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The History of Christian Thought by Paul Tillich


Paul Tillich is generally considered one of the century's outstanding and influential thinkers. After teaching theology and philosophy at various German universities, he came to the United States in 1933. For many years he was Professor of Philosophical Theology at Union Theological Seminary in New York City, then University Professor at Harvard University. His books include Systematic Theology; The Courage to Be; Dynamics of Faith; Love, Power and Justice; Morality and Beyond; and Theology of Culture. This material was prepared for Religion Online by Herb and June Lowe.


Lecture 26: Medieval Theology. Thomas Aquinas and Duns Scotus.


We must now go into the main problems of the medieval development. I just finished yesterday by saying that the conflict between Aristotle and Augustine characterizes the medieval situation. Let me first make clear what Aristotle means for the Middle Ages in the moment in which he was discovered in the beginning of the 13th century, with the help of the Arabic philosophers.

1) Aristotle's logic was always known, but this was used as a tool and didn't influence the content of theology directly. When the whole work of Aristotle was rediscovered, it was a complete system in which all realms of life were discussed – observations about nature, about politics, about ethics, an independent secular world-view, including a system of values and meanings. The question was: How could a world which was educated in the Augustinian ecclesiastical tradition deal with this secular system of ideas and meanings? This was the first thing Aristotle meant. It is a little as though theology for centuries asked the question: How can the scientific revolution which has been going on since the 17th century be mediated with the Christian tradition? It was a similar problem for the Middle Ages.

2) Aristotle gave basic metaphysical categories, such as form and matter, actuality and potentiality. He gave a new doctrine of matter, of the relationship of God and the world, and all this on a basis of an ontological analysis of reality.

3) This was perhaps the most important point: He gave a new approach to knowledge. The soul has to receive impressions from the external world. Experience is always the beginning, while in the Augustinian tradition immediate intuition was the beginning. The Augustinians were, so to speak, in the Divine center and judged the world from there. The Aristotelians looked at the world and concluded to the Divine center.

The conclusion, therefore, with which I want to deal first is the question of knowledge. The whole movement of Augustinianism and Aristotelianism must be understood from here. The question was: Is our knowledge a participation in the Divine knowledge of the world and of Himself, or must we, in the opposite way, recognize God by approaching the world from outside? Is God the last or the first in our knowledge? The Augustinians answered: the knowledge of God precedes any other knowledge, it is the first one, we must start with it. In ourselves we have the principles of truth. God is the presupposition even of the question of God, as He is the presupposition of every question for truth. He is, says Bonaventura, the Franciscan Augustinian leader of that time, in the 13th century, "most truly present to the soul and immediately knowable." The principles of truth are the Divine or the eternal light within us. We start with them. We start with our knowledge of God and we go from there to the world, using the principles of the Divine light which are in us. This Divine light or these principles are the universal categories, especially the so-called "transcendentalia" those things which transcend everything special and given: being, the true, the good, the one: these are ultimate concepts; we have immediate knowledge of them, and this knowledge is the Divine light in our soul. Only on the basis of this immediate knowledge about the ultimate principles of reality can we find truth in the empirical world. In every act of knowledge these principles are present. Whenever we say "something is so," whenever we make a logical judgment about something, the ideas of the true, of the good, of being itself, are present; or, as Bonaventura says, "being itself is what first appears in the intellect," and being itself is the basic statement about God. This means: every act of cognition, every cognitive act, is made in the power of the Divine light, Of this Divine light, of these principles in us, the Franciscans said that it is uncreated; we participate in it. This makes that somehow no secular knowledge exists. All knowledge is in some way rooted in the knowledge of the Divine in us. There is a point of identity in our soul, and this point precedes every special act of knowledge. Or I could describe it in the following way: Every act of knowledge – about animals, plants, bodies, astronomy, mathematics – is implicitly religious. A mathematical proposition as well as a medical discovery is implicitly religious because it is possible only. in the power of these ultimate principles which are the uncreated Divine light in the human soul. This is the famous doctrine of the inner light, which was also used by the sectarian movements and by all mystics during the Middle Ages and the Reformation period, and which finally underlies even the rationalism of the period of the Enlightenment. They all are philosophers of the inner light, even if this Divine light later on became cut off from its Divine ground.

