Given my complaints about the perennial accusation that philosophy never settles anything, I figure it'd be worth offering some examples of philosophical knowledge. (Nothing is for certain, of course, but I think that the following claims are at least as well-established as most scientific results.) Feel free to add you own examples in comments.
1. Knowledge does not require certainty. But nor does justified true belief suffice.
2. Psychological egoism is false: it is possible to act from non-selfish desires, i.e. for some good other than your own welfare.
3. Rational egoism is false: we are not rationally required to always and only act in our own self-interest.
4. (E.g. Moral) Principles may take situational variables into account without thereby sacrificing their claim to objectivity.
5. The question whether God actually exists is independent of the question whether there is genuine normativity ("ought"-ness).
6. Valuing tolerance needn't lead one to moral relativism. (Quite the opposite.)
7. Red herrings may (and black ravens may not) constitute evidence that all ravens are black.
8. It's not analytic (true by definition) that cats are animals. But it is metaphysically necessary: there is no possible world containing a cat that is not an animal.
Slightly more controversial (but still extremely well-supported, IMO):
9. "Common-sense" morality, with its agent-relative ends, is self-defeating.
10. Capitalism is not intrinsically just. (Libertarianism must be defended on consequentialist grounds, if any. Those who think otherwise are confused about the nature of property and coercion.)
11. It is possible for desires (or ultimate ends) to be irrational. So there is more to rationality than just instrumental rationality.
12. One may be harmed by events that took place prior to their coming into existence.
And those are just the examples I found from a cursory glance through my archives. What else would you suggest?