Soul and Essence in the Phaedo: Socrates’ Final Proof and Aristotle’s Categories

This article examines the ontological structure underlying Socrates' final proof of the soul's immortality in Plato's Phaedo (102–105), focusing on the doctrine of eponymy and its bearing on Aristotle's Categories. Three ontological levels are distinguished: separate Forms, immanent characters, and particular participants named after the opposites inhering in them. When Plato contrasts "what Simmias is" with "what Simmias has," he is not invoking species-membership grounded in a corresponding Form, but pointing to the individual soul as the guarantor of diachronic identity. The relationship between permanent "bringers" of opposites (fire, snow, the triad) and the characters they always possess is better understood through the Aristotelian notion of per se accident than through strict essential predication. Aristotle's Categories critically reworks this Platonic framework: eponymy is transformed into paronymy, governing the inherence of properties in substantial subjects, while synonymous predication is introduced to express essential species and genus membership. The result is a systematic inversion of Platonic ontology, in which sensible particulars, endowed with essences of their own, become the primary subjects to which everything else belongs.