From “The Ethics of Liberty“:
“Smith has a property right to the ideas or opinions in his own head; he also has a property right to print anything he wants and disseminate it. He has a property right to say that Jones is a ‘thief’ even if he knows it to be false, and to print and sell that statement.
“The counter-view, and the current basis for holding libel and slander (especially of false statements) to be illegal is that every man has a ‘property right’ in his own reputation, that Smith’s falsehoods damage that reputation, and that therefore Smith’s libels are invasions of Jones’s property right in his reputation and should be illegal.
“Yet, again, on closer analysis this is a fallacious view. For everyone, as we have stated, owns his own body; he has a property right in his own head and person. But since every man owns his own mind, he cannot therefore own the minds of anyone else. And yet Jones’s ‘reputation’ is neither a physical entity nor is it something contained within or on his own person. Jones’s ‘reputation’ is purely a function of the subjective attitudes and beliefs about him contained in the minds of other people. But since these are beliefs in the minds of others, Jones can in no way legitimately own or control them. Jones can have no property right in the beliefs and minds of other people.”