Porphyry’s Expositio per interrogationem et responsionem can help us to understand some obscure passages of chapter seven of Aristotle’s Categories, focused on the relative (πρός τι). The Porphyrian analysis of πρός τι presents indeed developments which are both useful for the understanding of the Aristotelian text and very innovative too. First, we can mention the general Porphyrian thesis according to which categories are predicates. This theory fits very well with πρός τι, which are predicates corresponding to properties that subjects only possess because of an observed reciprocal relationship. This brings us to the second novelty of Porphyry’s analysis, really important for modern developments of the notion of relation, namely the difference between σχέσις and πρός τι, which depends on it. Finally, we will mention the important Porphyry’s contribution to the understanding of a particularly obscure issue concerning the relationship between the two definitions of πρός τι that Aristotle provides. Porphyry points out the Platonic origin of the first definition, without dismissing it though: instead, he will just consider it too vast and encompassing the true πρός τι, object of the second definition.

History of Philosophy | Philosophy and Religion