"Philosophy aims at the logical clarification of thoughts. Philosophy is not a body of doctrine but an activity." (4.112)

There is no subject matter for philosophy, so there are no propositions that can be called "philosophical." As a result, any propositions that purport to be philosophical are nonsense. Rather than conceive of philosophy as a body of knowledge like any other, Wittgenstein suggests that we conceive of philosophy as an activity directed toward all other bodies of knowledge. The role of philosophy is not to state truths about the universe, but to clarify the truths stated by the other sciences. Language can often confuse meaning, and it is the business of philosophy to clarify the logical structure of language.