"Trigger Warning" -- That Phrase Apparently Doesn't Mean Anything

Jerry Coyne, writing in The New Republic, inadvertently summarizes what I consider the ur-feature of all writing on "trigger warnings" (this is apparently from last year, but TNR's Facebook feed decided I should read it now). Discussing a call from some students to provide a trigger warning for Ovid’s “Metamorphoses" due to its graphic depiction of sexual assault (a student survivor who expressed concerns about how the material was presented said she felt "dismissed" by her professor), Coyne writes the following sentence:

That professor was clearly wrong to dismiss the student, and perhaps he or she might have mentioned beforehand that there is violence and sexual assault in Ovid, but that’s as far as I’d go.

So, Coyne would go as far as giving advance notice that their might be troublesome material in the selected readings. Or, put another way, we might say he'd "warn" his students about content which might "trigger" them.

But a "trigger warning"? Heaven forfend!

Given what Coyne agrees would have been appropriate, I confess its no longer clear to me what he thinks a "trigger warning" is. But you can be sure that the ensuing 10 paragraphs will explain why -- whatever it is -- it's the beginning of academic fascism the likes of which threaten the very foundations of the American university.