Guns give one power. The power in itself is neither good nor evil; what you choose to do with that power is what has moral weight.
Possessing power means that first, you are capable in theory of confronting opposing power and defeating it. Second, it means that you now have the responsibility of deciding when to use force. This means grappling with the thorniest moral problems that we face, and making clear decisions on what is right and what is wrong. Third, because you have power, you have a reciprocal responsibility to use your power for the good of others. By carrying a weapon, you are accepting an obligation to protect those around you.Abandoning that power, you deny the claim that others have on you to defend the society against evil. "Cops should carry guns; citizens should just call for help." This is the plea of those who do not want to take responsibility for themselves, and who are threatened by those of us willing to do so.
[Via the 128th Carnival of the Vanities at Belief Seeking Understanding]