Jacques Maritain Center : A First Glance at St. Thomas Aquinas / by Ralph McInerny


Thomas lived at a time when direct access to all the writings of Aristotle became possible for the first time in the West in perhaps seven hundred years or more. For those who read Latin but not Greek — Thomas Aquinas was one of them -- this was the first time, period. Boethius, who died in 524, knew Greek and set out to translate all of Plato and Aristotle into Latin, but he succeeded in putting into Latin only a few Aristotle's logical works.

However, translated first into Syriac and then into Arabic, Aristotle had a distinguished career in the Moslem world. In the twelfth century, notably in Spain where Islam and Christianity met, works of Aristotle hitherto unknown were turned into Latin. The trickle became a flow and thirteenth-century Paris saw the formation of the university, the quarrel between secular clergy and Franciscans and Dominicans, and most fraught with significance for the intellectual life of the Church, the reaction to Aristotle.

The Quest for Wisdom

The term 'philosophy' for Aristotle is an umbrella under which all knowledge huddles. Whatever can be known, particularly insofar as it leads on to wisdom, is regarded as philosophical. Philosophy is the love of or quest for wisdom. What is wisdom? Such knowledge as men can achieve of the divine Theology is the culmination of Aristotelian philosophy.

In the Aristotelian cosmos, the planets wheel round the earth, the whole being enclosed in a sphere of vast but finite extent. What lies beyond? Don't ask. Wonder at the night sky is the origin of philosophy, Aristotle says, along with marveling at eclipses and pondering the relation of the nine planets to one another and the earth.

On earth itself, there is a common stuff or matter which permits ordered change throughout the whole hierarchy of earthly things. Men and rocks have a common matter, but man is the epitome of changeable things. What sets him off is mind and thanks to mind this thing among things can come to know and thus to possess the whole order of things. Cosmos means order.

Peculiarly human doings, the kind of activities that set us off from everything else, involve mind. Sometimes mental activity aims only at its own perfection, that is, gaining the truth, but often knowledge is sought to perfect something other than the knower. Aristotle calls these, respectively, theoretical and practical knowing.

Practical knowing involves finding the means for the achievement of some end or good, and insofar as we can distinguish between that good which is the individual's, the good he shares with others in his household, and the good he shares with others in his city. Aristotle speaks of three practical sciences, ethics, economics, and politics.

Success in the practical order opens up the possibility of pursuing knowledge for its own sake. Thus celestial navigation leads to astronomy as surveying leads to geometry. Aristotle distinguishes natural philosophy from mathematics easily enough and then, with far more difficulty, argues for an ultimate science which he calls variously first philosophy, wisdom, and theology. This third theoretical science came to be called metaphysics.

Schematically, then, the division of philosophical labor looks like this:


Theoretical Mathematics

Natural philosophy



Practical Economics


For two-thirds of these sciences there is at least one Aristotelian work that answers to them. Aristotle wrote a work in fourteen books called the Metaphysics and he wrote a Politics. He wrote three ethical treatises, the Nicomachean Ethics, the Eudemian Ethics, and the so-called Magna Moralia. We have no mathematical or economic works from him. It was in natural philosophy that he was most prolific, writing a Physics, On the Heavens, On Generation and Corruption, and Meteorology. In the sciences of life, he wrote On the Soul, On the Generation of Animals, The Parts of Animals, On Sense and the Sensed Object, On Dreams, and so on.

Pagan philosophy had been known largely by hearsay for centuries, snippets culled from the Fathers, some few books of Aristotelian logic, a partial translation of Plato's Timaeus. Suddenly as it must have seemed, a vast library of erudition drops from the heavens. What to make of it was an understandably pressing matter.

The Errors of Aristotle

If the Fathers of the Church, many of whom knew pagan philosophy well, were of several minds as to its relation to Christianity, it is not surprising that thirteenth-century Christians were divided in their attitude toward this new learning. The matter was complicated for them because Islamic commentaries on Aristotle often accompanied the work itself into Latin, so that an appraisal of the interpretations of Averroes and Avicenna, to take the most notable examples, along with the text of Aristotle was part of the task facing medieval schoolmen.

