David Hume
David Hume (1711—1776) was a Scottish philosopher, historian, and essayist whose work reshaped the intellectual basis of medicine in three lasting ways. His empiricist account of causation challenged the assumption that physicians could directly observe causes of disease — they could observe sequence and correlation, not causal necessity. His moral philosophy of sympathy supplied John Gregory with the theoretical basis for a new professional ethics. And his observation that one cannot logically derive what ought to be from what is — the is-ought gap — created a persistent problem for medical ethics that modern bioethics has never fully resolved. Hume’s deathbed composure in the face of mortality also made him, for his contemporaries, a living demonstration of Enlightenment secular values in medical context.
Empiricism and Medical Knowledge
Hume’s project in A Treatise of Human Nature (1739—40) was to extend Newtonian method — careful observation and induction — from the natural world to the study of human nature itself. He declared that all sciences, including mathematics and the natural sciences, were “in some measure dependent on the science of Man,” making the study of human nature the foundation of all other knowledge.(Porter, 2000) This ambition directly paralleled the ambitions of the Edinburgh medical school, where clinical observation rather than theoretical system was becoming the methodological ideal.
[GAP: Discussion of Hume’s epistemology as the core of the project] [GAP: Hume’s argument that experience provides impressions from which ideas are derived] [GAP: Claim that all meaningful knowledge traces back to original impressions] [GAP: Concepts not grounded in experience are empty] [GAP: Tension between Hume’s empiricism and rationalist medical traditions of Stahl, Boerhaave, and Cullen] Between 50,000 and 100,000 people had been executed as witches across early modern Europe, and belief in witchcraft and demonic possession had been shared by educated and common people alike.(Andrew Scull, 2015)
King’s analysis of medical explanation identifies the problem Hume’s empiricism posed for the dominant medical tradition. The virtus dormativa — explaining that opium puts patients to sleep because it has a sleep-inducing power — was precisely the kind of empty explanatory circle that Hume’s analysis exposed: a concept with no experiential content that merely restated the explicandum in different words, adding nothing to understanding.(King, 1978) Both Hume and Molière had noticed this failure of occult-quality reasoning; King shows that the nominalist tradition from which the critique drew was ancient, but Hume’s systematic empiricist epistemology gave it new philosophical rigor.
Causation and Clinical Reasoning
Hume’s most consequential contribution to the philosophy of medicine was his analysis of causation. Examining our ordinary belief that causes produce effects, he argued that no single observation — and no accumulation of observations — could ever perceive causal necessity. What we observe is constant conjunction: event A is regularly followed by event B. We then develop a habit of expectation that A will be followed by B. But the necessity we feel is psychological, not logical. It comes from within us, not from the world.
This creates a serious problem for medicine. The clinical relationship is structured around causal claims: this herb reduces fever because it acts on inflammation; this treatment cures typhoid because it kills a bacterium. Hume’s analysis shows that even the strongest empirical generalizations — the ones built on thousands of clinical observations — cannot be logically derived from those observations alone. Induction cannot prove what it appears to prove.
Broussais engaged this problem directly in a supplement to On Irritation and Insanity (1831), arguing against Hume’s position that sensory phenomena do not include the relation of cause and effect. Broussais maintained that induction, like perception, is a brain operation; the difference is merely that induction follows from and requires perception, not that it comes from a separate faculty.(Broussais, 1831) This materialist response — reducing Hume’s epistemological problem to a physiological one — was characteristic of the French clinical school, which preferred to bracket skeptical philosophy rather than answer it.
The medical significance of Hume’s problem of induction extends beyond clinical reasoning to statistical methodology. The early use of statistical methods in medicine — James Jurin’s work on smallpox inoculation, actuarial tables of mortality, the clinical trials of the late Enlightenment — implicitly relied on the inductive inference Hume had destabilized.(Porter, 2000) It was not until the twentieth century, particularly through the work of Karl Popper, that philosophy of science reckoned seriously with what Humean skepticism meant for scientific medicine’s claims to knowledge. Evidence-based medicine, which emerged in the 1990s, can be read as a practical institutional response to the Humean problem: if we cannot logically prove causal claims, we can at least rank the quality of our evidence for them.
Hume’s Problem and Evidence-Based Medicine
The is-ought gap has a close epistemic cousin in medicine: the gap between statistical evidence and individual clinical decision. Hume showed that no amount of general observation licenses a necessary claim about the particular case. A drug that works for 80 percent of patients may or may not work for the patient in front of you. The evidence-based medicine movement, beginning with Archie Cochrane’s arguments in the early 1970s and consolidating in the 1990s at McMaster, represents one attempt to manage rather than solve this Humean problem: randomized trials and systematic reviews are not ways of transcending induction, but ways of disciplining it.
Carel’s phenomenology of illness captures a closely related failure of inductive confidence at the experiential level: just as Hume showed that our instinctive faith in induction is rationally unjustified but practically inescapable, patients discover that their tacit certainty about their own bodies — the unquestioned faith that one’s heart will keep beating, that one’s legs will carry one — is similarly unjustified but lost when illness strikes.(Carel, 2016) Bodily trust is the lived equivalent of Hume’s problem: a certainty we cannot ground but cannot do without, whose loss is catastrophic.
The Is-Ought Problem and Medical Ethics
Hume observed in the Treatise that moral writers habitually shift, without explanation, from statements about what is the case to statements about what ought to be done. This logical gap — between descriptive and prescriptive claims — has particular force in medicine. The history of clinical practice is full of arguments that move from natural facts to moral conclusions: that it is natural for women to be subordinate and therefore medicine should enforce that subordination; that a given condition is a disease and therefore it should be treated; that certain sexual practices are pathological and therefore they require correction. The is-ought gap names the logical flaw in each of these moves.
