Is St. Thomas’s Aristotelian Philosophy of Nature Obsolete?

By C. Robert Koons

“The Analytic Thomist,” Rob Koons, delivered the 2021 Aquinas Lecture at the University of Dallas. Here he engages the possibility of a bridge between philosophy and metaphysics proper. Koons boldly lays out his position: without Aristotelian metaphysics, there is no Aristotelian philosophy of nature, and there is no philosophy of nature in Aristotle without acknowledging his natural science. His lecture thus challenges Thomists and their respective approaches to hylomorphism and their all too frequent quickness to discard it. (Koons lays down the gauntlet. if one denies hylomorphism there can be no transubstantiation!) 
       A bonus addition to this volume in the Dallas lecture series is Koon's “Aristotle, god and the Quantum.”   

• Language: English
• Publisher: St. Augustines Press
• Release date: Aug 12, 2022
• ISBN: 9781587314339

Book preview

Introduction

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Quantum mechanics is one of the most successful theories in the history of science. In some form, it is here to stay. The discovery of the quantum in the early twentieth century has transformed our understanding of the natural world in ways that few have fully grasped. In fact, the quantum revolution is a wholesome development from a theological perspective, reconciling our scientific view of the world with the possibility of human agency.

The Greek philosopher Aristotle (382–322 BC) had a theory of nature that offered a number of advantages from the viewpoint of both humanism and biblical theology. While Aristotle recognized a profound difference between human beings and other substances, based on our unique rationality, he avoided Platonic dualism, and he conceived of human aspirations as continuous with the striving of all natural things to their essential ends, providing an objective basis for norms in ethics, aesthetics, and politics.

Aristotelianism has undergone a great revival in the intervening 40 years, with Aristotelian approaches to ethics, both in terms of virtue ethics (e.g., Alasdair MacIntyre and John McDowell) and in the natural goodness theories of Philippa Foot and Michael Thompson, and with stalwart defenses of Aristotle’s approach to science by David Charles, James Lennox, Michail Peramatzis, and others. Hylomorphism of a sort has gained wide acceptance in contemporary metaphysics.

Is Aristotelian Natural Philosophy Necessary?

But this revival would seem to be ill-fated unless we can somehow overcome the challenge from modern science. Aristotle’s hylomorphism, his theory of form and matter, appears both in his Physics and in his Metaphysics. It is a theory that bridges the divide between the philosophy of nature and metaphysics proper. So, we must ask two questions: can we have an Aristotelian metaphysics (a theory of being as such) without an Aristotelian philosophy of nature? And can we have an Aristotelian philosophy of nature without Aristotelian natural science? Many Thomists in the twentieth and twenty-first centuries have answered Yes to one or both of these questions, but I believe that the right answer to both is, No.

Those who answer Yes to the first question defend a position we could call Aristotelianism without hylomorphism. And those who answer Yes to the second question I call Aristotelian quietists. Quietists insist that we must adopt both an Aristotelian metaphysics and an Aristotelian philosophy of nature but insist that this twin adoption has no implications for the practice of the sciences. Consequently, Aristotelian natural philosophy becomes unfalsifiable, justified by common human experience in a way that cannot be unseated by scientific discoveries.

I want to argue for two claims: first, that the theological and philosophical consequences of both anti-hylomorphism and quietism are quite devastating. And, second, that a re-conceiving of contemporary natural science in Aristotelian terms is not only possible but desirable.

Let’s consider briefly the consequences of deleting hylomorphism from Aristotelianism, for that matter.

I will mention just two typical examples.

First, transubstantiation. If bread and wine are not hylomorphic, then no instance of bread or wine is essentially bread or wine. They are simply congeries of elementary particles, which are at certain times accidentally so arranged as to constitute bread or wine. When Jesus says, this is my body, He is therefore referring to the particles, and so it would be the particles that are turned into His Body and Blood. Since these elementary particles never corrupt (at least, not within the time frame of billions or trillions of years), it would follow that transubstantiation is practically irreversible, which would lead to many absurdities in practice.

In addition, elementary particles don’t have accidental intrinsic properties, only accidental arrangements in space. Hence, there are no properties that could be sustained in the Host after transubstantiation, and so the appearances of the Host (color, shape, taste, etc.) would have to be mere illusions.

Second, the human soul and body. If nature is not hylomorphic, then the human body consists of a large number of elementary particles arranged accidentally in space. The human soul cannot be responsible for the existence or character of these particles, since they are not (in this epoch) capable of generation, corruption, or intrinsic alteration. Consequently, the human soul cannot be the formal cause of the body. So, what can the relationship be between soul and body? It must be something like efficient causation only—the soul is merely a motor that moves particles in some extra-physical manner. If so, the body is extrinsic to the soul, and thus the human being consists entirely of the soul alone, with the body as an accidental accoutrement. Abandoning hylomorphism means falling into Cartesian dualism and angelism.

To summarize: if we want a non-dualistic anthropology and a Catholic account of the Eucharist, we need an Aristotelian philosophy of nature.

So, hylomorphism seems to be non-negotiable for Catholics. Can we have a hylomorphic philosophy of nature while accepting an anti-Aristotelian natural science? The quietist strategy typically follows Jacques Maritain in distinguishing natural philosophy from what he called empiriological science. On this picture, our natural philosophy must be hylomorphic, but natural science need not be, because the methods or aims of the two are disjoint. Personally, I don’t think that the methodological and epistemological distinctions between ancient natural philosophy and modern natural science are in fact clear or deep.