We can also call this attitude. That is what the Franciscans tried to maintain in spite of the fact that they also had to use Aristotelian concepts such as form and matter, and potentiality and actuality. So we have here in the Augustinian-Franciscan development, from Augustine to Bonaventura, a philosophy which is implicitly religionist or theonomous, in which the Divine is not a matter of conclusions but is a matter of preceding every conclusion, making conclusions possible. It is the philosophy of religion – perhaps some of you have seen in the Union Review a few years ago, when I wrote an article about "The Two Types of Philosophy of Religion" – this is the one type I called it at that time the ontological type; I can also call it the mystical type, or the type of immediacy. I would also like to call it the theonomous type, in which the Divine precedes the secular.

The opposite type is the Thomistic. Thomas Aquinas cuts the immediate presence of God in the act of knowing. He denies it. He also says of course, that God is the first in Himself, but he says God is not the first for us. Our knowledge cannot start with God – although everything starts with Him – but our knowledge must reach Him by starting with His effects: the finite world. So we must start with the Divine effects and conclude from there to the cause. In other words, man is separated from being itse1f, from truth itse1f, and from the good itse1f. Of course Thomas could not deny that these principles are in the structure of man's intellect, but he calls them created light and not uncreated light. They are not the Divine presence in us, so to speak, but they are works of God in us; they are finite. In other words, in having an act of knowledge, we do not have God, but with these principles we can find God. It is not that we start with the Divine principles in us and then discover the finite world, as in the Franciscans; but it is that we start with the finite world and then perhaps are able to find God, in acts of cognition, of knowledge.

Now against this Thomistic theory the Franciscans said that this method, which of course must start in a good Aristotelian way – with sense experience – is good for scientia (for "science" in the largest sense of the word) but that this method destroys sapientia, wisdom. Sapientia means the knowledge of the ultimate principles; this means the knowledge of God. One of Bonaventura's followers made this prophetic statement, that in the moment in which you follow the Aristotelian-Thomistic method and start with the external world, then you will lose the principles. You will win the external world – he agreed with that; he knew

empirical know ledge can be won only in this way – but something is lost: sapientia , the wisdom which is able to grasp intuitively, within oneself, the ultimate principles. Thomas answered that the knowledge of God, as every knowledge, must start with sense experience and must reach God on this basis in terms of rational conclusions, which are derived from the sense experience.

This is the fundamental discussion. Here the two types diverge, and they have been divergent ever since, in the Western world. This divergency is the great problem of all philosophy of religion, and, as I will show now, is the ultimate cause for the secularization of the Western world – :cause," of course, in the cognitive realm; there are other causes, too. In the cognitive realm this is the cause, that here the Aristotelian method is put against the Augustinian, and slowly from Thomas Aquinas the method of starting with the external world prevailed.

Thomas knew that these conclusions, although they are logically correct, do not produce a real conviction. Therefore they must be completed by authority. In other words, the Church guarantees the truth which never can be fully reached in terms of an empirical. approach to God. So we now have the situation clear: In Bonaventura we have theonomous knowledge in all realms of life; we have no knowledge whatsoever without beginning with God. In Thomas we have autonomous knowledge, scientific method, as far as it goes; but Thomas himse1f knew that it doesn't go very far and therefore it must be completed by authority. Now this is the meaning of the heated struggle between the Augustinians and the Franciscans in the 13th century. It was a gap, but at that time the gap was not yet visible. Thomas' genius, his power to take in almost everything, his power of 'mediating – of which I have spoken – his personal and even mystical piety, was able to cover the gap, and is able to cover the gap even in present-day Catholicism, but the gap was there and had consequences reaching far beyond everything Thomas himself realized.

This came out in the 3rd man of the 13th century, Duns Scotus. He was not a mediating but a radical thinker. He was one of those who tear up what seems to be united. He fought against the mediations of Thomas Aquinas. On the other hand, he did not follow his own Franciscan predecessors. He followed Thomas in a complete acceptance of Aristotle, but he realized the consequences which Thomas Aquinas still was able to cover.

For Duns Scotus there is an infinite gap between the finite and the infinite. Therefore the finite cannot reach cognitively at all, neither in terms of immediacy – as the older Franciscan wanted – nor in terms of demonstrations, as the Dominicans, with Thomas Aquinas, wanted.. He criticizes – and insofar as you are nominalists, you will like this criticism – even the transcendentalia, the ultimate principles. He says: Being itself (esse ipsum) is only a word; it points to an analogy between the infinite and the finite, but only an analogy. The word "being" does not cover God as well as the world. The gap is such that you cannot cover them in terms of one word, not even in terms of the verum,bonum,unum, the true, the good, and the one, and that means, being itself. Therefore :Only one way is open to receive God, namely the way of authority, the way of revelation received by the authority of the Church.

