As a reaction to an argument, which is by definition verbal (no physical contact between the two has been reported, at least that I know of), is it in any way reasonably described as self defence to shoot someone ? Even if physical contact without any form of weapon had been involved ? Even if the opponent had had a weapon.......unless this was in the USA where carrying guns is approved of both socially and by the law ? Does anyone in authority over there ponder over what is good for society, or is that too much mental effort to be expected ?