Trigger warnings: Annoying, well-meaning, not a threat to free speech.

For a certain kind of centrist liberal who is hypervigilant about the re-emergence of ’90s-era “political correctness,” the phrase trigger warning can be a little triggering. Trigger warnings, Heer argues, are less a product of “radical freaks” dominating academia and social media and more the result of “a thriving vernacular therapeutic culture, where ordinary citizens borrow concepts from psychology and use them as tools of self-improvement, often, in the process, forming distinct political and social identities.” Specifically, Heer argues, it’s not knee-jerk political correctness but the widespread popular understanding of post-traumatic stress disorder that’s at the root of this new enthusiasm for content warnings and safe spaces. The diagnosis has expanded as scientific evidence on memory has backed up the idea that “for certain people the memory of a trauma always exists, lying just below the surface of consciousness, ready to be triggered.” There’s also a growing belief—which surely needs more research—that even people who don’t have PTSD diagnoses can still be “triggered” into unnecessary emotional suffering when unpleasant memories are dredged up. But while most of trigger warnings’ proponents mean well, there’s no scientific evidence to suggest that these warnings can prevent panic attacks or other manifestations of PTSD.