René Descartes

René Descartes (1596–1650) spent the most productive two decades of his career not as a philosopher in a library but as a natural investigator in the Dutch Republic, working through butchers’ scraps and dissected animals to understand how the human body works. His central argument about medicine: the body is a machine with no internal intelligence, no guiding vital spirit, no purpose of its own. Everything it does obeys the same mechanical laws that govern clocks and water pumps. This claim established the conceptual framework within which most subsequent Western medicine has been conducted, and it created a problem (the separation of mind from body) that clinical practitioners are still negotiating. Descartes never practiced medicine, but the program he announced shaped iatrophysics, influenced the neurology of Thomas Willis, and provided the philosophical ground for later reductionist biomedicine. Whether that program succeeded or failed, and in what sense, is one of the more contested questions in the history of medicine.

The Dutch Years and the Medical Turn

Descartes arrived in the Dutch Republic in 1628 and remained there, working in various cities, until 1649. The received story about Descartes places him alone with his stove, doubting everything, deriving the world from pure reason. Cook’s reading of the Dutch evidence argues differently: in the Republic, Descartes moved away from his early concerns for knowledge via contemplation and became absorbed in the investigation of the precise details of nature, especially animal and human bodies (Cook, 2007). His Dutch interpreters (a large proportion of whom were physicians) read him primarily as a theorist of matter and body, not as a skeptic about sensory knowledge.

The intellectual environment that shaped him in this direction had roots in Dutch natural philosophy. Isaac Beeckman (1588–1637), the son of a candlemaker who became a natural philosopher and physician, preceded Descartes in developing what he called a systematic mechanical or “mathematico-physics.” When Descartes met Beeckman in Breda in 1618, the two collaborated almost immediately, deriving together a new mathematical law describing free fall. Margaret Jacob, in her analysis of this encounter, identifies Beeckman as “the first mechanical philosopher of the Scientific Revolution,” arguing that his systematic philosophical approach to mechanical problems (positing atomic construction of matter and contact between bodies as the key to all natural forces) preceded and shaped Descartes’s own development (Cook, 2007).

Descartes’s 1629–30 plan to ‘explain all the phenomena of nature’ led him to intensive anatomical study in Amsterdam (Cook, 2007). He wrote to his correspondent Marin Mersenne that he ‘wanted to begin to study anatomy’ and was ‘studying chemistry and anatomy simultaneously; every day I learn something that I cannot find in any book’ (Cook, 2007).

The Aristotelian World Descartes Was Arguing Against

To understand what Descartes was doing, it is necessary to understand the Aristotelian physiology that provided his target. The Galenic tradition that still dominated university medicine in the seventeenth century held that venous blood was formed in the liver from digested food and issued to the body’s parts in a continuous ebb-and-flow alternating motion. Arterial blood, enriched with vital spirits generated in the left ventricle from the heart’s innate heat, was regarded as a physiologically distinct substance serving different purposes.(Hall, A. Rupert, 1954) The entire system was coordinated by faculties (capacities like attraction, alteration, and expulsion) that caused each organ to act on the materials passing through it according to its natural purpose.

The Aristotelian framework that underlies this physiology carried an epistemological claim as consequential as any anatomical doctrine: that true scientific knowledge (scientia) required causal demonstration through the four causes, and in particular through formal and final causes. Aristotelian natural philosophers of the sixteenth century explicitly denied that mathematics was a genuine science on these grounds: it described quantitative properties without revealing the essences of things or the purposes that organized them.(Peter Dear, 2001) The philosopher’s task, on this account, was to explain why natural things behaved as they did by identifying their natures and ends, not to describe their mechanical sequences.

