Stanford Encyclopedia of Philosophy (2008)
A system of categories is a complete list of highest kinds or genera. Traditionally, following Aristotle, these have been thought of as highest genera of entities (in the widest sense of the term), so that a system of categories undertaken in this realist spirit would ideally provide an inventory of everything there is, thus answering the most basic of metaphysical questions: “What is there?”. Skepticism about the possibilities for discerning the different categories of ‘reality itself’ has led others to approach category systems not with the aim of cataloging the highest kinds in the world itself, but rather with the aim of elucidating the categories of our conceptual system. Thus Kant makes the shift to a conceptualist approach by drawing out the categories that are..