In the postscript to The Concept of Law, H.L. A. Hart describes the on-going debate inspired by his book, focusing on the criticisms of Ronald Dworkin. In this essay, I will discuss Dworkin’s criticisms of Hart, as well as Hart’s responses, showing that while Hart responds adequately to some criticisms, he fails to respond adequately to others. I will also reconstruct and evaluate the arguments ... [Show full abstract] given for and against the separation thesis by Dworkin and Hart. Finally, I will argue that the debate about the separation thesis – the thesis that morality and law are separable – is misguided, conflating as it does two distinct questions. These are the questions of what the positive law is, that is, the law that is posited in a specific time and place, and of what the natural law is, that is, the law that (if it exists) is universal and timeless. Once we distinguish these questions, we will see that the answer to the question of whether law is separable from morality depends on which sense of ‘law’ is relevant, and that there are two different answers corresponding to the two senses of positive law and natural law. Positive law is separable from morality while natural law is not.