 Doubts about possibilities for discovering the one true category system have led many to eschew talk of category systems altogether, and others to adopt some kind of relativism about category systems that ceases to take systems of categories seriously as candidate lists of the single set of highest genera under which anything falls (or could fall). Jan Westerhoff (2005), for example, argues that there is no unique, absolute set of ontological categories. On his view categories in metaphysics turn out to be analogous to axioms in mathematical theories; in each case, there may be more than one way to systematize our knowledge from a relatively simple basis. The result is a kind of relativity about systems of categories: “which set of ontological categories we choose is primarily a matter of convenience, in the same way as specific axiomatizations of propositional logic or Newtonian mechanics are more convenient to use than others” (2005, 218). As a result, Westerhoff argues, we must reassess the importance of ontological categories in metaphysics – these should not be considered “the most fundamental parts of the world, but... the most fundamental parts of our systematization of the world” (2005, 135).