Alfred Russell Whitehead is said to have said that all philosophy is a series of footnotes to Plato and Aristotle. It is a good saying and wouldn’t be such a memorable falsehood if it did not contain a strong element of truth. It is a falsehood because, in the tradition of Western philosophy the Pre-Socratic philosophers deserve a mention. But just as obvious, there are more philosophical problems than were dreamt of by Plato and Aristotle in their philosophies (but perhaps not many more) and, equally, the repertory of arguments pro and con, the range of responses to these problems, has been enlarged well beyond the category of footnotes. But one can easily mistake the show for the substance in respect of touted philosophical advances. Another way of making Whitehead’s point would be to say that Plato and Aristotle ‘set the agenda’ and this would be more true as well as more trendy, but still a falsehood. However, there is one philosophical problem which has not advanced far beyond the elaboration of Plato’s

arguments and the development of challenges to it: the problem of political obligation.