St. Thomas Aquinas died on March 7, 1274. This month, then, marks the 700th anniversary of that event, and is a fitting time to offer an assessment of Aquinas’s contribution to Christian philosophy and theology.

Most Protestant clergymen have a small, if not always accurate, core of information about Thomas. They know he lived sometime between Augustine and Luther; but so, of course, did all the other theologians and philosophers of the Middle Ages. They know he effected a synthesis between the philosophy of Aristotle and Christian theology. They know too that his philosophy became for much of the twentieth century the controlling influence on Roman Catholic thought. Most Protestants also recall that Aquinas developed a number of arguments for the existence of God. And a few may remember that his most famous writings are the Summa Contra Gentiles, an apologetic work in which he explained and defended his understanding of the Christian faith against unbelievers, and the massive Summa Theologica, left unfinished at his death. To this list most Protestants could also add that Aquinas was canonized (in 1323); after all, how else does a Roman Catholic become a saint?

Unfortunately, such “common knowledge” about Aquinas is not always accurate. For one thing, it is something of an oversimplification to say he synthesized Aristotle and Christianity. There were many more influences (Greek, Roman, and Arabic) at work in his philosophy than Aristotle. Then too, the theistic arguments that Protestants often borrow from Aquinas turn out to be quite different arguments (and weaker ones, at that) than those he himself seems to have proposed.

Aquinas appeared on the scene at a time when many of his contemporaries believed that Christianity was threatened by the greatest intellectual challenge in its history. That threat, the philosophy of Aristotle, was first introduced into the Christian world about A.D. 1200. Even if Aristotle’s philosophy had been properly understood and stated in accurate Latin translations, it would have been a potent enough challenge to medieval Christianity.

But the Aristotelianism of the thirteenth century came complete with interpretations by Muslim philosophers like Averroes (1126–1198), who confused a number of Aristotle’s doctrines with those of certain Neo-platonists. This form of Aristotelianism rejected the doctrine of creation, denied personal survival after death, and placed numerous limitations on the extent of God’s knowledge and power. It had previously been recognized as a threat to Islamic theology, and charges of heresy within Islam had already been placed against adherents of these views. The Roman church sought to counteract the influx of these new and dangerous ideas by banning the teaching of certain elements of Aristotle’s thought. But the ban was unsuccessful, especially at places like the University of Paris, where a group of Latin Averroists accepted Aristotle’s philosophy as true even though they recognized its incompatibility with Christian doctrine.

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During the thirteenth century, intellectuals in the Christian world took a variety of positions regarding the new philosophy. (1) There were some (it may be helpful to regard them as the liberals of the thirteenth century) who followed Averroes in proclaiming the supremacy of philosophy over revealed truth. They maintained that whenever a clear conflict between faith and reason arose, reason must always be accepted over faith. (2) There were those on the other hand (the fundamentalists of their century, perhaps) who insisted on the supremacy of faith. They argued that wherever revelation teaches one thing and Aristotle the opposite (regarding creation, for example), Aristotle must be rejected. In any conflict between the two, faith is to be preferred to reason. (3) There were even some who appeared to maintain a double theory of truth. (Dare we label them the dialectical theologians of their age?) That is, some, like Siger of Brabant (whose position is open to a different interpretation), seem to have held that a proposition can be true in philosophy and its contradictory true in theology.

Paul Tillich often sounds like a twentieth-century Siger of Brabant. In his Dynamics of Faith, for example, Tillich insists that the meaning of truth for faith is something quite different from its meaning for science, history, and philosophy. As Tillich puts it, “The truth of faith cannot be made dependent on the historical truth of the stories and legends in which faith has expressed itself … [nor can faith] be shaken by historical research even if its results are critical of the traditions in which the event is reported” (Dynamics of Faith, Harper & Row, pp. 87, 89). In other words, faith is immune from difficulties raised in science, history, and philosophy because it belongs to a different domain.