It did not take long before disagreements between Aristotelian teachings and Christian beliefs began to be noticed. These "errors of Aristotle" motivated theologians like St. Bonaventure in their hostility to Aristotle. Masters in the Arts Faculty at Paris seemed oblivious to the theological difficulties and appeared to theologians to be adopting a schizophrenic view.

It is difficult to overstate how much hung in the balance in this controversy. St. Thomas the philosopher cannot be understood apart from this urgent need to figure out how a Christian should regard pagan philosophy in its formidable Aristotelian form.

Let us mention three of the "errors" theologians found in Aristotle.

The Denial of Personal Immortality -- Aristotle sought grounds for asserting that the human soul survives death in the peculiar character of thinking, an activity radically different from a physical change involving matter. Guided by Averroes, some theologians took Aristotle to mean, not that your intellect and mine have this character which enables them to survive, but that some intellect apart from our souls, a kind of angel that thinks through with us, survives, not you and me. But clearly this conflicts with the Christian belief that we are destined for an eternal life and will answer for how we have lived on earth.

The Eternity of the World -- Aristotle held that the world and time have always existed; indeed, he denied that the world as a whole could come to be. But this seems flatly to contradict the belief in creation and creation in time.

The Denial of Providence -- Aristotle describes God as thought thinking itself, adding that it would be demeaning if God's knowledge depended upon anything less than himself. This appears to mean that God does not know the world. And that conflicts with belief in divine providence.

Clearly these are central matters and we would not expect any Christian to be indifferent to them. What could he do but condemn Aristotle?

Coherent Christianity

In comparing the Modern and Classical big pictures, we mentioned the fundamental law of reality and thus of thinking, namely the Principle of Contradiction. It is impossible for a thing to be and not to be at the same time and in the same respect. The reflection of this in knowledge is that it is impossible for a proposition and its contradictory opposite to be simultaneously true. The believer accepts as true that the world was created in time, that God's eye is on the sparrow and He knows the number of hairs on our head, that the human soul is destined for an eternal life. In all consistency, the believer must reject as false what contradicts these truths. It would be irrational for him to do otherwise.

On this there should be no disagreement among Christians. Thomas Aquinas would have no quarrel with Bonaventure in rejecting as false the above errors of Aristotle. Thomas differs from Bonaventure in two particulars. First, he is never content simply to say that whatever conflicts with revealed truth is, of course, false. Second, he undertook a close and painstaking reading of the works of Aristotle which resulted in a set of commentaries on Aristotle which have no rival.

The first step, again, is this. Let P stand for "God knows things other than Himself -- indeed, He knows whatever is or can be." The Christian believes this to be true. By that very fact, he must reject --P as false. And --P is taught by Aristotle.

That might be the end of the matter, if one overlooked the fact that Aristotle did not simply assert that God is thought thinking itself. The claim occurs in reasoned discourse. If -- P is arrived at by way of discourse, reasoning, argument, that discourse, reasoning, argument must be defective if P is true, as the believer firmly holds it to be. The second step, accordingly, must be to show what is wrong with the argument.

Taking that second step carries one swiftly beyond hearsay, received opinion as to what Aristotle teaches. The second step requires a careful reading of the text of Aristotle.

This is the step Thomas took, and with surprising results. That he as a theologian would be interested in Aristotle follows from the historical situation we are indicating. But that he should have undertaken the book by book, chapter by chapter, line by line, commenting on Aristotle is remarkable because these commentaries with perhaps one exception are not the product of courses he gave. This was a moonlighting effort, and one undertaken, as our chronology makes clear, when Thomas was not short of things to do.

Translators of Aristotle, like Barker who translated the Politics, tell us how previous sweeping theories often evaporate before this sustained immersion in the text. So it was that Thomas's careful reading of Aristotle led him to a quite different view of those "errors" than was common among theologians. In 1270, four years before his death, and in 1277, three years after it, there were condemnations of certain propositions and in the case of the 219 propositions condemned in 1277, some held by Thomas were included.

In a nutshell, Thomas taught that Aristotle's description of God as thought thinking itself does not involve a denial of providence, that Averroes's interpretation of intellect is incorrect and that Aristotle is teaching personal immortality, and finally that while Aristotle did indeed teach that the world had always been he did not thereby deny that it was created. God could have created the world from all eternity.