Within this tradition, the body was understood through analogies to organized communities rather than to machines. Francis Glisson (1597–1677), Regius Professor of Physic at Cambridge and a key figure in the reception of Harvey, developed a natural philosophy in which matter was self-mobile, or “energetic,” in his terms, deriving from his belief that matter was, like spirit, ultimately a divine emanation.(French, 1994) This position was radically different from Cartesian natural philosophy, in which all motion is derived from elsewhere and imposed on matter from outside. For Glisson, as for much of the Aristotelian tradition, the activities of the living body expressed an internal principle of organization, not an external mechanism. Glisson attacked Descartes’s account of the heartbeat on three grounds: Descartes wrongly attributed heat to the heart walls rather than to the blood itself, confused ordinary physical heat with innate heat, and could not explain an eel heart that, separated from the body, continued to beat even when bloodless.(French, 1994)

The Aristotelian opponents of mechanism were not simply defending ignorance. Their objections had substance. Harvey himself had concluded that arterial blood differs from venous not by the addition of spirits but by being the same blood restored, a claim about the innate mobility of blood that distanced his later views from the heat-driven Cartesian model and undermined the traditional role of spirits without accepting mechanical explanation.(French, 1994) What individual thinkers made of Harvey’s doctrines depended, as Roger French’s William Harvey’s Natural Philosophy (1994) argues, on what was already in their minds before they read about the circulation: their natural philosophy, their religious commitments, and their professional obligations.(French, 1994) The Paracelsian and chemical physicians were generally unlikely to agree with Harvey because their rejection of traditional anatomy, preferring cosmic anatomy and the doctrine of signatures, was alien to Harvey’s Aristotelian anatomical program.(French, 1994)

The Body as Machine

The core of Descartes’s medical philosophy is contained in his account of animal and human physiology, developed across the Discourse on Method (1637), the Description of the Human Body (written during his Dutch period, published posthumously), and The Passions of the Soul (1649). His position was this: everything the animal body does is explicable in terms of the arrangement of its parts and the laws governing matter in motion. No animal, for Descartes, requires a soul to explain its behavior. The body was not maintained alive and active by vital forces, spirits, or souls, but solely by the interrelations of its mechanical parts; death was due to a failure of those parts.(Hall, A. Rupert, 1954) The heart beats not because vital heat animated by spirit drives it, but because the blood, entering warm chambers, expands and contracts in a sequence analogous to a mechanical pump. Digestion, sensation, and reflex movement operate by similar mechanical principles.

Descartes was working in full awareness of Harvey’s De Motu Cordis (1628), which had demonstrated the circulation of the blood through quantitative and experimental argument. Harvey’s great merit in making this discovery, as A. Rupert Hall summarizes in his Scientific Revolution (1954), was not introducing new facts but integrating known but ineffective facts into a new generalization: showing that if the vascular system was analyzed hydraulically, treating the heart as a pump and blood as a fluid, conclusive experiments on blood flow could be made.(Hall, A. Rupert, 1954) Descartes accepted Harvey’s doctrine that blood circulates around the body, finding it compatible with what he already had in mind. But he could not accept Harvey’s account of the forceful systole, the heart’s muscular ejection of blood, and replaced it with a theory of forceful diastole: a “fire without light” or natural heat implanted by God in the heart that was great enough to vaporize drops of blood entering from the veins, producing an explosive expansion.(French, 1994) Descartes was so committed to this account that he told correspondents that if what he had written about the heart was wrong, then so was the rest of his philosophy.(French, 1994) When Fortunatus Plemp pressed him with experimental objections, Descartes was compelled to modify the theory, shifting from simple vaporization to a “fermentive ebullition” requiring only a trace of blood that activated a ferment in the heart’s substance.(French, 1994) Even the most deductive of natural philosophers was not immune to experimental pressure.

Roger French’s William Harvey’s Natural Philosophy (1994) argues that Harvey’s and Descartes’ natural philosophies were mutually exclusive at the level of epistemology: Harvey sought causal knowledge of purpose (historia-actio-usus-utilitas) through sensory observation and the Socratic method, while Descartes excluded purposive causes and derived knowledge deductively from first principles of particulate mechanism.(French, 1994) Descartes explicitly claimed that the heart’s motion was as mathematically necessary as clockwork, asserting that it followed from the mere disposition of the organs in a way visible to the eye and testable by experience.(French, 1994)

The shift to diagrammatic explanation in natural philosophy contributed to displacing teleological from mechanistic explanation.(French, 1994) Traditional faculties like attraction could not be represented in geometrical diagrams.(French, 1994) Regius’s pump diagrams represented a universal in the way a geometrical figure stands for all right-angled triangles.(French, 1994) But this diagrammatic representation lost much of the old structure of knowledge, and above all it had no place for the Aristotelian final cause.(French, 1994) The spread of mechanical diagrams in medical literature was not merely aesthetic; it was an epistemological transformation made visible.(French, 1994)(French, 1994)

Where Harvey drew on Aristotelian teleology to explain the heart’s role, treating the heart as the seat of innate heat and vital principle, Descartes drew on mechanism. The physician’s task, on this account, was to understand the arrangement of the machine’s parts and correct mechanical failures, not to support any internal healing tendency, and not to negotiate with a vital economy whose intelligence exceeded the physician’s own.