To his credit, Aquinas would have no part of any of these moves to resolve the conflict between revelation and man’s claims to truth. He repudiated the double theory of truth. Two contradictory propositions, even if found in different areas like science and theology, cannot both be true at the same time and in the same sense. If Aristotle should prove to be correct about a certain belief that contradicts Scripture, the Christian should not hedge or hide behind a dubious theory of truth but be honest enough to admit that Scripture is wrong. But also, the Christian should examine every alleged conflict between philosophy and theology. Perhaps he will find that the conflict is only apparent, or perhaps he will even discover that it is the philosopher who is in error. Aquinas went even further and insisted that faith and reason, properly understood, can never conflict. God’s word is true and what God teaches will always be consistent with whatever truth men discover.

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So far, so good. But of course, everything Aquinas has said up to this point was maintained before him by St. Augustine. Aquinas broke with Augustine by insisting that there are really two different types of knowledge. There is the natural knowledge we find in philosophy, and there is supernatural knowledge, revealed by God and discussed by theology. Aquinas then introduced a sharp cleavage between faith and reason, after all. While faith and reason were not logically incompatible, they were psychologically different activities of the soul, each with its own specific domain. The domain of reason was all truth that man could acquire unaided by divine revelation. This domain, which Aquinas identified with philosophy, included all the scientific, ethical, psychological, and philosophical knowledge that man could gain through divine revelation.

There was one item of knowledge, however, that could be known by either reason or faith: the knowledge that God existed. If one had the interest to study them and the ability to understand them, there were sound philosophic proofs for God’s existence. But those unable to follow the philosophic proofs could know the existence of God by resting in the truth of divine revelation.

Coincidentally, Aquinas’s bifurcation of faith and reason provided him with one way of resolving some of the problems posed by Aristotle’s philosophy. This was the case with Aristotle’s teaching about the eternity of the world, a view clearly in conflict with the Christian doctrine of creation. Contrary to other Christian apologists of his day such as St. Bonaventure, Aquinas argued that human reason (philosophy) is incapable of discovering whether or not the world had a beginning in time. The doctrine of creation is a truth of faith, not a truth of reason. It can be known only by divine revelation. If Aristotle was wrong on this point (and, Aquinas suggested, Aristotle may only have been reporting the opinions of his predecessors), it was largely an error of overestimating the bounds of human reason.

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Of course, not all the difficulties raised by Aristotle’s philosophy could be disposed of so simply (and I do not suggest that Thomas’s attempt was completely successful). Other problems required a drastic reinterpretation of the text of Aristotle. And so, Aristotle’s apparently clear renunciation of survival after death in De Anima was blunted by Thomas’s reinterpretation of Aristotle’s famous doctrine of the active intellect. According to Aristotle, there is an active intellect that alone makes knowledge possible and that is immortal and everlasting. The Averroists had followed Plotinus and denied the particularity of the active intellect in favor of a cosmic principle of intelligence. But Aquinas insisted that Aristotle meant to teach that each human being has a separate, active intellect that is immortal. Thus, given Aquinas’s restructuring of Aristotle’s doctrine, one could be an Aristotelian and still believe in the Christian doctrine of personal survival after death.

Some Roman Catholic historians of philosophy, such as Father F. C. Copleston, have raised doubts about the accuracy of Thomas’s interpretation. But Aquinas was not only attempting to show Aristotelians that their philosophy need not be incompatible with Christian truth; he was also trying to show non-Aristotelian Christians that they had nothing to fear from the new philosophy. And in a situation like that faced by Thomas, good public relations can easily outweigh bad exegesis.

Aquinas did not stop with his attempt to show that Aristotelianism could be made compatible with Christianity. He proceeded to build a remarkable system of thought in which answers were proposed to a wide variety of important problems in psychology, physics, metaphysics, ethics, and other areas of human knowledge. In other words, Aquinas was not content to relate the Christian view of God and the world to the view of the classical world. He was also concerned to relate his Christian world-view to the problems of his own time and meet head-on the challenges of competing theories. While I may be unable to recommend Thomas’s system, I can heartily endorse his ideal. Christians ought to be engaged in developing a view of life and the world as a whole, in showing the implications of Christian theism for every area of human knowledge.

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Probably no aspect of Aquinas’s thought has had more influence outside Roman Catholicism than his arguments for the existence of God. Many Protestants have also relied either on Thomas’s statement of “The Five Ways” or on later modifications of these arguments. Critics of theism have often used Aquinas’s arguments as their foil in an effort to discredit the rationality of belief in God.

