Rediscovering Aristotle, Aquinas, and Classical Theism: an interview with Edward Feser

Is Ancient Philosophy Still Relevant? Rediscovering Aristotle, Aquinas, and Classical Theism: an interview with Edward Feser

Dr. Edward Feser is an Associate Professor of Philosophy at Pasadena City College in Pasadena, California. A former atheist, Dr. Feser converted back to the Catholicism of his youth after an extensive study of St. Thomas Aquinas’ thought and philosophy. Called “one of the best contemporary writers on philosophy,” he currently specializes in metaphysics, natural theology, philosophy of mind, and moral and political philosophy. A prolific writer, he is the author of Philosophy of the Mind (Oneworld, 2007), Aquinas (Oneworld, 2009), and The Last Superstition: A Refutation of New Atheism (St. Augustine Press, 2010). His essays have appeared in publications such as First Things, National Review, and Public Discourse. Dr. Feser has lectured at New York University, Princeton University, and Oxford University, educating the public on Scholasticism.


In your book The Last Superstition, you argue that the biggest mistake of modern philosophy is the abandonment of Aristotelian-Thomistic (A-T) metaphysics. For those of us who are not as familiar with A-T metaphysics, could you describe three major characteristics of this framework and how they differ from the modern understanding? What led to the abandonment of A-T amongst modern philosophers and why do you think it was a mistake?

If I had to boil the A-T position down to three key themes, the first would be Aristotle’s theory of actuality and potentiality. The pre-Socratic philosopher Parmenides famously held that change is an illusion. The reason is that he thought change would involve a transition from non-being to being, from nothing to something. So, since something cannot come from nothing, change cannot occur. Aristotle’s response was to argue that we need to distinguish between actual being and potential being. For example, a rubber ball might be actually red, actually spherical, and actually solid, but it is also potentially green (if you paint it), and potentially flat and squishy (if you melt it). Though not actualized, these potentialities are not nothing, but something really there in the ball. The ball really does have the potential to melt in a way it does not have (say) the potential to grow wings. And this gives us a way to see how change is possible, contrary to what Parmenides claims. For change is not the transition from non-being to being, but rather from one kind of being to another. It is the transition from potential to actual.

Now, once in place, this distinction between actuality and potentiality does an enormous amount of work in A-T philosophy. For example, as I show in detail in my book Scholastic Metaphysics, Aristotle’s famous doctrine of the Four Causes – formal cause, material cause, efficient cause, and final cause – naturally flows out of it. That doctrine is the second key A-T theme I would emphasize. The formal and material causes of a thing are related to each other as actuality is to potentiality. For a thing’s form – the form of a stone, or of a tree, or of a dog, or whatever – is what makes it actually a thing of a specific kind. Its matter is the potentiality to take on form (which is why physical things are imperfect and unstable to the extent that they are – their matter is always ready to lose the form it has and take on another). A thing’s efficient cause is what actualizes the potential of its matter to take on this or that specific form. Finally, a potentiality is always a potentiality for some outcome or range of outcomes. It “points to” or is “directed toward” that outcome. That is where final cause, or directedness toward an end, comes in.

Now, the doctrine of the Four Causes itself does an enormous amount of work in A-T thinking. For instance, it gives us the conceptual apparatus in terms of which to understand the relation between soul and body, since A-T regards the soul as the formal cause of the living body and the body as matter of a type which has the potentiality to take on such a form. The idea of final cause is crucial to the very possibility of morality, certainly as A-T natural law ethicists understand it. It is also crucial to understanding the way the mind fits into the natural order, since the intentionality of the mental – a thought’s directedness toward its object – is an instance of final causality. Perhaps the most important application of the whole A-T metaphysical apparatus, though, is to natural theology, and that is the third key A-T theme I would emphasize. When we unpack the nature of physical things as composites of form and matter and the nature of causality as the actualization of potentiality, we find that no physical thing could continue in existence even for an instant unless actualized by a divine Uncaused Cause – or, more precisely, a “purely actual actualizer.” That is to say, the existence of a physical thing at any moment presupposes that there is something which actualizes it but which does not itself need to be actualized, because it has no potentiality in need of actualization. This is the philosophical core of the A-T understanding of God, from which the key divine attributes can all be derived.

