It’s a Schrödinger’s Cat dilemma. Instead of a cat, we have a legally armed citizen. Instead of a box, we have a Waffle House. All armed people are simultaneously law-abiding and crazy until they pull out their gun and we see which one they are. Call it Schrödinger’s Gun.
10 October 2015: A (presumably legally) armed customer shoots a burglar trying to rob a Waffle House.
27 November 2015: A (presumably legally) armed customer shoots a waitress in the head because she asked him to put out his cigarette.
Both stories happened in in America, both in gun-friendly states, nearly within a month of each other. Both shooting victims died shortly after.
The question in my mind, if I am in a Waffle House and I see a gun: “Which one of these guys is it?” So far, there is no way for the non-gun carrying citizen to tell which armed citizens are whack-o nut jobs and which are law-abiding until after the bullets are flying.