Unfortunately, many of these uses of the arguments have grossly misrepresented Aquinas’s position. Aquinas is thought to have argued that there must be a First Cause or a Prime Mover because it is impossible that there should be an infinitely long series of causes or motions. But Thomas specifically stated that philosophy was incapable of showing either the possibility or impossibility of an infinite series. It was precisely for this reason that Aquinas concluded that philosophy could establish neither the truth nor the falsity of the doctrine of creation in time. It is highly unlikely that Thomas would have ignored this very point that he had taken such pains to establish in arguing for something as important as God’s existence.

One way to distinguish the two interpretations of Thomas’s theistic arguments is to picture a very long row of toppling dominoes. Imagine too that we have the power to move back in time and follow the series of dominoes as they fall. According to one interpretation, Aquinas is thought to have argued that there must be something that causes the first domino to fall. Without such a First Cause (first, that is, in the temporal sense) or Prime Mover, the first domino would not have fallen, and if the first had not fallen, the second would not have fallen, and so on.

David Hume, in the eighteenth century, successfully demolished this type of argument for God’s existence. As Hume showed, even if God were the cause of the first domino’s falling, there would be absolutely no reason to believe that that First Cause is still around now. Presumably, Hume argued, theists are interested in establishing not the existence of a God who may have existed only at the beginning of things but an eternal God upon whom the continuing existence of the world depends. It was exactly this latter notion of God that Thomas’s argument (properly understood) was supposed to establish.

While Hume’s arguments were successful in undermining some theistic proofs, they were totally irrelevant to what Aquinas meant to say. Instead of Aquinas’s God being the First Cause in a temporal sense, he was the First Cause in an ontological sense. That is, God was the primary cause of the entire series of causes, the ontological ground without which the entire series of causes would not have existed. God is not merely the Being who moves the first domino. He is the Being who makes the dominoes, sets them up, and supports them in their existence. God is not simply a Cause that may have existed once and then disappeared. God is the eternal and necessary ground for everything that has being, for every causal relation, for every change that takes place. Thus reinterpreted, Aquinas’s theistic arguments successfully avoid many of the common objects to the cosmological argument. Unfortunately, for proponents of natural theology, even these reinterpreted arguments are open to serious objections (see Donald Burrill, editor, The Cosmological Arguments, Anchor, 1967).

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The fortunes of Thomas’s thought waxed and waned during the centuries. There were periods of tremendous influence in countries such as sixteenth-century Spain. However, there has been nothing in the history of Thomism quite equal to the influence his thought achieved in the twentieth century. Much of this was due to various ecclesiastical declarations such as Pope Leo XIII’s encyclical Aeterni Patris (1879), which urged Catholic bishops to “restore the golden wisdom of Thomas and to spread it far and wide for the defense and beauty of the Catholic faith.” Pope Pius X went even further and warned Roman Catholic philosophers and theologians against deviating from the thought of Aquinas.

The revival of Thomas’s thought in the twentieth century took three predictable courses. First, there were the dullards and mimics whom we find in every age and school of thought who followed lemming-like what was thought to be orthodox Thomism. There were philosophy departments in some Catholic colleges that never permitted their students the luxury of reading Kant, Hume, Descartes, Plato—or even Aristotle. Their only textbooks were the writings of Thomas and approved expositions of the Thomist system.

But there was, second, a group of Thomist scholars who led the way in applying the principles of St. Thomas to the new problems of this new century. Scholars like Etienne Gilson produced outstanding historical studies of medieval philosophy. Other scholars like Jacques Maritain proposed answers to a wide variety of contemporary philosophic and scientific concerns. Thomism underwent subtle mutations and accommodated itself to such twentieth-century movements as existentialism, phenomenology, and analytic philosophy. Nor has the revival of Thomism been confined to Roman Catholicism. Many Protestants have profited from reading the works of non-Roman scholars like C. S. Lewis, Eric Mascal, and Austin Farrer.

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The third group comprises those who, like Bernard Lonergan, have rediscovered Thomas for themselves and gone on to work in the contemporary situation, developing new positions. However, as yesterday’s outstanding spokesmen for Thomism fade from the scene, Thomism appears more and more to be in a state of disarray.

