The principal purpose of philosophy?

"And all this pertains how, exactly?" Ferbin asked. His feet were sore and he was growing tired of what seemed to him like pointless speculation, not to mention something dangerously close to philosophy, a field of human endeavour he had encountered but fleetingly through various exasperated tutors, though long enough to have formed the unshakeable impression that its principal purpose was to prove that one equalled zero, black was white and educated men could speak through their bottoms.

- Iain M Banks, Matter, 2008.