[cobrausn]

In response to your first argument - simple. Punish the crime where applicable and move on. In my examples, you have effectively tied a person's hands by banning the use of firearms, and now they are dead because of it. They had no chance because you wanted to feel safer. In your example, I merely enable people to act rationally and in their best interest by allowing them to own a firearm for their defense and the defense of others - this sometimes goes wrong, as people do not always act rationally. I don't feel bad about that, as they are responsible for their actions, not me, much in the same way I don't feel bad about owning a vehicle when someone drives theirs through a crowded market.

In response to your second argument, we can go on about that all day as to who is capable of evil and who is not (the answer is probably everyone). My point still stands - violent crime is on the decline, and no amount of hyping up the (relatively) few deaths that occur per year due to some 'random crazy guy with a gun' is going to change that fact. Most gun violence is drug related.

In the end, this argument comes down to a principle. Are you willing to try and disarm everyone to make a 'safer' society, even though you know that in doing so you are basically denying people the right to defend themselves, saying that their death is necessary to prevent the death of many more (maybe) and a generally safer society (arguably)? Or are you willing to give people the ability to purchase weapons from a legal (regulated) market to defend their lives, knowing that, in the end, the police can't be everywhere and can't save everyone?

Both have pros and cons, but I find the first option to be a particular form of collective restraint against the freedom of the individual that is morally unacceptable. Your mileage may vary.