Isagoge: Chapter 2:3 — Of the Nature of Genus and Species

I’ve been taking a lot longer to get through this than I’d hoped, for which I apologize; I’ve been struggling through a cold for the last week, and haven’t felt up to struggling through Porphyry.

Today’s paragraph is long and daunting, but I think it’s actually fairly straightforward. Remember that last time we looked at the definition of genus. Today we move on to the definition of species. First, Porphyry gives what I imagine was the common, familiar definition of species in his day:

Species indeed is predicated of every form, according to which it is said, “form is first worthy of imperial sway;”….

Every form, in other words, is a species. However, that’s not what we usually mean:

…still that is called species also, which is under the genus stated, according to which we are accustomed to call man a species of animal, animal being genus, but white a species of colour, and triangle of figure.

OK, so we’re entering familiar territory; now, what else does Porphyry have to tell us? Feel free to read the passage; I think he rather belabors the point, but it’s more straightforward than it looks.

Nevertheless, if when we assign the genus, we make mention of species, saying that which is predicated of many things differing in species, in reply to what a thing is, and call species that which is under the assigned genus, we ought to know that, since genus is the genus of something, and species the species of something, each of each, we must necessarily use both in the definitions of both. They assign, therefore, species thus: species is what is arranged under genus, and of which genus is predicated in reply to what a thing is: moreover, thus species is what is predicated of many things differing in number, in reply to what a thing is. This explanation, however, belongs to the most special, and which is species only, but no longer genus also, but the other (descriptions) will pertain to such as are not the most special. Now, what we have stated will be evident in this way: in each category there are certain things most generic, and again, others most special, and between the most generic and the most special, others which are alike called both genera and species, but the most generic is that above which there cannot be another superior genus, and the most special that below which there cannot be another inferior species. Between the most generic and the most special, there are others which are alike both genera and species, referred, nevertheless, to different things, but what is stated may become clear in one category. Substance indeed, is itself genus, under this is body, under body animated body, under which is animal, under animal rational animal, under which is man, under man Socrates, Plato, and men particularly. Still, of these, substance is the most generic, and that which alone is genus; but man is most specific, and that which alone is species; yet body is a species of substance, but a genus of animated body, also animated body is a species of body, but a genus of animal; again, animal is a species of animated body, but a genus of rational animal, and rational animal is a species of animal, but a genus of man, and man is a species of rational animal, but is no longer the genus of particular men, but is species only, and every thing prior to individuals being proximately predicated of them, will be species only, and no longer genus also. As then, substance being in the highest place, is most generic, from there being no genus prior to it, so also man being a species, after which there is no other species, nor any thing capable of division into species, but individuals, (for Socrates, Plato, Alcibiades, and this white thing, I call individual,) will be species alone, and the last species, and as we say the most specific. Yet the media will be the species of such as are before them, but the genera of things after them, so that these have two conditions, one as to things prior to them, according to which they are said to be their species, the other to things after them, according to which they are said to be their genera. The extremes on the other hand, have one condition, for the most generic has indeed a condition as to the things under it, since it is the highest genus of all, but has no longer one as to those before it, being supreme, and the first principle, and, as we have said, that above which there cannot be another higher genus. Also, the most specific has one condition, as to the things prior to it, of which it is the species, yet it has not a different one, as to things posterior to it, but is called the species of individuals, so termed as comprehending them, and again, the species of things prior to it, as comprehended by them, wherefore the most generic genus is thus defined to be that which being genus is not species, and again, above which there cannot be another higher genus; but the most specific species, that, which being species is not genus, and which being species we can no longer divide into species; moreover, which is predicated of many things differing in number, in reply to what a thing is.

What Porphyry has done is make explicit something that I had eventually figured out from Aquinas’ use of the terms: a species can itself be a genus containing species of its own. Some genera (i.e., the Categories) have no higher genus; some species (e.g., “man”) contain only individuals, rather than subspecies. And there are some in the middle. As Porphory points out, Socrates is a man, that is, a rational animal; an animal is an animated body; and a body is a material substance. To use a modern example, a genus is like a folder on your computer’s hard drive, and a species is like a subfolder. “My Computer” is like a Category, and a folder that contains only files is like a most special species, one that is not a genus in turn.

I confess that it rather amuses me to think of “man” as being “most special”.

3 Responses to “Isagoge: Chapter 2:3 — Of the Nature of Genus and Species”

  1. Good job. The same conclusion can be gleaned from classification of life.

  2. Will says:

    Actually, I don’t see what that page has to do with this passage, except that both refer to “genus” and “species”. I grant you, the use of these terms in taxonomy stems from Aristotle and Porphyry…but the kingdoms, phylums, etc., would all be genera in Aristotle’s terms, and I don’t believe that taxonomic divisions are done in the same was as Aristotelians divisions. Finally, the problem domain in Porphyry’s text is logic and metaphysics rather than taxonomy.

    So (he asked politely) what was your point again?

  3. Only that you were right: “a species can itself be a genus containing species of its own.”