Materialism
In the philosophy of medicine, materialism is the thesis that the body and its diseases are composed entirely of matter and can be understood through matter’s properties. The thesis sounds simple, but everything depends on what matter is. For Descartes, matter was extension, shape, and motion — the body a machine. For Diderot, matter was endowed with sensibility and could organize itself into living forms. For contemporary neuroscience, matter is neurons, synapses, and electrochemical signals. The history of materialism in medicine is largely a history of arguments about whether the concept of matter is rich enough to account for life, or whether life requires something that matter, however reconfigured, cannot provide.
The Mechanical Body
The most influential medical materialism was the one Descartes proposed in the seventeenth century: the body is a machine, operating by the same laws as any other piece of matter in motion. Drew Leder’s phenomenological analysis traces the consequences. Descartes reconceived the principle of life as located in the body — in the heat of the heart — rather than in the soul, but this concession to vitality was made possible only by modeling life itself on the workings of an inanimate machine. The living body became, in Leder’s phrase, an “animated corpse.” (Leder, 1990) Modern medicine followed this logic by using the corpse — the dead body opened by dissection — as both a methodological tool and a regulative ideal for knowledge of the living body. (Leder, 1990)
Herman Boerhaave, the pre-eminent physician of the early Enlightenment, built his clinical system on this foundation. At Leiden, he promoted a mechanistic disease explanation within a corpuscular matter theory, construing health as hydrostatic equilibrium — a balance of internal fluid pressures. (Porter, 1997) Disease was mechanical obstruction or imbalance; treatment was directed at restoring the machine.
Henri Bergson, writing two centuries later, identified the deepest philosophical commitment embedded in this view. Radical mechanism, epitomized by Laplace’s demon, treats time as having no efficacy — a metaphysic in which the totality of the real is postulated complete in eternity and duration is merely an appearance of ignorance. (Bergson, 1911) For the mechanistic materialist, the future adds nothing to the present; everything is in principle calculable from initial conditions.
The Anti-Materialist Counterattack
Georg Ernst Stahl, Boerhaave’s contemporary and rival, attacked this reductionism directly. Organisms, he insisted, were more than the sum of their parts, and purposive human actions could not be explained by mechanical chain-reactions alone. Activity presupposed the guiding purposive power of a soul — Stahl’s animism. (Porter, 1997) Stahl’s solution created as many problems as it solved (how does the soul act on the body?), but his identification of the problem was precise: mechanistic materialism leaves out exactly those properties of organisms — self-regulation, purposive behavior, development — that make them organisms rather than clocks.
Charles Wolfe argues that the actual historical situation was not a binary opposition between mechanism and vitalism but a “triangulation” among three positions: mechanism, animism, and vitalism. After Stahl, vitalism was progressively confined to the life sciences: vitalists never reclaimed the inorganic world as their territory, and the vital principle was forever localized in the organism.(Wolfe, Charles T., 2010-2015) (Wolfe, Charles T., 2010-2015) The Montpellier vitalists, who first used the term “vitalism” as a self-designation in the late eighteenth century, explicitly distinguished their position from both Stahl’s animism (too metaphysical) and mechanism (too physical). Charles-Louis Dumas, Dean of the Montpellier Faculty of Medicine, described vitalism as a middle position articulating an “intermediate principle” with properties different from both matter and soul. (Wolfe, Charles T., 2010-2015)
The Seventeenth-Century Revival of Atomism
The ancient atomist tradition re-entered European thought through Pierre Gassendi (1592-1655), a Catholic priest who substituted Epicurean atomism for Aristotelian philosophy while stripping it of its atheistic connotations. Unlike Descartes, who rejected ancient authority entirely, Gassendi retained a humanist framework — he looked to classical antiquity for his philosophical models and simply replaced Aristotle with Epicurus. (Peter Dear, 2001) Robert Boyle then coined the term “mechanical philosophy” to encompass all corpuscular-mechanical approaches, deliberately blurring the metaphysical differences between Descartes and Gassendi (including their disagreement over the existence of a true vacuum) while stressing the hypothetical rather than certain status of such explanations. (Peter Dear, 2001)
The medical reception of this revived atomism was complicated. Herman Boerhaave, as a student at Leiden in 1689, attacked Epicurean materialism with violent rhetoric, calling the doctrines of Hobbes and Spinoza “recalled from the realm of Hell” and condemning their assertion that “the mind is a mass composed of a varying structure of atoms.” Within a decade, however, Boerhaave had abandoned metaphysics entirely in favor of the position that observation and experience, not deduction, yield true knowledge. (Cook, 2007) His mature clinical system, built on mechanistic foundations, drew on the very corpuscular framework he had once denounced — though he was careful to ground it in empirical observation rather than in Epicurean metaphysics.