Thomistic Philosophy

Thomas was not alone in calling Aristotle the Philosopher. Dante called Aristotle the master of those who know. As a philosopher, Thomas is fundamentally an Aristotelian and the schema given earlier is the one he often sets forth when providing a map of the philosophical terrain. Principal sources of Thomas's philosophical views are the commentaries he wrote on Aristotle.

But if Thomas is fundamentally an Arisotelian, he has an Aristotelian appetite for whatever he can lay his hands on. Thus, Thomas finds room in his philosophy for the Neoplatonism available to him, particularly the writings of Pseudo-Dionysius the Areopagite -- pseudo, because he seems to have lived around 500 A.D. and can scarcely be the Dionysius converted by St. Paul. Thomas is hospitable to notions like participation that Aristotle dismissed as mere metaphor. Thomas is often said to have made a synthesis of all available philosophical currents, and this is true, but a synthesis is not a hodgepodge. The condition for entry into the Thomistic synthesis is compatibility with its Aristotelian base.


On the Eternity of the World against Murmurers

If we suppose, in accordance with the Catholic faith and contrary to what some philosophers mistakenly thought, that the world has not existed eternally and its duration had a beginning, as Holy Scripture which cannot deceive attests, a doubt arises whether it could always have been.

In order to get to the truth of this matter we should first set down wherein we agree and wherein we disagree with our opponents.

Were it to be supposed that the world could always have been independently of God, as if something apart from Him could be eternal and unmade by Him, this would be an abominable error, not only in the eyes of faith but even among philosophers who maintain and prove that whatever in any way exist must be caused by Him who fully and most truly has existence. However, we must ask if it would be maintained that something always existed yet was caused by Go with respect to all that it is.

Were this to be judged impossible this would either be because God could not make something that always was or that it could not come to be even if God could make it. All would agree on the first point, namely, that given His infinite power God can make something always was. But it remains to be seen whether something that always was could come to be.

The claim that it could not come to be can be understood in two ways, that is, as being true for one of two reasons: either because of the absence of a passive potency or because it is conceptually incoherent.

In this first way, it could be said that before an Angel was made the Angel could not come to be because no passive potency preceded its existence, since it is not made from some underlying matter. Nonetheless, God was able to make the Angel and was able to bring it about that the Angel came to be, because he did and it is. So understood, it must be simply granted according to the faith that something caused by God could not always be, if to hold this is to maintain that a passive potency always existed, which is heretical. But it does not follow from that that God cannot bring it about that some being should always be.

In the second understanding something is said not to have happened because it involves conceptual incoherence, on the order of an affirmation and its negation not being able to be simultaneously true, though some say that God could bring that about. Other say He cannot because it is a nullity. It is, of course, clear that He couldn't effect this because if he could He couldn't. Should someone hold that God can do this, the view may not be heretical but it is in my opinion false, in the way that the claim that the past was not involves a contradiction. Thus Augustine, in the book refuting Faustus, writes, "Whoever says, 'If God is omnipotent he can make the things that were such that they were not,' does not see that he is in effect saying, 'If he is omnipotent he can make what is true, as true, be false.'" Nonetheless there have been those who with great piety said that God can make the past not to have been past and it was not judged heretical.

Is there then conceptual incoherence, an incompatibility, between something's being caused by God and yet always having been? However this comes out, it not heretical to say that something caused by God has always been. I nonetheless hold that, if there is incoherence (self-contradiction) in the claim, it is false. If there is no incoherence, not only is is not false, it could not be otherwise and to say so is erroneous. Since it pertains to God's omnipotence to exceed all understanding and power, one who said that something could come about in creatures cannot be brought about by God would derogate from God's omnipotence. (Sins are not a counterexample, since as such they are nullities.)

The whole question than comes down to this: whether or not to be created by God in its complete substance is incompatible with not having a beginning of its duration.

That they are not can be shown in this way. There would be only two reasons for their incompatibility, whether the one or the other, or the two together: either because the efficient cause must precede its effect in duration, or because non-existence must precede existence in duration, which is why it is said to be created by God from nothing (ex nihilo).