Cook traces the historical roots of this separation to Descartes’s rejection of the classical doctrine of “right reason” — the unity of the true and the good.(Cook, 2007) Descartes set aside moral questions as beyond natural philosophy.(Cook, 2007) [GAP: The original paragraph then claimed that Hume and Kant codified the is/ought distinction and drew a consequence for medicine, but these claims are not supported by the cited card.]
This problem does not appear only at the philosophical margins. Every clinical decision involves a normative premise: that health is to be promoted, that suffering is to be relieved, that patient preference matters. None of these premises can be derived from medical science alone. Pellegrino and Thomasma identified this clearly in their critique of principle-based ethics: the postmedieval erosion of virtue ethics in medicine was driven partly by Humean moral philosophy, which had shifted attention from the character of the physician-agent to acts and principles, leaving medical ethics with rules that required independent philosophical grounding.(Pellegrino, 1993)
Influence on Bioethics: The Beauchamp and Childress Connection
The most direct line from Hume to contemporary bioethics runs through John Gregory and Francis Hutcheson to Thomas Beauchamp and James Childress. Jonsen identifies Gregory, writing in Edinburgh in the 1760s and 1770s, as Hume’s friend and colleague who explicitly adapted Hume’s moral philosophy of sympathy to medical practice. Gregory’s Lectures Upon the Duties and Qualifications of a Physician (1772) grounded the central medical duty — to relieve suffering and cure disease — in the natural and intuitive sympathy Hume placed at the foundation of all moral life.(Jonsen, 2000) As Laurence McCullough has argued, Gregory’s lectures applied Hume’s concept of sympathy to the ethics of medical practice in a philosophically systematic way, making the Lectures the foundational document of a new professional ethics grounded in Scottish moral philosophy rather than religious obligation.(Jackson (ed.), 2011) From sympathy as the basis of morality, Gregory derived confidentiality, truth-telling, and collegial restraint as specific medical duties.
McCullough shows that Thomas Percival, Gregory’s successor in the invention of modern medical ethics, explicitly drew on Hume’s moral science of sympathy alongside Baconian scientific method and the commitments of Dissenting Unitarianism.(Mccullough, 1998) Percival’s Medical Ethics (1803) — the text that introduced the term “medical ethics” into the literature — was thus partly a Humean document, translating a philosophic account of natural sympathy into a code of professional conduct.
Beauchamp and Childress, in Principles of Biomedical Ethics, invoke Hume directly on the question of reciprocity as a foundation for beneficence.(Tom L. Beauchamp, James F. Childress, 2013) Hume argued that our obligations to benefit others arise from social interaction: “All our obligations to do good to society seem to imply something reciprocal. I receive the benefits of society, and therefore ought to promote its interests.”(Tom L. Beauchamp, James F. Childress, 2013) For Beauchamp and Childress, this notion of reciprocity provides an independent justification for obligations of beneficence, particularly in healthcare and research.(Tom L. Beauchamp, James F. Childress, 2013)
The Scottish Enlightenment and Medicine
Hume was embedded in the Edinburgh intellectual circle that produced a distinctively medical form of Enlightenment. Adam Ferguson, John Millar, Adam Smith, and Dugald Stewart — alongside Hume — developed “conjectural history” and stadial theories of social progress as replacements for biblical chronology.(Porter, 2000) This way of thinking, which traced the development of human society through stages from hunting through commerce, influenced medical thinking about the natural history of disease and the developmental history of the body.
David Hume, along with The Spectator, Mary Anne Radcliffe, and William Shenstone, expressed that the “vulgar” were inferior in taste and understanding.(Porter, 2000) Hume specifically addressed himself to “the elegant part of mankind, who are not immersed in mere animal life,” a phrase that captures his condescension toward the merely corporeal.(Porter, 2000)
The Enlightenment also promoted a shift away from the Christian ars moriendi — the scripted pious deathbed — toward a secular ideal of peaceful death. Hume’s own death in 1776 became a celebrated instance of this new ideal. James Boswell, who forced himself on the dying Hume, was scandalized to find the unbeliever dying “easy,” without recantation or fear. The scandal registered what was at stake: Hume’s serene deathbed was a demonstration that secular philosophical composure could substitute for religious consolation — a claim with direct implications for medical practice and the management of dying.(Porter, 2000)
Print Culture and the Public Physician
The print revolution and the rise of the reading public brought new cadres of knowledge-mongers into being in Britain, serving as society’s eyes, ears, brains and mouthpieces.(Porter, 2000) Both Johnson and Hume recognized that the progress of printing had produced “a sudden and sensible change” in public opinion within fifty years.(Porter, 2000) Johnson ruled that “the mass of every people must be barbarous where there is no printing and consequently knowledge is not generally diffused.”(Porter, 2000)
William Buchan’s Domestic Medicine (1769) criticized physicians for making medicine a mystery, comparing their practices to priestcraft, and sought to render medicine more extensively beneficial to the common reader by expounding an enlightened philosophy of health through reason, temperance, hygiene, and heeding Nature’s laws.(Porter, 2000)
See Also
- John Gregory
- Thomas Percival
- Francis Hutcheson
- Adam Smith
- Scottish Enlightenment
- Empiricism in Medicine
- Causation in Medicine
- Bioethics
Sources
- Jackson, Mark (ed.). Oxford Handbook of the History of Medicine. Oxford University Press, 2011. Chapter 30. [Source ID: jackson-oxfordhandbook-2011]