Thomas Sydenham allied himself more closely with Hippocratic physiatry than any physician of his era, viewing nature as the primary healer of acute diseases and most disease manifestations as nature’s effort to expel the materia peccans, with fever as its chief instrument (Neuburger, 1943). By contrast, Jean Fernel argued that the physician’s role exceeded that of a mere servant of nature, positioning art as sometimes surpassing nature and the physician as “primary worker,” especially in serious diseases where nature alone cannot suffice (Neuburger, 1943). Fernel did not refrain from valuing artificial assistance as higher and more extensive, asserting that the physician is not merely “minister naturae” but must actively intervene (Neuburger, 1943).

The ancient precedent for this view was Asclepiades of Prusa, who in the first century BCE had denied the vis medicatrix naturae, calling it a fantasy and arguing that recovery depended entirely on the physician’s intervention (Neuburger, 1943).

Campaign to Replace Aristotle

Descartes had a deliberate programme for inserting his natural philosophy into the universities. He sent review copies of the Discourse on Method to targeted physicians and university teachers and planned to use formal academic disputations, with Henricus Regius as his agent at Utrecht, as the vehicle for displacing Aristotle from the curriculum.(French, 1994) Cornelis van Hogelande articulated the epistemological stakes explicitly: “thinking mechanically” excludes “reasons sought from purpose,” directly inverting Harvey’s Aristotelian epistemology in which purposive causation was the only route to true knowledge.(French, 1994)

The campaign ended in catastrophe at Utrecht in 1640–41. Regius, disputing without first consulting Descartes, published theses proposing that man, composed of the two mutually exclusive substances of mind and body, was a unified being only per accidens. At the disputation there was shouting and stamping; the rector and professors marched out; the whole enterprise of inserting Cartesian natural philosophy into the university effectively came to an end.(French, 1994) Calvinist theologian Gisbertus Voet had laid the groundwork for this outcome by arguing that Descartes’ foundational methodological doubt about God’s existence was atheism, and that a purely rational system of the world provided no moral control over society, linking philosophical novelty to social revolution.(French, 1994)

Descartes’s approach to experimental evidence compounded the difficulty. He wanted to perform all observations himself, or else pay artisans to do them, since the incentive of financial gain would ensure they would do exactly what they were told. He sidestepped the problem of establishing trust in experimental results by a supreme selfishness: what convinced him should be good enough for anyone and everyone.(Peter Dear, 2001) Harvey, by contrast, had legitimated his circulation doctrine by invoking the institutional authority of the College of Physicians, informing potential critics that the learned Doctors had attended his demonstrations and been in “full agreement.”(Peter Dear, 2001) Descartes’s deductive method generated a different style of credibility claim, and a more vulnerable one.

The Scientific Revolution Context: Mathematics Against Aristotle

Descartes’s project was part of a broader mid-seventeenth-century contest over what counted as legitimate knowledge of nature. Peter Dear’s Revolutionizing the Sciences (2001) shows that Aristotelian natural philosophers of the previous century had explicitly denied mathematics the status of a true science because it lacked causal demonstrations: mathematical proofs described quantitative properties without reaching the essences of things.(Peter Dear, 2001) The physico-mathematical movement (Galileo, Kepler, Beeckman, and Descartes) worked, by different routes, to overturn this hierarchy and claim that mathematical or mechanistic description gave genuine knowledge of nature’s causes.

What Galileo, Bacon, and Descartes accomplished, in Dear’s reading, was to elevate operational and mathematically structured knowledge to the prestige formerly held by contemplative Aristotelian natural philosophy.(Peter Dear, 2001) Thomas Hobbes diagnosed precisely what was at stake in the experimentalist version of this program: he argued that Boyle’s experimental philosophy failed to achieve true natural philosophy, because experiments could only display phenomena, not demonstrate necessary causes. Genuine science, for Hobbes, required mathematical demonstration: conclusions proved with necessity, like geometrical proof.(Peter Dear, 2001) Descartes would have agreed with Hobbes’s critique, though not with his conclusions. The deductive structure of Cartesian physics was an attempt to achieve the necessity that experiment could not deliver.