The first thing to show is that it is not necessary that the efficient cause, namely God, precede His effect in duration, should He so will.

The first, then. No cause which produces its effect immediately (subito_ need precede its effect in duration. But God produces His effect, not through motion, but immediately. Therefore, it is not necessary that He precede his effect in duration.

The first premise is inductively evident from all immediate (subitis) changes, such as illumination and the like. Nonetheless, it can be proved as follows.

In any instant in which a thing exists, the principle of its action can be posited, as is clear in all generable things since in that instant in which fire begins to be, heating begins. But in sudden operation, its beginning and end are at the same time, indeed are the same, as is the case with all indivisibles. Therefore in any instant in which an agent producing its effect subito is given, the term of its action can also be posited. But the term of its action is at the same time as the things having been made. Therefore, it is not incoherent to posit a cause producing its effect suddenly (subito_ and not preceding it in duration.

It would be incoherent to say this of causes which produce their effects through motion, since the beginning of motion precedes its end. Because we are accustomed to makings which involve motion they do not easily grasp the claim that an efficient cause does not precede its effect in duration. So it is that many unlearned men, taking into account only a few things, arrive at easy answers.

The fact that God is a voluntary cause presents no difficulty to this, because it is not necessary that the will precede its effect in duration, nor the voluntary, unless it acts through deliberation, something we would not attribute to God.

Furthermore, the cause producing the whole substance of the thing is no more restricted than the cause producing the form in the production of the form, indeed less so, because it does not produce by educing from the potency of matter, as the one producing form does. But an agent which produces form alone can so act that its effect is whenever it is, as is the case with the sun's shining. Much more then can God, who produces the complete substance of the thing, bring it about that his effect is whenever He is.

Furthermore, if there should be a cause whose effect does not precede from it in any instant in which the cause exists, this can only be because the cause lacks something: a complete cause and its effect exist simultaneously. But God lacks nothing. Therefore His effect can always be when He is, so He need not precede it in duration.

Furthermore, the will of the one willing does not diminish its power and this is especially true of God. But everyone who considers the arguments Aristotle fashioned to prove that something was always from God because a thing always produces its like have objected that this would obtain only if God did not act voluntarily. But even given that He acts through His will, it nonetheless follows that He can bring it about that a thing caused by Him should always be.

It is clear then that it is not incoherent to say that an efficient cause does not precede its effect in duration because God could not have brought about the self-contradictory.

It remains to be seen whether it is repugnant to intellect that something is said to be whether it is repugnant to intellect that something is said to be made from nothing (ex nihilo) because non-existence must precede existence in duration.

That it is not repugnant is shown by the remark of Anselm in the Monologion, Chapter 8, where he is discussing how the creature is said to be made from nothing. He writes, "The third interpretation of what is meant by saying something is made from nothing is when we understand it to be made and there is nothing from which it was made. Something similar in meaning seems involved when a man grows sad without cause and it is said that nothing saddens him. On this understanding, remembering what was said above, apart from the highest essence all the things that are from Him, are made from nothing, that is, not from something else. There is nothing absurd in that." On this exposition what is made is not ordered to nothing as if, prior to its being, nothing existed, and only afterward something is.

Furthermore, should it be supposed that the relation to nothing implied in the proposition is positive, in this sense that for the creature to be made from nothing means to be made after nothing, the preposition 'after' implying an order absolutely. But there is order and order, namely, that of duration and that of nature. If then the proper and particular does not follow from the common and universal, it would not be necessary that from the fact that the creature is said to exist after nothing, nothing should have been prior in duration and afterward there was something. It suffices that nothing is prior to being in nature. That in a thing which belongs to it of itself is prior to what it owes to another. But existence is something the creature has only from another; considered as left to itself it is nothing. So in the creature nothing is naturally prior to existence.

