Neo-Aristotelian Perspectives on Contemporary Science
edited by william m. r. simpson, robert c. koons, and nicholas j. teh
routledge, 352 pages, $140
n Raphael’s School of Athens depicts Aristotle and Plato at then center of a group of ancient Greek philosophers modeled on Raphael’sn contemporaries. Plato’s finger points upward, while Aristotle’s hand isn held at waist height, stretched out toward the ground. The image capturesn the major philosophical difference between the two great thinkers ofn antiquity: While Plato thought that real things (what he called then “forms”) lie outside our experience, Aristotle believed that real thingsn (which he called “substances”) are in the everyday world around us. This isn why so much of Aristotle’s work covers topics which would now be then subject of empirical science (animal biology, the weather, and so on). Withn his commitment to the reality of the ordinary things we experience and hisn tireless need to classify and taxonomize, Aristotle was in some ways then first systematic scientist of the Western world.
n Aristotle’s view that substances are the fundamental realities was putnforward in his difficult and influential work known as the Metaphysics. We owe the term “metaphysics” itself to Aristotle,n though in a rather indirect way. When his works were collected in then edition made by Andronicus of Rhodes in the first century b.c., then writings dealing with substance and causation were placed after his theoryn of nature, which appeared in the book known as the Physics (fromn the Greek word for nature, phusis). Hence, the work was describednas “what comes after the Physics,” from which we derive our word metaphysics. Yet this word has something of a philosophicaln justification, too, for while Aristotle’s Physics deals withn questions about time and change, the Metaphysics goes furthern (“after physics,” as it were) and asks about being as such. What does itn mean for anything to be?n
n Aristotle approaches this question by describing the nature of the mostn fundamental beings, those he called “primary substances.” His paradigm of an substance is an organism: an individual horse or human being. It isn crucial, then, that Aristotle’s word “substance” does not mean “stuff” (asn in “tar is a thick, black, viscous substance”). It means, rather, an fundamental being.n
n Primary substances are characterized by their essences. All beings can ben classified in terms of genera and species: Thus, human beings are of then genus animal, and the species rational. It is of then essence of human beings in general, then, to be rational animals. But whatn is it to be a primary or individual substance—say, an individual humann being? Aristotle argued that each individual substance was a kind ofn compound, made of matter organized in a certain way. The way in whichn something is organized he called its form. This is known as then“hylomorphic” view of substance, from the Greek hyle (matter) and morphe (form).n
n The form of an individual substance is the essence of the kind ofn substance, exemplified in an individual member of that kind. This is then crucial difference between the Aristotelian and Platonic conceptions ofn form. For Plato, the ordinary things we see around us are in some wayn imperfect versions of the real forms which lie outside experience. Then forms are not in the objects themselves; if anything, the objectsn approximate to their forms. Individual horses approximate to, orn participate in, or imperfectly resemble the “form of the horse.”n
n For Aristotle, by contrast, the form of a substance is in the substancen itself (in traditional terminology, it is immanent, rather thann transcendent). Moreover, the form explains the characteristic activity of an substance, as being in accordance with what it is ultimately for:n The form is the principle that governs the activity of a substance, thatn which explains why a substance does what it does. The goal of a humann being, for example, is to live a life of rational activity; somethingn having the essence of a rational animal will strive toward this goal. Thusn Aristotle’s theory of substance is sometimes called a “teleological”ntheory: It describes a substance in terms of its characteristic goal (telos in Greek).n
n It is a commonplace of the history of science and philosophy that thisn Aristotelian philosophy—which dominated the academic (or scholastic)n philosophy of the Middle Ages in the monasteries and universities ofn Europe—was overthrown by the Scientific Revolution of the sixteenth andn seventeenth centuries, a revolution embodied in the works of Galileo,n Francis Bacon, and René Descartes. Scholastics had thought of everything inn the world as having purposes and goals. The new philosophers of then Scientific Revolution conceived the world instead in terms ofn mathematically measurable mechanisms. Galileo famously spoke of “this grandn book the universe, which . . . is written in the language of mathematics,n and its characters are triangles, circles, and other geometric figures,n without which it is humanly impossible to understand a single word of it.”n The new mathematical or “mechanical” philosophy scorned the Aristoteliann philosophy of the scholastic period. Francis Bacon said that Aristotlen “made his natural philosophy a mere bond-servant to his logic, therebyn rendering it contentious and well nigh useless.” In other words, hisn philosophy of nature was a priori (prior to experience) and basedn purely on the concepts of things derived from logical classification.n Despite misrepresenting Aristotle’s own dedication to empirical inquiry,n this kind of criticism stuck. In the wider culture, the rejection ofn scholasticism was immortalized by the remark of the doctor in Molière’sn play The Hypochondriac, that opium puts us to sleep because it hasn a “dormitive virtue” (virtus dormitiva).
