Sextus Empiricus

Introduction

Sextus Empiricus is the Greek philosopher and physician of the late second and early third century CE whose surviving works are the principal source for ancient skepticism and the canonical statement of the Pyrrhonian tradition. The Outlines of Pyrrhonism (Pyrrhōneioi Hypotypōseis) and the eleven books of Against the Mathematicians (Adversus Mathematicos) together constitute the most extensive surviving Hellenistic philosophical corpus from any tradition and are the principal channel through which the skeptical framework reached the Renaissance and modern philosophy.

The surviving works are organized as systematic attacks on the dogmatic positions of the other Hellenistic schools. The Outlines gives the compressed statement of the Pyrrhonian framework and method; the Against the Mathematicians gives the detailed application of the method against the dogmatic positions of grammarians, rhetoricians, geometers, arithmeticians, astrologers, musicians, logicians, physicists, and ethicists. The combined work is the most systematic skeptical engagement with the broader Hellenistic intellectual landscape that survives from antiquity.

Life

Almost nothing is known of Sextus's life beyond what can be inferred from his writings. The biographical record gives no birthplace, no teachers, no students, no institutional affiliation beyond his identification as a physician of the empiric school of medicine (from which his name Empiricus derives — he is Sextus the Empiric, the medical practitioner of the empirical school, not Sextus the Empiricist in any anachronistic philosophical sense).

The dates are inferred from internal evidence in the writings and from the absence of any reference to Sextus in Galen's late-second-century medical corpus. The range 160–210 CE is the conventional contemporary estimate; some scholars have argued for slightly earlier or later dates within the same general period.

Sextus's medical training matters for understanding his philosophical writings. The empiric school of Hellenistic medicine practiced under skeptical principles — they followed empirical patterns of treatment without committing to theoretical claims about underlying causes. The framework was congruent with the philosophical Pyrrhonism Sextus systematized; his medical and philosophical commitments were continuous expressions of the same underlying skeptical orientation.

The works

The surviving Sextus corpus consists of two major works.

The Outlines of Pyrrhonism (Pyrrhōneioi Hypotypōseis) is the compressed three-book introduction to Pyrrhonian skepticism. Book I gives the general framework and the principal modes; Books II and III apply the framework to logic, physics, and ethics. The book is the canonical introductory statement of skepticism and the principal text for understanding the Pyrrhonian method.

The Against the Mathematicians (Adversus Mathematicos; literally Against the Learned) is the eleven-book detailed engagement with the dogmatic disciplines. The traditional division has Books I–VI as Against the Professors (against grammarians I, rhetoricians II, geometers III, arithmeticians IV, astrologers V, musicians VI) and Books VII–XI as Against the Dogmatists (against logicians VII–VIII, physicists IX–X, ethicists XI). The contemporary scholarly convention numbers them as one continuous series, though the original organization into the two halves is preserved in most editions.

The standard Greek texts are in the Loeb Classical Library edition by R. G. Bury (four volumes, 1933–49; revised translations available); the Teubner edition by Hermann Mutschmann and Jürgen Mau (1912–62) provides the critical text. Recent English translations include the Hackett edition by Benson Mates (The Skeptic Way, 1996, of the Outlines), the Cambridge translations by Julia Annas and Jonathan Barnes (Outlines of Scepticism, 1994; revised 2000), and Richard Bett's translations of the books Against the Logicians, Against the Ethicists, and Against the Physicists (Cambridge, 1997 onward).

Central doctrines

The skeptical method

The central methodological framework is the production of isostheneia (equal weight of opposing arguments) leading to epochē (suspension of judgment) leading to ataraxia (tranquility). The skeptic encounters dogmatic claims about the nature of reality; for each such claim, the skeptic produces arguments of equal weight on the opposing side; the equal weight of opposing arguments produces the suspension of judgment; the suspension of judgment produces the tranquility that the dogmatic schools had promised but failed to deliver.

The method is not a system of doctrines but a practice. The skeptic does not claim that suspending judgment is correct or that the suspension of judgment produces tranquility as a matter of necessary truth; the skeptic reports that, in their experience, the practice produces these results, and recommends the practice on that basis. The skeptic's reports about the practice are themselves not dogmatic claims but expressions of how things appear to the skeptic in the present moment.

The ten modes of Aenesidemus

The Outlines Book I (sections 36–163) gives the canonical statement of the ten modes — the ten standard ways of producing the equal weight of opposing arguments that leads to suspension of judgment. The modes were originally formulated by Aenesidemus in the first century BCE; Sextus preserves and refines them.

The ten modes appeal to differences in perception. Different animals perceive differently (mode 1); different humans perceive differently (mode 2); the different senses report differently (mode 3); the same person perceives differently under different circumstances (mode 4); perception depends on position and distance (mode 5); on the medium between perceiver and perceived (mode 6); on the quantities and compositions of objects (mode 7); on relations among things (mode 8); on the frequency or rarity of phenomena (mode 9); on the customs, laws, and beliefs of different peoples (mode 10).

