Just kudos to everyone here for a thoughtful and civilized discussion of these issues.
We have
lots of returned vets at my college. (Funny how the military does not prepare folks for well-paying jobs in civilian life.) I would say that I have had at least one in every single class I have taught in the past ten years. Usually more than one. Male, female, recently discharged short-timer, retired career military, US, foreign.
[1] Most probably should be in some kind of mental health treatment, and are not. A few are likely of the "walking time bomb" variety.
I had an older Asian vet (who had evidently seen/done way too much bad war stuff) in one of my classes.
[2]His PTSD got triggered by bad news about Afghanistan. Once he went off on our building secretary and had to be escorted out of the building. He was
scary. Is he
dangerous? Who knows?
Another much younger baby-faced latino guy had also seen/done too much war stuff in Iraq. He had the thousand mile stare. Whenever he spoke about his military service he would shift into "robot-speech mode". He was
scary. Is he
dangerous? Who knows?
Still another two returned long-time military buddies always sit together in the back row. If there are no open seats in the back row, they will stand if they have to. Because they cannot have anyone where they can't see them. They have told me this in office hours. They have also told me they have no fear and can take care of themselves in any situation. One of them shifts his eyes left to right every few minutes. It's unnerving. They are
scary. Are they
dangerous? Who knows?
Problem is, if ever one of these folks goes postal and shoots up the campus, the media will crucify all of us professors, staff, and administrators. "You clearly saw the signs and
did nothing?" But what are we supposed to do? We are not qualified as mental health professionals. We are not trained to work with former combat vets. As a public institution, we cannot discriminate against anyone just because we think
they might someday do something.
The gun advocates say more of us faculty and students should be armed on campus. We should not have to wait for uniformed security staff or city police to take down anyone who goes off. When colleges object to that 'solution' people think it must be because we are all a bunch of wussy, anti-American, 2nd Amendment hating libruls who want the students in our care to die.
Well, yeah, there is that.

What we need is more guns in nervous, random, untrained hands--more possible stray bullets, more smoke, more ricochet, more confusion and sound distortion. Sure.
With a large, spread out campus of thousands of students aged 16-60+, a day care facility with little kids, lots of foreign exchange kids, plus refugees and immigrants taking ESL classes
[3], and oh yes plenty of beautiful large trees, low bushes, and scattered varying height buildings providing lots of hiding places for the shooter, what could possibly go wrong?