If one fails in any one of these three areas, one excludes oneself from the philosophical conversation. The clarity of a proposition, and its relevance or logical relationship to the progress of a dialogue, depends on its constituent concepts. Consequently, philosophy is also concerned with the nature and composition of concepts. Philosophy presupposes a situation of controversy, doubt or ignorance. Philosophy can arise within any science or discipline, whenever the agreed-upon methods and standards of that discipline are insufficient to settle some question.
Philosophy is infamous for being unprogressive.
The same schools of philosophical thought, platonists, Aristotelians, empiricists, skeptics, materialists, and so on, persist from era to era, and the same philosophical questions and debates recur endlessly. This lack of evident progress is not surprising, since philosophy does not define a specific subject matter, but instead consists by definition of those questions on which progress is most difficult. If a question can be resolved by some empirical, mathematical, legal or political method, then we assign that question to the appropriate special science or discipline, such as geology, algebra, or law. It is only the questions that resist such resolution that we assign to the domain of philosophy. Nonetheless, despite the intrinsic difficulty of philosophical questions, philosophy does in fact make progress.