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date: 28 November 2022



  • Marquis Berrey


Empiricists were a self-identified medical sect of the Hellenistic and Imperial periods who shared a common experiential methodology about the purpose and practice of medicine. Denigrating unobservable causes and experimental medicine, they espoused a sceptical, passive approach to accumulated observations about the body and the natural world. Since few Empiricist texts survive, historical knowledge depends largely on the medical doxographies of later ancient physicians who were not Empiricists. Doxographies report that Empiricists practiced a controlled experiential medicine based on personal observation, written reports from previous physicians, and analogical reasoning from known to unfamiliar conditions. The importance of chance and memory to their medical practice along with a willingness to compare themselves to tradesmen of lesser status distinguished their philosophical medicine from other ancient medical sects.


  • Science, Technology, and Medicine

Empiricists (Gk. empirikoi, Lat. empirici) were a self-identified sect or school (hairesis) of physicians from the Hellenistic and Imperial periods who shared a common experiential methodology about the purpose and practice of medicine. Empiricists practiced a controlled experiential medicine for individual therapeutic success based on personal observation, written reports from previous physicians, and analogical reasoning from known to unfamiliar conditions. Twenty-one named Empiricists are known to have practiced. The prosopographic record of the sect begins from Philinus of Cos, a renegade student of Herophilus of Cos, and lasts until about 200 ce. Later Empiricists sought their origins in Hippocrates or other early physicians; these first founders of medical empiricism are mythic fictions, but the controversy over primacy between deductive knowledge and knowledge gained from sense experience has its roots in Greek philosophical disputes from the 5th century bce (Ps.-Galen Intr. 4.2, 14.683K; Hippocrates On Ancient Medicine). With the Rationalists and Methodists, the sect played a major role in Hellenistic and Imperial disputes. Empiricists likely started the controversy by falsely labelling all their opponents dogmatikoi “Dogmatists” or “Rationalists” for similar methodologies, although the Herophileans, Erasistrateans, and others did not altogether identify as a group. The Empiricists practiced allopathic healing, aligning themselves with the ancient Hippocratic therapeutic tradition of detailed observation and patient individuality. The purpose of Empiricist medicine was effective therapy. Empiricists practiced with success in internal medicine, pharmacology, surgery, and exegesis of Hippocratic texts.

The best sources for understanding the ancient Empiricists are the medical doxographies and surviving fragments. The Empiricists survive as fragments or testimonia in other authors, as well as the recent papyrus find P.Oxy. 5231. The authors transmitted in manuscript who may be Empiricists are Apollonius (8) of Citium and the philosopher Sextus Empiricus who, despite his epithet, once agrees with the Methodists (PH 1.34, 236–237). The variously hostile or sympathetic medical doxographies of Celsus, Ps.-Galen, and Galen present an overview of Empiricist methodologies that need to be balanced against extant fragments.


The philosophical justification of the Empiricists to medical practice was empeiria (experience). Empiricists divided experience into three parts of what they called the tripod (tripous): observation, history, and transition. Empiricists accumulated experiences through individual inspection (autopsia) and observation (tērēsis) of phenomena, before committing their experience (peira) to memory. Empiricist observation was the repeated passive observation of the body and the natural world, not an active intervention into the regular order. They directed their attention to observable phenomena only, arranging descriptive symptoms into so-called syndromes rather than investigating causes or diseases (Ps.-Galen Intr. 3.2, 14.678K). While it was a matter of dispute with their opponents how often a phenomenon needed to be observed before it counted as an established experience, Empiricists set no numerical standard (Galen Med. Exp. 115–120). Since one individual’s lifetime did not suffice to observe everything in medicine, Empiricists relied on earlier practitioners’ communicated experience (Galen Subf.Emp. 8). This history (historia) encompassed both oral and written sources, although oral history was probably restricted to teacher-pupil relationships. In extant evidence, early Empiricists relied almost exclusively on the written experiences of the Hippocratic Corpus (Apollonius of Citium 3.24, 82.1–6; cf. Celsus 8.4.3–4, 8.15.5). Later Empiricists collected and compared the written experiences of multiple medical authors, including doctors who were not Empiricists. To tabulate authorities separated in space and time into one list would resemble the collective medical empiricism of Early Modern casuistic medical texts, but there is no clear evidence for works in list form from ancient Empiricists. Finally, in those times when an Empiricist physician might encounter a symptom, a syndrome, or even a materia medica new to him, he would resort to analogical reasoning. The Empiricist would use “transition from the similar to the similar” (metabasis tou homoiou toi homoiōi) by analogically reasoning from known qualities of similar materia medica and syndromes of visibly similar appearance (Galen Subf. Emp. 9). Hence experiential medicine would use past practice as a reliable guide to the future with varying expectations of success, depending on the degree of similarity. The principle of analogical reasoning had heuristic potential for medical discoveries but the Empiricists did not use it in this way. Since the point of medicine was effective therapy, certainty was not possible.


