κατηγορήματα
There are five predicables:
1. Genus est unum, quod de pluribus specie differentibus in eo quod quid est praedicatur. “Curved, closed line”—the genus of the circle—is predicated of many things that are distinct in species (ellipse). Still, the predicate captures what the circle in itself is.
2. Species est unum, quod de pluribus solo numero differentibus in eo quod quid est praedicatur. The individual circle solo numero differunt.
3. Differentia specifica aut διαφορά est unum, quod de pluribus praedicatur in quale essentiale, “with respect to that which belongs to what they are,” such as the rationality of the human being.
4. Proprium est unum, quod de pluribus praedicatur in quale necessarium, a “necessary” determination that belongs to the thing, but also lies outside of the essential context of genus and species.
5. Accidens est unum, quod de pluribus praedicatur in quale contingens, insofar as that which is addressed is “haphazard” (συμβεβηκός). [Cf. Porphyrii Introductio in Aristotelis Categorias a Boethio translata. In: Commentaria In Aristotelem Graeca. Editum consilio et auctoritate Academiae Litterarum Regiae Borussicae. Voluminis IV pars I. Berlin 1887. pp. 23-51, here pp. 26-39.] [GA18:18-20]