3 Unsolved dilemmas: the concept of matter in the history of philosophy and in contemporary physics

Philip Clayton
By the end of the modern period, a particular world view had become firmly entrenched in the public understanding. Unlike most philosophical positions, which are sharply distinguished from scientific theories, this world view was widely seen as a direct implication of science, and even as the sine qua non for all scientific activity. For shorthand, let’s call this view “materialism.”
Materialism consisted of five central theses:
(1) Matter is the fundamental constituent of the natural world.
(2) Forces act on matter.
(3) The fundamental material particles or “atoms” – together with the fundamental physical forces, whatever they turn out to be – determine the motion of all objects in nature. Thus materialism entails determinism.
(4) All more complex objects that we encounter in the natural world are aggregates of these fundamental particles, and their motions and behaviors can ultimately be understood in terms of the fundamental physical forces acting on them. Nothing exists that is not the product of these same particles and forces. In particular, there are no uniquely biological forces (vitalism or “entelechies”), no conscious forces (dualism), and no divine forces (what came to be known as supernaturalism). Thus materialism implied the exclusion of dualism,1 downward causation (Bøgh Andersen et al., 2000), and divine activity.2
(5) Materialism is an ontological position, as it specifies what kinds of things do and do not exist. But it can also become a thesis concerning what may and may not count as a scientific explanation. When combined with a commitment to scientific reduction, for example, it entails that all scientific explanations should ultimately be reducible to the explanations of fundamental physics. Any other science, say biology or psychology, is incomplete until we uncover the laws that link its phenomena with physics. In its reductionist form – which historically has been its most typical form – materialism thus excludes interpretations of science that allow for “top-down” causation, also known as “strong emergence.”3 Materialists may be divided on whether, and if so how soon, these reductions will actually be accomplished. Still, it is an entailment of materialism in most of its modern forms that an omniscient knower would be able to reduce all higher-order phenomena to the locations and momentums of fundamental particles.
In the following pages I argue that we have both philosophical and scientific reasons to doubt the adequacy of this widely accepted doctrine of materialism. In the history of Western philosophy, as we will see, it has turned out to be notoriously difficult to formulate a viable concept of matter. And physics in the twentieth century has produced weighty reasons to think that some of the core tenets of materialism were mistaken. These results, when combined with the new theories of information, complexity, and emergence summarized elsewhere in this volume, point toward alternative accounts of the natural world that deserve careful attention and critical evaluation.

3.1 The concept of matter in the history of philosophy

A strange dynamic emerges when one begins to study the history of the concept of matter in Western philosophy. It appears that, each time the greatest systematic philosophers have attempted to define it, it has receded again and again from their grasp. The very philosophers who claim to offer a resolution of the conceptual problems and a synthesis of opposing schools – Plato, Aristotle, Thomas Aquinas, Descartes, Leibniz, Hegel, Whitehead – repeatedly fail to supply a substantive concept of matter, leaving the reader each time merely with lack, or privatio: nothing instead of something. When one adds the recurring paradoxes that arise within philosophical theories of matter to the developments in physics sketched in the following section, one begins to wonder whether there is something fundamentally flawed in the idea of a world built up out of matter.
Although the description just given applies to a whole series of philosophers in the West, it fits the philosophy of Plato with particular accuracy. Plato inherited a rich tradition of natural philosophy developed during the pre-Socratic period. Numerous philosophers had developed divergent accounts of what could be the arch, or ultimate principle, which for many amounted to an account of the nature and properties of matter. Thus for Thales all was ultimately water; for Empedocles it was the four elements of earth, air, fire, and water; for Parmenides, the logos, or reason; and for Heraclitus, the principle of change itself (“you can never step into the same river twice”). Plato realized that this diversity of incompatible positions confronted philosophy with a series of dilemmas: Is everything part of a single unity, or does “the many” represent the ultimate truth? Is change real, or is it illusory? What unifies the diversity of appearances? As is well known, Plato found his solution in the doctrine of the “Forms.” What is ultimately real is the eidos: the idea of a thing. These ideas exist in a purely intellectual realm and serve as the patterns or exemplars after which all existing things are modeled. This object is a tree because it participates in the form of treeness, and that is a just state because it participates in the form of justice.
However, Plato’s theory had an unfortunate consequence, for it implied that the material world must be in some sense illusory. What is ultimately real are the forms; hence, to the extent that a form is embodied, it becomes less real. Thus, in the famous illustration of the divided line at the end of Book 6 of the Republic (Plato, 2000, 509d–513a), the further one descends from the realm of the forms, the less reality is possessed by the objects one encounters. They represent doxa, or mere opinion. The Myth of the Cave at the beginning of Book 7 likewise shows that the “knowledge” we think we have in the realm of matter is illusory. Reality only truly emerges when one ascends to the realm of the forms. In Plato’s myth, this is the world above ground as seen in light of the sun, which presumably stands for the form of the Good (ibid., 514a–529a).4 Conversely, the movement downward from intellect to matter is simultaneously a movement from knowledge to “mere opinion” and from reality to illusion.
