Thomas Aquinas: Basic Philosophical Writing

From the Summa Theologiae and The Principles of Nature

Thomas Aquinas, Steven Baldner, Steven Baldner

• Publisher: Broadview Press
• Year: 2018
• ISBN:
  9781460406502
• Topic: Philosophie
• Subtopic: Philosophie des Mittelalters & der Renaissance

This volume contains new translations of the essential philosophical writings of Thomas Aquinas, from the Summa Theologiae and The Principles of Nature. The included texts represent the breadth of Aquinas's thought, addressing causality, the fundamental principles of nature, the existence of God, how God can be known, how language can be used to describe God, human nature (including the nature of the soul, free will, and epistemology), happiness, ethics, and natural law. The goal of these translations is twofold: to allow Aquinas to speak for himself, but also to make his thought accessible to the contemporary reader without the burden of unnecessary adherence to convention. A thorough introduction to Aquinas and his ideas is included, as is a series of useful appendices connecting Aquinas's arguments to those of Anselm, Scotus, Ockham, and others.

Chapter 1: The Principles of Nature

Section 1: The Three Principles

Notice the difference between what can exist, although it does not, and what exists. That which can exist we call being in potency; that which already exists we call being in actuality. There are, furthermore, two kinds of being: a thing’s essential or substantial being, for example, being a human person, which is being absolutely; the other is accidental being, for example, being pale, which is being in a qualified way.

Something is in potency to every kind of being. For example, the human sperm or ovum is in potency to being a human person; likewise, the person is in potency to being pale. Both that which is in potency to substantial being and that which is in potency to accidental being can be called matter, as the sperm and ovum are the matter of the human person, and the human person is the matter of paleness. There is, however, a difference, because the matter that is in potency to substantial being is called the matter “out of which” the thing arises, whereas the matter that is in potency to accidental being is called the matter “in which” the accident arises.

To speak accurately, what is in potency to accidental being is called the “subject,” and what is in potency to substantial being is called the “matter.” As an indication of this, we say that accidents “belong in a subject,” whereas the substantial form does “not belong in a subject.” The difference between “matter” and “subject” is that the subject does not gain its being from any accidents it happens to have, for it has complete being in itself; a human person, for example, does not have being from a pale colour. Matter, on the other hand, does have its being from something else, because all by itself its being is incomplete. Hence, we can say as a general truth that form gives being to matter, and a subject gives being to its accidents, but not the other way around. Nevertheless, we sometimes use one term in place of the other, as “matter” may be used in place of “subject,” or vice versa.

Just as whatever is in potency can be called matter, so whatever gives rise to being can be called form, whether the being in question is substantial or accidental. A human person, for example, who is potentially pale becomes actually so through the form of paleness, and the sperm and ovum, which are potentially a human person, become an actual person through the soul.¹ Since the form makes actual being, the form is thereby called actuality. Further, what makes substantial being actual is the substantial form, and what makes accidental being actual is called the accidental form.

Because generation occurs when a form is acquired, there are two kinds of generation that correspond to the two kinds of form: generation in an absolute sense corresponds to substantial form, and generation in a qualified sense corresponds to accidental form. When a substantial form is brought into being, we say that something has simply come into being. When, however, an accidental form is brought into being, we do not say that something has simply come into being, but that, while already existing, it has come to be this modified thing. For example, when someone becomes pale, we do not say, absolutely, that the person comes into being or is generated, but rather that he or she becomes pale or is changed in colour. Furthermore, two kinds of corruption correspond to the two kinds of generation, namely, corruption absolutely and corruption in a qualified sense. Absolute generation and corruption belong only in the category of substances, but generation and corruption in the qualified sense belong to all the different kinds of accidents.

Since generation is a kind of change from non-being to being, and, contrariwise, corruption is a change from being to non-being, generation does not come about from just any non-being but only from the non-being that is being-in-potency. The statue, for example, comes into being from the bronze, which is a statue in potency, not in actuality.

