How does Rothbard defend the idea of self-ownership?
By proving that we all have self-ownership. I have a right to own myself, while you do not. You cannot make me do anything because I own myself, therefore I have rights. You can argue with me, sure, but you cannot harm me. I have self-ownership.
How does he think goods in the state of nature come to be owned by individuals?
Because things that do not have a will of their own, cannot object to anything you do to them. If I were to walk up to a couch and strip it away of all cushion, it wouldn’t say,”Hey! Stop it!”, because it does not have a will or soul.