Now, the reasons the early modern philosophers moved away from all this are complicated, and that is a story I tell in The Last Superstition and elsewhere. Part of it had to do with the rise of modern science, though not in the way people think. For one thing, there were of course Aristotelian scientific ideas which turned out to be wrong, but the metaphysical ideas I just sketched had no essential connection to them. They can be disentangled, as later Aristotelian and Thomistic philosophers have shown. But some of the early moderns were inclined to throw the baby out with the bathwater. Perhaps more important, though, was that the early modern thinkers wanted to redirect Western thought in a more this-worldly and practical direction. Thinkers like Bacon and Descartes emphasized that science ought to be a tool for mastering the natural world and developing new technologies. This required focusing on those aspects of nature which could be precisely predicted and controlled, which in turn entailed modeling nature in mathematical terms as far as possible.

The trouble is that notions like potentiality, final cause, and formal cause do not fit a mathematical model of the world. They are irreducibly qualitative rather than quantitative notions. So, they were simply put aside. At first they were treated as merely irrelevant to the specific purposes of empirical science, but gradually this attitude morphed into the more extreme judgment that they had no validity at all, not even in metaphysics. And as I argue in The Last Superstition and elsewhere, this move is the source of the intractability of many of what people think of as the “traditional” problems of philosophy. For example, when final causality or directedness toward an end is no longer regarded as a real feature of the natural world, goodness comes to seem a mere projection of our subjective value judgments. The very possibility of an objective morality becomes problematic. The intentionality or directedness of mental phenomena also comes to seem an illusion. Reasoning causally from the world to a divine sustaining cause becomes difficult when the very existence of a thing at any moment is no longer seen as a matter of a potentiality which needs actualizing. And so forth.

If A-T notions are irreducibly qualitative rather than quantitative, how ought we understand A-T in light of modern science and mathematics? How would you describe the nature of the relationship between the two, and can one inform the other?

The answer is that A-T and modern science are complementary descriptions of the natural world. Modern physics captures the mathematical structure of the world, but mathematical structure cannot be all there is, since there has to be some underlying reality that has the structure. A-T captures what that underlying reality must be like, metaphysically, in order to have the structure physics describes, or any other structure for that matter.

Many of the puzzles that modern physics famously confronts us with are the result of mistaking its mathematical descriptions for the whole of the phenomena they describe, when in fact they are merely partial descriptions. That does not mean they are incorrect descriptions, of course, but they are still partial. Hence in relativity theory, as interpreted in Minkowski’s terms, the universe is described as if it were a four-dimensional static “block.” Change is treated as if it were unreal, existing only in the mind of the observer. But among the puzzles this raises is the question: how does the observer himself fit into this static block? We seem stuck with a radically dualist position where the flux of our conscious experiences – which, of course, provide the empirical evidence in terms of which physical theory is justified in the first place – stands entirely outside the static physical world, and yet in some mysterious way is supposed to arise from the latter.

Quantum mechanics, meanwhile, seems to describe a world wherein causality is absent. The reason for these strange results, however, is that these theories are trying to capture their respective domains – the large-scale structure of time and space in the case of relativity, the micro-level structure of matter in the case of quantum mechanics – in entirely mathematical terms. And you simply are never going to capture all of reality that way. In effect, relativity gives us a description of the world that is an approximation of actuality without potentiality. That is why, as Karl Popper noted, the world relativity describes seems Parmenidean. Quantum mechanics, on the other hand, in effect gives us an approximation of potentiality without actuality. Indeed, Heisenberg thought that quantum mechanics had rediscovered something like the Aristotelian idea of potentiality. Now, if you describe potentiality without actuality you are (given the A-T account of causality as the actualization of potential) naturally going to seem to be describing a world in which causality is absent.

