Alessandro di Afrodisia sulla differenza specifica. Un argomento “dialettico”

In his commentary on Aristotle, Metaph. B, Alexander of Aphrodisias distinguishes two aspects of specific differentiae: 1. when considered in themselves (e.g., rationality), differentiae are qualities and fall outside substance; 2. when considered as part of the species (e.g., rational insofar it is mentioned in the definition ‘rational animal’), differentiae are ranked under the divided substantial genera (e.g. animal) (Alex. Aphr. In Metaph. 205, 29-206, 1). This article elucidates this passage within the broader framework of Alexander’s doctrine of specific differentiae. Furthermore, it suggests that Alexander’s distinction between rationality and rational underlies an argument concerning differentiae in Plotinus’ treatises On the Genera of Being (VI 3 [44], 5, 23-29).