Aristotle, a one-time student of Plato’s, was disturbed by the implication that matter might just be an illusion. At first it seemed as though his philosophical system had solved the problem. For Aristotle, each existing object was in fact a “unity” of form and matter. Hence his metaphysical proposal is known as “hylomorphism,” from the Greek hyl (“matter”) and morph (“form”). Matter was supposed to answer Plato’s unsolved problem: What is it that changes or becomes? As Mary Louise Gill shows in her classic study, Aristotle’s concept of matter lies “at the intersection of [his] theory of substance and his theory of change” (Gill, 1989, p. 3).
Matter is “that from which a product is generated that is present in [the product], as the bronze of a statue and the silver of a bowl” (Aristotle, 1934, II.3, 194, 23–26). Aristotle believed that postulating this matter as a metaphysical ultimate would allow him to explain what makes this particular object what it is:
What is the cause of the unity of the spherical and the bronze? Indeed the difficulty disappears because the one is matter, the other form. So what is the cause of this, of something in potentiality to be in actuality, except the maker, in the case of things [for which] there is generation? For there is no other cause of the sphere in potentiality being a sphere in actuality, but this was the essence for each.
(Aristotle, Metaphysics Z, 1933, 1945a, pp. 25–33)
Gill comments, “According to the account of composites in Z, matter like bronze is a distinct subject to which the spherical shape belongs. Thus, the shape is in the bronze, as this form in this matter … The problem of unity for material composites is, one must specify two distinct things – the matter and the form” (Gill, 1989, p. 142).
The problems begin to arise when one seeks to understand what this matter is actually supposed to be. Aristotle never succeeded in developing a systematic theory of matter, and additional postulates are required to make his scattered comments consistent. Freudenthal notes in his work on Aristotle’s theory of material substance:
[I]n [his] theory of matter there is no “necessitation from below”: Aristotle’s matter does not organize itself spontaneously into structured substances such as living beings. But, obviously, forms emerge in matter – living beings come to be … It follows that the account of structures existing in the material world cannot be given within the framework of Aristotle’s sole theory of matter, and so must involve additional explanatory postulates.
(Freudenthal, 1995, p. 2)
In fact, the problem is worse. In Aristotle’s system, whenever some thing is differentiated from other things – whenever it is this rather than that – it is distinguished thanks to its form. Pure matter, then, must be purely undifferentiated stuff. Matter is the hypokeimenon , that which lies beneath (cf. the Latin subjectum); it is what takes on all the properties of the thing without itself having any intrinsic properties. But if it has no form and properties of its own, it cannot be directly grasped by reason. Matter as hypokeimenon stands closer to the idea of khôra (“receptacle”) in Plato’s Timaeus (1965) – the container or space in which something else takes place.5 Matter is that unknown which, when combined with form, produces this or that specific object. But taken by itself it is completely unknown, mysterious. Matter is that which forever eludes the grasp of the philosopher. (Perhaps this embarrassing consequence of Aristotle’s philosophy has something to do with the fact that, when experimental natural science started to emerge in the early modern period, it found itself forced to break free from the strictures of Aristotelian natural philosophy and to begin again on a different basis.)
Predictably, during the many centuries dominated by Platonism, the same difficulties arose that we noted above. Plato’s great disciple, Augustine, faithfully passed the Platonic view of matter into the tradition of Christian philosophy, where it remained dominant in the West for the next 1000 years. Both matter and evil represented a privation of being or goodness (privatio boni) rather than positive principles in their own right. Even Plotinus, the great mystical philosopher who sought to synthesize Plato and Aristotle in the third century, continued the tradition of locating essential reality at, or above, the level of intellect. For him, as for the Gnostic religious philosophies of the Hellenistic period, matter was that from which one must flee in order to experience salvation or liberation – or knowledge. A similar idealist strain continued to dominate through the long history of Neo-Platonism in the West.6
Aristotle’s old problem was repeated in the work of Thomas Aquinas in the thirteenth century. In contrast to the Platonic theologians, Aquinas sought to affirm the empirical world and to take seriously the creation of a material world by God. Following Aristotle, he viewed objects as a combination of form and matter. At first it looked as though Aquinas was able to offer a more adequate theory of matter than Aristotle because his theology allowed for the possibility that God created the matter of the universe ex nihilo. One might expect that the creation of the world by God would lend matter a more solid existence and assure its ontological status.
