Kansas Progress Institute

The probability of gunshot death depends (among other factors) on the number of guns in the environment, and approaches zero as the number of guns approaches zero.  It is very reasonable to assume that the number of non-gunshot deaths prevented by guns is less than the number of gunshot deaths caused by guns.  In other words, drawing a gun to ward off a knife attack is a very rare event.
Consequently the safety argument for individuals to possess guns, even if true, would have to depend on the pre-existence of other guns in the environment.  In a social policy sense, it is an entirely circular argument.