The Reconfiguration of Matter
The standard narrative — that early modern materialism was “mechanistic materialism” (matter as size, shape, and motion) — is, Wolfe argues, historically inaccurate. Early modern materialists regularly embraced active, self-moving, and chemically rich conceptions of matter. (Wolfe, Charles T., 2010-2015)
John Toland’s Letters to Serena (1704) marks a decisive step. Toland rejected the strong distinction between matter and motion: “Activity ought to enter into the Definition of Matter, it ought likewise to express the Essence thereof.” (Wolfe, Charles T., 2010-2015) This was not a minor revision. If matter is inherently active rather than inert, then the mechanical materialist’s picture of dead stuff moved by external forces dissolves.
As matter was endowed with further properties — desire, appetition, instinct, and memory in Maupertuis; irritability and sensibility as physiology incorporated these concepts — it became vitalized. A “vital chemistry” emerged, visible in Venel’s Encyclopédie article on chemistry, in which chemical processes in living bodies were understood as qualitatively different from those in inert matter. (Wolfe, Charles T., 2010-2015)
Vital Materialism
Denis Diderot extended Toland’s insight by making sensibility (sensibilité) a universal and essential property of matter. The living body was a “laboratory” in which sensibility shifted from an inert to an active form. (Wolfe, Charles T., 2010-2015) This was a materialism that refused to treat matter as dead — that insisted matter itself could feel, organize, and create.
Wolfe identifies the resulting position as vital materialism, and argues that vitalism and materialism should not be opposed. On one side, matter was being reconfigured to possess irreducibly vital properties. On the other, the Montpellier vitalists insisted on the irreducible materiality of the living systems they studied. The life they were interested in was not that of a vital principle, archaeus, or entelechy — it was that of a living body, or organism. (Wolfe, Charles T., 2010-2015)
Yet vital materialism was not a wholesale holism. It retained a reductionist dimension in its approach to body-soul relations, treating the soul’s properties as explicable through the material organization of the body while refusing to treat matter as merely inert. La Mettrie’s L’Homme-Machine, the most notorious materialist text of the century, proposed a soul-to-body reduction — it never reduced the properties of the living body to those of inanimate matter. (Wolfe, Charles T., 2010-2015)
Friedrich Engels’ canonical claim that eighteenth-century French materialism was mechanistic is, Wolfe demonstrates, multiply wrong: it neglects the strong concern with embodiment in the French materialists, the chemical emphasis in Diderot and his circle, and the emergence of active matter theory from Toland onwards. (Wolfe, Charles T., 2010-2015) The same critique applies to contemporary “New Materialism,” which claims as novel a concern with active, embodied, self-organizing matter that was already fully articulated in the eighteenth century. (Wolfe, Charles T., 2010-2015)
The Limits of Material Explanation
The question of whether a materialist framework can account for life remained open. Bergson argued that life is “tangent, at any and every point, to physical and chemical forces” but is no more made of them than a curve is composed of straight lines. Vital activity constitutes a mechanics of transformation rather than of translation. (Bergson, 1911) The physico-chemical sciences track what Bergson called the katagenetic (descending) processes of energy expenditure; the anagenetic (constructive) work that builds living tissue defies such reduction. (Bergson, 1911)
From the vitalist side, Johann Christian Reil proposed in the early nineteenth century that the cause of organic formation lies in “the nature of animal matter” itself — a “special sort of crystallisation.” Driesch identifies Reil as the first clear representative of a vitalist theory grounded in the concept of living matter rather than in soul or vital force as external principles. (Driesch, 1914) Even Justus von Liebig, the great chemist, maintained that while chemistry could produce organic substances, it would “never be in a position to create an eye, a hair, or a leaf,” because the form of higher organized atoms was conditioned by vital force rather than chemical force alone. (Driesch, 1914)
