THE CATEGORIES
© George MacDonald Ross, 1975–1999
Chapter 5
[18] Substance, [n.2] in the most primary and basic and strictest sense, is that which neither is predicated of any subject, nor is in any subject — for example, an individual person, or an individual horse. I call ‘secondary substances’ both the species [n.3] which the substances called ‘primary’ belong to, and the genera which these species belong to — for example, an individual person belongs to the species ‘human being,’ and the genus of this species is ‘living being.’ [20] So these are called ‘secondary substances’, such as ‘the human being,’ or ‘the horse.’
It is obvious from what has been said, that both the name and the definition [n.4] of what is said of a subject are necessarily predicated of that subject. For example, ‘human’ is said of an individual human being as subject, and the name is predicated, since you will predicate the name ‘human’ of some individual human. And the definition of ‘human’ will be predicated of some individual human, since both an individual human and the species ‘human being’ are also a ‘living being’. Consequently, both the name and the definition are predicated of the subject.
Generally speaking, we cannot predicate of a subject either the name or the definition of things which are in that subject. However, in some cases, nothing prevents us from predicating their name of the subject, though it is impossible to do this with their definition. For example, whiteness in a subject can be predicated of the body of the subject (since a body is said to be white), but the definition of ‘white’ can never be predicated of a body.
Everything else either is said of a primary substance as its subject, or is in one of these subjects. This is obvious from what is given as an example in each case. For instance, ‘animal’ is predicated of ‘human’, therefore ‘animal’ is also predicated of the individual human. For if it were not predicated of any individual human, nor would it be predicated of [22] ‘human’ in general. Again, colour is in body, therefore it is in any individual body; for if it were not in any individual body, it would not be in body in general. Consequently, everything else either is said of a primary substance as its subject, or is in one of these subjects. So if there were no primary substances, it would be impossible for anything else to exist.
Of the secondary substances, species is more a substance than genus, since it is closer to primary substance. If you are explaining what a primary substance is, your explanation will be more informative and appropriate if you give its species rather than its genus. For example, if you are explaining what an individual person is, your explanation will be more informative if you say they are a human being, than if you say they are a living being. This is because the former is more specific to the individual human, and the latter is more general. And if you are explaining what an individual tree is, your explanation will be more informative if you say it is a tree, than if you say it is a plant.
Furthermore, primary substances most deserve to be called ‘substances’ because they underlie all the others, and all the others are predicated of them, or are in them. And the relation between species and genus is the same as that between primary substances and all the others. This is because genera are predicated of species; but the converse does not hold, since species are not predicated of genera. So it follows from this too, that species is more a substance than genus. . . . .
[28] It appears that every substance indicates ‘thisness’. [n.5] In the case of primary substances, it is indisputably true that they indicate ‘thisness’, since what is revealed is an individual which is numerically one. But in the case of secondary substances, the grammatical form of language makes it seem that ‘thisness’ is indicated when we say ‘human’ or ‘animal’; whereas what in fact is indicated is ‘what-it-is-like-ness’. [n.6] For ‘human being’ and ‘living being’ are predicated not of one subject, as in the case of primary substance, but of many. They do not indicate ‘what-it-is-like-ness’ unambiguously, as ‘white’ does, since ‘white’ does not indicate anything other than ‘what-it-is-like-ness’. But species [30] and genus determine the ‘what-it-is-like-ness’ of a substance, since they indicate what the substance is like. What is determined by a genus is of wider scope than what is determined by a species, since if you say ‘living being’, you cover more things than if you say ‘human being’. . . . .
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