However, Aquinas, later baptized as “the theologian” of the Catholic Church, failed to solve the conundrum of matter. Since God, the ultimate definer of Being (esse ipsum), is pure Spirit, not embodied in or dependent upon matter in any way, the relation of matter to God as its ultimate source remains a dilemma. How could God create something essentially different from himself? (The relation of God to evil remains equally puzzling, again suggesting the parallel that we noted in Augustine: matter evil.) The problem is reiterated in Aquinas’s anthropology: the essence of the human person is the soul, which is each person’s “form” or essence. If the person is to be complete, his or her soul must be reunited with the body after death. Yet the nature of this matter, which is somehow supposed to be necessary for full existence, remains unthought. To the extent that Aquinas’s theology came to supply a normative framework for much of subsequent Christian theology, especially in the Roman Catholic tradition, his inadequate answer to the problem of matter continues to influence Western thinkers to the present day.
René Descartes, the so-called “father of modern philosophy” in the West, at first seemed to make progress on this ancient dilemma. In his Meditations of 1640 (Descartes, 1968–1969), he insisted that there are two ultimate kinds of substance: res cogitans, or “thought,” and res extensa, or “matter.” As the text proceeds, however, it gradually becomes clear that, although Descartes has guaranteed matter a clear ontological status, its role remains subordinate to thought. The essence of the person is the mind or consciousness, which stands in an absolute contrast to the body. Thus Descartes writes in the Discourse, “I knew I was a substance the whole essence of which is to think, and that for its existence there is no need of any place, nor does it depend on any material thing, so that this ‘me’, that is to say the soul … is entirely distinct from the body” (ibid., p. 101). Or, in his most pithy expression, “I exist and am not a body; otherwise, doubting of my body I should at the same time doubt myself” (ibid., p. 319).
Descartes could never solve the problem of the interaction of mind and body because he had defined them at the outset as two diametrically opposed substances with no common ground.7 Faced with this sort of ultimate dichotomy, all that remains is to center one’s philosophical system on the one or the other. Descartes, still deeply influenced by the disembodied God of Western theism, made the (for him) obvious choice and placed all value upon the side of mind, will, and rationality.
Gottfried Wilhelm Leibniz represents a particularly interesting instance. His metaphysical theories were highly influential, and through his disciples Wolff and Baumgarten remained dominant in European thought until the time of Kant. Leibniz was deeply intrigued by the development of mechanistic physics in the seventeenth century and contributed to its development in a major way through the invention of the differential calculus. His philosophy of infinitely divisible particles would, he believed, provide a metaphysical platform for unifying this new physics with the Western metaphysical tradition, and with Christian theology in particular. This meant, however, that Leibniz had to show how the resulting universe could be created and ruled by God, could be purposive and meaningful, and could be compatible with the perfect goodness of its omnipotent Creator. With this goal in mind, he defined the existence of individual atoms or “monads” as purely mental sources of activity:
The Monad, of which we will speak here, is nothing else than a simple substance, which goes to make up composites; by simple, we mean without parts … There is nothing besides perceptions and their changes to be found in the simple substances. And it is in these alone that all the internal activities of the simple substance can consist.
(Leibniz, 1992, pp. 67, 70)
In his lengthy correspondences, Leibniz tried to work out an adequate theory of matter. Taken all together, he argues, the “simple substances” produce the behaviors in the world that physicists study. But individually, each one is as we are: a center of intellectual activity, will, and understanding. Cells and electrons may possess much less understanding than we humans do, but they are mental agents nonetheless. Further, each monad is “windowless,” which means that it does not actually perceive its surrounding particles and is not influenced by them in any way:
In a way, then, we might properly say, although it seems strange, that a particular substance never acts upon another particular substance nor is it acted upon by it. That which happens to each one is only the consequence of its complete idea or concept, since this idea already includes all the predicates and expresses the whole universe … There is also no way of explaining how a Monad can be altered or changed in its inner being by an other created thing, since there is no possibility of transposition within it, nor can we conceive of any internal movement which can be produced, directed, increased or diminished there within the substance … The Monads have no windows through which anything may come in or go out(Leibniz, 1992, p. 25, 68).8
The entire appearance of a smoothly running machine that the universe possesses is the product of a “pre-established harmony,” for which God must be given the credit.