Descartes chose a medical topic (the motion of the heart and blood) as his prime example of natural philosophy, yet the medical and university component of the seventeenth-century new philosophy has been consistently undervalued by historians, who have focused on physical and mathematical aspects of the scientific revolution.(French, 1994) The mechanical devices that circulated through seventeenth-century medical controversy (clocks, pumps, syringes, bellows, cupping-glasses) functioned as both rhetorical analogies and physical experimental apparatus, reconceptualizing bodily functions and reframing what questions about the body were worth asking.(French, 1994) Pecquet’s Experimenta nova anatomica (1652), which used physico-mathematical experiments on vacua to deny attraction in the heart’s diastole, marked a watershed: it symbolized both the beginning of general acceptance of Harvey’s doctrines and the spread of a mechanical vision of the body.(French, 1994)

Regius the Cartesian argued that form is merely a congeries of accidents and that all motion is local motion, thereby providing the philosophical basis for interpreting valve action as purely mechanical rather than purposive.(French, 1994)

The Misreading of the Meditations

The Meditations has been systematically misread: most readers interpret it as casting doubt on sensory knowledge, so that only pure intellect can be known with full clarity (Cook, 2007). Cook argues the opposite: Descartes’s goal was to show that knowledge of God and the intellect is more certain even than our dependable sensory knowledge of the material world, which he held should not be doubted (Cook, 2007).

Descartes himself said so explicitly. In the final pages of the Meditations, he wrote that the “great benefit of these arguments is not, in my view, that they prove what they establish (namely that there really is a world, and that human beings have bodies and so on) since no sane person has ever seriously doubted these things.” His point was about the relative certainty of different kinds of knowledge, not about whether the body and the material world exist (Cook, 2007).

This matters for understanding Descartes’s medical thought because the standard reading has produced a Descartes whose primary contribution to medicine was epistemological doubt (skepticism about sensory knowledge) rather than positive material investigation. The Dutch physicians who read and deployed Cartesian ideas were not skeptics about the senses. They were empirical investigators committed to describing material structures. Swammerdam’s microscopical work on insects, conducted in explicit awareness of Descartes, exemplifies this: carefully empirical, resistant to causal speculation beyond what observation warranted, and using hedged probabilistic language rather than mechanistic certainty (Cook, 2007). The grip of the mechanical philosophy in this period was related not to Descartes’s metaphysics but to something more concrete: the promise, realized through the microscope, of actually seeing the tiny machines on which life was built (Cook, 2007).

Mind, Body, and the Clinical Wound

The element of Cartesian philosophy that left the deepest mark on clinical medicine was not the body-as-machine as such, but the strict separation of body from mind. For Descartes, body and mind are entirely distinct substances. The body is extension: matter occupying space, governed by mechanical laws. The mind is thought: a thinking thing with no spatial extension. They interact, but they are not the same kind of thing. The pineal gland, in Descartes’s account, is where the soul acts on the body and the body acts on the soul; the passions are bodily perturbations that produce corresponding movements in the mind.

This dualism created an immediate practical problem: if mind and body are entirely distinct substances, how does the physician treat the whole patient? The question was not simply philosophical. It touched everything from how pain was to be understood to whether emotional states could cause physical disease. Descartes himself, in the closing lines of the Meditations, had argued that disease arises from errors in judgment: the body produces sensations that the mind misinterprets, leading to actions that are not beneficial.(Cook, 2007) If this were taken seriously as medical doctrine, illness was partly a failure of reason, correctable by careful self-examination. Descartes hoped to extend life through the correct regulation of the mind-body relationship, placing himself in the long tradition of dietetic medicine that went back to the Hippocratic notion of diaita, regimen as a way of life.(Cook, 2007)

Descartes resolved to devote his life to acquiring knowledge of nature for more reliable medical rules, acknowledged the necessity of constant observations, and confirmed that his experimental work was mainly medical through his argument on animal physiology (Cook, 2007). He developed an explanation of the passions as arising from the material world (Cook, 2007). This explanation was extended by Dutch physicians into a full materialist view, which informed regenten’s governance based on human nature rather than virtue (Cook, 2007).

