
Medieval Theories of the Categories (SEP)
This entry is intended as a brief and general introduction to the development of category theory from the beginning of the Middle Ages, in the sixth century, to the Silver Age of Scholasticism, in the sixteenth. This development is fascinating but extraordinarily complex. Scholars are just beginning to take note of the major differences in the understanding of categories and of how these differences are related to the discussion of other major philosophical topics in the Middle Ages. Much work remains to be done, even regarding the views of towering figures, so necessarily we have had to restrict our discussion to only a few major figures and topics. Still, we hope that the discussion will serve as a good starting point for anyone interested in category theory and its history.
1. Issues
Philosophers speak about categories in many different ways. There is one initial, and rather substantial, difference between philosophers who allow a very large number of categories and those who allow only a very small number. The first include among categories such different things as human, green, animal, thought, and justice; the second speak only of very general things such as substance, quality, relation, and the like, as categories. Among twentieth-century authors who allow many categories is Gilbert Ryle (b. 1900, d. 1976). Roderick Chisholm (b. 1916, d. 1999) is an example of those who have only very few. Medieval authors follow Aristotle’s narrow understanding.
The disagreement concerning categories in the history of philosophy does not end there. Even if we restrict the discussion to a small number of items of the sort that Aristotle regards as categories, many issues remain to be settled about them, and philosophers frequently disagree about how to settle them. These issues may be gathered into roughly ten groups.
The first group comprises what may be described roughly as extensional issues; they have to do with the number of categories. The extension of a term is comprised by the things of which the term can be truthfully predicated. Thus the extension of ‘cat’ consists of all the animals of which it is true to say that they are cats. Philosophers in general frequently disagree on how many categories there are. For example, Aristotle lists up to ten, but gives the impression that the ultimate number is not settled at all. Plotinus (204/5–270) and Baruch Spinoza (1632–77) reduce the number radically, but their views do not by any means establish themselves as definitive. In the Middle Ages the number of categories is always small (ten or less) but it nonetheless varies.
Read the rest here: https://plato.stanford.edu/entries/medieval-categories/






