Nicholas Jolley,9 a well-known Leibniz scholar, thinks that it is obvious that Leibniz in the end reduces what we call matter to a merely epiphenomenal property of the monads. He cites a passage from a letter Leibniz wrote to De Volder: “I do not really eliminate body, but I reduce it to what it is. For I show that corporeal mass, which is thought to have something over and above simple substance, is not a substance, but a phenomenon resulting from simple substances, which alone have unity and absolute reality.”10 In the same letter Leibniz writes that bodies are just “sets of harmonized perceptions.”11
There is some evidence to suggest that Leibniz never found a position on matter that he was satisfied with, and as his correspondences with De Volder and Bernoulli progress he continually weakens the concept of matter presupposed there. He seems most concerned to show that the laws of nature can be preserved even under a phenomenalist theory of matter. Sometimes Leibniz pushes his system to its logical conclusion and ends up with idealism. But more often he is working, as L. J. Russell argues, “to escape the extreme interpretation of the doctrine of substance to which his metaphysical and logical speculations of 1686 had led.”12
Does he succeed in the end? Most commentators say no. The conclusion of Georges Friedmann’s masterful comparison between Leibniz and Spinoza is that “The philosophy of Leibniz is, at core, a monism of the spirit”; or at least it is a philosophy “where, despite the efforts of the author, the reality of matter and its borders with spirit are evasive and fragile” (Friedmann, 1962, p. 245f). Throughout the correspondences Leibniz continues to speak as if there is matter, and hence motion and empirical perception. He does well to do so, as a thoroughgoing idealism would make it more difficult (to put it mildly) to individuate the mental substances that are the building blocks of his metaphysics. But matter is at best a by-product of the mental substances, and at worst an illusory category incompatible with what is at root an idealist system. Thus, it appears, the first major metaphysical system written after the dawn of modern physics turns out to be a form of unmitigated idealism. Matter, it seems, is merely an appearance, an illusion foisted upon us by an inaccurate comprehension of the world around us.
Nineteenth-century German philosopher Georg Wilhelm Friedrich Hegel claimed to offer the great philosophical synthesis of all knowledge and of all previous philosophies. He believed that the dichotomy between mind and matter, like all previous dichotomies, was something he could leave behind. In Hegel’s writings, one does indeed find numerous attempts to incorporate the results of the natural science of his day. Unfortunately, however, in the development of Hegel’s system the concept of mind or spirit (Geist) dominates yet again. Although one may not perceive it fully until the end of history, the force that moves all things and propels history forward is Absolute Spirit, not matter. The Phenomenology of Spirit (1807) chronicles the history of “Spirit coming to itself”; the history of Spirit, it turns out, provides the ultimate explanation and the ultimate moving force for all that is. If there is a material aspect of the Absolute, it remains strangely silent in Hegel’s work. In the end, matter does not play any stronger role than in the work of Hegel’s predecessors. As Stojanow notes correctly, “Hegel, abiding by his purely epistemological approach, examines only the ideal side, only the actuality, the pure activity, actus purus; he abstracts the latter from the material entelechy. According to Hegel matter is the purely passive substratum of each alteration, becoming and activity” (Stojanow, 2001).
Of course, Hegel does include a philosophy of nature as part two of his massive Encyclopedia of the Philosophical Sciences (1830). Some scholars have used contemporary science to attempt to vindicate Hegel’s philosophy of nature.13 But overall, I suggest, the growth of science has rendered much of Hegel’s philosophy of nature obsolete.14 Indeed, the subordination of the material moment is implicit already in his theory of self-consciousness. As he writes in the History of Philosophy:
The meaning … is not, however, that natural objects have thus themselves the power of thinking, but as they are subjectively thought by me, my thought is thus also the Notion of the thing, which therefore constitutes its absolute substance…. It is only in thought that there is present a true harmony between objective and subjective, which constitutes me.(Hegel, 1974, pp. 149–150)
Finally, one must add the name of perhaps the greatest Western metaphysician of the twentieth century, Alfred North Whitehead. Whitehead was the first major metaphysical thinker to write his system after the breakthroughs of Einstein’s theories of special and general relativity. His Process and Reality (1929) is meant to be an empirically sensitive work, a response to scientific developments in physics and cosmology that is continually open to revision. But commentators have also recognized that Whitehead’s proposals are deeply reliant on something like a Leibnizian atomism. The great Whitehead commentator, David Ray Griffin, has shown that Whitehead’s system amounts to a form of “pan-experientialism” (Griffin, 2001). Every part of the physical world consists of individual moments of experience or “actual occasions.” Each actual occasion receives the input of its environment as data and then synthesizes it according to its own unique moment of creativity. This metaphysic yields the startling conclusion that the fundamental constituents of the universe are not merely material; every part of the universe also includes an element of mental experience. Actual occasions at lower levels of the natural hierarchy obviously have experiences that are less complex and less rational than our own; still, they remain genuine experiences. Whitehead does speak of both a mental and a physical pole in the experience of each unit of reality (each “actual occasion”).15 But he generally places the stress on the creative process; the physical dimension concerns what is left over after the process of becoming (“concrescence”) has ended. What we call materiality is always in part a by-product of earlier acts of creative synthesis by the “actual occasions” of the past.
