A vice-principal in Pearl, Mississippi, for example, ended a shooting rampage at his school by confronting the killer with his licensed handgun and holding him for police. A few years ago a janitor on Vancouver Island saved several primary school students from a cougar attack when he shot the animal with a .303 Enfield he had in the janitors shack - which, by the way, was against school rules. The media do not give these incidents as much coverage as they do bloody massacres such as the one in Colorado. The main argument in favour of allowing responsible adults to carry concealed guns is not self defence but deterrence. There is ample evidence from criminology that criminals are opportunists.
Deterrence works because criminals prefer to attack easy victims.
For example, by locking your house or your car, you ve increased the difficulty in breaking in, so that criminals are motivated to seek easier targets. This is deterrence. Surveys of armed criminals show that they are rational enough to fear running into armed victims. Because they are afraid of getting hurt, they pick other targets. Thus, if we allow responsible people to defend themselves with concealed handguns, there should be fewer violent crimes.