Abstract

Which categories of entities qualify as ontological categories? Which combinations of categories qualify as adequate systems of ontological categories? These are the two questions the author focuses on in this article. Contrary to the usual praxis in contemporary ontological literature, he addresses both questions conjointly. First, the author presents some problems of characterizing ontological categories in purely extensional terms, i.e. as widely inclusive natural classes. Second, he introduces the transversality requirement: ontological categories should be individually and naturally domain-transversal, i.e. ontological categories must be neutral concerning different scientific disciplines like physics, biology and mathematics. As a result, ontological categories must have instances in any domain of reality. Finally, the author checks the adequacy of some systems of ontological categories according to this criterion and meets some possible objections.