In this brief sketch of the history of Western metaphysics, we have seen that the problem of matter remains an unsolved conundrum. Although the problem was continually reformulated and redefined, every attempt to understand matter ends up focusing on the active principle of the intellect – that which makes understanding possible – rather than on what was to be understood, which was matter qua non-mental. Again, it is as if matter continually recedes from our grasp. One even wonders: Could it be that matter is in its essence that which cannot be understood, that which inevitably recedes from us as we approach it? Here one thinks of the notion of the “transcendental signified” in the work of the influential French philosopher, Jacques Derrida (1995b, 1998). If the parallel indeed holds, matter is another name for what Derrida called la différance: that which is always different from our formulations and which is always deferred into the future whenever we seek to understand it. One suspects that “matter” is being used simply as another name for the Unknown.

3.2 Matter in contemporary physics

In the opening we reviewed the fundamental tenets of materialism: reality consists of fundamental material particles; these basic particles, together with the forces that act upon them, determine the behavior of all objects in the world; all else is built up out of these constituents; and reductionism is true. In Steven Weinberg’s reductionist program, for example, all causal arrows point upward from the fundamental microphysical causes, and all explanatory arrows point downward (Weinberg, 1994).
Initially, it would seem that physics offers a much more useful approach for understanding matter than does metaphysics. After all, physical science was born out of the decision to eschew the vagaries of metaphysical reflection and to work instead to “save the appearances.” The goal of physics is to construct a series of hypotheses that adequately describe, explain, and predict the movements (dynamics) of the objects we observe. For several hundred years, physicists succeeded beyond all expectation at deriving principles and laws capable of explaining the behavior of objects in the physical world based on this world view.
The materialist program of research was admirably described in Book One of Thomas Hobbes’ great seventeenth-century work, Leviathan (1651), and in John Locke’s epistemological method in the Essay Concerning Human Understanding (1690). Hobbes began with the premise that all is “matter in motion”; the crucial task that then arises is to understand exactly how things move – and how the illusion that non-material things exist might have arisen out of the purely material world. This program has been called the “analytic” or “compositional” method: one identifies the basic building blocks of reality and then shows how more and more complex wholes are constructed out of these building blocks, until one had reconstructed the full world of human experience. Run the tape backwards – that is, decompose or deconstruct experience into smaller and smaller parts – and you arrive again at the fundamental constituents of reality. Classical examples of this research program include Locke’s exclusion of secondary qualities and Hume’s exclusion of enduring subjects and metaphysical causes, viz. anything beyond “constant conjunction.”
The initial results of the materialist program in early modern science were astounding. The attempt to formulate fundamental laws of motion in the work of Galileo, Kepler, and especially Newton were staggeringly successful; as Alexander Pope wrote, “Nature and nature’s laws lay hid in night; God said ‘Let Newton be’ and all was light.” Newton’s mechanics seemed to offer support for the metaphysical position of materialism, the view that all things are composed of matter. His laws in the Principia for the first time provided explanatory principles that could explain the motion of all objects, from falling bodies to distant planets. The laws presupposed a primary matter on which forces such as kinetic energy and the gravitational force act. Newton’s second law, for example, specified the exact relationship between force and the mass of a particular object: f = ma. In a similar manner, he defined the force of gravity in terms of the mass of the two attracting bodies using the equation
(3.1)
That is, two bodies attract each other with equal and opposite forces; the magnitude of this force is proportional to the product of the two masses and is also proportional to the inverse square of the distance between the centers of mass of the two bodies.
With the work of Priestley, Lavoisier and others, chemistry yielded her secrets to what appeared to be the same method of analysis. At first blush, it appeared that biology would offer yet another example of the same principle. All one had to do, it appeared, was to dispense with medieval metaphysical assumptions – the plenum, the a priori hierarchy of unchanging species, and the assumption of divine purpose – and an equally physics-based biological science could emerge. This, at any rate, is how Darwin’s breakthroughs were viewed during most of the twentieth century. For a while, it was even believed that Comte’s manifesto had opened the door for similar successes in the social sciences, and that we were well on our way toward realizing that goal through the work of Durkheim in sociology, Tyler in anthropology, and the early Freud in psycho-physiology.
If all composites reduce down to basic parts, and if, once given the basic parts and fundamental physical laws, one can reconstruct the compositional process up to and including the most complicated entities and behaviors of which we are aware, then all existing objects (it was assumed) must be something like mereological sums of basic units of matter, and their identity conditions must be specifiable in this fashion. The successes of the various sciences from physics to neuroscience, combined with the shared method that all scientists seem to use, were taken to be sufficient to establish this conclusion.
