Aquinas

A Beginner's Guide

Edward Feser

• Publisher: Oneworld Publications
• Year: 2009
• ISBN:
  9781780740065
• Topic: Theologie & Religion
• Subtopic: Religiöse Biographien

Charting the life and thought of this hugely influential medieval thinker. One of the most influential philosophers and theologians in the history of Western thought, St Thomas Aquinas established the foundations for much of modern philosophy of religion, and is infamous for his arguments for the existence of God. In this cogent and multifaceted introduction to the great Saint's work, Edward Feser argues that you cannot fully understand Aquinas' philosophy without his theology and vice-versa. Covering his thoughts on the soul, natural law, metaphysics, and the interaction of faith and reason, this will prove a indispensable resource for students, experts or the general reader.

1

St. Thomas

If we want to study Aquinas we should pay him the compliment of treating as important what he thought of as important. To study Aquinas as Aquinas is a poor piece of flattery, since Aquinas cared very little for Aquinas, while he did care for God and for science.

C. F. J. Martin, Thomas Aquinas: God and
Explanations, p. 203.

One approach to the study of the history of philosophy is to situate the great thinkers of the past within the historical contexts in which they worked and determine what social, political, cultural, and philosophical circumstances influenced their ideas. This approach certainly has its value, especially insofar as it can help us correctly to understand what a philosopher meant in saying this or that. If pursued too single-mindedly, however, it can distract us from what the thinkers themselves considered important. The philosophers of the past did not write in order to reflect their times or to provide future historians with something to do. Their work was intended to point beyond itself to something else – to the truth about things – and what matters ultimately is whether they succeeded. As Aquinas himself once wrote, “the study of philosophy is not about knowing what individuals thought, but about the way things are” (In DC I.22). This is the point of the remark by Christopher Martin quoted above. The main value of studying what Aquinas or any other thinker said about God, science, or some other topic is to find out whether what he said is true, or at least likely to lead us closer to the truth. As Martin goes on to add, studying a thinker of the past, specifically, has value insofar as it can help us determine whether what we take for granted in the present is itself true:

If we want to know about the existence of God, or about the nature of science, we should read Aquinas, not merely the writers of this century … The great benefit to be derived from reading pre-modern authors is to come to realise that after all we [moderns] might have been mistaken.

That Aquinas’s work should be read as a challenge to us today – and a challenge, as we shall see, not merely to our conclusions, but to many of our premises too – is a central theme of this book. Whether one thinks that challenge ultimately succeeds or not, it is important to treat Aquinas as in this sense a living author rather than a museum piece.

Martin’s reference to “science” might strike some readers as odd. Wasn’t Aquinas a philosopher and a theologian, rather than a scientist? And given his concern with God and other matters of religion, weren’t his opinions matters of faith rather than reason, scientific or otherwise? Yet the assumptions behind such questions are precisely the sort that Aquinas’s philosophy challenges. For Aquinas, a science is an organized body of knowledge of both the facts about some area of study and of their causes or explanations (In PA I.4); and while this includes the fields typically regarded today as paradigmatically scientific (physics, biology, and so forth), it also includes metaphysics, ethics, and even theology. Furthermore, these latter sciences are as rational as the ones we are familiar with today. To be sure, a part of theology (what is generally called “revealed theology”) is based on what Aquinas regards as truths that have been revealed to us by God. To that extent theology is based on faith. But “faith,” for Aquinas, does not mean an irrational will to believe something for which there is no evidence. It is rather a matter of believing something on the basis of divine authority (ST II-II.4.1), where the fact that it really has been revealed by God can be confirmed by the miracles performed by the one through whom God revealed it (ST II-II.2.9). In any case, there is another part of theology (known as “natural theology”) that does not depend on faith, but rather concerns truths about God that can be known via reason alone. It is these purely philosophical arguments of natural theology with which we shall be concerned in this book, along with Aquinas’s views in metaphysics, ethics, and psychology (which includes the study of the human mind, but extends well beyond this, as we will see).

