The moral problem of authority is the challenge of reconciling legitimate authority (the right to rule) with the demands of freedom and rationality. In this book, it is argued that authority can have legitimacy, but when it does it generates a moral dilemma, where the obligation to obey comes at some cost to freedom and reason. Hence, not only does this book depart from the views of those who insist that authority can never have legitimacy, but also those who maintain that insofar as authority is legitimate it simply satisfies the demands of freedom or rationality. The book examines both what it is that justifies authority (in particular focusing on membership, and the goods of membership) as well as what type of reason an authoritative directive is, how it can come into conflict with other reasons, and how those conflicts are resolved. A central concern therefore is rationality, the kinds of reasons we give in politics, and how those reasons operate: an authoritative directive is a reason that operates by excluding other reasons, but it too can be defeated by conflicting reasons. In fact, when authority has legitimacy, it is the focal point of moral conflict. Therefore, although this book offers a novel defence of authority itself, it does so as part of a value pluralist account that highlights the tragic nature of our experience where we often must do some wrong no matter what we do.