One further inference that several thinkers drew from Descartes’s dualism was a claim about gender. If the mind, as res cogitans, has no sex and is simply rational thought untethered from the body’s material arrangements, then women’s minds are as rational as men’s. François Poulain de la Barre made this argument explicitly in the 1670s, and his aphorism “the mind has no sex” circulated through Parisian salon culture.(Peter Dear, 2001) The gender politics of Cartesianism were not an afterthought. They followed directly from the most abstract feature of the system: the claim that mind and body are substances of entirely different kinds.

Phenomenological Critique: The Body That Descartes Forgot

The dualism of mind and body that Descartes codified is not merely a theoretical error in the history of philosophy. It has a specific clinical consequence that twentieth-century phenomenologists identified with precision: it makes it impossible to account for the patient’s experience of illness.

Descartes’s theory of pain exemplifies the problem. He proposed a mechanical nociceptive model: nerve fibers function as wires running from peripheral receptors to the brain, where a signal arrives and pain is registered. As Ivan Illich describes the standard textbook version: “The flame particle jumps from the fire, touches the toe, moves up the spinal cord until a little bell goes off in the brain and says, ‘Ouch. It hurts.’”(James Aho, Kevin Aho, 2009) This account works adequately for acute, localizable pain from peripheral injury. It fails for what Illich calls “deep pain,” the pain of chronic illness, which is better understood as a matter of attitude, cultural interpretation, and existential meaning rather than as a mechanical signal.(James Aho, Kevin Aho, 2009)

Illich’s critique, as Kevin Aho summarizes it in Body Matters (2009), goes further: by transforming pain into a neurological complaint to be “mechanically managed,” modern medicine smothers pain’s intrinsic question mark and forecloses the existential questions that suffering raises.(James Aho, Kevin Aho, 2009) A Cartesian account of pain as mechanical signal transmission has no resources for distinguishing the pain that, like tuberculosis in the Romantic period, becomes a culturally charged sign, a mark of sensitivity even of value, from the pain that is simply aversive. Pain, on the phenomenological account, is not a simple sensation but a “performance of suffering” shaped by cultural interpretation, personal meaning, and the social gaze of others.

The deeper problem Husserl identified was with the Cartesian picture of consciousness itself. Husserl recognized that it is a mistake to imagine an empty consciousness confronting an external world of objects. The fundamental discovery of phenomenology is that consciousness has the structure of intentionality, consciousness is always “consciousness of” something.(Bortoft, Henri, 1996) The Cartesian picture, in which a disembodied mind peers out at a body-machine through the pineal gland, misrepresents the structure of both mind and body. The phenomenologists argued that what Descartes called the body was never actually experienced by anyone: what is experienced is the lived body (Leib), which is not a mechanism at all but the medium through which the world becomes meaningful.

Descartes’s Separation from Moral Philosophy

Descartes made one further move that contemporaries recognized as consequential, and that shaped the long-term relationship between medicine and ethics. He consistently argued that human beings cannot know the purposes for which God created the universe, and that this rendered moral philosophy (which depends on knowing the right, which means knowing ends) inaccessible from natural philosophy (Cook, 2007). Natural philosophy could describe how bodies worked. It could not, by its own methods, derive how bodies ought to be treated.

This was not a position without precedent. But Descartes articulated it at the moment when natural philosophy was acquiring real explanatory power, and his articulation helped establish what David Hume and Immanuel Kant would later formalize as the distinction between “is” and “ought” (between descriptions of how the world operates and prescriptions about how it should be managed (Cook, 2007). Contemporaries correctly identified this move as placing Descartes alongside Machiavelli and Spinoza as thinkers who derived behavior from material nature rather than from rational virtue. In medicine, the separation eventually produced the methodological commitment to describing biological mechanisms without asking whether those mechanisms are being deployed in the service of the patient’s good) a problem that remains, in altered form, at the center of contemporary philosophy of medicine.

