1. The Existence of Substance
The existence of substantial beings, or substances, is
accepted without question both by Aristotle and St.
Thomas, and there is no indication they ever thought or
were even tempted to think otherwise. For them, then,
substance is (or comes to) an evident fact, at least in the
sense that experience reveals it almost immediately, with
little or no sifting required. Yet modem philosophy, from
Locke down, sees nothing but difficulties in the thought of
substance and soon arrived at the point where, as though
by custom decreed, its denial was a matter of course. What
are these hurdles that seem so insurmountable?
By definition, or of its very nature substance (it is said)
lies beyond the senses; this alone should render its existence
suspect. Behind this mistrust there broods of course the
epistemological doctrine that all knowledge is of appearances
and cannot overreach them. Since you can only know
(runs the contention) what falls to the senses, to hold for
the existence of substance is utterly arbitrary and unwarranted,
if not indeed contradictory.
But granted (continues the argument) that common sense points to the existence of this latent, inert subject out of which the philosopher fashions his notion of substance, this proves nothing. Common sense is here led astray by a circumstance of the logical order, that every proposition has a subject; which no one denies, but it does not follow that things in reality must have one, too. In fine, those who put forth the metalogical subject, which is substance, are guilty of unwarranted reification, converting the logical subject of the proposition into a real subject of appearances. This and more has been laid against substance. Yet for the most part, as we shall see, modern philosophy's attack against it falls wide of the mark, having addressed itself in no small measure to misconceptions. Still, the effort was not entirely wasted on followers of St. Thomas, for it obliged them to take a closer look at their doctrine of substance the better to maintain the ground on which it rests.
a) The simplest and most obvious way to substance is by examining that most common occurrence, change. Given in knowledge is a world of multiplicity with variety; not only are things many, but many-sided as well. Some aspects of these things change constantly, others appear more lasting. Water, a familiar example, goes from cold to hot, and conversely. As the temperature rises no one doubts that the water remains water. We could not even conceive of it as becoming warmer and registering a change of degree on the calorimetric scale unless it remained the same water. No matter how much it changes, if nothing remained from the original water, then what is now hot would not be the same water that was cold. Yet common sense tells us it is the same, though not the same temperature. Thus, the notion of change necessarily implies the notion of subject or substrate, a thesis set forth at great length in Aristotle's classic analysis of the principles of nature.
It is true, of course, that what is subject of change may, at another time or in another respect, be the thing that changes, in which case we must look for a further subject, anterior to the first. But the anteriorisation of the subject cannot go on indefinitely; the succession must come to an ultimate subject, one that is essentially (by nature) subject. It is precisely in this way, by tracing the course of change to its ultimate ground, that Aristotle makes his case for prime matter, which in a way is prior even to substance. For the present purpose we need not carry the analysis all the way back to prime matter. The issue here is substance, the existence of which is proclaimed by those lesser changes called accidental, for they are simply unintelligible without an abiding substrate, abiding and (unlike prime matter) already determined of nature. Every change, in short, which leaves the essential nature of a thing unchanged supposes the persistence of the nature, supposes, that is, substance. b) The demonstration of substance through the analysis of change is unquestionably valid. All the same, it does not bring directly to light what is most essential to substance; nor is it from this angle that Aristotle in the Metaphysics approaches the study of this (the first) predicamental being. Here, in the main, is what he says at the beginning of Book Z:
Being has several meanings. On the one hand it means essence and the determined individual; on the other hand it signifies that a thing has this quality or this quantity or any of the like predicaments. But though there are these many meanings of being, it is obvious that being, in the primary sense, is the essence, which indicates the substance of a thing. . . . Other things are called being only because they are quantities of being in this primary sense, or qualities of it, or affections, or some similar determination of it. .. . Thus it is clearly by this category that the other categories each exist. Consequently, being in the fundamental sense, not this or that mode of it but being without qualification, must be substance. 1
In Aristotle's view, accordingly, substance has not only the status of substrate but also the position of primary being, of principle of existence (in some respect) for the other modes of being. The passage just cited brings this out. What may be overlooked, yet is of great significance, is the controlling factor behind the thought of the passage; it is, once again, the analogical character of being, which for Aristotle is essentially an analogy of attribution. The modalities of being are many; this is fact. But the multiplicity is unintelligible, unaccountable, unless it have some common bond or unity; to have this unity it must be brought together under some first term, which in this case will be the first and essential mode of being (at least within a certain order of things). Such is substance, which in this perspective comes out more than substrate; it comes out as principle that renders unity and thereby intelligibility to the data, the multiform data, of reality.
c) In the light of what has now been established we can formulate an answer to the contention that substance is a fictitious entity or (if that is going too far) that it does not yield to perception, since this takes in only appearances, accidents. This criticism needs correction on the data of perception. What is immediately given in perception is neither appearances (phenomena) in the subjectivist sense nor substance as such; it is rather the concrete individual being embodying both substance and accidents in one indiscriminate whole. Thereafter, by analysis, we discern one from the other, the concourse of various and varying modalities from the unvarying substrate or substance. Not that substance as such meets the sense, but that which meets the sense, the concrete individual with its fluctuating modalities, has no intelligibility without recourse to substance, the substrate and primary being in one; in this the complex of accidents finds a rationale, a standing in reason as well as in reality. All which comes to this: that substance, while not an immediate perception, is an immediate inference - a necessary one, at that.
This conclusion leads on to another, also highly important. That substance exists is evident, in the sense we have just explained; but which thing in nature is an individual substance and which is not, we do not know with the same immediacy. As a matter of fact, read strictly the foregoing analysis compels the existence of but one created substance. Nevertheless, the plurality of substance is far more in conformity with the presentations of experience. Thus, it seems virtually impossible to deny substantial individuality to living things and, though here the thing is less clear, to ultimate elements of the inorganic kingdom.
Finally, we come to the objection that substance is but an unwarranted transposition of a circumstance of logic into a circumstance of reality. Against this we urge the following: when you analyze the judgment aright, you find that the modes of predication correspond with factual, not fictitious, modes of objective being. Logic corresponds with reality because the predications of logic are conditioned by objective determinations of being, and not the other way round. The predicaments, in short, and therefore substance, have existential import as well as logical signification.