This is a great example. It is strange for me imagining that some people think it is wrong to kill a man who fires a gun into a crowd until one of the bullets he fires hits an innocent person. Having that attitude ensures that damage to innocents will be done and throws away any possible ability to prevent harm from coming needlessly, senselessly and purposelessly to innocents. Clearly risk is reason for aggression, when the risk is high and lacks any credible reason for existing. Sure a man should be able to own a grenade and carry it with him, perhaps the grenade may malfunction and explode, but that potential for risk is coupled with the credibility of having some conceivable reason for owning an explosive device. There is no reason I would accept as legitimate for a man to without provocation fire a gun into a crowd, and it is crazy to think that it is wrong to put a bullet through him until one of his bullets has gone through an innocent person. Waiting for his bullet to go through an innocent person ensures an innocent person will be wounded, I do not see a person who fires a gun into a crowd as being innocent, they are guilty of needlessly greatly increasing the risk to others rights to life and safety.