It seems ludicrous that the ubiquitous "trigger warnings" are spreading from the internet to college syllabi, but I submit that what's ludicrous is the "trigger" part, not so much the warnings. Putting "trigger warnings" everywhere makes it seem as if many of us are on the verge of an uncontrollable meltdown. All it would take is being exposed to one blog post, or even a two line tweet. On the other hand, take the "trigger" out of "trigger warning" and you just have "warnings," which do seem appropriate in some cases. I don't have to see my students as utterly fragile and constantly "triggerable" to worry that in depth exposure to certain topics could be seriously problematic for some of them. I do issue warnings sometimes. For example, in my class on the meaning of life I issue a warning because of the amount of time we spend talking about death, suicide, and meaninglessness.
I learned a few years ago that these warnings really are important when a student of mine had herself hospitalized for suicidal impulses on the eve of my meaning of life midterm, which covered the articles on death we'd been reading for several weeks. "Death is nothing to us..." No, that's not a claim you should be immersing yourself in when you're deeply depressed and having suicidal thoughts. It was all to the good that I'd told the students at the beginning of the semester (verbally and in writing) that they should seek counseling if they found our topics disturbing, and that the course might not be appropriate for all.
But that's not to say I'm going to issue "trigger warnings," flagging every mention of rape, abortion, or whatever. Not only does this insult students' emotional intelligence, but it's impossible to know what course content to watch out for. Long, long ago I taught an ethics course with the usual frequent references to drowning children--Peter Singer's pond, James Rachels' bathtub, and a few more. After the class was all over, a student told me her baby had drowned within the last year. I am very sorry to have caused her additional pain, but I don't think we can look at every student as "in recovery" like this student really was, nor can we imagine what all students may be recovering from.