Four contemporary theories of ontological categories

The aim of this paper is to present and compare four theories of ontological categories propsed in the last decades by: Hoffman and Rosenkrantz, Lowe, Thomasson, and Westerhoff. The paper takes form of a series of 32 questions concerning ontological categories, grouped under 6 labels: 1) The goal of the project of a given author, 2) The nature of categories, 3) Differences between categories, 4) System of categories, 5) How should the system of categories be obtained?, 6) Is there something beyond categories? Each question is followed by four answers that can be found in the works of the mentioned authors. At the end of the paper, there is a short discussion concerning possible ways of deciding between th four theories, and some reasons in favor of Lowe’s theory are tentatively put forward.