n This customary story of the Scientific Revolution and its rejection ofn Aristotelian scholasticism is incomplete and inaccurate in many ways. Notn all great philosophers of the period rejected Aristotelian thinking in itsn entirety. Gottfried Wilhelm Leibniz (1646–1716) criticized scholasticn philosophers who “believed they could explain the properties of bodies byn referring to forms and qualities, without taking the trouble to find outn how they worked: as if we were happy to say that a clock has an time-indicative quality deriving from its form, without considering whatn all that amounted to.” But despite this criticism, Leibniz said thatn Aristotelian substantial forms “are not so far from the truth, nor son ridiculous, as the common run of our new philosophers suppose.” Substancen and form could be used to explain the ultimate nature of things, Leibnizn believed, even if they are not needed to explain ordinary, everyday things,n like the time-keeping properties of clocks. It is also important ton remember that within the Catholic intellectual tradition, Aristoteliann ideas continued to be taught in universities and seminaries for centuriesn after the Scientific Revolution.n
n Nonetheless, Aristotelian metaphysics was largely absent from what might ben called (with apologies to the seminaries) mainstream philosophy fromn Descartes to the present day. Metaphysics took various forms between thennand now, but almost none of it involved Aristotelian notions of telos, form, or substance. The history of philosophy in then twentieth century is instructive. In English-speaking (“analytic”)n philosophy, the attitude to metaphysics—that is, to abstract,n non-scientific, or non-empirical speculation about the nature ofn reality—was dominated by the critique of the logical positivists of then pre–World War II Vienna Circle. These philosophers proposed thatn verifiability by empirical science was the measure of meaningfulness forn claims about the world. Metaphysical claims—including but not limited ton traditional Aristotelian claims about substance, essence, form, and son on—would be examples of the unverifiable. Metaphysics was dismissed asn outdated pseudoscience.
n Some logical positivists traced their inspiration from the philosophy ofn David Hume (1711–1776), who had proposed a division of claims into thosen that are “matters of fact” and those that involve only “relations ofn ideas.” Ordinary empirical claims are in the first category, whilen mathematics and logic are in the second. If some inquiry—Hume famously tookn “divinity or school metaphysics” as an example—fits into neither category,n then his advice was to “commit it then to the flames: for it can containn nothing but sophistry and illusion.” This sums up the logical positivists’n approach to metaphysics (and theology, for that matter).n
n Nonetheless, Hume had a metaphysics of his own—a rather austere one, but anmetaphysics nonetheless. His metaphysics denied that there was any necessity in reality at all: Things happen as they do not becausen of any necessity or essence or ultimate reason, but because they just do.n The world is a regular place; things happen in generally unsurprising ways;n but this is not an indication of any deeper necessity in nature.n Causation—what Hume called “the cement of the Universe”—is just a matter ofn the “constant conjunction” of things of similar kinds: Smoke always followsn fire, and so on. Defenders of Hume’s metaphysics called the summaries ofn these regularities “laws” and interpreted scientific laws asn generalizations of this kind. With the demise of logical positivism in then 1950s and ’60s, Humean theories of cause and law became the foundations ofn metaphysics in analytic philosophy. Indeed, if you had left the world ofn philosophy in the 1970s, you might have thought that Humean, empiricist,n science-based metaphysics was the only metaphysics worth taking seriously.n
n Things did not stay like this, however. Aristotelian metaphysics started ton return, and the volume under review is one of many books that have come outn in recent years defending Aristotelian views of causation, substance,n attribute, and even essence and form. How did this change come about? Andn how can Aristotelian metaphysics—which, if the standard history is to ben believed, was rejected on the basis of discoveries of modern science—ben part of a serious, scientific worldview? How can serious thinkers proposen “neo-Aristotelian perspectives” on contemporary science? John Haldane, inn the preface to Neo-Aristotelian Perspectives, poses the challengen by asking why this project isn’t like “astrological perspectives onn astronomy.”
