Background to Question 11
of the ‘De Veritate’

by John Ziegler

How the question on The Teacher in St Thomas’s ‘Quaestiones Disputate de Veritate’ came to be written, and how it was not the end of the story, is a study in itself. It is, in miniature, the story of how the philosophical thought of Aristotle might have failed ever to be understood in Christendom, and it is the story of innovation, of novelty, in the service of orthodoxy.

The Greeks were the first we know of to wonder about reality as they found it, not as to how they might make use of it, but simply to know. Their bent of mind gave us philosophy, a Greek term meaning love of wisdom.

If you wonder as they did, two things strike you: things change, and yet they are stable. I mean that they are stable from instant to instant, in spite of change. If there were no reason whatever for such stability as things have, then neither would there be any stability from instant to instant. There would be pure change, pure chaos. Change and stability are opposites, and since opposites cannot have the same reason (they’re opposites), then not only must there be a reason for the stability of things, but there must be another reason for change.

The reason for stability came to be called form, a common word used for shape, and shape is one of the stabilities. The word was used by those who developed philosophy to mean the reason for any stability: so, not only is the shape of this rock stable over time, which is one thing, but moreover while it is a rock it remains what it is, and is not simultaneously a cat or a tree or a whole botanical garden. So Greek philosophy came to speak of the form of shape, of heat, of cat. Form, then, meant any determinacy, any reality by reason of which there was stability.

Plato, the teacher of Aristotle, had a stunning insight into this fundamental notion of form. Indeed, the insight so struck him that he thought that forms were something separate from things - things changed; so, he thought, forms, those reasons opposite to change, must be separate from things. He proposed a world of forms not only distinct from but separate from the world our senses know. These are the famous Platonic Forms. For Plato, this was the genuine, the real, world; and the world our senses know merely a pale and insubstantial imitation of it.

Aristotle saw that it was unreasonable to think that.

Things are stable in themselves, and are changeable in themselves, so these reasons must be, not merely mental explanations, or realities separate from things, but realities in things. For Aristotle, the reason of stability, form, and the reason for change, which he called matter, are the very realities which actually constitute things: things are, after all, both stable and changeable.

Very well. Now, in his reflections on sense knowledge and on understanding, Aristotle saw something that philosophers of recent times, many of them, miss: that sense knowledge, including that of imagination, is of things with all their array of individual characteristics - the cat I see has one white foot, this triangle I imagine is made of wood and is painted blue; but that we have a knowledge which is of just forms, of just what is relevant - my idea of what cat consists of ignores white-footedness, the definition of triangle which I understand leaves out anything to do with wood or blueness. That is, whilst sense knows things complete in their materiality, understanding knows their forms apart from that materiality, apart from their matter. Plato was not totally wrong: there is a world of forms, but it is in intellect.

What Aristotle saw was that it must be a function of intellect to separate forms from matter, from the way they are known in sense, so that they might then inhabit the intellect. He used these terms: the intellect in its function of separating the forms he called the intellect acting, or agent intellect; and the intellect in its function of being determined (in order to understand) he called the intellect determinable, or possible intellect.

The scene changes. The Greek civilisation slowly declines. What we call Christendom is established in the west of the Asian and in the European continents. The Roman sovereignty wanes. In Syria, however, there are still Greek institutions of learning (why did the Romans never contribute significantly to philosophy?) about the first half of the seventh century AD when Islam begins.

Islam drove the nations called Arab to flower as one of the brilliant civilisations of the world. At a time when what history calls the Dark Ages had overtaken Christendom, the Arab world flowered in sciences, arts, politically and intellectually. This civilisation far outshone Christendom, in the achievements for which civilisations are praised, for hundreds of years. Medicine, mathematics (algebra is Arabic; and our arithmetic is done in Arabic numerals, not Roman) and all the arts. And philosophy. And then, suddenly, it lost its impetus and faded. Why? It would be fascinating to know.

