What if the "truth" is "Science is not the truth"?Science lives because it is the truth, no matter what the truth is.
Ok, now back to seriousness.
From the context of a scientific approach to knowledge, the reason philosophy still exists is because it challenges premises. Premises should be challenged at every tier of knowledge. There is no reason to believe there is a magic cutoff below which the current state of knowledge should be taken as perfect, complete, and infallible, and only knowledge above the cutoff is subject to inquiry.
I can't speak for philosophy, but I know advances are still being made in the very low levels of mathematics, including mathematical logic.
Besides, upon what can you base your judgement that the very foundations of your beliefs are correct?