ABSTRACT
It has long been recognized that contemporary world politics is having to cope with an increasing variety of forms of community, however central a form the state is still thought to be. There is, of course, considerable disagreement about the implications of this; whether it presages a change in the kind of international system we have or whether it is simply a change in degree, but about the fact itself there can surely be little disagreement. Among the more important implications of this development, however, are widely held to be its effects on structures of political authority and the character and possibility of ethical and effective political action. While there are, of course, many ways of trying to assess these implications, the one I follow here is to seek to locate them in what is, as I hope to show, at least a plausible trajectory for contemporary world politics: to wit, the claim that the world is increasingly, at least in some areas, analogous to the (European) medieval one.
