Guns deter crime in much the same way that the tradition of honor duels deterred impoliteness.
For myself, and I am sure for many others as well, the primary reason I care about Gun Ownership is the power disparity between the government and its civilians. I have traveled to India and to Asia, and I have seen the weapons that police are carrying - in the South of South Korea, police were guarding a hotel where a meeting was taking place with MP5s. There was not even the threat of a threat, and yet they deemed it fitting to arm themselves with sub-machine guns. That is South Korea - I can only imagine what countries with more draconian governments are like.
an armed society is a polite society.
the reverse is true. too.