In this way we have two positivisms. The religious or ecclesiastical positivism: since we cannot reach God cognitively, we must accept what is given to us by the Church. On the other hand, we have the positivism of the empirical method: what is positively given in nature, we must discover by the methods of induction and abstraction -- now the gap of which I spoke has become visible. In Thomas it was closed; in Duns Scotus it is opened up, and never has been closed again. And it is still our problem, as it was the problem of the people of the 13th century. While in Bonaventura God is known immediately, He is present before anything else is present in us while in Thomas He can be proved by demonstrations, but authority must help, because it is not completely certain in this way; in Duns Scotus neither immediacy nor demonstrations is left, so only revelation and authority accepted in faith can help. – Now if you have understood this, then you are really in the center of any important philosophy of religion. This is the real problem.

Now the gap opened up by Duns Scotus becomes a very large gap a century later in Occam, the real father of nominalism. God cannot be approached at all in terms of atonomous knowledge. He is out of reach. Everything could be the opposite of what is. Therefore He can only be reached by our subjection to the Biblical and ecclesiastical authorities. And we can subject ourselves to them only if we have the habit of grace, only if grace is working in us and makes It possible for us to receive the authority of the Church. Cultural knowledge the knowledge of science, is completely free and autonomous, and religious knowledge is completely heteronomous. So when I come back now to the characterization of the early Franciscan-Augustinian situation, I can say: the original theonomy – God always the prius of every knowing – has been disrupted into complete scientific autonomy on the one side, and complete ecclesiastical heteronomy on the other side. That is the situation at the end of the Middle Ages. And since the Middle Ages are based on a system of mediation, the Middle Ages came practically to an end in the moment in which these mediations broke down.

When I bring this down to the traditional question of reason and revelation, I can express it thus: In Bonaventura reason is in itself revelatory, insofar as in its own depths the principles of truth are given. This of course doesn't refer to the historical revelation in Christ, but refers to our knowledge of God. In Thomas reason is able to express revelation. In Duns Scotus reason is unable to express revelation. In Occam revelation stands beside and in opposition to reason. At the end of the Middle Ages the religious and the secular realm are separated, but they are not separated in the way in which they are today – as a consequence of this separation in the Middle Ages – but the Middle Ages still wanted for centuries its traditional unity. Therefore the Church now developed its radical heteronomous claim to rule all realms and to control them, but now from outside. And now the desperate fight between autonomous secularism and heteronomous religious developed. Don't confuse the late Middle Ages with the earlier Middle Ages. As long as the tradition was in power, the Middle Ages were not heteronomous; they were theonomous, which is something quite different. But at the end an independent secular realm was established, and the question was: Is the Church able to control this independent realm? And the ways in which the Church was deprived of this power are the ways of Renaissance and Reformation.

One of the ways I wanted to mention, and which appears already at that time, was the way of the double truth, which is very illuminating for the situation. Some people seriously – not only diplomatically, in order to hide themselves – believed, in reality, that a statement about the same matter can be contradictory and nevertheless true theologically though wrong philosophically, and vice versa, so that people asserted the whole heteronomous system which the Church as long as it was in power still could maintain, and on the other hand, they developed autonomous thought. And if the proposition came into conflict, then they took refuge in the so-called ‘double truth. Of course for many this was a way of hiding, but it was more than this: it was the belief that these realms are so separated that you can say in one realm the opposite of what you say in the other.

This is the epistemological problem, and it was a very fundamental one, but of course – as behind all problems in philosophy and theology – it is always the problem of God which is decisive, and so I now go to the doctrine of God in medieval thinking, and I come again partly to these three men of the 13th century.

The medieval idea of God has three levels:

1) The first and fundamental level is the idea of God as primum esse, the first being, or prima causa, the first cause. By "cause" here is meant not as "cause and effect," as we have it in the realm of finitude – the word "prima," "first," means not the first according to time, but the ground of all causes, so that the term "cause" is here used more symbolically than literally. It is the creative ground in everything, creatrix universa1ium substantia, the creative substance of everything that is. This is the first statement about God. He is the Ground of Being, as I like to express it, or being itself, or the first cause – all these terms point to the same meaning.