Of course, this widespread response left the mind–body problem unsolved, because consciousness does not appear in the equations. Nonetheless, many materialists viewed this fact as a merely temporary embarrassment. The natural sciences would eventually succeed in understanding all human thought in terms of the neural structures, chemical composition, and electrodynamics of the brain and central nervous system. When the knowledge of all things has been reduced to fundamental particles and to universal physical laws, they maintained, the victory of materialism will be complete.
Yet somewhere near the beginning of the last century, the project of materialist reduction began to run into increasing difficulties. Special and general relativity, and especially the development of quantum mechanics, represented a series of setbacks to the dreams of reductionist materialism, and perhaps a permanent end to the materialist project in anything like its classical form. (Arguably, the electrodynamics of Faraday and Maxwell, together with the science of thermodynamics, already began to suggest revisions to classical materialism, but this claim is more widely contested.) In the contemporary scientific picture of the world, the most fundamental level of analysis of the physical world is quantum physics, the study of the subatomic particles and energies of which the macrophysical world is composed. (Physicists may someday be able to demonstrate that quantum physics is a limit case of a more fundamental set of equations, such as those of string theory or M-theory, but no such demonstration has yet been produced.)
Note, however, that the physics of the quantum world bears scant resemblance to the physics that produced and justified the classical formulations of materialism. Consider the following anomalies:
(1) Physical particles such as electrons are at this scale convertible to pulsations of energy or waves. With Röntgen’s discovery of the phenomenon of radioactivity, in which solid objects gradually convert themselves into radioactive waves, physicists began to realize that there is no fundamental ontological division between matter and energy. Einstein’s famous equation, E = mc2, probably the best-known physics equation of all time, offered a precise quantitative recipe for converting mass to energy (or energy to mass) and has been repeatedly verified by experiment since his time. (The American use of atomic weapons on the cities of Hiroshima and Nagasaki subsequently provided the world with an unforgettable lesson on what it means to multiply m by such a large quantity as c2.)
(2) This convertibility was given canonical status in Schrödinger’s wave equation and took popular form in von Weizsäcker’s principle of complementarity.16 Complementarity in physics means that a single (mathematically well-defined) phenomenon can be described in multiple, apparently incompatible ways – for example, as both a wave and a particle – depending on the interests of the observer and the experiment she or he designs.
(3) Under the standard (“Copenhagen”) interpretation of quantum physics, the world cannot be understood as ultimately determinate. Heisenberg’s principle of indeterminacy means, on this view, not only that we cannot know the precise location and momentum of a subatomic particle, but also that the particles themselves simply do not have a precise location and momentum (Heisenberg, 2007/1958). But how is one to conceive matter if the physical world lacks precise location and momentum at its most fundamental level? Certainly the standard conception of matter – as involving billiard-ball-like objects that are at a certain place at a certain time and have a specific momentum at every moment of time – collapses with the discovery of indeterminacy.
(4) It is also well known that the indeterminate nature of quantum states is resolved into a precise state at the moment of measurement. The mathematics describes a superposition of possible measurements, which is resolved at the moment of measurement into a single observed state.17 This phenomenon, known as the “collapse of the wave function,” suggests that the observer plays some constitutive role in making the physical world become what we perceive it to be at the macrophysical level – a collection of clearly defined and locatable objects.18 But the physical world that is constituted or constructed (to whatever extent) by subjective observers is hardly the material world conceived by classical physics!
(5) A later by-product of research in quantum physics has been quantum field theory. From the standpoint of field theory, individual subatomic particles are expressed as “localizations” of the quantum field at a particular place and time. Thus the famous French physicist Bernard d’Espagnat argues that it is no longer accurate to understand objects as objects; they should really be understood as properties of a field: ways in which the field is manifested at a particular place and time. To d’Espagnat, a French example comes to mind: what we used to think of as quantum particles turn out to be less like the Eiffel Tower than like some qualities that are in (or, that we observe in) the Eiffel Tower, such as its height, size, or shape. So we must ask: what is it that these qualities are qualities of? According to d’Espagnat’s controversial book, In Search of Reality (d’Espagnat, 1983), the only possible answer is that the quantum state vector expresses properties of some deeper underlying reality. Since we know its manifestations to us – we know what it is like when measured – and since quantum physics forbids us to speak about what it is “really like” when not measured, d’Espagnat speaks of it as a “veiled reality” (d’Espagnat, 1995). His is a sort of realism at a distance: we cannot say that reality is “just this way or that,” since our observations and what we observe are intertwined; and yet we can say that the-world-as-observed is a manifestation of the real; reality really takes this or that form in our observations. Unfortunately, for traditional theories of matter, however, this “veiled reality” can be neither mental nor material, insofar as it precedes the mind–matter distinction altogether.19
(6) Finally, more recent work on nonlocality further undercuts classically materialist views of matter. In a series of experiments, initially designed by Alain Aspect to demonstrate the violation of Bell’s inequalities, two linked photons are fired in opposite directions. A measurement of the spin made on one particle instantly resolves (creates?) the plane of spin of the other one. Yet, given the distances, which in the experiments now exceed 10 km, no message could be sent between the two particles except at a velocity that exceeds the speed of light, which is impossible. Some argue that the experiments demonstrate the possibility of superluminal action at a distance, whereas others maintain that two particles separated by great distances can still act as one object (Grib and Rodrigues, Jr, 1999; Maudlin, 2002). In either case, the experiments force upon us a view of the physical world that lies well outside any common-sense conception of matter.
