Is political philosophy too ahistorical?

The accusation that contemporary political philosophy is carried out in too ahistorical a fashion depends upon it being possible for historical facts to ground normative political principles. This they cannot do. Each of the seven ways in which it might be thought possible for them to do so fails for one or more of four reasons: History yields no timeless set of universal moral values; it displays no convergence upon such a set; it reveals no univocal moral or cultural context in the present; the failure of an ethical tradition to successfully respond to criticism over a long period of time is no guarantee of its inability to do so. Because historical critiques of contemporary normative thought rely upon one or more of these things holding true, they are, as a class of arguments, to be rejected.