This is just a very random idea that came across my mind. I wish to have this unlearned opinion judged by a more academically rigorous community.
I was thinking the other day that, since very little philosophical consensus could be reached (It seems that all the once-philosophical problems that have been settled have been re-categorised as natural science or mathematical science), we study philosophy mainly to be able to distinguish the 'lesser of two evils', i.e. to be able to critically analyse arguments to spot their merits and deficiencies, or to be 'less wrong'.
But remember that philosophy, by definition, concerns itself with truth. Critiquing other's arguments does not sound like an ultimate goal of philosophy. At least this is unlikely what some great philosophers would have envisaged.
Therefore I hereafter propose this (very random, coming from an untrained mind) view on philosophy: that philosophy, albeit the ultimate truth is unknowable by philosophical methods, pursues truth by negating what, within the boundaries of reason, could be effectively negated. Thus it characterises truth negatively.
E.g. That mind and body are the same identical being is not sufficiently true as Descartes's arguments refuted it. Yet that mind and body are different might still be not sufficiently true.
I think this problem reduces to asking about why little philosophical consensus could be reached.