2) This substance cannot be understood in terms of the inorganic realm – for instance, as an inorganic substance like fire or water, as the old physicists did – nor in the biological situation, as a life process, but it must be understood as intellect. The first quality of the Ground of Being is intellect. Intellect doesn't mean intelligence, but it means the point in which God is for Himself subject and object at the same time; or, as it was carried through, God knowing Himself and knowing the world as that which He is not. The Ground of Being, in other words – the "creative substance" – is a bearer of meaning. The world – this is the consequence – is meaningful, can be understood in words which have meaning. The logos, the word, can grasp it. In order to understand reality, we must presuppose that reality is understandable; and reality is understandable because the Divine ground has the character of intellect. Only because the Divine intellect ~ the ground of everything, is knowledge possible.

3) The third characteristic, which comes from the Christian Augustinian tradition – while the intellect comes from the Greek Aristotelian tradition: God is will. Will, of course, if applied to God and the world, is not the psychological function which we know in ourselves, but it is the dynamic ground of everything. It is the productive power of the Ground of Being. This will has the nature of love – in good Augustinian tradition. The creative substance of the world has meaning and has love – is intellect and will, symbolically speaking. And as with respect to knowing we said that God knows Himself, so we must now say that God wills or loves Himself as the absolute good, indeed as the ultimate aim of everything. And He loves the creatures in giving them, in a graded way. the good of which He is the ultimate Ground. Therefore they all are longing for Him, and He is for them the object of that love which everything has and every being has, the love toward that in which it sees its ultimate good. Now this is the medieval idea of God. This God is not called a person. The word "person" is never applied to it in the Middle Ages. for two reasons:

1) because the Trinitarian "faces" or "countenances" are called personae: the Father is persona, the Son is persona. and the Spirit is persona. But persona here means more a special characteristic of the Divine ground, expressing itself in an independent hypostasis. Therefore we can say the term persona has been applied to God only in the 19th century, when God was made into a person, and the greatness of the classical idea of God was destroyed by this kind of speaking. Of course this structure. including being, intellect and will. is analogous to our experience of our own being, and if we call ourselves "person" we must call God also "Person." But this is something quite different from calling God "a Person" First of all. He is being itself. He is the Ground of Being in everything. The personal side is expressed in intellect and will. and their unity. But to speak about a person would have been absolutely heretical for the Middle Ages; it would have been Unitarian heresy for them. because this would exclude that God has three personae. namely. expressions of His being.

Now about the relationship of intellect and will in God. there the same fight was going on as about the epistemological problem. For the Thomistic tradition, intellect is characteristic of God and man. Thomas argues that only because man is intellect is he able to be distinguished from an animal. An animal would be a man in the moment in which it was able to put purposes intellectually before the will. But the animal only wills. without purpose – in the sense in which we ascribe it to man. Therefore for Thomas the intellect is that which makes man man and therefore is the primary characteristic of God.

Intellect is the insight into the universally true and good. But Duns Scotus opposed this doctrine. In him God and man are will. Will is universally creative. There is no reason for the Divine will other than the Divine will itself. There is nothing which determines the will. The good is good because God wills that it is. There is no intellectual necessity that the world is as it is, that salvation is as it is. Everything is possible for God except not to be God – that's impossible for Him. This is what Duns Scotus called His potentia absoluta . the absolute power of God. But God uses His absolute power only in order to create a given world in which there are definite orders. Therefore he called this potestas ordinatus. the ordered power of God. Here he distinguishes these two: the world as we know it. and the purpose of salvation as we know it by revelation. is not necessarily so as it is. but now. after it has been given. it is so as it is; it is by Divine ordered power. But behind this stands something as a threat. The world is not as it is from eternity. There is no real necessity that it is as it is. The threatening absolute power of God behind the ordered power may change everything. Duns Scotus didn't believe that this would happen. but it can happen.

Now what does such an idea mean? It means that we have to accept the given, that we cannot deduce it. that we have to be humble toward reality. We cannot deduce the world or the process of salvation in terms of, for instance. with Anselm's doctrine of atonement. where he tried to deduce in terms of necessity the way of salvation between God and Christ. and man. Duns Scotus would say there is no such necessity; this is a positive order of God. Now here in this idea of the absolute power of God. we have the root of all positivism. in science as well as in politics. in religion as well as in psychology. In the moment in which God became "will". who is only determined by Himself and His own will, and not by the intellect – in this moment the world became incalculable, uncertain, unsafe, and we are demanded to subject ourselves to what is given. All the dangers of positivism are rooted in this concept of Duns Scotus. And so I consider him, more than anybody else, the turning point in the history of Western thought.

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