These weird results, then, are merely an artifact of the method of trying to capture everything in a mathematical model. As E. A. Burtt put it in his influential book The Metaphysical Foundations of Modern Physical Science, modern scientists, even those who claim to eschew metaphysics, often end up making a metaphysics out of their method. They mistake what is really just an idealized model of the world for the world itself. A-T gives you the rest of the picture. And it argues that you can never really eliminate its key notions – actuality, potentiality, formal and material cause, efficient causality and teleology – but merely move them around. The most science can do is to tell us that this or that particular application of these notions was mistaken. What it cannot do is eliminate them altogether or show that they have no application at all.

For example, the modern Darwinian synthesis in biology tells us that a specific kind of teleological description is mistaken. But it by no means gets rid of teleology altogether. On the contrary, it presupposes a kind of teleology or final causality insofar as it is very difficult, and I would say impossible, to describe the relevant genetic phenomena without bringing in teleology at some level. That is why computational descriptions (of genes as “software,” “programs,” etc.) are so hard to avoid in this context, and these descriptions are implicitly teleological. Part of the reason more people do not see this is that they presuppose a cartoonish understanding of what Aristotelians mean by final cause. There are different kinds of teleology, but any process that exhibits “directedness” toward a certain characteristic outcome or range of outcomes would be teleological or an instance of final causality.

It is also difficult to argue persuasively for A-T without discussing epistemology. On what grounds can we describe reality using A-T concepts? How do we know that those concepts are true?

The idea that metaphysics in general and A-T metaphysics in particular has some frightfully difficult epistemological burden to meet before it can get going is not uncommon – perhaps especially in theology, rather than in philosophy (which has moved beyond the anti-metaphysical prejudices common in the mid-twentieth century. Catch up already, theologians!). But I would say that this attitude is unfounded.

To be sure, modern philosophy has for much of its history tended to make epistemology primary and metaphysics secondary. The idea from Descartes onward has tended to be that you first inquire into how we can know anything, and then, after settling that, you address questions about what objective reality is like. But classical and medieval philosophers would regard this as getting things the wrong way around, and A-T philosophers would certainly think it gets things the wrong way around. Metaphysics comes first, and any epistemological position itself always presupposes, implicitly if not explicitly, a metaphysical position of some sort. Even to ask “But how do you know that such-and-such a metaphysical claim is true?” itself presupposes notions of truth and of mind according to which the mind might get things wrong, and that is a metaphysical assumption. So, the idea that metaphysics has to answer to some purely epistemological tribunal before it can even get started is a myth.

A second problem is that it is simply sloppy procedure to raise sweeping questions about how metaphysics in general can be justified, or even about how A-T metaphysics in general can justify its claims. The right way to proceed is to begin with something very specific. So, for example, consider the theory of actuality and potentiality. The A-T philosopher will start by pointing out that there is simply no way that the reality of change can coherently be denied. Even if you doubt that the external world is real or that real change occurs within it, you still have to transition from one thought to another in order to come to that conclusion, and that itself entails change. So, change of at least some sort exists. Now, the next step would be show that unless there is a real distinction between potentiality and actuality, change would not be possible. Any attempt to sidestep the distinction between potentiality and actuality can be shown at least implicitly to collapse into a Parmenidean position on which change is entirely illusory, and again, no such position is coherent.

So, we work from change to actuality and potentiality, and then we go from there. The way we proceed depends on the specific issue, and on what the critic is willing to concede. Suppose the critic concedes that there is at least some mind-independent reality. (If he is not willing to concede this there are arguments we can give to show him why he is wrong, but of course, most people will concede at least that much.) Suppose, for example, that he concedes the reality of at least those entities and processes described by physics and chemistry. The A-T philosopher will argue that there is no way to make sense of such phenomena unless they too have an actuality/potentiality structure. But for them to have such a structure entails, on analysis, that they have a form/matter structure, and that they also manifest a kind of efficient and final causality, because all of that falls out of the actuality/potentiality analysis when it is unpacked. Then we go on from there to show that the same thing is going to be true of any higher-level irreducible features of the world (such as biological phenomena) that the critic is prepared to recognize.

