Thomas as a Christian holds that the world and time had a beginning. Aristotle holds the opposite; indeed, he dismisses as ridiculous the claim that the whole realm of motion could have begun.
As we have seen, this is one of those "errors of Aristotle" that led so many of Thomas's contemporaries to see pagan philosophy as a threat. And they have a case.
Let P stand for the claim "The world had a temporal beginning" and --P for the claim "the world did not have a temporal beginning." This is contradictory opposition of the first water. Only one of these can be true, and means that the other is false. Thomas holds P, Aristotle holds --P. If Thomas is right, Aristotle is in error. If Aristotle is right, Thomas and all Christians, Jews, and Muslims are in error.
One of the clichés of our own day is that Aristotle denied that the world is created. Thomas, of course, held that it was, and therefore a chasm opens between the two men that can never really be bridged by Thomas's undeniable respect for Aristotle. This received opinion, like the fears of Thomas's contemporaries, fails to benefit from the distinctions Thomas himself made.
Or did he? In a famous passage, Thomas sums up the views of Plato and Aristotle in this way.
Some progressed further and used their mind to distinguish substantial form from prime matter which they held to be uncreated; they perceived transformation to come to be in bodies with respect to essential forms, of which transformation they posited some universal causes, the ellipsis according to Aristotle, the Ideas according to Plato (Summa theologiae Ia.44.2).
That makes it look as if prime matter escapes the divine causality, is uncreated, and is thus a principle rivaling God himself. But Thomas goes on.
Some advanced to consider being as such and asked after the cause of things, not only insofar as they are such and such, but insofar as they are beings. What is the cause of things insofar as they are beings is their cause not only insofar as they are of a certain kind thanks to accidental forms, nor insofar as they are of this or that kind thanks to substantial forms, but also everything else pertaining to their being in any way whatsoever.
Is Thomas excluding Aristotle from that latter group? Let's find out.
The way Aristotle poses the question relies on a distinction between being at rest and being in motion. He asks if there was a time when everything was at rest, nothing in motion, and then motion began? And he answers in the negative.
He has defined motion as the act or fulfillment of the movable insofar as it is movable. Motion thus presupposes the presence of the things that are capable of motion. The subject which is in potency is presupposed, and this means either the substance which can have a different quality or quantity or place or the ultimate subject, prime matter, which can receive another essential form. Change presupposes a subject. If we say that prior to all change that which is capable of change is at rest, then there must have been an earlier change, because rest is opposed to motion. Indeed, rest is the privation of motion.
A Christian like Thomas looking at this passage in the Physics will put it this way. Every change presupposes a subject and what comes to be comes to be from that subject. Indeed, the subject is that to which the change is attributed. If this is true, then it is impossible for something to come to be from nothing. Wasn't this what Parmenides said? How can you attribute change to nothing? But that things came to be from nothing is precisely what we believe. It looks, then, as if our belief not only contradicts Aristotle but that creation ex nihilo makes no sense.
The passages we quoted earlier are from the First Part of the Summa theologiae. Later, commenting on the Physics, Thomas said this. (It seems worthwhile to quote him at length. He is more intelligible than any paraphrase of mine could be.)
It is clear that any particular active power presupposes matter, which is produced by a more universal cause, as the artisan uses the matter nature provides. But from the fact that every particular agent presupposes a matter it does not itself produce, we should not think that the first universal agent, which is causative of all being, presupposes anything which would not have been caused by him.
Nor indeed is this Aristotle's meaning. For he proves in Metaphysics II that that which is maximally true and maximally being is the cause of the being of all other existents. Hence, to be in potency, which is the mark of prime matter, is derived from the first principle of being, which is maximal being. Nothing need be presupposed to its action which is unproduced by it.
Since every motion requires a subject, as Aristotle here proves and as is true, it follows that the universal production of being by God is neither motion nor a change, but is a simple emanation. That is why 'become' and 'make' are equivocally common to this universal production of things and other productions.
If then we understand the production of things to be from God eternally, as Aristotle and some Platonists do, far from being necessary, it is impossible, that some unproduced subject be presupposed by this universal production. So too, if according to the teaching of our faith we hold that He did not produce things from all eternity, but produced them after they were not, it is not necessary to hold there is a subject of this universal production (Physics VIII.2.974)
Aristotle's claim that every change presupposes a subject does not conflict with a belief in a creation from nothing, that is, a production which does not presuppose any preexisting subject of the change. What is clear is that universal production of things can be called a change only equivocally.