The Arabs began to philosophise. They had, in this, the benefit of a more or less unbroken line of Greek learning in the schools of western Asia. But those schools had no notable philosophers and in a mediocre way had preserved without much discrimination what had been the corpus of Greek philosophy. The Arabs, without a philosophical tradition of their own simply took ‘Greek philosophy’, rather compounded as they found it of eclectic elements of both Plato and Aristotle, as being synonymous with philosophy. So Algazel, one of the first, adopted, as Philosophy, something inconsistent. Through him the two greatest, Avicenna and Averroes, obtained the doctrine which is at the root of our question.

Somehow, and strangely, we find in Avicenna the doctrine that the agent intellect is not, as Aristotle meant, an aspect of the intellect in each man, but that it is a Platonic Form, unique, separated from the world, one only for all men. The successor of Avicenna, Averroes, goes further. For him, the possible intellect, allowed by Avicenna to be in each man, is also unique, separated, a Platonic Form.

The scene changes again. A hundred or so years before the time of St Thomas, some in Christendom, emerging from the recession of the Dark Ages, in what we can call a backwater of civilisation, see in this brilliant Arab world a sort of mentor. It is akin to, say, the citizens of a bush town looking to the amenities, ideas, and benefits to be had in a large city.

It is not that philosophy had been lost altogether to the West in the intervening centuries. Rather, Aristotle had been lost to the West, but Plato and the opinions of those who followed him had not. Learning had not been utterly extinguished during those ages. But what there was, was Platonic. Augustine is Platonic, purged indeed of what is distinctly at odds with revelation.

Here, then, for some, was ‘Aristotle’; Aristotle, but as interpreted, or misinterpreted, by these brilliant Arab philosophers. But those who began to study this ‘Aristotle’ did not know - the Arabs did not know - that it was a distorted Aristotle. There began to be a strain, particularly an Averroist strain, of philosophy that believed itself to be Aristotelian, which emerged in the emerging universities of Europe.

But what did this ‘Aristotle’ teach? That there was but one intellect for all men? Then, what becomes of the economy of the New Testament, of the system of reward and punishment in the future life, pertaining, as they do, to individuals? (For both Plato and Aristotle saw that the soul is immortal. But it is immortal in its powers of intellect and will.) Faced with this charge, those holding this doctrine - and because they were teaching in the universities, which were religious more than secular schools, they were mostly theologians - began to take refuge in the contention that something could be true in philosophy but false in theology; the doctrine that came to be called the doctrine of the Two Truths.

As this situation came to be, the Dominican Albert, whom history calls the Great, the teacher of Thomas, saw that it was an urgent task to consult the texts of Aristotle themselves to exorcise them of the misinterpretation of the Arabs (which was originally the misinterpretation of those Greek schools). And so it is no surprise to see his pupil (some great masters are overshadowed by their own pupils) embark on a life-long project, with much more besides, to meditate and to teach a genuine Aristotle, but not only to teach him (there has been no better interpreter) but to go beyond him, to complete him, to teach a doctrine that, while it includes Aristotle, and an Aristotle occasionally purged of an error, is his own. We justly call that doctrine Thomism.

Thomas was appointed professor of theology at the University of Paris in 1256. He taught there for three years before undertaking, among other things, a large project, with Greek scholar William of Moerbeke and other Dominicans, on the translation of and commentary upon most of the works of Aristotle, in Italy. He returned, as we shall see, to Paris as professor in 1268. At that time a professor of theology considered it his business also to be a philosopher, so that, for instance, a major work on theology would also be a work on philosophy: we look to Aquinas’s encyclopaedia of theology, his Summa Theologiae, also as a major source of his philosophical doctrine. A master (professor) was expected to hold public disputations several times a year as part of his teaching programme. A disputation would be essentially public, would invite objections to the main thesis, would deliver that thesis, and answer the objections. The De Veritate is the record of the larger part of the disputations conducted by Thomas at Paris over those three years, and he certainly carried out his obligations since it is the record of some two hundred and fifty ‘articles’, most of which would have been separate disputations. Now the relevance to what we have seen is that the doctrine that produced the Two Truths had begun to be in evidence at Paris. We find clear evidence of that in the reply of Thomas in the first article of the question.