Comte’s ordering of the sciences attempted a philosophical resolution: biology occupied a position that could not be reduced to mechanics, and the vital principle transcended mechanical parts even as it had to be studied empirically. (Canguilhem, 1994) Wolfe observes that the “vitalism problem” — why organisms differ from entities describable in purely physico-mechanical terms — is post-Cartesian in origin. It emerged not as an ancient puzzle but as a response to the hegemony of mechanistic science, and it appeared as a named problem at roughly the same time that “biology” was named as a science. (Wolfe, Charles T., 2010-2015)
The question that accusations of “vitalism” have been used to suppress — what Wolfe shows was typically a polemical act by scientists seeking to delegitimize predecessors as metaphysicians — is not whether matter is all there is, but whether the concept of matter available to any given generation is sufficient to explain what living bodies do. (Wolfe, Charles T., 2010-2015) That question remains open.
Ancient Atomism and Its Medical Afterlife
The genealogy of materialism in medicine extends to the fifth century BCE. Democritus of Abdera proposed that the cosmos, including the body, was composed of indivisible particles — atoms — moving through void. He was not primarily a physician, but his influence on medical thought was considerable and long-lasting: an Alexandrian catalogue of his writings included works on prognosis and dietetics, and he maintained medical followers well into the Roman Empire. (Nutton, 2023) The famous story of Hippocrates finding him dissecting animals near Abdera, though probably legendary, captures the tradition’s perception that Democritus straddled the boundary between natural philosophy and medical observation.
The medical consequences of Epicurean atomism, Democritus’s philosophical heir, can be traced into the Roman period. Asclepiades of Bithynia, the most influential immigrant doctor in late Republican Rome, reformulated Greek medicine on corpuscular foundations: he held that the body was built from invisible particles whose free and balanced motion through theoretical pores constituted health, and that disease resulted from a blockage or flood of these particles. (Nutton, 2023) This was not pure Epicurean doctrine — Asclepiades adapted atomist physics to clinical use — but it represents the most sustained ancient attempt to ground medical practice in a materialist physics of the body.
A second, doctrinally distinct atomism arose in early Islamic theology. The early mutakallimun held, as Goodman summarizes in Islamic Humanism (2003), that substance (jawhar) was an unextended atom and that all differentiation between substances was accidental, with God creating and recreating the world moment by moment.[good-ih03-ch04-002] This Kalam atomism shares the corpuscular ontology of the Greek tradition but pairs it with an occasionalist metaphysics that severs natural causation: where Democritean atoms move by their own properties, the jawhar of Kalam exists only at the moment God re-creates it. The medical implications were limited — Kalam atomism was a theological doctrine, not a clinical framework — but the position remained available as a counter-tradition through which later Arabic philosopher-physicians defined their own atomisms (al-Razi most prominently).
Nineteenth-Century Scientific Materialism
A second wave of medical materialism rose in mid-nineteenth-century German-language science. Driesch identifies four circumstances that shaped biological thought in the second half of the century: “the rise of materialistic metaphysics (Moleschott, Vogt, Büchner), Darwinism explaining purposive construction by chance, the law of conservation of energy, and improved microscopic investigation of living structures — each reinforcing mechanistic dogmatism.”(Driesch, 1914) What is now usually called “vulgar materialism” — the position that thought is a secretion of the brain, that mind reduces without remainder to matter — belongs to this period; its key texts (Vogt’s Köhlerglaube und Wissenschaft, Moleschott’s Der Kreislauf des Lebens, Büchner’s Kraft und Stoff) circulated widely outside university lecture halls and made materialism a public position rather than a strictly philosophical one.