n The first factor in the rebirth of Aristotelianism came from an unexpectedn place: formal logic, in particular the logical theories developed in then 1960s and ’70s by Saul Kripke, one of the great philosophers of the laten twentieth century. A teenage prodigy, Kripke developed a way to understandn the logic of possibility and necessity (so-called “modal logics”), whichn led to certain natural metaphysical interpretations. Philosophers hadn talked for some time in terms of necessary truth as truth in all possiblen worlds. Kripke introduced a precise way of formulating this idea, andn pursued its interpretation into a metaphysics of essence and necessity. Onen central idea was that if we want to make sense when we say that somethingn is necessarily such and such (for example, that a person is necessarilyn human), we should think of this as a feature that it has in all possiblen worlds in which it exists. But if this is the right way to think, then wen must also be able to identify the same individual in these differentn possible worlds. And in order to do this, there must be something about itn which makes it the individual it is in each of the worlds in which itn exists. And what is this but its essence?n
n Kripke extended the idea of essence beyond individuals to kinds of things,n such as gold and water. We can imagine that gold might have a slightlyndifferent color, for example, but what makes it the case that it is gold we are imagining, rather than something that is rather liken gold in certain respects? Kripke argued that to identify gold in differentn possible situations requires that gold have an essence. He proposed thatn the essence of an element is its atomic number, so gold is essentially then element with the atomic number 79. The details do not matter here; what wasn important was the idea that the world has a natural order, an order whichn is neither imposed by our interpretation nor just the order of Humean lawsn of nature. Human beings discovered that water is H2O; we did notn invent this fact. What we were discovering, Kripke and his followersn argued, is not just a law or regularity: It is rather the essence of then natural kind water. These ideas are clearly Aristotelian in inspiration.n
n Essences are, of course, anathema to Humean metaphysics and to then post-positivist philosophy of W. V. Quine and his followers (Quine himself said that Aristotle’sn distinction between essence and accident is “surely indefensible”). Butn armed with Kripke’s logical and metaphysical framework, people could defendn essence against the Quinean critique. More recently, self-identifiedn Aristotelians such as Kit Fine have argued that the natural order of then world requires that certain things are more fundamental than others, andn that fundamental things stand in a relation to non-fundamental things thatn can be called “grounding.” For example, the United Nations genuinelyn exists; it is an entity, but no one would claim it is a fundamental entity.n The United Nations is made up of entities, nations, which perhaps have moren of a claim to be real, and these things themselves are made up of entities,n human beings, which an Aristotelian would call substances. It is assertedn that the less fundamental entities can be grounded in the being andn activity of more fundamental entities. (In the volume under review, Robertn Koons discusses grounding in the context of an Aristotelian philosophy ofn physics.)n
n The second area of philosophy in which Aristotelian ideas has returned isn the philosophy of causation (or causality): the study of cause and effect.n According to Hume’s influential conception of causation, “all events seemn to be entirely loose and separate.” There is no necessary connectionn between distinct existences. Yet Humeans always had trouble with causaln relations that were a result of so-called “dispositional” properties:n solubility, fragility, and so on. These are properties that are describedn in terms of the effects that their possession is “disposed” to bringn about—dissolving, breaking, etc. How can all events be “loose and separate”n if some events (such as dissolving) seem to be essentially orn metaphysically connected to their causes (solubility)?
