In reply to:

If a murderer wants you dead, are you going to try to reason with him ? Or defend yourself.

This presupposes that the murderer is staring me in the face, with weapon drawn.

True, it might be a little late for this, but if you had the chance to prevent someone from becoming a murderer in the first place, wouldn't you take it? Aren't preventive measures better and less costly (both in terms of dollars and lives) than reactionary measures?