The necessary consequence of man's right to life is his right to self-defense. In a civilized society, force may be used only in retaliation and only against those who initiate its use. All the reasons which make the initiation of physical force an evil, make the retaliatory use of physical force a moral imperative. If some "pacifist" society renounced the retaliatory use of force, it would be left helplessly at the mercy of the first thug who decided to be immoral. Such a society would achieve the opposite of its intention: instead of abolishing evil, it would encourage and reward it.
The necessary consequence of ...
Quotes from the same author
If you want to know the one reason that's taking me back, I'll tell you: I cannot bring myself to abandon to destruction all the greatness of the world, all that which was mine and yours, which was made by us and is still ours by right - because I cannot believe that men refuse to see, that they can remain blind and deaf to us forever, when the truth is ours and their lives depend on accepting it.