Sam Harris wouldn't want to live in one:
A world without guns is one in which the most aggressive men can do more or less anything they want. It is a world in which a man with a knife can rape and murder a woman in the presence of a dozen witnesses, and none will find the courage to intervene. There have been cases of prison guards (who generally do not carry guns) helplessly standing by as one of their own was stabbed to death by a lone prisoner armed with an improvised blade. The hesitation of bystanders in these situations makes perfect sense—and "diffusion of responsibility" has little to do with it. The fantasies of many martial artists aside, to go unarmed against a person with a knife is to put oneself in very real peril, regardless of one’s training. The same can be said of attacks involving multiple assailants. A world without guns is a world in which no man, not even a member of Seal Team Six, can reasonably expect to prevail over more than one determined attacker at a time. A world without guns, therefore, is one in which the advantages of youth, size, strength, aggression, and sheer numbers are almost always decisive. Who could be nostalgic for such a world?
He follows up:
There are, of course, other ways to stop a person with a knife. You can use a chair, a baseball bat, or any weapon that gives you a range advantage. To do this successfully, however—especially against someone who is determined to kill you—you should really be someone who is trained to fight with weapons, not a randomly selected elementary school teacher. The only thing that will reliably give the average person a true advantage over a killer with a knife, is a gun.