Isagoge: Chapter 1: Object of the writer, in the present Introduction

Porphyry lays out his intent, as follows:

Since it is necessary, Chrysaorius, both to the doctrine of Aristotle’s Categories, to know what genus, difference, species, property, and accident are, and also to the assignments of definitions, in short, since the investigation of these is useful for those things which belong to division and demonstration, I will endeavour by a summary briefly to discuss to you, as in the form of introduction, what on this subject has been delivered by the ancients, abstaining, indeed, from more profound questions, yet directing attention in a fitting manner, to such as are more simple.

So he’s going to explain to us the five predicables: genus, difference, species, property, and accident. It’s worth noting that Porphyry was a neo-Platonist, and though he’s commenting on Aristotle he does so from a Platonist point of view–and (according to the footnotes) using Plato’s own words as much as possible.

division and demonstration: According to Plato, dialectic consists of division, definition, demonstration, and analysis. Demonstration is presumably the use of the third act of the mind, rational argumentation. I’m not sure what falls under division, but as it is listed before “definition” it presumably has to do with making distinctions and coming to terms.

Anyway, he’s going to keep things simple:

For instance, I shall omit to speak about genera and species, as to whether they subsist (in the nature of things) or in mere conceptions only; whether also if subsistent, they are bodies or incorporeal, and whether they are separate from, or in, sensibles, and subsist about these, for such a treatise is most profound, and requires another more extensive investigation.

In short, Porphyry is going to eschew metaphysics.

Even though this passages tells us what the author is not going to talk about, it’s still the most famous and influential part of the whole work, being a concise statement of the Problem of Universals. Philosophy is first of all about the questions you ask, and many, many people found Porphyry’s questions to be a useful jumping-off point.

Nevertheless, how the ancients, and especially the Peripatetics, discussed these and the other proposed subjects, in a more logical manner, I will now endeavour to point out to you.

That is to say, he’s going to talk about the teachings of Aristotle and his followers.


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