n Humeans have responded by arguing that such dispositionality is not a realn feature of the world, but only an artifact of our description of it. Whatn causes dissolving is the interaction between certain events (being put inn water, say) and the “structural” or “categorical” properties of thingsn (molecular structure, and so on). And these interactions are covered byn laws of nature, as per the usual Humean theory of causation. Defenders ofn dispositions push back against this: How do we actually specify thesen supposed “structural” properties? Isn’t structure partly characterized inn dispositional terms (for example, in terms of the ability to resistn pressure at various points)?n
n This line of thought can be supported by looking closely at what the lawsn of nature actually say. Many laws of nature characterize the properties ofn things in terms of the effects that an object’s having these propertiesn lead to. For example, Newton’s second law of motion defines the forcen exerted on a body as the product of its mass and its acceleration (forcen equals mass times acceleration or f=ma). Defenders of the realityn of dispositions argue that this law can be understood as a definition ofnwhat, say, an object’s mass—one of its properties—really is: It is a disposition to accelerate under a given force, inn accord with that equation. So rather than just describing a mere regularityn between “loose and separate” existences, as the Humeans say, laws liken Newton’s should be understood as defining the nature of properties in termsn of their characteristic effects—that is, in dispositional terms.n
n This kind of challenge to the Humean view led to the development ofn sophisticated theories of properties understood as “causal powers.” Thisn terminology was introduced in an influential book by Rom Harré and E. H.n Madden in 1975, and the basic idea has been developed more recently inn various ways by George Molnar (Powers, 2003), Stephen Mumford andn Rani Lill Anjum (Getting Causes from Powers, 2011), and Annan Marmodoro (The Metaphysics of Powers, 2010). Marmodoro is one ofn the recent philosophers who have brought out most explicitly then Aristotelian roots of the powers-dispositions view of causation, linkingn it to Aristotle’s famous discussions of potentiality and actuality. Hern work is well represented in the volume under review by an essay (cowrittenn with Christopher Austin) linking the notion of potentiality with then concept of the unity of an organism. In an interesting and complementaryn discussion, Janice Chik Breidenbach’s essay defends the Aristotelian viewn that substances themselves can be causes (it was the horse that knockedn down the gate, not just some event involving, for instance, the horse’sn legs). And Humeanism in metaphysics as a whole is discussed in Williamn Simpson’s essay on why dispositions cannot be fully or properlyn accommodated within a Humean framework.n
n A third important factor in the revival of Aristotelian metaphysics comesn from the development of the philosophy of science itself. Again, then crucial immediate historical precursors were the logical positivists andn those influenced by them. The logical positivists had seen scientificn theories as aiming at the statement of laws of nature which were as generaln and exceptionless as possible. The paradigm was physics: Laws such asn Newton’s aim to state the most general truths about how the universen behaves. According to the positivists, the fact that Newton’s laws are notn actually true should not be blamed on their claim to generality. Rather,n these philosophers looked to replace these laws with laws that were equallyn general. This idea—science aims at laws, and laws should be regarded asn statements that are as general and exceptionless as possible—came undern critical scrutiny in work from the 1970s and ’80s. This work emphasized then partial, local nature of scientific theory, the importance of modeling inn science, and the unrealistic character of the positivists’ description ofn science as a list of statements of universal laws. An influential figuren here is Nancy Cartwright, who gave an alternative description of science inn terms of the measurement of “Nature’s capacities.” Rather than beingn something of which one single scientific story could be told—in a “theoryn of everything,” as it were—the world is, in Cartwright’s image, irreduciblyn “dappled.” It is made up of a plurality of different kinds of things, aboutn which there is no one fundamental account, only separate accounts forn separate kinds of things and their various capacities. This is clearly ann Aristotelian picture, as Cartwright herself acknowledges, with its emphasisn on capacities (a notion closely related to that of a power or disposition)nand on things being of different kinds. In Neo-Aristotelian Perspectives, Xavi Lanao and Nicholas Tehn apply some of Cartwright’s ideas to argue that even classical mechanicsn does not conform to the “fundamentalist” picture of science criticized byn Cartwright.
