Due to the length of this subject I will be posting only on numbers I-IV today
I. Actuality and Potentiality.
II. The becoming of a substance.
III. Prime Matter and Substantial Form.
IV. Role of matter and form. Their relation.
V. Evolution or succession of forms.
VI. Principle of individuation.
VIII. Essence and existence.
I. Actuality and Potentiality. Our supposition of a motionless and dead universe is after all only an artifice of our didactic method. For it is evident that the things which we have described are actors in a cosmic drama: they are borne on the stream of change, and nothing is motionless.
Molecules or atoms, mono-cellular beings or organisms, all are subject to the law of change. Substances, together with their accidents, are constantly becoming. The oak tree develops from an acorn, it becomes tall and massive, its vital activities are constantly subject to change, and the tree itself will eventually disappear. So also the lion is born, develops and grows, hunts its prey, propagates its kind, and finally dies. Again, human life, both in its embryonic and more developed forms, is a ceaseless process of adaptation. If we wish to understand the full meaning of reality, we must throw being into the melting pot of change. Thus the static point of view, or the world considered in the state of repose, must be supplemented by the dynamic point of view, or that of the world in the state of becoming. Here we come across a further scholastic notion,-namely, the celebrated theory of actuality and potentiality, which may well be said to form the keystone in the vaulting of metaphysics.
This theory results from an analysis of what change in general implies. What is change? It is a real passage from one state to another. Schoolmen reason thus: If one being passes from stat A to state B, it must posses already in state A the germ of its future determination in state B. It has the capacity or potentiality of becoming B, before it actually is B. To deny this quasi-preexistence, in fact, involves the denial of the reality of change, or evolution of things. For, what we call change would then simply be a series of instantaneous appearances and disappearances of realities, with no internal connection whatever between the members of the series, each possessing a duration infinitesimally small. The oak tree must be potentially in the acorn: if it were not there potentially, how could it ever issue from t? On the other hand, the oak is not potentially in a pebble rolled about by the sea, although the pebble might outwardly present a close resemblance to an acorn.
Act or actuality (actus) is any present degree of reality. Potency (potentia) is the aptitude or capacity of reaching that stage of reality. It is imperfection and non-being in a certain sense, but it is not mere nothing, for it is a non-being in a subject which already exists, and has within itself the germ of the future actualization.
The duality of act and potency affects reality in its inmost depths, and extends to the composition of substance and accident, matter and form.
II. The becoming of a substance. To say that a concrete substance-for instance, this oak tree, this man,-is in the process of becoming means that it is realizing or actualizing its potentialities. A child is already potentially the powerful athlete he will some day become. If the is destined to become a mathematician, then already in the cradle he possesses this aptitude or predisposition, whereas another infant is deprived of it. All increase in quantity, all new qualities, activities exercised and undergone, all the new relations in which the subject in question will be engaged with surrounding beings, all its various positions in time and space, were capable of coming into existence, before being in fact. Substance is related to its accidents like potentiality to actuality.
Viewed in the light of this theory, the doctrine of substance and accident loses its naive appearance. A growing oak tree, a living man, a chemical unit, or any one of the millions of individual beings, is an individual substance which is in a process or state of becoming, inasmuch as its quantity, qualities, activities, and relations are actualizations of the potentialities of the substance. Leibnitz was in point of fact following this Thomistic doctrine when he said: “the present is pregnant with the future.”
But while Leibnitz taught also the eternity and the immutability of substances, which he called monads, Aquinas and the Schoolmen went further into the heart of things. It is not only the quantity or quality which changes when, for example, an oak tree grows, or its wood becomes tougher, it is not merely its place which changes when it is transplanted, ot its activities which develop,-in all these cases it is the substance, the oak tree, which is so to speak the subject of these accidental changes. But the very substance of a body may be carried into the maelstrom, and nature make us constant witnesses of the spectacle of substantial transformation. The oak tree dies, and from the gradual process of its decomposition there come into actual existence chemical bodies of various kinds. Or an electric current passes through water: and behold in the place of water we find hydrogen and oxygen.
III. Prime Matter and Substantial Form. When one substance changes into another, each has an entirely different specific nature. An oak never changes into another oak, nor one particle of water into another. But out of a dying oak tree, or a decomposed particle of water, are born new chemical bodies, with quite different activities, quantities, relations, and so on. substances differ not only in degree, but in kind.
Let us look more closely into this phenomenon of basic change from one substance into another, or into several as in the case of water and the hydrogen and oxygen which succeed it. If Aquinas had been asked to interpret this phenomenon, he would have said that every substance that comes into being in this way consists ultimately of two constituent elements or substantial parts: on the one hand, there must be something common to the old state of being and the new-to water and hydrogen for instance-and on the other hand there must be a specific principle proper to each. Without a common element, found equally in the water and in the hydrogen and oxygen, the one could not be said to ‘change’ into the other, for there would be no transposition of any part of the water into the resulting elements, but rather an annihilation of the water, followed by the sudden apparition of hydrogen and oxygen. As for the specific principle, this must exist at each stage of the process as a peculiar and proper factor whereby the water as such differs from the hydrogen or oxygen as such.
This bring us to the theory of ‘primary matter’ and ‘substantial form’ which is often misunderstood. It is in reality nothing more than the application of the theory of actuality and potency to the problem of the transformation of bodies: before the change, hydrogen and oxygen were in the water potentially. The primary matter is the common, indeterminate element or substratum, capable of receiving in succession different determinations. The substantial form determines and specifies this potential element, and constitutes the particular thing in its individuality and specific kind of existence. It enables it to be itself and not something else. Each man, lion, oak tree, or chemical unit possesses its form, that is, its principle of specific and proper reality. And this principle or form of any one thing is not reducible to that which is proper to an oak tree is altogether distinct from that of man, hydrogen, and so on.
IV. Role of matter and form. Their relation. Each thing that concerns the state of indetermination of a being follows from its prime matter. This applies especially to quantitative extension; for, to possess quantitative parts, scattered in space, is to be undetermined.
On the other hand, each thing that contributes to the determination of a being-its unity, its existence, its activities-is in close dependence upon the formal principle. Thus form unifies the scattered parts, it provides the substance with actual existence and is the basic root of all specific activity.
It follows from the above that matter and form cannot be found independently of one another in beings which are purely corporeal. They compenetrate each other like roundness and a round thing. To speak of a prime matter existing without a form, says Thomas, is to contradict oneself, for such a statement joins existence-which is determination-with the notion of prime matter-which is that of indetermination.
We may now come back to the conception of individual substance from which we started (VIII,1). A corporeal being consists of two substantial parts-matter and form-neither of which is complete. Only the being resulting from the union of both is complete or individual substance, to which belongs the proper perfection of self-sufficiency and of being incommunicable to each other. -Excerpted from The Philosophical System of St Thomas Aquinas by Maurice De Wulf. Public domain text.