Canguilhem: Mechanism, Vitalism, and What Descartes Suppressed

The most rigorous philosophical account of what Descartes’s mechanism displaced (and why what it displaced refused to stay displaced) comes from Georges Canguilhem’s Knowledge of Life (2008 [1952]). Canguilhem argued that the persistence of vitalism throughout the history of biology cannot be compared to the persistence of phlogiston or geocentrism, because vitalism has a vitality of its own: it is an illusion, if it is one, of a different order, and that difference requires philosophical explanation.(Canguilhem, Georges, 1952/2008)

What vitalism expresses, on Canguilhem’s account, is not a doctrine but an exigency (a permanent demand of life within the living, the self-identity of life immanent to the organism.(Canguilhem, Georges, 1952/2008) This exigency explains vitalism’s characteristic vagueness compared to the precision of mechanism: if it is above all a demand rather than a theory, then it will always have difficulty formulating itself in terms of precise determinations. The mechanist’s criticism that vitalist concepts like “vital force” and “vital principle” beg the question is formally correct) but the exigency they imperfectly express is not thereby eliminated.(Canguilhem, Georges, 1952/2008)

Medical vitalism, Canguilhem argues, is indissociable from naturalism: it expresses a distrust of the power of technique over life, rooted in the Hippocratic confidence in the natura medicatrix, the healing power of nature as a real force in recovery that the physician’s art should support rather than override.(Canguilhem, Georges, 1952/2008) This is precisely the tradition that Cartesian mechanism set itself against. Jan Baptist van Helmont (1580–1644), whose work straddles the same period as Descartes’s own Dutch years, represents a vitalism that is simultaneously a return to Aristotle and Hippocrates beyond Descartes: organized around the Archei, a hierarchy of directing and organizing forces resembling, as van Helmont put it, the leader of an army more than a worker, rather than around the unified mechanical laws Descartes posited for all matter.(Canguilhem, Georges, 1952/2008) Helmontian medicine occupied an intermediate position between Paracelsianism and the new science — more careful in its experimental methods than Paracelsianism, vitalistic in its chemical principles — and from the mid-seventeenth century it posed the strongest alternative to Galenic therapeutics that the period produced.(Wear, 2000)

Canguilhem writes that the rebirths of vitalism translate, in discontinuous fashion, life’s permanent distrust of its own mechanization, and in them we find life seeking to put mechanism back into its proper place within life.(Canguilhem, Georges, 1952/2008) Descartes’s program accomplished something of permanent value by justifying experimental inquiry in biology against vital spirits and occult agencies, as Hall observes: so long as spirits or the Paracelsian archeus ruled the body, it was futile to interpret physiological phenomena through physics and chemistry.(Hall, A. Rupert, 1954)

The Successor Program: Cartesians and Their Successors

The Cartesian natural philosophy Descartes established did not survive unchanged into the next generation. Christiaan Huygens and Jacques Rohault, two of the most prominent adopters of Descartes’s approach to physical explanation, departed significantly from the master’s conception of true natural philosophy as represented in the Discourse on Method and the Principles of Philosophy. They did so by emphasizing the hypothetical character of their explanatory mechanisms.(Peter Dear, 2001) Huygens reinterpreted Descartes’s metaphysical arguments regarding matter as describing only the limits of human understanding, not guarantees about reality: human beings cannot understand explanations couched in terms other than inert matter in motion, but there is no guarantee that this human inability reflects the true condition of things.(Peter Dear, 2001) This was a quieter, more defensible form of mechanism, and a form that quietly abandoned Descartes’s claim to have derived the structure of the world from certain first principles.

Leibniz proposed a “pre-established harmony” to solve the Cartesian mind-body interaction problem: God arranged mind and body to run in perfect parallel without causal interaction, so that mental events and physical events correspond without causing each other.(Peter Dear, 2001) This eliminated causation between mind and body entirely.(Peter Dear, 2001) By the later eighteenth century, what counted as “Newtonianism” was itself a hybrid of Newton’s, Descartes’s, Leibniz’s, and many others’ ideas, and what counted as Newtonian differed substantially from what Newton himself had believed.(Peter Dear, 2001)

