20 On Genus
On Genus that Socrates be black because the same thing can be the per accidens suppositum of two contrarics, although not simultaneously, but only successively.
20: On Genus Next we should speak of the five universals. Following Porphyry we shall first discuss the notion ofa genus.
Both Aristotle and Porphyry define the notion of a genus in the following way: A genus is that which is predicated in quid of many things differing in species.!
Itshould be noted that in this definition a genus is not something outside the mind belonging to the essence of those things of which it is predicated. It is rather a certain intention of the mind predicable of many, standing not for itself, but for the thing which it signifies. Similarly, whenI utter the proposition Man is an animal' one word is predicated of another word, but the word we predicate does not stand for a word. We do not intend to use the word for itself but for the thing which it signifies; thus it is predicated ofa thing. In the same way the mental intention that is a genus does not stand for itself when predicated but for the thing it signifies. Therefore when a genus is predicated of a species, it is not asserted that the subject is the predicate, nor that the predicate belongs to the subject in real existence. It is asserted, rather, that what 1s designated by the subject is the very thing that is designated by the predicate. But the intention genus is not predicated of things outside the mind. Such things cannot be subjects for that intention. On the contrary it is predicated of the signs of such things; nevertheless, the genus does not belong to the essence of those things, for no intention of the soul can belong to the essence of any external thing.
It follows, therefore, that the genus is not a part of the species; and, further, that the genus does not designate a part of the species. On the contrary the genus designates the whole thing, and in the strict sense of 'to designate' it does not designate matter more than form or vice versa. However, using the word in a loose sense, one can say that the genus sometimes designates the matter and not the form; but this is only to say that in every object signified by such a genus the matter has the same definition as the genus, but the form does not.
But even so, not every genus (even speaking in this loose sense) signifies the "1024 31-32; Isagoge, chapter II (p. 611, Owen).