Quite a lot of people in the USA, and some in other countries, seem keen on the idea of carrying a gun for self-defence.
In principle, the idea that we should all have the means to defend ourselves is a good one. Unfortunately, a gun is inherently an offensive weapon that has no defensive capability. The only way of using it for defence is to “hit back first”, which is likely to work well only against an incompetent opponent; and tends to yield cases of innocent people being shot by mistake. A truly defensive weapon, such as Isaac Asimov's force shield, would be much better if available.
There are two situations in which you might consider carrying a gun (assuming that it's legal to do so).
- Violent crime is common in your area. In this case, a gun may be useful in some cases, although it will be either useless or worse than useless in other cases (someone holding a gun becomes a high-priority target for armed opponents). You can decide whether carrying a gun improves your chances or not. However, my personal preference would be to try to move out of the violent-crime area and settle down somewhere more peaceful.
- Violent crime is uncommon in your area. In this case, a gun may be useful only in a low-probability event. If you decide to carry a gun, for consistency you should probably guard yourself against other low-probability events. For instance, you should wear a helmet in the street in case something falls on you; you should carry a lightning conductor in case of thunderstorms. You should ensure that your home has an air-raid shelter, and stock up with food and survival gear in case civilization collapses. If you live in the USA, you should move out, because the Yellowstone Supervolcano could blow at any time and devastate the country.
It's a matter of opinion whether ordinary private individuals should be allowed to own guns freely, with restrictions, or not at all. I'm accustomed to live in countries in which gun ownership is heavily restricted, and I like it that way: I think countries with such restrictions are safer places to live. However, if most people in another country want guns to be freely available, that's fine with me; I'm not obliged to visit that country.
I'm aware that many American libertarians regard gun ownership as an essential liberty. I'm not completely sure of myself on this point, but I don't think it is. Even libertarians must accept some restrictions on liberty: we shouldn't be free to go around killing people, for instance. And, if we shouldn't be free to kill people, why should we be free to buy a tool whose primary purpose is to kill people? We should be entitled to defend ourselves, but I think we should all look for non-lethal methods of doing so. Some methods already exist; given more research, better methods would be found.
If guns are legal, I suggest that any innocent person who gets shot (or his next of kin) should be entitled to heavy compensation from the gun user or owner; even if the shooting is by accident or mistake. Gun owners, like car owners, should insure themselves so that they can pay up if required.