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). It should be up to you to 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.
As a good libertarian myself, I believe it should be legal to carry a gun for your own defence, if you really think it's useful. However, in a peaceful country I wouldn't expect many people to think it useful. There may be a small minority who have some particular reason to fear attack.
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.