Sextus Empiricus

Sextus Empiricus

Around the turn of the third century AD a Greek physician wrote down a story about a painter. Apelles was painting a horse and could not get the foam at its mouth right. Attempt after attempt failed, until he gave up in frustration and flung at the picture the sponge he had been using to wipe his brushes. Where it struck, it left a perfect image of foam. The physician, Sextus Empiricus, offered this as the truest picture of his own school. The skeptics began like every other Hellenistic sect, seeking tranquility, and they pursued it the obvious way, by trying to decide which appearances are true and which false. They failed; the arguments on each side kept coming out equally strong. And when they finally stopped deciding and suspended judgment, the thing they had been chasing arrived on its own, "as if by chance, as the shadow follows a body." Pyrrhonism is the one philosophy in the Western canon whose founding discovery is that its goal cannot be reached by aiming at it, and its great codifier was not a wrecker of philosophy but a working doctor who compiled a library of every argument that had ever made a confident person hesitate.

An ability, not a creed. The cartoon skeptic believes nothing, sneers at everything, and announces that knowledge is impossible. Sextus would point out that the last of these is a doctrine, and doctrines are exactly what he does not hold. The Greek word skepsis means inquiry, and the opening lines of the Outlines of Pyrrhonism sort all philosophers by where their inquiry ended: some say they have found the truth (the dogmatists), some declare it impossible to find (he files the later skeptical Academy here, and calls this negative dogmatism), and some are still searching. The skeptics are the searchers, and their school takes its name from Pyrrho, the wandering contemporary of Alexander who first made suspension of judgment a way of life rather than a conclusion. What Pyrrho lived and never wrote, Sextus systematized: skepticism, he says, is not a set of beliefs but an ability, a practiced skill of setting against every appearance and every argument its equal opposite, until the two sides balance so exactly (the technical term is equipollence) that assent becomes impossible. Suspension of judgment follows, and tranquility follows that. Nothing is asserted about how things really are; the skeptic reports only how things appear to him at the moment, the way a patient reports a symptom.

The doctor's hand. About the man himself we know almost nothing: a physician, active around the turn of the third century, placed by different scholars in Alexandria, Athens, or Rome, heir to a chain of skeptical teachers running back through Aenesidemus to the old Pyrrhonian revival. Even his name is a clinical note, since "Empiricus" ties him to the Empiric school of medicine, though in the closing chapter of Book I he remarks that the Methodic school suits a skeptic better, because it never theorizes about hidden causes and simply lets the patient's condition guide treatment, the way thirst guides a man to water (PH I.236-241). The medical habit runs through everything he wrote. Dogmatism is treated as a disease of rashness and conceit; arguments are remedies, graded in strength to match the ailment; and the skeptic's own formulae are designed to flush themselves out of the system once they have worked, "just as cathartic medicines not only purge the body of humors, but carry off themselves with the humors" (PH I.206). Even the saying "I determine nothing" determines nothing about itself (PH I.197). The school had thought its own self-reference problem through with a thoroughness that still surprises logicians who come to the text expecting an easy refutation.

The ten modes and the five. The working machinery of the school is a set of argument patterns, the modes, for manufacturing equipollence on demand. The ten modes attributed to Aenesidemus (PH I.36-163) generate undecidable conflicts of appearance: animals with different sense organs perceive different worlds; people differ from one another; the senses disagree among themselves; circumstances such as fever, love, grief, or drunkenness transform what appears; the oar looks bent in water and straight in air, and nothing presents itself except from some position, at some distance, in some mixture, in some quantity, relative to some observer, against some custom or law. The five modes of Agrippa (PH I.164-177) are leaner and deadlier: disagreement, infinite regress, relativity, arbitrary hypothesis, and circular reasoning. Ask why anyone believes anything, and the justification either regresses forever, stops at an unargued assumption, or loops back on itself. That trilemma is still the engine room of epistemology; foundationalism and coherentism are the two standing answers to Agrippa, the argument runs on under new names in every contemporary theory-of-knowledge syllabus, and no one pretends the case is closed. Very little in the modern problem of justification cannot already be found, fully armed, in these few pages.

