"The mere fact that an individual argues presupposes that he owns himself and has a right to his own life and property. This provides a basis for libertarian theory radically different from both natural rights theory and utilitarianism."
"Think of it this way. You don’t care about all this if people are leaving you alone. You just go about your business. But if there is a dispute over your body—say someone wants to rape you or enslave you. Then either they are willing to try to justify it, or not. If not, then they are just criminals and you have to deal with them with force or whatever. If they try to justify then they have to do so in a peaceful context. And remember: all justification is necessarily argumentative justification. That means any conceivable justification, that is, any possible norm that could conceivably be justified, has to be compatible with the norms of argumentation. And those include: peace; the presumption that there is value to cooperation; the presumption that it is desirable that people have the ability to control their own bodies (not only to argue during the argument, but to have survived in the world to the point of making the argument, which requires (unmolested) use of scarce means; etc.
The point is that you can never justify a socialist or criminal ethic. How could you do so? You would have to make an argument, in the course of a peaceful argumentation, that peace is bad. This cannot be done. It is a contradiction. So if you want to commit aggression, you either have to just do it and give up on the idea that you can justify it; or, if you try to justify it, you have to recognize that it cannot be done. By examining the structure of this from the outside, we can recognize that no socialist ethic can ever, in practice, be argumentatively justified.
And to say you do not own yourself outside of argument, is simply to say that some form of socialism is justified. How can two supposedly civilized, mutually-rights-respecting, peace-desiring people (in an argument) ever argue that it’s okay to hit people who have done nothing wrong? If you make that argument, then you have no grounds for refusing to coerce the other guy into accepting your argument—which is contrary to the nature of argumentation which presupposes that each side has the right to disagree with the other and is not being coerced."