As it is commonplace to point out, the institutions and officials that make up contemporary states perform actions that would, if they were performed by a private individual, strike us as deeply problematic. They use force and the threat of force to ensure compliance with their rules, and they require those in their jurisdiction to provide material support for their activities. Now, a central question in political philosophy is: When is the exercise of political power legitimate? This question asks what the basis is for taking actions such as these to be morally permissible, when it seems that in many other circumstances they would not be so. This question is of interest not only because we want to know whether these practices of states can be vindicated, but also because, supposing that they can, understanding the scope of the legitimate exercise of political power is of great importance. What scope, if any, should be given to democratic procedures? What rights, if any, must be protected by a constitution? In order to answer such fundamental questions about the shape our political institutions should take, we need to have an account of what can render the exercise of political power legitimate in general.