How a skeptic gets out of bed. The oldest objection says the skeptic cannot live his skepticism: without beliefs he would starve, walk off cliffs, touch fire. Sextus answers with the fourfold rule of life (PH I.23-24): the skeptic follows the guidance of nature, the necessity of the feelings, the tradition of laws and customs, and the teaching of the arts. Hunger leads him to food and thirst to drink; he honors the pieties of his country; he practices his craft of medicine. None of this requires a theory. "It appears to us that honey is sweet. This we concede, for we experience sweetness through sensation. We doubt, however, whether it is sweet by reason of its essence" (PH I.19-20). The skeptic never denies the appearances; he declines only the extra step, the dogma about hidden natures. And here lies the therapeutic claim. The ordinary person suffers twice, once from cold or pain itself and again from the conviction that these things are bad by nature, a conviction that adds dread before and regret after. The skeptic, holding no such conviction, suffers only the first, unavoidable layer, and so achieves what Sextus calls moderate feeling in things forced upon us and tranquility in matters of opinion. It is a modest promise, honestly costed, and closer to a clinical outcome than to a creed.

What this room reads. The corpus is anchored by Mary Mills Patrick's Sextus Empiricus and Greek Scepticism (1899), a public-domain study that includes her complete English translation of Outlines of Pyrrhonism Book I, the book in which Sextus defines the school, runs the ten and the five modes, and explains the skeptical way of life. Beside it sit her late survey The Greek Sceptics (1929, Columbia University Press, public domain in the United States since January 2025), which narrates the whole tradition from Pyrrho through the Academy to Sextus, and R. G. Bury's Loeb translations of Against the Logicians (1935) and Against the Professors (1949), both in the American public domain because their copyrights were never renewed. The Bury volumes print Greek and English on facing pages, so retrieval occasionally surfaces a Greek snippet beside the translation. Citations follow the standard scheme: PH I.12 for the Outlines, M VII.166 for the polemical works. Two gaps are disclosed plainly: Outlines Books II-III and Against the Physicists and Against the Ethicists (M IX-XI) have no openly downloadable public-domain text, so the chat answers questions on those books from general scholarship and says so when it does.

The book that returned. For most of the Middle Ages Sextus went unread, a doctor's compilation gathering dust in Greek. Then the manuscripts came west, and in 1562 Henri Estienne printed a Latin Outlines; Gentian Hervet's complete Latin Adversus Mathematicos followed in 1569. The effect on European philosophy was detonative. Montaigne worked the skeptical formulae into the Essays, struck a medal stamped with his question "Que sais-je?", and through him the recovered Pyrrhonism reached every literate doubter in Europe. Descartes designed the Meditations as a machine for passing through Pyrrhonian doubt and out the other side, which concedes the seriousness of the challenge in the act of answering it. Hume judged the Pyrrhonian arguments unanswerable in the study and unlivable in the street, and built his mitigated skepticism on exactly that tension. Hegel, who scorned the modern skeptic's pose, called the ancient version the serious one and folded its negative power into his own method, describing the path of the Phenomenology as a self-completing skepticism. A philosopher who asserted nothing ended up supplying the stress test that every modern system of knowledge has had to pass, or visibly fail.

The living use of Sextus is not a position you adopt but a discipline you acquire, and it takes about a week of practice to feel it work. When you notice yourself certain, build the strongest case for the other side, not a strawman but an equal; hold the two in view; watch what happens to the certainty. Sometimes it survives, and is the better for it. Sometimes it dissolves, and what replaces it is not paralysis but a cooler, more inquiring relation to the question, which is what he meant by tranquility. The Outlines Book I in this room reads in an afternoon, and the chat is built for precisely the old exercise: bring it the opinion you are most sure of and ask for the counter-case at full strength. Eighteen centuries on, the physician's sponge is still wet.