Aquinas’s life and works

Thomas was born circa 1225 at Roccasecca, near the town of Aquino in southern Italy, from which his aristocratic family derived its name (hence the sobriquet “Aquinas”). At five years old he was sent by his parents to be educated at the Benedictine Abbey at Monte Cassino, in the hope of setting him on the path to attaining, eventually, the prestigious position of Abbot. But while studying at Naples as a teenager, Aquinas came under the influence of the new Order of Friars Preachers, also known as the Dominicans after their founder St. Dominic. Attracted by its devotion to study and teaching, he joined the order at nineteen, much to the chagrin of his family, whose worldly ambitions for Thomas did not square with the Dominican life of poverty and simplicity. In the hope of getting him to change his mind, his brothers abducted him and put him under house arrest at the family castle at Roccasecca for about a year, though he spent the time committing to memory the entire Bible and the four books of the Sentences of Peter Lombard (a theological textbook then widely in use). Notoriously, they even went to the extent of sending a prostitute into his room on one occasion, but he chased her away with a flaming stick pulled from the fireplace, which he used afterward to make the sign of the cross on the wall. As the story has it, he then kneeled before the cross and prayed for the gift of perpetual chastity, which he received at the hands of two angels who girded his loins with a miraculous cord. Eventually his brothers relented and he was allowed to return to the Dominicans.

While a student at what would become the order’s study center in Cologne, Aquinas acquired the unflattering nickname “the Dumb Ox” due to his taciturn character coupled with his considerable girth. The former trait owed largely to a humble unwillingness to call attention to himself, and despite his portliness it is said of Aquinas that he ate only once a day in order to devote himself more fully to his work. In any case, his genius became evident before long, leading his mentor Albert the Great (c. 1200–1280) famously to predict that the Ox’s “bellowing” would someday be heard throughout the world.

The works of Aristotle (384–322 B.C.) had during the preceding century become once again available to scholars in the Latin West, which led to a renewed interest in his philosophy, and Albert was at the time the foremost thinker of this Aristotelian revival. Aquinas would go on to become an even more influential proponent of Aristotle, and was recommended by Albert in 1252 for a position as a lecturer at the University of Paris, where Aquinas was a great success. It was apparently during this time that he composed the short treatises On the Principles of Nature and On Being and Essence, which set out his core metaphysical ideas. This period also gave rise to the much longer treatment of disputed questions On Truth.

After 1259 Aquinas returned to Italy and produced the massive Summa contra Gentiles, a treatise devoted to defending the claims of orthodox Christianity against a wide variety of objections presented by Jews, Muslims, pagans, and heretics. Following this he began work on the even more massive (and never completed) Summa Theologiae, a systematic treatment of all the main issues of theology organized around the theme of how things ultimately derive from, and are destined to return to, God, their first cause and last end. Along the way it deals with a wide variety of topics in metaphysics, ethics, psychology, and other subjects. These two Summae are generally regarded as Aquinas’s masterpieces. In the course of working on the second, he would also produce many other works, apparently intended in part as preliminary treatments of certain topics to be dealt with in the Summa Theologiae. These include treatises on disputed questions On the Power of God and On the Soul and a series of commentaries on the works of Aristotle.

This latter, commentarial project had another purpose as well, one to which Aquinas’s eventual return to Paris may be related. The use of Aristotle’s philosophy in expounding and defending Christian doctrine was highly controversial in Aquinas’s day. Aristotle had taken several positions (such as the view that the universe had no beginning) that seemed incompatible with the claims of Christianity. So too had the followers of Averroes (1126–1198), the Muslim philosopher whose interpretation of Aristotle was regarded by many as authoritative. The Averroists had held, for example, that the human race shares a single intellect, which appears incompatible with the notion that each human being has an individual immortal soul. More traditional theologians thus regarded Aristotelianism as theologically dangerous, and preferred the Neoplatonic tradition in general, and Augustinianism in particular, as more suited to the needs of Christian theology. The controversy between defenders and critics of Aristotelianism was particularly fierce at the University of Paris, and Aquinas was determined to show that, when rightly understood, Aristotle’s philosophy was not only compatible with Christianity, but the best means of expounding and defending it. In effect, he took a middle position between Averroism and Augustinianism, seeking to avoid the extremes of the former while showing that the key elements of the latter tradition could be incorporated into a broadly Aristotelian worldview. The result was a unique synthesis that has since come to be known as Thomism (after “Thomas,” the name by which Aquinas was known during his lifetime).