Thomas thus takes what initially seems to conflict with the faith as an occasion to distinguish creation from change in the usual sense, which presupposes a subject. All creation presupposes is an agent who can produce the total being of the effect.
This may seem tricky. What had seemed to be a rejection of the Christian belief in creation is turned into a clarification of the way creation differs from change. But isn't Aristotle saying that change is all there is, there is no such thing as creation?
That is tantamount to another question. Does Aristotle hold that there is some first principle on which all else depends? That Aristotle holds that matter and motion have always been is clear enough. What is not clear is whether that answers the question.
Thomas wrote a little polemical work called "On the Eternity of the World Against Murmurers." It casts a great deal of light on the matter before us.
If the question asked is whether anything can exist eternally apart from the divine causality, both believer and philosopher will answer no. Like the believer, the philosopher would consider it an "abominable error" to say otherwise. Everything that is is caused by that which maximally is. This is a philosophical tenet which, as we have seen, Thomas ascribes to Aristotle. That there should be two things, God and the world, both eternally existent but having no relation to one another of cause and effect, makes no sense. If that isn't crystal clear at the moment, fear not. We will be coming back to it later.
Is it thinkable that something be at one and the same time caused by God and exist from all eternity? Thomas wants to know if there is conceptual incompatibility between the two, such that whatever is caused by God is not eternal and whatever is eternal is not caused by God. If there is such incompatibility, it will of course be false to speak of an eternal created being. On the other hand, if an eternal created being is possible, then God could create it. What Thomas wishes to show is that it is not self--contradictory to say that something owes its existence to God with respect to all that it is and that there is no beginning to its duration.
If there were a self-contradiction, this would be due to one of two things being true or their both being true: (1) an efficient cause must precede its effect in duration; (2) non-being must precede being in duration. There are created causes which do not antedate their effects, as the sun does not exist and there are illuminated things. Why then maintain that the creator must precede his effects in duration? Because unlike the sun he must act freely? But he is free to create from all eternity, so freedom does not seem a constraint.
The second looks tougher. If things are said to be created ex nihilo, this seems to require that before they exist there is nothing, and that thus non-being precedes being in duration. But the nothing from which things are created is not a previous state of affairs or a subject which could be something but at the moment is nothing. What then does it mean? "That a creature should exist it has from another; left to itself it would be nothing: hence nothing is by nature prior to existence in it." This analogy occurs to Thomas: the sun might always illumine an object, but left to itself it [the object], would not be illuminated. So its being in darkness is naturally prior to its being illuminated whether or not there was ever a time when it was not illuminated.
No wonder then that neither Augustine nor the great philosophers saw any contradiction here. Thomas adds that if we examine closely the doctrine of those who held that the world has always been, we find that they nonetheless held that the world is God's effect.
Saving Aristotle?There is no reason to think that Thomas was out to save Aristotle at all costs, especially if the cost was an accurate rendition of what Aristotle wrote and meant. He saw himself as differing from Aristotle in maintaining, on the basis of revelation, that the duration of the world had begun. He rejects the view of those who maintained that an eternally created world is conceptually incoherent. Whether or not the world has always been, it has been created from nothing. Aristotle was right to say that the world of change and motion could not itself come into being as the result of a change. But that does not prevent its having come into being in a different way, that is, without presupposing a potential subject, something that could be but is not yet the world.
If it is true that the duration of the world began, we know this thanks to revelation. Aristotle held that the duration of the world had never begun. This is a coherent claim but false. But it is false on a basis unavailable to Aristotle, namely, revelation, so it is no defect of Aristotle's account that he did not think the world's duration was finite. Thomas understands Aristotle to be saying that the world has always been and has always been dependent on the first principle of being, maximal being.
His contemporaries accused Thomas of Aristotelianizing the faith; later he was accused of baptizing Aristotle. If he had done either, it would have been unconsciously. The fact is he did neither. He read Aristotle closely and expresses what he had read. The upshot is no surprise to him. Good philosophy and the faith are not at odds.
[1] Now, what has been said makes it clear that God brought things into being from no preexisting subject, as from a matter.