So, the right way to proceed is work up like this, case by case and in careful detail. Asking vague and sweeping questions like “How do we know A-T metaphysics is true?” is no more helpful than asking sweeping questions like “How do we know biology is true?” or “How do we know history is true?” We need to proceed by addressing specific issues in a systematic way, and that is how contemporary A-T metaphysicians proceed. For example, that is how my book Scholastic Metaphysics proceeds and how David Oderberg’s book Real Essentialism proceeds.

In your opinion, what is the strongest objection against the A-T framework? How would you respond to that objection?

Well, let me answer this way. What people take to be the strongest objection is the claim that modern science has undermined the A-T framework. Sometimes this objection takes the bolder form of saying that science has positively refuted the various specific components of the A-T picture. Sometimes it takes the weaker form of saying that science has at least made it unnecessary to make use of the A-T framework.

Is this a strong objection, in either form? I do not think so. It is more of a cliché or a piece of conventional wisdom that everyone thinks “everyone knows.” Usually such objections are merely casually and confidently asserted rather developed in any detail. And when they are developed, they turn out to rest on a number of begged questions, non sequiturs, straw men, failures to make crucial distinctions, and so forth.

For example, the critics routinely conflate scientific questions and metaphysical questions. They suppose that since certain empirical claims associated with medieval Aristotelian science have turned out to be mistaken (e.g. the idea that the earth is at the center of the solar system, or that the natural place of sub-lunar objects is the center of the earth), it follows that the whole Aristotelian metaphysical apparatus (of actuality and potentiality, the four causes, etc.) is also mistaken. That simply does not follow. Or they suppose that if an idea is not useful for the specific purposes of physical science, then it must not have any utility at all. Which also does not follow. Or they conflate a particular application of a metaphysical idea and the idea itself. For example, they suppose that if this or that medieval teleological analysis of some particular phenomenon is mistaken, then the whole idea of teleology itself is suspect.

The trouble is that when all of these fallacious arguments are exposed, there is very little if anything of substance left to the “science has undermined A-T” objection. The real issues are hardly even addressed. That, anyway, is what I have argued at length in places like my book Scholastic Metaphysics.

Divine Simplicity

You have also argued for the classical theistic doctrine of divine simplicity. How would you best explain this doctrine and why is it so important that both Christians and non-Christians understand this conception of God?

The doctrine of divine simplicity maintains that there is no composition of any kind in God – that is to say, that he has no parts. For example, he is not made up of physical parts like molecules and atoms, but he is also not made up of parts of any other kind, even of a subtle or metaphysical kind. He is not a mixture of actuality and potentiality, but rather is pure actuality. He is not composed of form and matter, nor is there in him any distinction between substance and attributes. He is not a member of a species that falls under a genus, and thus does not have some feature that would set him apart from other members of the species, or his species from other species in the same genus. He does not have an essence or nature distinct from his existence. And so forth.

One reason he cannot be composite in any of these ways is that anything that is composite requires a cause. For if a thing is made of parts of either a physical or a metaphysical kind, then there will have to be some principle distinct from it that accounts for how those parts come to exist together in the thing. For example, suppose that we accept the traditional definition of human beings as rational animals. Rationality and animality are not physical parts, but they are parts in the sense that there is no reason why they have to exist together. We need some account of how it is that rationality, which could exist apart from animality, and animality, which could exist apart from rationality, exist together in human beings. This is one reason why human beings require a cause. Now, if God were like that, then he too would require a cause. But of course, whatever else God is, he is not something which has a cause or could have a cause. If he had one, or even if he could in principle have had one, then he would not be the ultimate explanation of things. He would not really be God in the first place.

