Reply #2: Of course, this always presupposes that...

[Kutjara]

...it wouldn't be a teacher who flipped-out and started blasting. Never mind the scenario of a student who cold-cocks a teacher, takes his/her gun and goes on the rampage.

This view also makes the assumption that everyone with a gun is willing to engage a psychotic gunman, or take a human life. Not everyone is a Rambo-in-waiting.

The whole "if everyone had guns..." argument is a nonstarter on so many levels. It reminds me of Archie Bunker's line about the way to stop hijackings being to arm all the passengers.