2. Nature and Properties of Substance 2
a) Nominally, substance (from sub-stare: to be under)
means that which is under the appearances or accidents,
hence serves as their subject. But though substance gives
accidents their support, this property, as is the way of
properties, does not express what is most basic to it, its
essence. Aristotle comes closer when he writes: "Substance,
in the truest and most rigorous and primary sense of the
word, is that which is neither predicated of a subject nor is in a subject." 3 This definition, though indicative of the
essence of substance, describes it negatively, a "not-being
in a subject" - non esse in subjecto. Since substance, evidently,
is a positive perfection, it is more aptly denoted by
the expression "to be in itself" - esse in se.
Substance, then, can be conceived under various aspects,
and all of them come into play in the mind's discovery of
what it is. Our first idea of it is as support of accidents, then
as not being in another, and then as being in itself. Yet all
this still leaves us short of the true essential, the formal
constitutive, of substance. For, a predicamental division of
being (and such is substance) is not defined by its existence
but by its quidditative principle or essence. Since, then,
existence is not of the essence of a predicamental being, to
be perfectly correct we should define substance, not as that
which actually exists in itself but "that which is equipped
(aptum) to exist in itself and not in another as inhering in a
subject." In Scholastic idiom:
quod aptum est esse in se et non in alio tamquam in subjecto inhaesionis.
In addition, substance is sometimes spoken of as "selfbeing" or "being by itself" (per se ens), and "perseity" or self-beingness as its formal constitutive. This terminology is acceptable provided that the "by itself" be not taken in the causative sense. Strictly speaking, the only ens per se, being that exists by itself, is God. Substance is "by itself" only in the sense that it has everything it needs to receive existence. To receive existence, however, is to have it not in virtue of (or by) oneself but in virtue of another. We must not, then, read the full force of the word into the "perseity" of substance; the logical outcome would be pantheistic monism, an eventuality well exemplified in Spinoza.4
b) Aristotle, in an effort to pinpoint the nature of sensible substance in particular, asks whether it is identifiable with one or more of the following: the universal, the substrate, the form, and the composite of form and substrate.5 Ruling out completely the Platonist assertion that substance is the separate universal or idea, he builds to the conclusion that it is primarily form, hence the cause "in virtue of which matter is some determinate thing." Yet the substrate (or matter) is also given a measure of acceptance. His position, then, is this, that substance, though substrate, is also and most of all the formal principle, the determinate essence - a reminder, this latter, not to overdo the receptive or passive character of the material subject of accidents.6
c) In the Categories Aristotle enumerates six marks of substance, which are generally accepted in the Scholastic tradition. They are:
1) "not being in a subject"
2) "to be predicated univocally"
3) "to signify that which is individual"
4) "to have no contrary"
5) "not admitting of more or less"
6) "to be susceptive of contraries" 7
The first of these ("not being in a subject") does actually no more than repeat the negative formula for the definition of substance. The second ("to be predicated univocally") applies, of course, to second substance only, which is explained below under divisions of substance; whereas the third ("to signify that which is individual") holds true of first substance only, also explained below. The fourth ("to have no contrary") is true of both first and second substance, as is the fifth ("not admitting of more or less"). Regarding the fifth, however, note that it does not mean that one substance cannot be more truly or less truly substance than another, but that the same substance is not said to be now more now less the substance it is - a man (say) is not, at least metaphysically speaking, more man at one time than another. As for the sixth ("to be susceptive of contraries"), this is thought by Aristotle to be the most distinctive mark of all the true property - the proprium, as the Scholastics have it. No other mode of being admits of successive contraries while retaining its identity; the same color, to take an example, cannot be green, then red, but the same apple can (assuming the apple to be an individual substance). So much for the marks of substance, first gathered by Aristotle.
1) "non esse in subjecto"- [Tr.]
2) "univoce praedicari"
3) "significare hoc aliquid"
4) "non habere contrarium"
5) "non suscipere majus et minus"
6) "esse susceptivus contrariorum"