The framework gives the skeptic a systematic apparatus for showing that dogmatic claims about the nature of things cannot be settled by appearances. The same object appears different to different perceivers, in different conditions, from different positions; we cannot settle the question of how the object really is independently of perception, because every claim about the object must be made from some position whose appearance the other positions could equally well contest.

The five modes of Agrippa

The Outlines Book I (sections 164–177) gives the five later Agrippan modes that strengthen the skeptical apparatus. Mode 1 (disagreement): dogmatic positions disagree among themselves, and the disagreement cannot be settled by reference to any neutral authority. Mode 2 (infinite regress): any attempted justification of a position requires further justification, which requires further justification, in an infinite regress. Mode 3 (relativity): any judgment is relative to the perspective from which it is made. Mode 4 (assumption): any attempt to break the regress by assuming a starting point is an unjustified assumption that the skeptic can equally well refuse. Mode 5 (circularity): any attempt to justify a position by reference to other positions that the position itself justifies is circular reasoning that the skeptic can refuse.

The Agrippan modes have been continuously consequential in the history of epistemology. The contemporary engagement with foundationalism, coherentism, and infinitism in epistemology operates within the framework Agrippa established. The contemporary skeptical literature (Robert Fogelin's Pyrrhonian Reflections on Knowledge and Justification, 1994; Michael Williams's work on contextualism) draws directly on the Agrippan modes.

Action without belief

The central practical question for Pyrrhonian skepticism is how the skeptic can act when they have suspended judgment on all dogmatic positions. Sextus's answer: the skeptic acts according to appearances (without committing to claims about the reality behind the appearances), according to natural impulses (without committing to theories about why these impulses arise), according to the transmitted customs and laws (without committing to claims that the customs reflect any underlying truth), and according to the practical instruction of the arts (without committing to theoretical claims about what the arts reveal).

The framework parallels the Pyrrhonian fourfold practical framework Pyrrho himself had developed. The skeptic can live a recognizable human life, follow social conventions, practice a profession, raise children, and engage in the ordinary activities of human existence — without making the dogmatic commitments that the dogmatic schools had treated as necessary for any of these activities.

Reception

The ancient reception of Sextus was limited; the Pyrrhonian tradition was the minority position within Hellenistic philosophy, and Sextus's works did not achieve the wide circulation of the major Stoic, Epicurean, and Platonic texts. The Christian period largely set aside Pyrrhonian skepticism; the Patristic and medieval traditions found the suspension of judgment incompatible with the assent that Christian faith required.

The Renaissance recovery was decisive. Henri Estienne's 1562 Latin translation of the Outlines of Pyrrhonism brought the work to humanist circles; Gentian Hervet's 1569 Latin translation of Against the Mathematicians completed the corpus. The combination produced what Richard Popkin called the skeptical crisis of early modern European thought: the recognition that the ancient skeptical arguments had not been adequately answered by the Christian or scholastic traditions and that modern philosophy would have to address them directly.

Michel de Montaigne's Apology for Raymond Sebond (1580) is the major early modern engagement; the Apology uses the Sextan arguments to develop a Christian fideist position. Descartes's Meditations (1641) presents the Cartesian project as the response to the skeptical challenge; the cogito is the Cartesian attempt to find a starting point that survives the Sextan modes. Hume's engagement (especially in the Treatise Book I and in the Dialogues Concerning Natural Religion) develops a modern skepticism in continuity with the Sextan tradition.

The contemporary engagement is substantial. Richard Popkin's The History of Scepticism (1960, revised through multiple editions) is the canonical history of the early modern reception. Myles Burnyeat, Jonathan Barnes, Julia Annas, Richard Bett, Casey Perin, Diego Machuca, and the broader contemporary skepticism scholarship continue to develop the framework.

Continuing engagement

Major recent scholarly work includes Richard Bett's Sextus Empiricus and Ancient Scepticism (2019), the Cambridge Companion to Ancient Scepticism (Bett, ed., 2010), Diego Machuca's edited collections on Pyrrhonian skepticism, Casey Perin's The Demands of Reason (2010), and the broader work of Markus Lammenranta, Otavio Bueno, and Stefano Mecci. Active scholarly debates concern the precise interpretation of Sextus's framework (especially whether the skeptic can or cannot have beliefs of any kind), the relation between Pyrrhonian and Academic skepticism, the contemporary applicability of the modes, and the relation between Sextan skepticism and contemporary anti-skeptical strategies in epistemology.

Further reading

• Pyrrho — the founder of the Pyrrhonian tradition Sextus systematized
• Skepticism — the tradition Sextus's works systematize
• Ataraxia — the goal the skeptical practice produces through the suspension of judgment
• Descartes — the early modern philosopher whose method responds directly to the Sextan skeptical challenge
• Hume — the modern philosopher whose skepticism is in continuity with the Sextan tradition

The Greek philosopher and physician whose surviving works are the principal source for ancient skepticism and the canonical statement of the Pyrrhonian framework.