Principles of nature

This is a commentary on the Principles of Nature by Thomas Aquinas.

Since some things can be, although they are not, and some things now are; those which can be and are not are said to be potency, but those which already exist are said to be in act. But existence is twofold: one is essential existence or the substantial existence of a thing, for example man exists, and this is existence simpliciter. The other is accidental existence, for example man is white, and this is existence secundum quid. (¶1)

Thomas uses terms differently from how I do. As I said, it is impossible that “some things can be, although they are not”, since for non-being to be would be a contradiction. But some things can appear which do not, while others already appear. Some things, moreover, cannot appear, although they are – which is to say, they are unimaginable, but conceivable.

So, according to these differences, I will define my own terms as follows:

• intelligible, imaginable, apparent: act
• intelligible, imaginable, unapparent: potency
• intelligible, unimaginable: form
• unintelligible, imaginable, apparent: privation
• unintelligible, imaginable, unapparent: disordered image
• unintelligible, unimaginable: nothingness

According to my usage, forms are neither in potency nor in act, since potency and act only divide material things. The imagination is also capable of imagining appearances which cannot be understood, and I have no better name for those than “disordered images”, although this is new.

I will omit all paragraphs from this commentary which I believe can easily be interpreted according to my usage of the terms, and with which I would agree after this were done. Those are the majority, so this will be a short commentary, compared to the treatise itself.

In this way matter differs from subject because the subject is that which does not have existence by reason of something which comes to it, rather it has complete existence of itself (per se); just as man does not have existence through whiteness. But matter has existence by reason of what comes to it because, of itself, it has incomplete existence. Hence, simply speaking, the form gives existence to matter; the accident, however, does not give existence to the subject, rather the subject gives existence to the accident; although sometimes the one is used for the other, namely matter for subject and conversely. (¶4)

Again, existence here seems to mean appearance. But complete existence here seems to mean intelligible appearance, such as actual things – substances and accidents – have. In my terminology, I avoid using such imaginative language as of “giving” or “receiving” existence, as though existence is a ball which is passed around.

Besides this caveat about completeness, all unqualified instances of existence and being in this treatise seem to refer to appearance, as before.

From this it is plain, therefore, that there are three principles of nature: matter, form and privation. But these are not sufficient for generation. What is in potency cannot reduce itself to act; for example, the bronze which is in potency to being a statue cannot cause itself to be a statue, rather it needs an agent in order that the form of the statue might pass from potency to act. Neither can the form draw itself from potency to act. I mean the form of the thing generated which we say is the term of generation, because the form exists only in that which has been made to be. However, what is made is in the state of becoming as long as the thing is coming to be. Therefore it is necessary that besides the matter and form there be some principle which acts. This is called the efficient, moving or agent cause, or that whence the principle of motion is. Also, because, as Aristotle says in the second book of the Metaphysics, everything which acts acts only by intending something, it is necessary that there be some fourth thing, namely, that which is intended by the agent; and this is called the end. (¶18)

While the former parts of the work were properly demonstrated, the principles that “what is in potency cannot reduce itself to act”, and that “neither can the form draw itself from potency to act”, are simply stated and not proved. In lieu of proof, we get the statue example; but there is no reason to take this particular case as representative of all reality.

As I said in my metaphysics, I believe that efficient causes are implied by the understanding of apparent things because “something movable must be referred to the motions of [a moving] object in order that their particular arrangement in time and space may be understood”. I still believe that this is the proper concept of efficient causes, and I must regard Thomas’s explanation of them as merely conjectural. However, I will also define the agent as the efficient cause of a motion.

I have also not changed my definition of final causes from my metaphysics, which I mention because I am not sure whether Thomas’s definition of them is substantially different. Given a motion, however, I grant that its final cause may be said to be “intended by” its agent.

Element, on the other hand, is applied properly only to the causes of which the thing is composed, which are properly the materials. Moreover, it is not said of just any material cause, but of that one of which a thing is primarily composed; for example we do not say that the members of the body are the elements of man, because the members also are composed of other things; rather, we say that earth and water are the elements, because these are not composed of other bodies, but natural bodies are primarily composed of them. (¶24)

I quote this only because I have made a point to quote all the parts I disagree with, thereby agreeing with the other parts by implication, as long as they are interpreted according to my definitions. Obviously, I do not believe that earth and water “are not composed of other bodies”.

The primary elements, at the time of writing, seem to me to be the so-called “elementary particles”, as understood within the so-called “standard model of particle physics”; but I don’t really know or care what they are.

But, because every cause, as cause, is naturally prior to that which it causes, notice that we say a thing is prior in two ways, as Aristotle says in book XVI of the History of Animals. (¶31)

This one is just strange. The History of Animals does not have a “book XVI”, and at any rate, why would it be the source for a claim about priority? The Categories defines four senses of priority; of those, he seems to have meant the first two, which best apply to a cause and its effect.

The rest of the treatise seems right, and I have nothing to say about it.