Both of the books under review (R. Dworkin, Justice in Robes and N.E. Simmonds, Law as a Moral Idea) offer a challenge to the dominant jurisprudential tradition of legal positivism. Underlying this superficial similarity in aims is a sharp divergence in philosophical outlook. Whereas Dworkin's arguments operate within a body of background assumptions that he shares with his opponents, and which he has done much to shape, Simmonds sees his task as challenging those assumptions. This is particularly evident in the moral philosophies at the heart of each book: Dworkin (I argue) can be seen as offering a Protestant-voluntarist-atheist philosophy; whereas Simmonds resembles a Catholic-conservative-Aristotelian.