A: "Remember when you were little, and you learned that you could take things from other people?"
B: "Yeah."
A: "Remember how your parents told you not to?"
B: "Yeah."
A: "Well, suppose you didn't. Now, if you tried to take my wallet right now, what do you think I would do?"
B: "You'd put up a fight."
A: "Right. Now suppose there was a way to get me to give you my wallet with my complete cooperation. You'd need a hell of a threat, maybe bodily injury. Maybe the threat of massive, potentially fatal bodily damage. Now, you'd have to work out a lot to be able to swing a crowbar hard enough. What if there were an easier way? What if you used a gun to wield that threat of lethal or deadly force?"
B: "You'd give me your wallet."
A: "Exactly. Now, what would stop you from carrying that gun?"
B: "I dunno."
A: "Would a sign stop you from carrying that gun? Would a law? Would someone carrying a knife or a sword stop you from carrying that gun?"
B: "No."
A: "What would stop you from using that gun? Would it be another man with a stick? Or a sword? What about a big man with a stick, or a regular man with a sword?"
B: "Well, he'd have to get close enough."
A: "Right. What about another man with a gun? Would the sight of that gun stop you?"
B: "Maybe."
A: "What about if it's in my hand? Would that stop you?
What if it's in my hand, pointed at your head? Would that stop you?"