It doesn't follow that nothing and being are at once from the fact that there is no priority in duration, for it is not maintained that, if the creature always was, at some time it was nothing, but rather that its nature is such that it would be nothing if left to itself. For if we were to say that the air is always illumined by the sun, we must say air had been made lucid by the sun. And because whatever comes to be, comes to be from that which does not exist simultaneously with what is said to come to be, it must be said that if it was made lucid from the non-lucid, or shady, not in the sense that it ever was non-lucid or shaded but rather because it would be if the sun deserted it. This is crystal clear in the stars and planets which are always illumined by the sun.

It is clear, then, that when something is said to have been made by God and to have never not been, there is no incoherence. If there were it is marvelous it was not seen by Augustine, since this would be a quick way to disprove the eternity of the world. But he fashioned, in the eleventh and twelfth books of The City of God, many arguments to disprove the eternity of the world. Why would he have omitted this one [i.e., that it is incoherent to say the world is eternal?]

Indeed he seems to imply that there is no such incoherence, for speaking of the Platonists in the tenth book, chapter 31, he writes, "How they understood this does not seem to involve time but a principle of subordination. For, they say, just as if a foot were eternally in the dust, its imprint would always be there, yet no one would doubt it had been made by the foot, yet the one would not be prior to the other even though the one is caused by the other. So too, they say, the world and the gods created in it always were, since the one making them always exists, yet they are made." He never says this cannot be understood, but proceeds otherwise against the position.

So, too, in the eleventh book, chapter 4, he says, "One confessing that the world was made by God but wanting there to be no beginning in time of its creation, such that in a manner scarcely intelligible it was always made, say something indeed (and wish to defend God as it were from fortuitous rashness)" The reason it is scarcely intelligible was stated in our first argument.

It is cause for wonder then why the greatest philosophers seem unaware of the supposed incoherence. For Augustine says in the same eleventh book, chapter 5, referring to those mentioned in the previous text, "We now discourse with those who agree with us in saying that there are no bodies or natures of which God is not the creator," and later adds, "These philosophers surpass all others in nobility and authority."

Anyone thinking seriously of it then must conclude that those who held the world had always been but at the same time said it was caused by God, are guilty of no conceptual incoherence. Those who detect this incoherence, therefore, must alone be men and wisdom first arose with them!

Since some authorities seem to support them, however, we must show how weak that support is.

St. John Damascene, in On the Orthodox Faith, book one, chapter 8, says, "it is not in the nature of things that what is brought from non-being to being should be coeternal with Him who is without beginning and always is."

And Hugh of St. Victor, at the beginning of On the Sacraments, writes, "The power of the ineffable omnipotence cannot have something beside itself and coeternal that it uses in making."

But these and similar authorities can be understood by means of what Boethius says in the Consolation of Philosophy, Book Five, prose 6. "They are incorrect who when they hear that Plato held that this world neither had a beginning in time nor will have an and understand him to mean that this made world becomes coeternal with its maker. For it is one thing to endure through a life unending, which is what Plato says of the world, and another to be unending life whole and presently complete, which is clearly proper to the divine mind."

So it is clear that what some maintain does not follow, namely that creatures would be equal to God in duration. So understood, nothing can be coeternal with God because only God is immutable. This is clear from Augustine, City of God, book twelve, chapter 15, "Time which runs on mutably cannot be coeternal with immutable eternity. Thus if the immortality of the angels does not traverse time nor have a past which no longer is nor a future which is not yet, their movements go through successive times and change from future to past. They cannot, then, be coeternal with the creator of whom we cannot say there is any movement that no longer is or future that is not yet." So too in book eight of On Genesis Literally, chapter 23, "the nature of the trinity is wholly immutable and for this reason is eternal in such a way that nothing can be coeternal with it." And much the same can be found in the Confessions, book eleven, chapter 30.

They [Thomas's adversary, the murmurers] also adopt arguments from Aristotle, among which the most difficult has to do with the infinity of souls, because if the world has always been it would be necessary that there are now souls infinite in number. But this argument is not relevant, because God could make the world without animals and souls and make man when he did, the rest of the world being eternal, and thus an infinity of souls would not arise. Besides, it has not been shown that God could not create an actual infinite.

There are other arguments I won't consider now, either because they have been dealt with elsewhere or because they are so weak that of themselves they render the opposite position unlikely.

-- On the Eternity of the World Against Murmurers

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