[2] For, if a thing is an effect produced by God, either something exists before it, or not. If not, our assertion stands, namely, that God produces some effect from nothing preexisting. If something exists before it, however, we must either go on to infinity, which is impossible in natural causes, as Aristotle proves in Metaphysics II, or we must arrive at a first being which presupposes no other. And this being can be none other than God Himself. For we proved in Book I that God is not the matter of any thing; nor, as we have shown, can there be anything other than God which is not made to be by Him. It therefore follows that in the production of His effects God requires no antecedent matter to work from.
[3] Every matter, furthermore, is limited to some particular species by the form with which it is endowed. Consequently, it is the business of an agent limited to some determinate species to produce its effect from preexisting matter by bestowing a form upon it in any manner whatsoever. But an agent of this kind is a particular agent; for causes are proportionate to their effects. So, an agent that necessarily requires preexistent matter from which to produce its effect is a particular agent. Now, it is as the universal cause of being that God is an agent, as we proved in the preceding chapter. Therefore, in His action He has no need of any preexisting matter.
[4] Again. The more universal an effect is, the higher its proper cause, for the higher the cause, to so many more things does its power extend. But to be is more universal than to be moved, since, as the philosophers also teach, there are some beings -- stones and the like -- which are immobile. So, above the kind of cause which acts only by moving and changing there must exist that cause which is the first principle of being, and this, as we have proved in the same place, is God. Thus God does not act only by moving and changing. On the other hand, every agent which cannot being things into being except from preexisting matter, acts only by moving and changing, for to make something out of matter is the result of some kind of motion or change. Therefore, to bring things into being with preexisting matter is not impossible. Hence, God brings things into being without preexisting matter.
[11] The first existent, furthermore is necessarily the cause of the things that exist; for, if they were not caused, then they would not be set in order from that first being, as we have just shown. Now, the order that obtains between act and potentiality is this: although in one and the same things which is sometimes in potentiality and sometimes in act, the potentiality is prior in time to the act, which however is prior in nature to the potentiality. Nevertheless, absolutely speaking act is necessarily prior to potentiality. This is evident from the fact that a potentiality is not actualized except by a being actually existing. But matter is only potentially existent. Therefore, God who is pure act, must be absolutely prior to matter, and consequently the cause of it. Matter, then, is not necessarily presupposed for His action.
[12] Also, prime matter in some way is, for it is potentially a being. But God is the cause of everything that is, as was shown above. Hence, God is the cause of prime matter -- in respect to which nothing preexists. The divine action, therefore, requires no preexisting matter.
[13] Holy Scripture confirms this truth, saying, "In the beginning God created heaven and earth" (Gen.I:1) For to create means nothing else than to bring something into being without any preexisting matter.
[14] This truth refutes the error of the ancient philosophers who asserted that matter has no cause whatsoever, for they perceived that in the actions of particular agents there is always an antecedent subject underlying the action; and from this observation they assumed the opinion common to all, that from nothing, comes nothing. Now, indeed, this is true of particular agents. But the ancient philosophers had not yet attained to the knowledge of the universal agent which is productive of the total being, and for His action necessarily presupposes nothing whatever.
-- Summa contra gentiles, Book Two, chapter 16
[15] Furthermore, motion or change must precede that which results therefrom; for in the being of the made lies the beginning of rest and the term of motion. Every change, then, must be a motion or a terminus of motion, which is successive. And for this reason, what is being made is not; because so long as the motion endures, something is coming to be, and is not; whereas in the very terminal point of motion, wherein rest begins, a thing no longer is coming to be; it is. In creation, however, this is impossible. For, if creation preceded its product, as does motion or change, then some subject would have to be prior to it; and this is contrary to the nature of creation. Creation, therefore, is neither a motion nor a change.
-- Summa contra gentiles, Book Two, chapter 17
I answer that it must be said that whatever in any way is is from God. For if something is found to be shared by a thing, it is necessary that it be caused in it by that to which it belongs essentially, as iron is ignited by fire. It was shown above, in speaking of the divine simplicity that God is subsistent existence (ipsum esse per se subsistens). Again, it was shown that there can only be one subsistent existence just as if whiteness were subsistent, it would have to be unique since whitenesses are multiplied by their recipients. It follows that things other than God are not their existence, but share in existence. Therefore it is necessary that all the things which are diversified because of their different ways of sharing in existence, such that they are more or less perfectly, be caused by the First Being who most perfectly exists. That is why Plato said unity must be asserted prior to any multitude. And Aristotle said in Metaphysics II that what is fully being and fully true is the cause of every being and every truth, as the hottest is the cause of all heat.
-- Summa theologiae, First Part, Question 44, article 1