Since several people are pointing to Switzerland as possible evidence that guns are a deterrent to shootings, I think they would find the following thread informative.
http://www.reddit.com/r/guns/comments/u5fzh/ima_request_a_citizen_of_switzerland_willing_to/
A couple key takeaways. The Swiss have a mandatory draft*. As a result, most people have a gun. They are not allowed to carry this weapon in public loaded with few exceptions. One requirement for concealed carry is "stating plausibly the need to carry firearms to protect oneself, other people, or real property from a specified danger" so exceptions are mostly for people who have to deal with criminals: police officers, security, etc. When transporting the weapon, they must have the ammunition separate from the gun and their transportation must be direct. In other words, if they are transporting their gun, they are going to or from the shooting range, gun dealer, hunting grounds, etc. Testimonials from Swiss people say that they merely store it in the closet until they are forced by law to go to the shooting range for their annual test, a chore they dread as much as we dread jury duty. They may not even have ammunition at their house** (There was a bill to ban ammunitions in 2007, but I'm having trouble finding out if it passed). They don't have the corresponding gun culture that we have, they don't carry their gun for self-defense and they rarely use it for any other purpose than for official purposes. If you want to say that arming the teacher with a gun will plausibly deter shooters, pointing Switzerland is not a good example since the teacher wouldn't even be able to legally carry it in the classroom. If you want to say arming everyone will create mutually assured destruction on an individual scale, then Switzerland is not a good example since only special people qualify to carry guns in public.
*The idea is that should the country ever go to war, they will have a population ready for it. However, since Switzerland is neutral and no one thinks they are on the verge of war, this exercise is largely seen as a chore.
**One commenter says "The keep-your-rifle-at-home thing is a relic from the cold war where a likely scenario was that you'd have to shoot your way through "the enemy" to get to your barracks. However the only time the ammo you had at home got ever used was in family dramas (the husband going berserk and shooting wife/kids/himself) so we no longer recieve any ammo to take home."
http://www.reddit.com/r/guns/comments/u5fzh/ima_request_a_citizen_of_switzerland_willing_to/
A couple key takeaways. The Swiss have a mandatory draft*. As a result, most people have a gun. They are not allowed to carry this weapon in public loaded with few exceptions. One requirement for concealed carry is "stating plausibly the need to carry firearms to protect oneself, other people, or real property from a specified danger" so exceptions are mostly for people who have to deal with criminals: police officers, security, etc. When transporting the weapon, they must have the ammunition separate from the gun and their transportation must be direct. In other words, if they are transporting their gun, they are going to or from the shooting range, gun dealer, hunting grounds, etc. Testimonials from Swiss people say that they merely store it in the closet until they are forced by law to go to the shooting range for their annual test, a chore they dread as much as we dread jury duty. They may not even have ammunition at their house** (There was a bill to ban ammunitions in 2007, but I'm having trouble finding out if it passed). They don't have the corresponding gun culture that we have, they don't carry their gun for self-defense and they rarely use it for any other purpose than for official purposes. If you want to say that arming the teacher with a gun will plausibly deter shooters, pointing Switzerland is not a good example since the teacher wouldn't even be able to legally carry it in the classroom. If you want to say arming everyone will create mutually assured destruction on an individual scale, then Switzerland is not a good example since only special people qualify to carry guns in public.
*The idea is that should the country ever go to war, they will have a population ready for it. However, since Switzerland is neutral and no one thinks they are on the verge of war, this exercise is largely seen as a chore.
**One commenter says "The keep-your-rifle-at-home thing is a relic from the cold war where a likely scenario was that you'd have to shoot your way through "the enemy" to get to your barracks. However the only time the ammo you had at home got ever used was in family dramas (the husband going berserk and shooting wife/kids/himself) so we no longer recieve any ammo to take home."