Over-eager authors have jumped on these results, attempting to argue that they spell the end of physics or promise the final convergence of science and religion. One frequently finds titles such as: Atoms, Snowflakes and God: The Convergence of Science and Religion; The Science of God: The Convergence of Scientific and Biblical Wisdom; The Tao of Physics; and so forth (Capra, 1984; Hitchcock, 1982; Schroeder, 1998). Such conclusions are unjustified. Quantum physics is not a threat to physics but one of its most impressive successes in the last century. It is, however, a threat to a particular understanding of physics, for it is ultimately incompatible with the world view of materialism that dominated much of the physics of the modern period (Stapp, 2004).20 It is perhaps not an overstatement to say that the developments in physics briefly summarized here provide a powerful empirical refutation of that materialist world view.

3.3 Toward a new scientific world view

The two preceding sections reveal some of the conundrums that face any theory of matter today. Careful empirical study of the natural world has replaced classical concepts of matter with the strange, strange view of the world offered by contemporary physics. Physicists began with a solid concept of matter and with the world of everyday experience. But as they tested this concept in light of the scientific method and, in particular, the demands of the mathematical formalisms, they were led to results that cast into question all previous conceptions of matter. One has the sense that, at the end of the day, the speculation of the philosophers and the data from the scientists are pointing in the same surprising direction. At the root of all physical reality is not “primary matter” or little atoms of “stuff.” Relativity theory in cosmology and the complementarity thesis in quantum physics suggest that the basic reality is some sort of hybrid “matter–energy.” Quantum field theory and string theory (if it survives as a physical theory, which now seems unlikely) suggest the even more radical idea that this reality is more energy-like than matter-like. Either result is sufficient to falsify materialism in anything like the form that dominated the first 300 years of modern science.
So what do we conclude? I suggest that the lesson is twofold. On the one hand, those thinkers are misguided who seek to dispense with the notion of matter altogether. The conundrums are not resolved by turning one’s back on the mysterious nature of objects and particles in physics. Idealists who abandon the scientific study of the physical world in favor of mentalism or spiritualism “solve” the dilemma by ignoring the very fields in which it can be most fruitfully studied. After all, we are surrounded by physical objects. The things we touch and manipulate are not mere figments of our imagination; unlike our ideas, their “brute existence” frequently resists our will and wishes. Since there is no evidence that all objects are thinking, perceiving beings like us, we should take them to be different from ourselves, physical objects without mentality (in contrast to panpsychism). The commitment to do so launches one into the research program of contemporary science.
On the other hand, as we pursue the project of science, we discover that no simple concept of matter is adequate to the results of physics – or, as we also saw, to the demands of systematic philosophy. No “primary matter” serves as the basic stuff out of which all else is composed. Instead, the deeper one pursues the explanations, the more nonmateriality reveals itself in (or behind) the solid objects around us. Beginning with the oft-repeated observation that the solid object one touches is in fact composed mostly of space, one finds oneself confronted with as strange a world in physics as one will ever meet in the history of philosophy.
What is necessary, I suggest, is that we pursue this path of natural science as far as it can take us. No over-quick leaps into metaphysics will help; all such shortcuts leave one poorer in the end. But refusing to acknowledge the complex philosophical issues raised by today’s science equally impoverishes human understanding. Only a partnership of scientists and philosophers will make it possible to formulate an adequate post-materialist theory of the natural world.
The move beyond materialism may have started with physicists; it is to them that we owe many of the revolutionary new concepts, including the radically new notions of information explored elsewhere in this volume. Physics suggests theories of reality in which information takes over the roles that matter once played, as in John Wheeler’s slogan “it from bit” and Anton Zeilinger’s recent extension of Wheeler’s work into experimental quantum physics.21 Physics may also suggest an “entanglement of matter and meaning.”22 But in recent years the baton has passed to the biological sciences, where new insights into the nature of information are now receiving empirical support. One thinks in particular of the studies of “top-down constraints” in systems biology,23 biosemiotics, and form-based (morphological) theories of causality (see T. Deacon, in Chapter 8 of this volume). Taken together, I suggest, these new lines of inquiry are putting the final nails in the coffin of the materialist world view once touted as science’s crowning glory.24

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1 The classic materialist view of consciousness is expressed in Crick (1994).
