Although the two ways of doing philosophy complement each other, they none the less differ in the direction of argument and, in so far as they have them, their starting points. Philosophy of, as I shall term it, starts from where we are, and works back to where we can be; by contrast, philosophy sans phrase, or pure foundational philosophy, as I shall call it for the sake of clarity, although later we shall see that the word 'foundational' has misleading connotations, starts from where we should be, and hopes to reach where we actually are, or if not, to show us where we ought actually to be. Their ambitions and achievements are correspondingly different. Philosophy of is characterized by a desire to keep one's feet on the ground, not to make speculative leaps that outrun the warranted certainty of reason, and a willingness to be an under-labourer in the fields of knowledge rather than to queen it over the other sciences. The philosophers of common sense have never minded being dull, so long as they were sure of not saying anything extravagant or false. Not for them exciting speculations that time might be unreal or the Absolute not identical with itself; sufficient for them that Mr Bradley can catch trains, and that there are some tame tigers in London Zoo. The progress made by its pedestrian practitioners may have been unremarkable, but has been real, and has been appropriated, if only anonymously, into our common culture. Pure foundational philosophy, by contrast, aims high. It seeks some single, unified, synoptic vision that shall give us a key to the whole of understanding, and has always been ready to correct, and often to enjoy correcting, the errors and follies of those who have not seen the light. It has never tried to be dull, and if in other respects its ambitions have outrun its achievements, at least in this it has succeeded in its aims. But its message is more heard than heeded, and it is the fate of revisionary philosophy to be often discussed and seldom believed.
(J. R. Lucas, "Philosophy and Philosophy Of," Proceedings of the British Academy 72 [1986]: 247-67, at 248-9 [italics in original])
