It is well known that desperate people can attack others in attempts to steal. Firearms give individuals a much greater ability to defend themselves and others from attacks. If many civilians have this defense, fewer people will attempt to attack. Those who do attack can be more often stopped.
Furthermore, even fully automatic firearms should be considered acceptable options for self defense. They can be used in situations were a larger firearm can be conveniently stored. Although most fully automatic weapons are too powerful to be effectively used for self defense, those that use smaller calibers such as the .25 ACP give wielders substantial firepower and low recoil, both desirable qualities.