In 1272 Aquinas returned once again to Italy. While saying Mass in Naples one day in 1273 he went into a trance, and appears to have had a mystical experience, after which he was unable to resume work on the Summa Theologiae. Famously, he explained that after what he had seen, everything he had written now seemed to him “like straw.” Called to attend the Second Council of Lyons, he apparently hit his head against a low-lying tree branch while on the journey, and sustained a serious injury. He was taken to the Cistercian abbey at Fossanova, where he was nursed by the monks, but died on March 7, 1274.

In addition to his profound humility, the character traits for which Aquinas was most notable included a deep piety and an astounding capacity for sustained abstract thought. It is said of him that he was so single-minded in his devotion to God that he would leave the room when discussion turned away to some unrelated subject. He could become so absorbed in prayer or in a chain of philosophical or theological reasoning that he would sometimes forget where he was, fail to perceive the people around him, and even (as one account has it) fail to notice the flame from a candle he was holding as it burned his hand. According to another famous story, while at dinner with King Louis IX of France he got thinking about the Manichaean heresy, struck the table exclaiming “That settles the Manichees!” and called for his secretary to take down the argument that had just occurred to him. Suddenly realizing where he was, Aquinas apologized and explained to the other startled guests that he thought he was alone in his room. Related to this tendency towards abstraction appears to have been an extraordinary unflappability. Anscombe and Geach relate a story according to which Aquinas once came upon “a holy nun who used to be levitated in ecstasy.” His reaction was to comment on how very large her feet were. “This made her come out of her ecstasy in indignation at his rudeness, whereupon he gently advised her to seek greater humility.”

2

Metaphysics

Even among contemporary philosophers who are otherwise unfamiliar with his work, it is fairly well known that Aquinas held that the existence of God, the immortality of the soul, and the content and binding force of the natural moral law could be established through purely philosophical arguments (as opposed to an appeal to divine revelation). But those arguments themselves are in general very badly misunderstood by those who are not experts on Aquinas. The reason is that most contemporary philosophers have little or no awareness of just how radically different the fundamental metaphysical assumptions of ancient and medieval philosophers are, in general, from the assumptions typically made by the early modern philosophers and their successors. A distinctive conception of causation, essence, form, matter, substance, attribute, and other basic metaphysical notions underlies all of Aquinas’s arguments in philosophy of religion, philosophy of mind, and ethics; and it is a conception very much at odds with the sorts of views one finds in Descartes, Locke, Hume, Kant, and the other founders of modern philosophy. While most contemporary philosophers would probably not identify themselves as Cartesians, Lockeans, Humeans, Kantians, or the like, their thinking about the metaphysical concepts just noted nevertheless tends, however unconsciously, to be confined within the narrow boundaries set by these early modern thinkers. Hence when they come across a philosopher like Aquinas, they unthinkingly read into his arguments modern philosophical presuppositions he would have rejected. The result is that the arguments are not only misinterpreted, but come across as far less interesting, plausible, and defensible than they really are. In rejecting them, as contemporary philosophers tend to do, they do not realize that what they are rejecting is a mere distortion or caricature of Aquinas’s position rather than the real McCoy.

An overview of Aquinas’s general metaphysics is therefore a necessary preamble to a consideration of his views in these other areas of philosophy. Such an overview would be of value in any case, for Aquinas’s metaphysical ideas are important and interesting in their own right. We shall also see that they are as defensible today as they ever were, and (ironically enough) that some work by contemporary philosophers, quite outside the camp of Thomists and otherwise unsympathetic to Aquinas’s overall project, tends to support this judgment.

