In his response to the fictitious “sensible knave” in the Enquiry Concerning the Principles of Morals, Hume argues that the practice of justice is always in our own interest. This article provides the first comprehensive interpretation of Hume's response, incorporating his discussion of virtue and happiness in his essay “The Sceptic.” It will be seen that this argument is a hedonistic one, resting on the superior pleasure and security of a life of modest wealth and intellectual cultivation. Hume's argument ultimately fails, and he knows it. He offers it nonetheless because it is generally true and socially beneficial.