Temkin’s analysis in The Double Face of Janus complicates the assumption that materialism and Darwinian transmutation went together as a package. Among German biologists in the 1848–1858 decade, the supporters of descent-with-modification were actually more numerous on the idealist side (Schleiden, Baumgärtner, Unger, Schaaffhausen, Nägeli), while the materialists divided: only Büchner supported transmutation outright; Vogt and Virchow were sympathetic but uncommitted; the strict mechanistic reductionists — Du Bois-Reymond, Helmholtz, Ludwig — were not pre-Darwin transformists at all.(Temkin, 1977) The materialist who insisted on the unity of matter and force was not necessarily a materialist about species origin. The two debates ran on partially independent tracks before On the Origin of Species fused them.
Twentieth-Century Materialism: Reduction, Elimination, and Exclusion
In the second half of the twentieth century, materialism stopped being a position one had to defend against dualism and became, almost by default, the working metaphysic of analytic philosophy of mind. Jaegwon Kim, who taught at Brown University and was one of the central voices of the period, locates the shift in two papers: Herbert Feigl’s “The ‘Mental’ and the ‘Physical’” (1958) and J. J. C. Smart’s “Sensations and Brain Processes” (1959), which together reintroduced the mind-body problem as a “mainstream metaphysical Problematik of analytical philosophy.” (Kim, Jaegwon, 1998) Smart’s brain-state identity theory was quickly overthrown by two arguments (Hilary Putnam’s multiple-realization argument and Donald Davidson’s anomalist argument), but, Kim observes, those very objections contained within them seeds for the alternative pictures that displaced identity theory: functionalism, on which mental kinds are functional kinds at a higher level of abstraction, and anomalous monism, on which there are no strict psychophysical laws. (Kim, Jaegwon, 1998) Almost no one reverted to Cartesian dualism. The mind-body problem became, and has remained, the problem “of finding a place for the mind in a world that is fundamentally physical.” (Kim, Jaegwon, 1998)
Paul Churchland, working in the same tradition from the West Coast, formalized the standing case for materialism in textbook form. The first argument is from simplicity: by Ockham’s Razor, the materialist hypothesis postulates only one kind of substance and one class of properties, while the dualist postulates two; if all else is equal, the simpler hypothesis should be preferred. (Churchland, Paul M., 2013) The second is from explanatory poverty: dualism cannot tell us anything about the internal constitution of mind-stuff, the laws governing it, its structural connection to the body, or its operations, because no detailed theory of mind-stuff has ever been formulated. Compared to the rich resources and explanatory successes of current materialism, dualism is not so much a theory as an empty space waiting for a genuine theory to be put in it. (Churchland, Paul M., 2013) The third is the argument from evolutionary history: the human species is the wholly physical outcome of a wholly physical evolutionary process, differing from simpler creatures in degree rather than in kind, leaving neither need nor room to fit nonphysical substances or properties into the scientific account of ourselves. (Churchland, Paul M., 2013) These arguments, together with the neural-dependence of all known mental phenomena and the explanatory successes of neuroscience, are what Churchland presents as a converging case for the identity theory rather than as conclusive proof. (Churchland, Paul M., 2013)
Three ideas dominated the post-identity-theory landscape: that the mental supervenes on the physical, that it is realized by the physical, and that it is emergent from the physical. (Kim, Jaegwon, 1998) Each was taken to license a “non-reductive physicalism,” the position that mental properties depend on physical properties without being identical to them. Kim’s central argument, developed across Mind in a Physical World (1998), is that this position is unstable. Mind-body supervenience, he insists, is not itself a theory of the mind-body relation; it merely states a pattern of property covariation, a “phenomenological” relation about how mental and physical properties co-vary, possibly as the manifestation of some deeper dependence relation that supervenience itself cannot supply. (Kim, Jaegwon, 1998) Supervenience is in fact consistent with mutually exclusive positions, including type physicalism, emergentism, epiphenomenalism, and physical realizationism. It marks a shared commitment of many incompatible mind-body theories rather than a theory in its own right. (Kim, Jaegwon, 1998) What it does mark is the boundary of minimal physicalism: it is the commitment shared by all positions that take mentality to be physically grounded, and is inconsistent only with extreme dualisms like Cartesian substance dualism that allow the mental world to float freely. (Kim, Jaegwon, 1998)