The Medical Programs Descartes Inspired: Iatrophysics and Its Successors

The most direct medical program descended from Descartes’s vision of the body as machine was iatrophysics (also called iatromechanics): the attempt to explain bodily function and disease in terms of the physics of levers, pumps, and hydraulic pressure. Giovanni Borelli, working in Naples in the second half of the seventeenth century, applied mechanical analysis to muscle contraction, calculating the forces required for various bodily movements. Richard Lower in England analyzed the heart as a muscle. The whole enterprise aimed at a medicine grounded in physics rather than in the humoral theory whose theoretical coherence Harvey’s discovery of circulation had already undermined. Lower also demonstrated in 1669 that the change in blood color from venous to arterial occurred in the lungs through the action of a “nitrous spirit” taken from inspired air, an important step toward the chemical revolution in physiology that Descartes’s framework had made possible by treating respiration as a material process.(Hall, A. Rupert, 1954)

Ackerknecht’s assessment of this program is direct: “As a whole both movements, iatrophysics and iatrochemistry, were bound to be failures.” Their history, he argues, demonstrates “the danger of premature application of basic scientific data to clinical medicine” and the enormous quantity of so-called “useless knowledge”, basic science, that must accumulate before such applications become clinically fruitful (Ackerknecht, 1955). [GAP: Explanation of why 17th-century physics and chemistry were insufficient for clinical explanation] [GAP: Examples of clinical phenomena that a hydraulic model cannot account for]

One visible index of the mechanist program’s success at the purely anatomical level was Marcello Malpighi’s observation, through the microscope, of blood passing from arteries to veins through capillary vessels in the lungs of a frog, the final link that clinched Harvey’s theory of circular blood motion and that had eluded Harvey himself for lack of adequate magnification.(Hall, A. Rupert, 1954) Descartes had promised that the tiny machines underlying life would eventually become visible. The microscope began to deliver on that promise.

Thomas Willis, working in England, represented a more modest and more durable version of the Cartesian program: he modernized learned medicine by incorporating mechanistic explanations while retaining the old structure of the disease narrative of hidden events in the body (Wear, 2000). Willis moved medicine away from Galenic qualitative theory (away from hot and cold and wet and dry as the fundamental explanatory categories) without abandoning the framework of rational causal explanation. Into this restructured narrative he incorporated the action of remedies, removing them from mere empirical medicine and placing them within a causal account. This was a successful partial mechanization, and it was Willis’s approach, not Borelli’s, that shaped the direction of educated medicine into the eighteenth century.

What Wear’s analysis of seventeenth-century English medicine makes clear is that even Willis’s partial success did not translate into changed practice at the clinical level. Purging, bleeding, and evacuative therapies continued to be performed enthusiastically across the period, despite the Helmontian attack on them and despite the theoretical collapse of their humoral rationale (Wear, 2000). The mechanical philosophies competing in seventeenth-century England (Gassendi’s, Descartes’s, Boyle’s, Newton’s) all claimed to replace Galenism, but “it was not until the end of the seventeenth century in England and well into the eighteenth century in continental Europe that Newton’s philosophy was accepted as the true mechanical philosophy” (Wear, 2000). Theory and practice were not tightly coupled. The theoretical demolition of the body’s purposive self-healing did not stop practitioners from trying to support it.

Harvey treated his work as philosophical rather than medical.(French, 1994) As his opponents argued loudly, the circulation had no medical use; Harvey made little attempt to explain the clinical significance of his discovery, and conspicuously avoided building up a therapeutic system on it in the years after 1628.(French, 1994)

The Long Consequence: Reductionism and Its Critics

Contemporary philosophy of medicine recognizes that Western medical researchers and practitioners consistently seek mechanistic hypotheses about the causes of clinical outcomes, and that this approach, while productive, generates persistent disputes about what it leaves out (Unknown, unknown). The reductionism/holism debate in medicine centers on whether genetic/molecular-level explanations are privileged, with critics arguing that overemphasis on geneticization misses phenotypic and environmental levels of explanation critical for understanding and treating disease (Unknown, unknown).

George Engel’s biopsychosocial model, proposed in 1977, was the most influential twentieth-century attempt to repair what Descartes’s dualism had separated: it argued that clinicians must account for physical, psychological, and social factors together rather than treating the body as a physical mechanism and everything else as secondary (Unknown, unknown). That the model still required explicit argument (that it needed to be proposed as a reform rather than simply assumed) reflects how thoroughly the mechanist separation of mind from body had become embedded in biomedical practice.

