The Nature of Government
The Virtue of Selfishness
The precondition of a civilized society is the barring of physical force from social relationships - thus establishing the principle that if men wish to deal with one another, they may do so only by means of reason: by discussion, persuasion and voluntary, uncoerced agreement.
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.