There are at least two distinct ways to evaluate a system such as Aquinas’s. First of all, we can take the system as a whole and decide whether it is an adequate or true account of reality. No doubt, an important part of such a procedure for the Christian is to examine the compatibility or incompatibility of the system with scriptural truth. Second, even should one find it necessary to reject the system as a whole, he may still find within it moments of truth that are helpful and illuminating. Such moments of truth can be found more easily in some systems than in others. There are undoubtedly moments of truth in the writings of Heidegger, Sartre, or Bertrand Russell. The Christian will certainly find many more such moments in Aquinas. For example, the evangelical can learn a great deal from the sound critiques that contemporary Thomists have offered against the major anti-theistic movements of our century. While many Protestants could find nothing more important to do than defend dispensationalism, Thomist scholars were combatting the great errors of the twentieth century—subjectivism, relativism, secularism, pragmatism, positivism, and Marxism.

Even so, the difficulties of Thomas’s Aristotelianism are so great as to make the entire system unsuitable for a biblically centered Christian philosophy. Some of these errors could no doubt be adjusted or modified, much as Aquinas himself sought to rework elements of Aristotle’s philosophy. But there are two errors so significant that they render Aquinas’s system beyond any hope of salvage.


blessings to shrive

the angels’ eyes

who cloud about us

wings riffling

among the leaves

(sigh of the wind

in a forest of living bones)

making do with thin

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dry loaves moist

leaves that float

on the air

wingtips shave & carve

the light roaring down,

make forms that blaze


among the clouds

that gather to gaze

at our amazing bones

all split

by urgent buds


First of all, Aquinas’s system cannot be saved from the irremediable defects of Aristotle’s metaphysics. To be sure, Aquinas tinkered here and there with such problems as God’s relation to the world. But there are more fundamental difficulties of which this is only the peak of the iceberg. Interested readers can explore these metaphysical problems in Gordon Clark’s Wheaton Lectures (reprinted in The Philosophy of Gordon H. Clark, Presbyterian and Reformed, 1968, chapter two; see also Clark’s Thales to Dewey, Houghton Mifflin, 1957, pp. 141–44). While we cannot enter into the complexities of Aristotelian metaphysics here, we can look at some problems of his epistemology.

Both Aquinas and Aristotle were empiricists. Both believed that sensory experience is the basis of all knowledge. Both denied the presence of any innate ideas in the mind of man. Thus, if man is to know God, this knowledge must be built up from a patient analysis of sense data.

But if we can learn anything from the history of philosophy, it is that a blank mind, a mind devoid of innate ideas or rational categories, cannot know anything. The inevitable result of empiricism is the skepticism of David Hume. And the only way to rescue philosophy from such a skepticism is to require that logically prior to man’s sensation of anything is the presence in his mind of certain ordering principles or innate ideas. This capacity to organize sensations, to recognize in them the universal principles that alone can serve as the basis of knowledge, was explained by St. Augustine as one result of man’s creation in the image of God. (See my book, The Light of the Mind, University of Kentucky Press, 1969, or my article, “Some Philosophic Sources for Augustine’s Theory of Illumination,” Augustinian Studies, Vol. II, 1971.) These difficulties carry over into Aquinas’s theory of analogy and his doctrine of how man can know God and communicate truth about God. (See The Philosophy of Gordon H. Clark, pp. 149–51.)

But perhaps an article like this should not end on a negative note. There are at least three accomplishments of Aquinas that evangelicals should note with appreciation.

1. Aquinas provided wisdom and inspiration to numerous philosophers, theologians, and representatives of other disciplines who applied what they learned from him to the new problems and challenges of their own time. Many of these contributions can be useful to evangelicals who study and use them with discernment.

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2. Thomas sought to develop a comprehensive and systematic world-and-life view. While it may be necessary to disagree with many features of his system, no one before him and few since him have developed any world view (theistic or secular) as complete as his.

3. Aquinas met the major intellectual challenge to the Christianity of his age on its own ground. Differences will arise over the exact way in which he answered that challenge, but evangelicals today should applaud his refusal to take refuge in pietism, fideism, or irrationalism.

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