Illich’s critique, made from a different angle in Limits to Medicine (1975), argued that the mechanization of medicine had produced a cultural consequence Descartes did not anticipate: when the body is treated as a machine requiring expert technical management, patients lose their capacity to deal with illness, vulnerability, and death as personal and autonomous experiences (Illich, 1975). This is not a Cartesian argument, and Illich himself did not frame it that way. But the problem he identified (the expropriation of the patient’s experiential authority over her own body) is one that follows naturally from a model in which the body’s processes are mechanical events to be analyzed by technically trained specialists rather than organic experiences to be interpreted by those who live in them.

Descartes spent his last months in Stockholm, where he had traveled at the invitation of Queen Christina of Sweden. He died in February 1650, of pneumonia. The body whose mechanics he had spent twenty years investigating gave out in a Swedish winter, far from Amsterdam and the slaughterhouses where he had done his best work. He left behind an unfinished manuscript, the Description of the Human Body, and a program so thoroughly absorbed into the methods of subsequent medicine that its outlines had, by the twentieth century, become almost invisible as choices.

See Also

• William Harvey
• Iatrophysics
• Mechanism, the broader philosophical program Descartes established for medicine
• Thomas Willis
• Giovanni Borelli
• François de la Boë Sylvius
• Vis Medicatrix Naturae
• Francis Glisson, vitalist critic and Cambridge transmitter of Harvey
• Mind-Body Problem (Medicine)
• Biopsychosocial Model
• Galenism
• Vitalism
• Georges Canguilhem

Sources

All claims cite evidence cards from:

• Cook, H.J. (2007). Matters of Exchange: Commerce, Medicine, and Science in the Dutch Golden Age. New Haven: Yale UP. [Source ID: cook-mattersofexchange-2007] — Lead authority
• Ackerknecht, E.H. (1955). A Short History of Medicine. New York: Ronald Press. [Source ID: ackerknecht-shorthistory-1955] — Lead authority
• Wear, A. (2000). Knowledge and Practice in English Medicine, 1550–1680. Cambridge: Cambridge UP. [Source ID: wear-knowledgepractice-2000] — Lead authority
• Neuburger, M. (1943). The Doctrine of the Healing Power of Nature Throughout the Course of Time. Tr. L.J. Boyd. [Source ID: neuburger-healing-power-of-1943] — Superseded-but-valuable
• Ankeny, R.A. & Reiss, J. (2016). “Philosophy of Medicine.” Stanford Encyclopedia of Philosophy. [Source ID: sep-philosophy-medicine] — Reference
• Illich, I. (1975). Limits to Medicine: Medical Nemesis. London: Calder & Boyars. [Source ID: illich-limitsmedicine-1975] — Oppositional authority
• French, Roger. (1994). William Harvey’s Natural Philosophy. Cambridge: Cambridge University Press. [Source ID: french-william-harvey-natural-1994] — Lead authority for Harvey/Descartes contrast, epistemological analysis, Utrecht crisis
• Hall, A.R. (1954). The Scientific Revolution, 1500–1800. London: Longmans. [Source ID: hall-scientific-revolution-1954] — Contextual authority for scientific revolution
• Dear, P. (2001). Revolutionizing the Sciences: European Knowledge and Its Ambitions, 1500–1700. Princeton: Princeton UP. [Source ID: dear-revolutionizing-sciences-2001] — Contextual authority for epistemology of experiment and Cartesian successors
• Aho, K. (2009). Body Matters: A Phenomenology of Sickness, Disease, and Illness. Lanham: Lexington Books. [Source ID: aho-aho-body-matters-2009] — Phenomenological critique
• Canguilhem, G. (2008 [1952]). Knowledge of Life. Tr. S. Geroulanos & D. Ginsburg. New York: Fordham UP. [Source ID: canguilhem-knowledgeoflife-2008] — Lead authority for mechanism/vitalism analysis
• Bortoft, H. (1996). The Wholeness of Nature: Goethe’s Way toward a Science of Conscious Participation in Nature. Hudson, NY: Lindisfarne Press. [Source ID: bortoft-wholeness-of-nature-1996] — Phenomenological authority for intentionality critique