So, one of the things at stake where divine simplicity is concerned is the very ultimacy of God. That is why in the classical theological tradition – whether in the thought of pagan Aristotelian and Neo-Platonic thinkers, or Christians like Augustine, Anselm, and Aquinas, or Jews like Maimonides or Muslims like Avicenna – divine simplicity is consistently insisted upon. Without it, you simply do not really have theism at all, but implicitly reduce God to the status of at best a very impressive sort of creature. Very powerful and forbidding to be sure, but still essentially creaturely insofar as he requires a cause outside of him and is thus not ultimate, not absolutely necessary, and so forth.

How can divine simplicity be reconciled with the doctrine of the Trinity and the Incarnation of Christ? Many Muslim theologians would point to divine simplicity as a reason why the Trinity and the Incarnation cannot be true. It seems unnecessarily complicated and rationally dubious that these characteristics of the Christian God can be reducible to authentic unity.

Actually, I would say that the doctrine of divine simplicity makes doctrines like Trinitarianism more plausible, not less. All adherents of divine simplicity – Muslims no less than Christians – would agree both that God is non-composite but also that he has various attributes such as power, intellect, will, and so forth. Now, it famously follows from divine simplicity that in some sense God’s power just is his intellect, which just is his will, and so forth – even though in us, of course, power, intellect, will, etc. are distinct attributes. How can this be true? The right answer, in my view, is to be spelled out in terms of Aquinas’s doctrine of the analogical use of language. But whatever one thinks of that, the point is that all adherents of divine simplicity are committed to making some sort of distinctions where the divine nature is concerned, otherwise there would be no point in insisting on these different predications (of power, intellect, will, etc.). The question is just how to understand those distinct predications.

Now, if that is true, then it is hardly a stretch to think that we can make a distinction between three divine Persons despite divine simplicity. Of course, I do not mean to imply that the Persons are exactly on a metaphysical par with attributes like power, intellect, and will. But still, no one who is willing to affirm both divine simplicity but also that there is power, intellect, will, etc. in God has any right simply to dismiss Trinitarianism as obviously incompatible with simplicity.

The case of the Incarnation raises unique issues of its own, since in addition to the idea that the incarnate Son is a distinct Person from the Father, we have the added complication that the Son takes on a body, which has material parts and so forth. But of course it must be kept in mind that simplicity applies in the first place only to Christ’s divine nature, not his human nature. But the same thing is true of the other divine attributes. It is not obvious why simplicity is more problematic for the Incarnation than other divine attributes are.

Opponents of divine simplicity often claim that divine simplicity “philosophizes” God and makes him extremely different from the God described in the Bible. These critics say that Scriptures portray God as a personal God emotionally affected by humanity’s actions, temporally intervening in his creation, and expressing real, defined, and different characteristics. This seems like a far cry from the abstract, changeless, and emotionless God posed by classical theists. How do you reconcile these two portraits of God?

The trouble is that people who raise this sort of objection typically do not do so consistently. There are lots of anthropomorphic texts in the Bible that these critics would themselves never take literally. They would not say that God must have eyeballs and nostrils, since the Bible speaks of God seeing and breathing. They would agree that that would not be consistent with God’s being the creator of the material world, since he can hardly be the creator of something which he is part of. Now, in rightly drawing this conclusion they are “philosophizing” God. They are drawing philosophical conclusions from what the Bible itself implies.

But proponents of divine simplicity are doing the same thing. They are saying that if you take seriously the idea that God is the creator of everything other than himself — which is a biblical idea — then you are, if you follow that idea out consistently, going to arrive at divine simplicity, because if God were composite or non-simple than he would require a cause of his own. You are also going to have to say that God does not undergo emotional changes or any other changes, or experience any passage of time. For if he did, then he would have potentialities that are actualized when he changes or passes from one moment to the next. And in that case he would not be simple, but rather be a mixture of actuality and potentiality.

So, it is no use for the critic to thump the Bible and pretend that that is some sort of refutation of divine simplicity. Both sides are “philosophizing,” and cannot fail to do so since the Bible itself raises philosophical questions. So the dispute between them is only going to be settled philosophically, and not merely by citing proof texts.

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