The deeper problem is mental causation. If a mental event M causes a physical event P*, but P* also has a sufficient physical cause P, then P threatens to exclude and preempt M as a cause: the physical cause is enough on its own. This is the causal exclusion problem, and Kim argues that token physicalism, on which each mental token is identical with some physical token, is not enough to dissolve it, because the question is about the causal efficacy of mental properties. (Kim, Jaegwon, 1998) Combined with the closure of the physical (any causal chain traced from a physical event stays inside the physical domain), the exclusion problem yields what Kim calls the supervenience argument: under mind-body supervenience, mental-to-mental causation requires mental-to-physical causation, since to bring about a supervenient property you must bring about one of its base properties. (Kim, Jaegwon, 1998) The mental cause and its physical base then both stand as sufficient causes of the same effect, leaving overdetermination, joint causation that violates closure, or no clear causal role for the mental at all. Kim concludes the dilemma in stark terms: whether mind-body supervenience holds or fails, mental causation becomes unintelligible. He calls the result “Descartes’s revenge against the physicalists.” (Kim, Jaegwon, 1998)
Kim’s response is that nonreductive physicalism cannot be had on the cheap. Functional reduction (first construing a mental property in terms of its causal role, then identifying it with whatever physical property fills that role) is the only way to preserve mental causation, and it is functionalism, rather than identity theory, that makes such reduction possible. (Kim, Jaegwon, 1998) Properties that resist functionalization, qualia chief among them, then face a hard choice: accept their causal impotence (epiphenomenalism) or eliminate them. (Kim, Jaegwon, 1998) On Samuel Alexander’s criterion of reality (that what is real is what has causal power, since something with no causal power “might as well, and undoubtedly would in time, be abolished”), eliminativism and epiphenomenalism converge: both come to mental irrealism, since a property without causal work has no claim on existence. (Kim, Jaegwon, 1998) Kim, who began his career sympathetic to non-reductive physicalism, in effect became the most rigorous critic of his own earlier position; the conclusion of Mind in a Physical World is that property dualism, anomalous monism, and nonreductive physicalism are not easily tolerated by a thoroughgoing physicalism, and that “physicalism cannot be had on the cheap.” (Kim, Jaegwon, 1998)
Paul Churchland, who taught at the University of California, San Diego, and is the most influential proponent of eliminative materialism, took the opposite branch of Kim’s dilemma. Where Kim presses the physicalist toward reduction, Churchland argues that the everyday vocabulary of beliefs, desires, hopes, and intentions, what philosophers call “folk psychology,” is not an incomplete representation of inner states but an outright misrepresentation. A mature neuroscience, on this view, will not reduce folk psychology to neural categories; it will eliminate it, replacing belief and desire with new theoretical kinds. (Churchland, Paul M., 2013)
The argument is largely inductive. Churchland points to the explanatory and predictive failures of folk psychology, the inductive lesson from the history of science that almost all early folk theories of nature were wildly wrong, and the implausibility of language-like “propositional attitudes” as a model of cognition that prelinguistic infants and nonhuman animals are supposed to share. (Churchland, Paul M., 2013) Folk psychology has enjoyed no significant changes in well over two thousand years; we still use the same conceptual framework to explain behavior as the ancient Greeks did. (Churchland, Paul M., 2013) The historical pattern in cases of failed folk theory is consistent: almost every prescientific folk theory of the natural world has turned out to be wildly wrong. Heat was not a subtle fluid (caloric); combustion was not the release of phlogiston; the stars were not embedded in crystal spheres; epileptic seizures were not signs of demonic possession; “witches” were not a kind of person. In each case the theoretical posit was eliminated rather than reduced; the relevant entities were dropped from our ontology. (Churchland, Paul M., 2013) If folk psychology is, as it appears to be, a stagnant pre-scientific theory, the inductive expectation is that its central posits will go the way of caloric and phlogiston.