In order that generation take place, therefore, three things are required: being-in-potency, which is matter; non-being-in-actuality, which is privation; and that through which the new reality becomes actual, namely, form. When, for example, a statue is sculpted from a piece of bronze, the bronze which is in potency to the form of the statue is the matter; the fact that the bronze is unshaped or not sculpted is called privation; and the shape by which the bronze is recognizably a statue is the form. This is not, however, substantial form, because the bronze before the coming of form or shape is an actual being, and its being does not depend upon that shape, which is an accidental form. All artificial forms, in fact, are accidental forms, because art operates only on that which is already naturally constituted as a complete being.

Section 2: Privation and Matter

There are, therefore, three principles of nature, namely: matter, privation, and form. One of these, form, is that which generation achieves, and the other two are those from which generation comes. Hence, matter and privation are the same in subject but different in meaning. Before it receives its form, that which is bronze is the same thing as that which is unshaped, but by one meaning it is called bronze and by another it is called unshaped. Hence, privation is called, not an essential principle, but an accidental principle, because it is an accidental feature of matter. If we say, for example, “the doctor is building,” this is accidental, for a person builds not by being a doctor but by being a carpenter, but it just so happens—accidentally—that this one person is also a doctor.

There are two kinds of accident: the necessary accident, which is not separated from the thing, like the ability to laugh in a human being; and the non-necessary accident, which is separable, like having a pale complexion. Accordingly, although privation is an accidental principle, it is still necessary for generation, because matter is never found without privation. Insofar as matter exists under one form, it has the privation of some other form, and vice versa. In fire, for example, there is the privation of air, and in air there is the privation of fire.²

Although generation occurs from non-being, we say that privation, and not negation, is the principle of generation, because the term “negation” does not imply a specific subject. The term “does not see” can be said even of non-beings, as, one might say, “the chimera does not see,” or also of beings which are not naturally able to see, for example, of rocks. Privation, however, is only said of some definite subject in which the quality can naturally be found, as blindness is only said of those things which can by nature have the ability to see.

Privation is called a principle of generation, because generation does not come about from just any non-being but from the non-being that is in some pre-existing specified subject. Fire, for example, does not come into being from just anything that is not fire but only from the sort of thing which is not fire but could naturally become fire. Privation, however, is a principle that is different from the other two (matter and form), because the others are principles both of being and of becoming. For example, in order that a statue come to be, there must be bronze (the matter) and there must be the final shape of the statue (the form), and these two must also be present when the statue is completely finished. Privation, however, is a principle of becoming but not of being, because while the statue is coming to be it must not yet be a statue, for if it were a statue, it would not be becoming a statue. What comes to be exists only in successive stages. In the completed statue there is no privation of the statue, because, just as there cannot be an affirmation and a negation at the same time, so there cannot be at the same time a privation and a possession. Furthermore, privation is an accidental principle, as was explained above, whereas form and matter are essential principles.

From what has been said, therefore, it is clear that matter differs in meaning from form and from privation. Matter is that in which form and privation are recognized, as shaped and unshaped are recognized in the bronze. Sometimes matter is considered with privation and other times without privation. Bronze, for example, as the matter of the statue does not indicate privation, for when I say “bronze” I do not necessarily imply that it is unshaped or not made; on the other hand, flour, which is the matter for the making of bread, implies in itself the privation of the form of bread, because when I say “flour,” I imply what is not yet made or is disordered, in relation to the form of bread. Since, in generation, the matter as subject remains but the privation does not, and since the composite is not made of matter and privation, the matter that does not imply privation is matter that remains [as the subject], but that which does imply privation is transient.

Note that matter in one sense is composed with form, in the sense that the bronze is the matter of the statue, but the bronze itself is composed of matter and form, and for this reason it is not called prime matter, because it has matter. The matter, however, that is understood to be without any form or privation, but is the subject of all form and privation, is called prime matter, for the reason that before it there is no other matter. This is also called in Greek hylé [ὓλη]. Because every definition and all knowledge comes from form, prime matter cannot be known or defined through itself, but it can be known or defined in comparison to other things. For example, prime matter is called that which is related to all forms and privations, just as bronze is related both to the actual statue and to the unshaped statue. Prime matter in this sense is matter without qualification. Something can also be called prime matter with respect to some category, as water is the prime matter of all liquid things, but it is not prime matter absolutely, because it itself is composed of matter and form and hence has a prior matter.³

Note, furthermore, that prime matter and also form are neither generated nor corrupted, because all generation is from something to something. That, however, from which generation takes place is matter; that to which it goes is form. If, then, matter or form were generated, there would be a matter of the generated matter, and a form of the generated form, and so on, infinitely. Hence, to speak properly, generation only belongs to the composite.

