Waluchow considers inclusive and exclusive legal positivism, first explaining that the idea behind the separation thesis is that there is nothing in the bare notion of law that guarantees that law has any degree of moral merit. He presents Ronald Dworkin’s challenge to the separation thesis, i.e., that since law necessarily consists not only of the so-called settled law (statutes, precedents, etc.) but also of the principles of political morality that are part of the best constructive interpretation of the settled law, the connection between what the law is and what the law ought to be is much stronger than the separation thesis allows for. He considers responses to Dworkin’s challenge: exclusive positivists insist that the separation thesis, properly understood, has it that, as a conceptual matter, legal validity cannot depend on morality, while inclusive positivists maintain that the thesis has it that legal validity can, but need not, depend on morality. Finally, Waluchow rejects Joseph Raz’s argument from authority, which supports the exclusivist interpretation, while accepting Jules Coleman’s argument from convention, which supports the inclusivist interpretation.