The challenge which faced all Greek intellectuals alike, can be reconstructed in the form of a dilemma. Either some way of fixing a descriptive meaning for the language of moral evaluation had to be found, or, in the absence of any such method, moral and political virtue would have to be taught as a way of living well in a world where prescription was the basis of morality. In either case the fact remained that virtue would have to be taught.

Those who, like Plato and Aristotle, opted for the first alternative were faced with the problem generated by their adherence to the old assumption: namely that the descriptive meaning of moral evaluation was discoverable only in terms of some social order, some polis, to be a good member of which was to be a good man. But the very fact that it was now problematic what one’s polis was, meant that the search for moral knowledge had to be seen as the proper object of some specialized form of enquiry into the question, that is, of what those social roles and relationships are, to understand which is to understand how the good man acts. Thus it is that if political virtue can be taught it also needs to be taught. It can be taught because everyone knows what the universal virtues of the political life are, and that they are virtues—for, as Thucydides had emphasized, even bad men justify their vices in the language of those virtues.