We say that prime matter is numerically one in all things. There are, however, two ways in which we understand “numerically one.” Whatever has one individual form, like Socrates, is numerically one, but prime matter is not understood to be numerically one in this way, since in itself it has no form. Something is also understood to be numerically one when it is without the characteristics that would make it numerically different. In this way we say that prime matter is numerically one, because it is understood without any characteristics that would result in something numerically different.

Finally, it is important to understand that, although matter does not have in its nature any form or privation, as, for example, the meaning of bronze includes neither shaped nor unshaped, nevertheless it is never found without form and privation. Matter exists at one time under one form, and at another time under another form. Just in itself, however, matter cannot exist at all, because actual being comes only from form, and matter does not include any form in itself or in its definition. It is being only in potency, and hence nothing actual can be called prime matter.

Section 3: The Four Causes

From what has been said, therefore, it is clear that the principles of nature are three: matter, form, and privation. These, however, are not enough for generation. What is in potency cannot bring itself into actuality, as the bronze which is potentially a statue cannot make itself into a statue, but it requires an agent that can draw the form of the statue from potency into actuality. As well, the form cannot draw itself from potency into actuality. I am speaking here about the form of a completed thing, which is the goal of any process of generation. Form, in fact, belongs only to the completed being, but the agent operates on the becoming, that is, it operates while the thing is coming to be. Beyond form and matter, therefore, there must be something that acts, and this is called the efficient cause, moving cause, agent, or that from which the beginning of motion comes.

Since, as Aristotle says in Book 2 of the Metaphysics,⁴ whatever acts does so by intending something, there must be a fourth thing, namely, that which is intended by the agent, and this is called the goal. Every agent, whether natural or voluntary, intends a goal, but this does not mean that every agent knows the goal or deliberates about it. Voluntary agents must have a knowledge of the goal, because their actions are not determined and can be done in opposite ways. It is, thus, necessary that such beings know the goal and determine their actions accordingly. The actions of natural agents, however, are determined, and hence it is not necessary that such agents choose actions to achieve a goal. Avicenna gives the example of a kithara⁵ player who strikes the notes of the chords without deliberating, since the notes are determined for him. If it were not so, then there would be delays in the striking, which would cause discord. Since even a voluntary agent, such as a kithara player, can operate without deliberating, it is all the more obvious that a natural agent can intend a goal without deliberating. For the natural agent, “to intend” means nothing other than to have a natural inclination toward something.

From what has been said, therefore, it is clear that there are four causes, namely, the material cause, the efficient cause, the formal cause, and the final cause. Although the terms “principle” and “cause” may be used synonymously, as is said in Book 5 of the Metaphysics,⁶ nevertheless in the Physics Aristotle distinguishes the four causes from the three principles.⁷ By “causes” he understands both the intrinsic and the extrinsic: matter and form are intrinsic to the thing because they are constituent parts of the thing; the efficient cause and the final cause are extrinsic because they are outside of the thing. By “principles,” however, he understands only the intrinsic causes. Privation, however, is not considered a cause, because it is an accidental principle, as has been said.⁸ When we speak of the four causes, we understand them to be essential causes, in relation to which the accidental causes are understood derivatively, because whatever is accidental is derivative from what is essential.⁹

Although Aristotle uses “principles” for intrinsic causes in Book 1 of the Physics, nevertheless, as he says in Book 11 of the Metaphysics, to speak most properly, “principle” is used of extrinsic causes, while “element” can be used of the intrinsic causes, which are the parts of a thing, and “cause” can be used of both. At times, one term may be used for another, for every cause can be called a principle, and every principle can be called a cause. Still, “cause” seems to add something beyond the general meaning of principle, because whatever is first can be called a principle, whether what follows depends upon it or not. For example, a knife grinder...