Aristotelian natural philosophy is and always has been empirical in nature. It’s certainly not strictly a priori in the Kantian sense. It also seems to me a mistake to think of Aristotelian natural philosophy as entirely deductive in nature. It is scientific explanations that are deductive, both for Aristotle and for modern science, explanations that occur within a mature science, a science whose discovery is empirical. It is true that Aristotelians add to the empirical side of the epistemology of the science the indispensable role of Noûs or understanding, that faculty by which we recognize that we have arrived at a true account of nature. But, given the under-determination of theory by all possible data, every realist epistemology must have some counterpart to Noûs, a faculty that enables us to choose wisely and reliably among multiple, empirically equivalent theories.

Did Aristotelian natural philosophy aim for a kind of certainty that natural science eschews? I don’t see much of a difference here. Many of Aristotle’s proposed principles and definitions are clearly tentative, and many of the conclusions of modern science are certain beyond a reasonable doubt.

There does seem to be some difference in aims, however. Aristotelian natural philosophy sought to find the definitions of substantial essences and accidental quasi-essences, while the modern natural sciences aim at the discovery of simple, mathematical laws. But are these really two different ends, or simply the same end conceived in two different ways? There is certainly a deep difference between Aristotelian natural philosophy and natural science as conceived of by logical positivists, neo-Humeans, instrumentalists, and pragmatists, but these are erroneous modern theories about modern natural science, not to be identified with modern science itself. Maritain’s suggestion that empiriological science was a different genus of inquiry made sense during the heyday of logical positivism, but few philosophers of science today would agree that the aim of natural science is simply to produce useful summaries of empirical observations. According to philosophers of science today, modern science shares Aristotle’s ambition of explaining natural phenomena in terms of the real essences of things.

In any case, I want to focus here on the first-order description of nature and put aside methodology and epistemology. What would an Aristotelian natural philosophy look like, if it renounced forever the need to be informed by detailed and progressive empirical inquiry? Charles De Koninck gives us some idea. In his 1934 book, Le Cosmos, De Koninck (De Koninck 1934) suggested that there are just four philosophical species: man, animal, plant, and the inorganic. This would mean that all inorganic substances would share exactly the same nature (or essence). A nature is, for Aristotle, the principle of change and rest, the ultimate foundation for all explanations of natural phenomena. How could rocks, lakes, clouds, beams of light, scatterings of neutrinos, plasma, black holes all share exactly the same nature? And if, as De Koninck admits, inorganic substance is defined negatively, as the absence of life, how can such a negative definition provide any inorganic things with a real nature at all?

How can such generic forms provide inorganic substances with per se unity? How can they distinguish one inorganic substance from another? It seems that they cannot, in which case we would have to conclude either that all of inorganic nature constitutes one gigantic substance, or that every fundamental particle constitutes a separate substance. But this will make the emergence of living things utterly mysterious, requiring them to corrupt the naturally incorruptible in order to secure their own matter.

It seems that by philosophical species de Koninck must mean something very different from what Aristotle meant. When we turn to human beings, the result would be that human nature would have to be similarly amorphous and plastic. Sexual reproduction and our sexual identities, for example, would be contingent accidents of human beings, and not essential to us, since they follow neither from our rationality nor from our animality as such. This would render Thomistic deductions of the secondary principles of natural laws, such as those governing sexual conduct in the Secunda Secundae Partis or the Summa Contra Gentiles, unsound.

Is Aristotelian Natural Philosophy Concordant with Modern Science?

What we must have is an Aristotelian philosophy of nature that is informed by and so accountable to detailed empirical investigation. Our natural philosophy should be continuous with our natural science, albeit at a higher level of generality and a deeper level of philosophical explanation. This does inevitably entail that Aristotelian natural philosophy (and so, ultimately, Aristotelian metaphysics) is in principle falsifiable, or at least subject to disconfirmation, by empirical results. Now, I think this is a plus, rather than a minus, since it provides an antidote to the temptation of apriorism in philosophy. And, as it turns out, natural science has not falsified Aristotelian natural philosophy—in fact, it provides strong empirical support for it, especially after the quantum revolution of the early twentieth century.

It is true, that in the so-called classical physics and chemistry of the period from Galileo-to-Rutherford, the appearances seemed to be against hylomorphism. If the ambitions of the physicalists and materialists of this period had been realized—if all natural phenomena could have been accounted for in terms of the locomotion of uniform, unqualified matter, then the framework of hylomorphism would have had no purchase.

But we must distinguish between aspiration and achievement. The physicalists aspired to make substantial form superfluous, but they did not in fact succeed in doing so. The introduction of gravity by Newton and of electromagnetic charge by Maxwell completely undermined the Democritean uniformity of matter that Galileo, Descartes, Boyle, and Hobbes had hoped for. The discovery of atomic elements and of elementary particles restored Aristotelian species and their definitions to the center of scientific theory. And natural science never achieved a complete reduction of chemical and biological kinds to facts about the movement and arrangement of physical particles. Chemists and biologists continued to appeal to the enduring natures of compounds and organisms in their scientific explanations of the phenomena.

Thus, the conflict was never between hylomorphism and modern science, but rather between hylomorphism and a certain philosophy of science—we might even call it an ideology of science (in Marx’s sense). This ideological ambition was to make fundamental physics play the role of the queen of sciences. But this ambition was never in fact realized, and it crashed catastrophically into the brick wall of quantum phenomena.

The quantum revolution of the last 100 years has transformed the image of physical and chemical nature in profound ways that are not yet fully understood by philosophers or physical scientists. The new image of nature has in fact revived Aristotelian modes of understanding across a wide swath of scientific disciplines, a transformation that has occurred spontaneously and almost without being noticed. As the neo-Aristotelian framework begins to take shape and to rise to the level of common knowledge, thereby influencing our metaphysical imagination, our understanding of our shared human nature and of our place in the cosmos will improve in ways that are quite concordant with classical Christian