Isagoge: Chapter 15 — Of Community and Difference of Species and Property

Species and property, compare and contrast:

In what respect species differs from genus and difference, was explained in our enunciation of the way in which genus, and also difference, differ from the rest; it now remains that we should point out how it (species) differs from property and accident.


It is common then to species and property, to be reciprocally predicated of each other, since if any thing be man, it is risible, also if it be risible, it is man, still we have frequently declared that risible must be assumed according to natural adaptation to risibility.

Right. Men are naturally able to laugh, even if this man never laughs, or has suffered an injury so that he physically is unable to laugh.

It is also common (to them) to be equally present, for species are equally present to their participants, and properties to the things of which they are properties, but species differs from property, in that species indeed may be the genus of other things, but property cannot possibly be the property of other things.

I’ll note (again) that Porphyry is taking property in the narrowest possible sense, here.

Again, species subsists prior to property, but property accedes to species, for man must exist, in order that risible may: besides, species is always present in energy with its subject, but property sometimes also in capacity, for Socrates is a man always in energy, but he does not always laugh, though he is always naturally adapted to be risible.

I’ve not run into this use of the words “energy” and “capacity”, but I suspect he means something like “act” and “potency”. Though that’s not quite right either; the species “man” is present in a baby, but the baby isn’t fully a man in act yet. Nevertheless, it’s clear enough what he means.

Once more, things of which the definitions are different, are themselves also different, but it is (the definition) of species to be under genus, and to be predicated of many things, also differing in number, in respect to what a thing is, and things of this kind, but of property it is to be present to a thing alone, and to every individual and always.

Um, what?

(Two more chapters!)

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