Thomas, as has been said, returned to Paris in 1268; in fact, he was recalled there from Italy by his Order because the situation at Paris with regard to the Two Truths had become intolerable. A professor in the faculty of Arts, Siger of Brabant, held that ‘Aristotelian’ doctrine that had come through Averroes, and the doctrine of the Two Truths, and there were others who held the same. It is not clear whether in response to something written by Siger, or by another, Thomas wrote, about 1270, his “On the Unity of the Intellect Against the Averroists”, in which he proves that the Agent Intellect, which must exist to extract what is understandable from things, and the Possible Intellect, which understands them, are each really powers of the intelligence of the individual human soul. The work was evidently written as an instrument not only of controversy, but also of rebuke. In it he uses the words of Aristotle, well known to him since that project in Italy, to refute the contentions of those who claimed the authority of Aristotle for their position; and he gives also proofs from reason. Having concluded his proofs, we find this: “If there be anyone boasting of his knowledge, falsely so-called, who wishes to say something against what we have written here, let him not speak in corners, nor in the presence of boys who do not know how to judge about such difficult matters, but let him write against this treatise if he dares, and he will find not only me who am the least of others, but many other lovers of truth, by whom his error will be opposed or his ignorance remedied.” In 1270 the Bishop of Paris condemned those propositions being taught that came from the interpretation of Aristotle by Averroes. But this did not stop the further spread of those ideas. In 1277 (Thomas had died in 1274) the same Bishop again condemned those propositions, plus others; and these others included some propositions of Aquinas. There is some evidence that the Bishop acted in haste. This is what the historian Gilson says about it: “The case of Thomas Aquinas is...striking. He [Aquinas] seems to have realized that, with respect to the rise of Aristotelianism and its problems, two attitudes were possible: either to adopt the language of Aristotle without conceding his fundamental principles, as Bonaventure was doing, or else to adopt both his language and his principles, but to transfigure their philosophical interpretation. This is what he himself undertook to do, or rather this is what he spontaneously did. The result was that, when the Averroists began to make trouble, he was mistaken by some for one of them. And indeed, in the sight of those who could not understand the deeper meaning of his philosophical innovations, Thomas Aquinas was bound to appear, if not as an Averroist, at least as a fellow traveller.” In 1278 the Dominicans decided to defend the doctrine of Aquinas, and it became soon the official teaching of their order. For the rest, Thomas was canonized so early as 1323. In 1324 the Parisian condemnation of his propositions was withdrawn as a dead letter.

That Question Eleven of the De Veritate is in four parts, all pertaining to the nature of teaching. The four were no doubt separate disputations. The first problem of this Question is: “Can a man or only God teach and be called teacher?” Before going on to give his reply, Aquinas writes the following preface to his answer:

There is the same sort of difference of opinion on three issues: on the bringing of forms into existence, on the acquiring of virtues, and on the acquiring of scientific knowledge:

Some have said that all sensible forms come from an external agent, a separated substance or form, which they call the giver of forms or agent intellect, and that all that lower agents do is to prepare the matter to receive the form.

Similarly, Avicenna says that our activity is not the cause of a good habit, but only keeps out its opposite and prepares us for the habit so that it may come from the substance which perfects the souls of men, the ‘agent intellect’ or some such [separate] substance.

They also hold that knowledge is caused in us solely by an agent free of matter. For this reason Avicenna holds that the intelligible forms flow into our mind from the [separated] agent intellect.


John Ziegler is a lecturer at the Centre for Thomistic Studies, in Sydney, Australia.

This article posted April 1997. It was published in Universitas, Vol 2 (1998), No. 1.
Permission is granted to copy or quote from this article, provided that full credit is given to the author and to the Centre for Thomistic Studies, Sydney, Australia.
We would be grateful to receive a copy of any republication.