of forgetfulness as a species of misplaced curiosity. The history of American popular culture is positively bursting with glories — take your pick from the songs of Cole Porter, the cartoons of Tex Avery, or the novels of Dawn Powell — worth remembering or rediscovering. Yet our current cultural gatekeepers ransack the past not out of a spirit of discovery but an ethic of accusation, recrimination, and, finally, cancellation. It isn’t “amnesia” so much as it is selective unearthing: As an arbitrary list of taboos is artificially expanded, the past is combed for thoughtcrimes — and nothing else....