Act and potency

The Greek philosopher Parmenides (c. 515–450 B.C.) notoriously held that change is impossible. For a being could change only if caused to do so by something other than it. But the only thing other than being is non-being, and non-being, since it is just nothing, cannot cause anything. Hence, though the senses and common sense tell us that change occurs all the time, the intellect, in Parmenides’ view, reveals to us that they are flatly mistaken.

The tendency of philosophers like Parmenides to pit the intellect against the senses and common sense is one that was firmly resisted by Aristotle. At the same time, Aristotle was loath simply to dismiss a theory like Parmenides’ on the grounds that it was odd or counterintuitive; it was important to understand exactly why such a theory was mistaken. Aquinas, who (as we have seen) esteemed Aristotle above all other philosophers, followed him in these attitudes, and also in his specific reply to Parmenides, which appealed to the distinction between act and potency.

Parmenides assumed that the only possible candidate for a source of change in a being is non-being or nothing, which (of course) is no source at all. Aristotle’s reply was that this assumption is simply false. Take any object of our experience: a red rubber ball, for example. Among its features are the ways it actually is: solid, round, red, and bouncy. These are different aspects of its “being.” There are also the ways it is not; for example, it is not a dog, or a car, or a computer. The ball’s “dogginess” and so on, since they don’t exist, are different kinds of “non-being.” But in addition to these features, we can distinguish the various ways the ball potentially is: blue (if you paint it), soft and gooey (if you melt it), and so forth. So, being and non-being are not the only relevant factors here; there are also a thing’s potentialities. Or, to use the traditional Scholastic jargon, in addition to the different ways in which a thing may be “in act” or actual, there are the various ways in which it may be “in potency” or potential. Here lies the key to understanding how change is possible. If the ball is to become soft and gooey, it can’t be the actual gooeyness itself that causes this, since it doesn’t yet exist. But that the gooeyness is non-existent is not (as Parmenides assumed) the end of the story, for a potential or potency for gooeyness does exist in the ball, and this, together with some external influence (such as heat) that actualizes that potential – or, as the Scholastics would put it, which reduces the potency to act – suffices to show how the change can occur. Change just is the realization of some potentiality; or as Aquinas puts it, “motion is the actuality of a being in potency” (In Meta IX.1.1770), where “motion” is to be understood here in the broad Aristotelian sense as including change in general and not just movement from one place to another.

So far this may sound fairly straightforward, but there is more to the distinction between act and potency than meets the eye. First of all, some contemporary analytic philosophers might object that a thing is “potentially” almost anything, so that Aristotle’s distinction is uninteresting. For example, it might be said by such philosophers that we can “conceive” of a “possible world” where rubber balls can bounce from here to the moon, or where they move by themselves and follow people around menacingly. But the potentialities Aristotle and Aquinas have in mind are ones rooted in a thing’s nature as it actually exists, and do not include just anything it might “possibly” do in some expanded sense involving our powers of conception. Hence, while a rubber ball has the potential to be melted, it does not, in the Aristotelian sense, have the potential to bounce to the moon or to follow someone around all by itself.

Second, and as indicated already, though a thing’s potencies are the key to understanding how it is possible for it to change, they are merely a necessary and not a sufficient condition for the actual occurrence of change. An additional, external factor is also required. Potential gooeyness (for example), precisely because it is merely potential, cannot actualize itself; only something else that is already actual (like heat) could do the job. Consider also that if a mere potency could make itself actual, there would be no way to explain why it does so at one time rather than another. The ball melts and becomes gooey when you heat it. Why did this potential gooeyness become actual at precisely that point? The obvious answer is that the heat was needed to actualize it. If the potency for gooeyness could have actualized itself, it would have happened already, since the potential was there already. So, as Aquinas says, “potency does not raise itself to act; it must be raised to act by something that is in act” (SCG I.16.3). This is the foundation of the famous Aristotelian–Thomistic principle that “whatever is moved is moved by another” (In Phys VII.2.891). (The principle is true, incidentally, even of ani...