2 The challenge to divine action is well spelled out in a series of books, Scientific Perspectives on Divine Action, edited by R. J. Russell, and published by the Vatican Observatory Press. See especially the summary volume in the series by R. J. Russell, N. Murphy, and W. Stoeger (2008).
3 The distinction between “strong” emergence, which affirms real causal activity at levels of organization higher than physics, and “weak” emergence, which denies this, goes back to Bedau (1997, pp. 375–399). For more detail on these concepts, see Clayton (2004).
4 See also Plato’s metaphor of the sun in Book 6, 507b–509c.
5 This is also the sense in which Jacques Derrida uses the term in his famous little book on khôra. See Derrida (1995a).
6 This is masterfully demonstrated in the work of Werner Beierwaltes, for example Beierwaltes (1972, 1985) and Beierwaltes, von Balthasar, and Haas (1974).
7 Thus Julius Weinberg writes, “It can be shown that Descartes has two different arguments for the distinction of mind and body. (1) It is possible, i.e. involves no contradiction, to think that I, as thinking, exist and that nothing extended exists, and since the existence, power, and veracity of God assures me that God can bring about whatever I can conceive, it is therefore possible that I exist without a body. Hence, body and mind are really distinct. (2) The essence or attribute of nature which is thought (cogitatio) is logically incompatible with that of extension. Hence these attributes cannot belong to one substance but only to two” (Weinberg, 1977, p. 71). Weinberg adds, “Descartes’ interest in the proof of a real distinction between mind and body is, at least, twofold. On the one hand, it forms the basis of a proof of the immortality of the soul … On the other hand, Cartesian dualism opens the way to a purely physical or even mechanical account of the physiology of the human body and, indeed, a purely physical account of the natural world” (Weinberg, 1977, p. 72).
8 See Leibniz (Discourse, p. 23): “God produces different substances according to the different views which he has of the world, and by the intervention of God, the appropriate nature of each substance brings it about that what happens to one corresponds to what happens to all the others, without, however, their acting upon one another directly.”
9 See Jolley (1993, pp. 384–423, especially p. 399). I treat Leibniz in greater detail in Chapter 4 of The Problem of God in Modern Thought (Clayton, 2000).
10 “Ego vero non tollo corpus, sed ad id quod est revoco, massam enim corpoream quae aliquid praeter substantias simplices habere creditur, non substantiam esse ostendo, sed phaenomenon resultans ex substantiis simplicibus quae solae unitatem et absolutam realitatem habent” (Gerhardt, 1875–1890, p. 275). Translated in Leibniz (1989, p. 181).
11 The process of development is nicely summarized in L. J. Russell (1981, pp. 104–18). Bernoulli’s best reconstruction is that Leibniz makes materia secunda out of points endowed with forms; a material substance is a punctum cum forma (Gerhardt, 1849–1863, 2:546f.).
12 Here I follow L. J. Russell (1981, p. 118).
13 See, for example, Burbidge (1996).
14 See Houlgate (1998).
15 For references to texts on the “mental” and “physical” poles, see the index to Whitehead (1978).
16 See von Weizsäcker (1976, 1980).
17 At least that’s the account given in the classical or “Copenhagen” interpretation of quantum mechanics. The “decoherence” school argues that the interaction of subatomic particles with the macrophysical world can be enough by itself to resolve the superposition into a single “coherent” macrophysically observable state. See Joos (2006, pp. 53–78).
18 The distance between this new view of the world and classical mechanics is emphasized in several of the contributions to Russell et al. (2000).
19 See Chapter 19, “The ‘ground of things’” in the last great work of D’Espagnat (2006, pp. 429–464).
20 See also his contribution to this volume: Chapter 6.
21 See Zeilinger (2004, pp. 201–220).
22 See Barad (2007). Barad is not an idealist, but she defends a form of realism that she calls “agential realism.” There is a similar entanglement of the objective and subjective world in the work of quantum theorists von Neumann and Wigner, among others; see again Stapp (2004).
23 See Chandler, Mason, and van de Vijver (2000): in particular, Josslyn (2000) and Lemke (2000); see also Palsson (2006).
24 An ancestor of this chapter was presented in January 2003 at Bangalore University, India, as part of a conference on “The Concept of Matter in Indian Philosophical Schools and the New Physics: Understanding Knowledge Systems”; that material appeared as “The Concept of Matter in Traditional Western Philosophy and in Contemporary Physics: The Unsolved Dilemma,” in Ananthamurthy et al. (2005, pp. 163–177). I am grateful to critical comments from Niels Henrik Gregersen and Mary Ann Meyers, and to Ashley Riordan for research assistance during the rewriting process.