In the same way, when we prevent the brigand from carrying on his trade—taking wealth by force—it is not because we believe in force as a means of livelihood, but precisely because we do not. And if, in preventing the brigand from knocking out brains, we are compelled to knock out his brains, is it because we believe in knocking out people's brains? Or would we urge that to do so is the way to carry on a trade or to govern a nation or that it could be the basis of human relationship?
In every civilized country, the basis of the relationship on which the community rests is this: no individual is allowed to settle his differences with another by force. But does this mean that if one threatens to take my purse, I am not allowed to use force to prevent it? That if he threatens to kill me, I am not to defend myself, because "the individual citizens are not allowed to settle their differences by force"? It is because of that, because the act of self-defence is an attempt to prevent the settlement of a difference by force, that the law justifies it.2