Empiricist methodology for effective therapy was a Sceptical reaction to the experimental scientific practices of Herophilus and Erasistratus of Iulis, paradigmatic dogmatikoi. Effective therapy did not need to be based on theoretical entities and exploratory physiology, for “it did not matter what made disease but what removed it” (Celsus Empiricists compared their practice to farmers and other experientially reasoning tradesmen (Galen Med. Exp. 98–99). The Empiricists rejected investigation into invisible causes and hidden things (adēla); for them nature was fundamentally unknowable (Celsus Anatomy was to be learned in course of medical treatment or using chance observation of opened and unburied bodies (Celsus; compounded drugs were developed by chance experiences (Galen MM 3.2, 10.164–166K). Using further language borrowed from the Sceptics, the Empiricists argued against other sects with isosthenia (equivalence), asserting that the doctrines of Herophilus and Asclepiades of Bithynia were equivalently believable (Celsus The sect became less dogmatic throughout its history with changes to tenets about causality, the use of other physicians’ written reports, and analogical reasoning. Three figures appear to have been instrumental in establishing doctrines and altering those of their predecessors: Serapion of Alexandria, Heraclides of Tarentum, and Theodas of Laodicea. Some later Empiricists even accepted a qualified reasoning about unobservable causes. Later Empiricists also accepted the diagnostic use of the pulse, which the Empiricist Heraclides had previously rejected (Galen Med. Exp. 109; Galen Diff. Puls. 4.4, 8.726–728K). The importance of chance and memory to their medical practice, along with a willingness to compare themselves to tradesmen of lesser status, distinguished their philosophical medicine from other ancient medical sects (Fig. 1).

Figure 1. “Reduction of the shoulder.” From the illustrated commentary to Hippocrates’ On Joints of Apollonius of Citium, Plut. 74.7, folio 185v. The scene shows a patient, physician, and physician’s aide (either an apprentice or a slave) resetting a dislocated shoulder joint. The figure illustrates Empiricist reliance on therapeutic training in apprenticeship and close imitation of Hippocratic therapeutic works. Florence, Biblioteca Laurenziana. MacKinney Collection of Medieval Medical Illustrations.


Medical doxographies continue to describe the Empiricists as one of the three medical sects for medical tyros even at the end of late antiquity (John of Alexandria Commentaria In Librum De Sectis Galeni), although these testimonia are probably pedagogical rather than philosophical in nature. In the Middle Ages and Early Modern periods, the Latin appellation empiricus and its vernacular cognates became a pejorative for a doctor without university training (cf. English “empiric”). The philosophical empiricism of the Early Modern period that valued induction and disparaged chance had no intellectual inheritance from the ancient medical sect.

Primary Texts

  • Apollonius of Citium: Greek Text and German Translation in Kollesch, Jutta and Fridolf Kudlien. Apollonii Citiensis In Hippocratis Articulis Commentarius. Corpus Medicorum Graecorum 11.1.1. Berlin: In Aedibus Academiae Scientarum, 1965.
  • Celsus. De Medicina 1.prohoemium. Latin text, French translation, and commentary in Mudry, Philippe. La Préface du De Medicina de Celse: text, traductione et commentaire. Lausanne, Switzerland: Institute de Suisse a Roma, 1982. English translation in Spencer, W. G. Celsus On Medicine: Volume 1: Books 1–4. Cambridge, MA: Harvard University Press, 1935.
  • Galen. Med. Exp. Arabic and Greek text in Walzer, Richard. Galen on Medical Experience. Oxford: Oxford University Press, 1944. English translation in Frede, Michael, and Richard Walzer. Galen: Three Treatises on the Nature of Science. Indianapolis, IN: Hackett, 1985.
  • Galen. Sect.Int. Greek text in Helmreich, Georgius. Galeni Pergameni Scripta Minora. Vol. 3. Lipsiae: Teubner, 1893. English translation in Michael Frede and Richard Walzer. Galen: Three Treatises on the Nature of Science. Indianapolis: Hackett, 1985.
  • Galen. Subf. Emp. Latin text in Deichgräber, Karl. Die griechische Empirikerschule: Sammlung der Fragmente und Darstellung der Lehre. 2d ed. Berlin: Weidmannsche Verlagsbuchhandlung, 1965. English translation in Frede, Michael, and Richard Walzer. Galen: Three Treatises on the Nature of Science. Indianapolis, IN: Hackett, 1985.
  • Ps.-Galen. Intr.: Greek text, French translation, and commentary in Petit, Caroline. Galien: Tome III: Le Médicin. Introduction. Paris: Les Belles Lettres, 2009.
  • Fragments and testimonia in Greek and Latin collected with essays in German in Deichgräber, Karl. Die griechische Empirikerschule: Sammlung der Fragmente und Darstellung der Lehre. 2d ed. Berlin: Weidmannsche Verlagsbuchhandlung, 1965.


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