Churchland’s positive proposal is that the framework that replaces folk psychology will come from neuroscience. If high-dimensional neural activation vectors and vector-to-vector transformations are the primary representations and computations of the brain, that gives substance to the claim that the concepts of folk psychology need not, and perhaps do not, capture the dynamically significant states of mind; the elements of cognition will turn out to have a character unfamiliar to common sense. (Churchland, Paul M., 2013) More speculatively, if materialism is true, the conceptual framework of a completed neuroscience will embody the essential wisdom about our inner nature, and learning to introspect within that framework, so that one spontaneously notices gluco-corticoid accumulations as cognitive weariness, dopamine release as reinforcement, particular activation patterns as visual sensations of red, could approximate a revelation. (Churchland, Paul M., 2013) The closing line of Matter and Consciousness is that the genuine arrival of a materialist kinematics and dynamics for psychological states will not eclipse our inner life but will dawn upon us as a revelation of its intricacies. (Churchland, Paul M., 2013)
Churchland is careful to grant that pure reduction and blanket elimination are extremes on a smooth spectrum; the live possibility is partial elimination and partial reduction, what he calls “revisionary materialism.” Where on the spectrum folk psychology will land is an empirical question, not one philosophy can settle in advance. (Churchland, Paul M., 2013) The standard self-refutation objection (that eliminative materialism cannot be meaningfully stated if true, because its statement presupposes the very mental states it denies) is structurally identical, Churchland points out, to a parodic anti-vitalism objection: “if my friend has no vital spirit he must be dead, and if he is dead his statement is just noise.” Both arguments beg the question by assuming the framework being challenged is necessary for meaning. (Churchland, Paul M., 2013)
The disagreement between Kim and Churchland is real but narrower than it looks. Both are physicalists; both reject substance dualism as a serious option; both think the layered model of supervening special-science properties is unstable when pressed on causation. They part ways on what to do about it. Kim argues that the special sciences, including a future scientific psychology, must be functionally reducible to lower-level physical properties or face elimination; the ontologically respectable mental properties are those that can be identified with their physical realizers. (Kim, Jaegwon, 1998) Churchland argues that folk psychology, with its categories of belief, desire, hope, and intention as currently structured, is unlikely to survive that reduction at all; the theoretical framework will be replaced by a successor framework drawn from neuroscience. The two positions converge on the conclusion that non-reductive physicalism is not a stable resting place. They diverge on whether what survives at the end is a reduced folk psychology or a successor theory that no longer mentions beliefs and desires.
Beyond its technical philosophical content, materialism carried significant political weight in its nineteenth-century medical applications. In mid-nineteenth-century Russia, laboratory medicine emerged as “a symbol of modernity and scientific method,” but it could also signify challenges to prevailing sociocultural norms: its exponents wielded it as “a progressive materialist force destructive of autocratic religiosity.”(Jackson (ed.), 2011) The identification of materialism with political opposition — and of idealism/vitalism with religious and political orthodoxy — was not merely a Russian phenomenon, but the Russian case illustrates with unusual clarity how philosophical positions in medical science could be recruited as weapons in political struggles that had little to do with experimental findings.
That convergence is itself a continuation of the older argument this page has been tracing. The eighteenth-century question of whether the concept of matter in any given generation is rich enough to account for what living, thinking bodies do reappears in the late twentieth century as the question of whether the concept of physical property is rich enough to account for mental causation, and whether folk-psychological categories track real causal kinds at all. The hegemony of mechanistic science that produced the “Vitalismus-Problem” in the eighteenth century produced, in the twentieth, the exclusion problem and the elimination thesis. The names of the players changed; the structure of the dispute did not.
See Also
Sources
Auto-generated from evidence card IDs listed in frontmatter.