"Laws that forbid the carrying of arms ... disarm only those who are neither inclined nor determined to commit crimes. Such laws make things worse for the assaulted and better for the assailants; they serve rather to encourage than prevent homicides, for an unarmed man may be attacked with greater confidence than an armed one."
-Thomas Jefferson, Quoting Cesare Beccari's "On Crimes and Punishment"
Read more here. Despite my issues with him, I think Lars nails it in this essay.