n To these factors must be added a fourth factor, which is often notn explicitly credited as an influence on the present rebirth ofn Aristotelianism: the influence of Catholic philosophy and its own resilientn metaphysics. It will not be news to readers of this journal that Catholicn seminaries and universities continued to teach Thomistic philosophy (itselfn a form of Aristotelianism), and leading Thomist (or Thomism-inspired)n philosophers such as Bernard Lonergan have had a wide influence, albeit onen which rarely made contact with mainstream metaphysics in the twentiethn century. Yet the revolt against the dominant Humean metaphysics in recentn decades has led to more dialogue (and even collaboration) between Catholicn and what I am calling mainstream philosophy. The present book is a goodn example. Many of the contributors are Roman Catholics—some knownn independently for their work in the philosophy of religion—and some teachn at Catholic universities in the United States. Their Catholicism playsn little direct role in their actual philosophical contributions to thisn volume, but it provides the intellectual framework within which many ofn these thinkers work.n
n One way in which Thomistic metaphysics influences the rest of philosophy,n for example, is in the question of the soul and its relation to the body.n It is easy to see why this should be such an important question forn Catholics. The traditional Thomistic view, drawn from Aristotle, isn hylomorphic: The soul is the form of the body’s matter. For Aristotle, anyn substance (like a human being) is a compound of form and matter; the mattern cannot exist without the form, and the form cannot exist without then matter. In the current volume, William Jaworski gives a clearn interpretation of how this view of the human being might “leave itn unmysterious how thought, feeling and perception can exist in the naturaln world.” Another important area where contemporary hylomorphists apply theirn ideas is the philosophy of biology, exemplified here in fine essays byn David Oderberg and Daniel De Haan.n
n I hope that these largely historical considerations begin to clarify whyn Aristotelian philosophy (in particular, metaphysics) has returned. But In hope they also show how Aristotelian metaphysics can be scientificallyn defensible. Remember that the worry was that the Scientific Revolution ofn the sixteenth and seventeenth centuries saw Aristotelian philosophy asn unscientific—in a sense, the traditional view is that science as an systematic attempt at genuine explanation only began with the rejection ofn Aristotelianism and scholasticism.
n But it should be noted that these are philosophical claims, not scientificn ones. Like the positivists’ claim that only what can be verified can ben genuinely meaningful, or the “scientistic” claim that science can explainn everything, these are not claims made within scientific theoriesn themselves. Indeed, metaphysical claims—about substance, cause, change,n potentiality, etc.—are very rarely settled by the content of scientificn theories. If you are interested in how change is possible, you will notn look to physics or chemistry. Physicists and chemists presuppose thatn change is possible and then go on to talk about the specific nature ofn specific changes. Similarly, physics and chemistry do not settle then question of whether the physical world is all there is; that question mustn be left to metaphysics.n
n Although science is not itself metaphysics, metaphysics of science isn unavoidable. Once we start theorizing at a certain level of generality, wen cannot escape metaphysical commitments. For example, if we ask what kind ofn entities physical theories are committed to, we may have to answer in termsn of traditional categories such as substance, property, object, process—orn specify some new categories. This does not mean that physicists must ben metaphysicians, only that if they enter into metaphysical speculation, theyn should acknowledge that others have been there before them, and that then questions are not easy. For example, in attempting to argue that a causaln connection exists between some phenomena, it is common to find scientistsn saying “correlation is not causation”—and they are right. But what isn causation, then, and how does it differ from mere correlation? Answeringn this requires metaphysics. Those philosophers and scientists who dismissn metaphysics, often casually and without much argument, have to demonstraten how they can do this without doing metaphysics themselves. I predict thatn they will not be able to do this. Even the logical positivists hadn metaphysical assumptions.n
n The lesson of this is that seventeenth-century science did not prove thatn Aristotelian metaphysics failed—this was simply a claim made byn philosophers. Whether science requires specific metaphysical assumptions orn not is itself a metaphysical debate, which requires knowledge of sciencen but is not settled by it. Aristotelian metaphysical categories—substance,n form, capacity, essence—can be intelligibly applied to the findings ofn science. Or, at least, there are no scientific arguments against this.n This is why Neo-Aristotelian Perspectives on Contemporary Sciencen is not analogous to neo-astrological perspectives on contemporaryn astronomy.
Tim Crane is professor of philosophy at the Central European University.
