← All philosophers
Portrait of Sextus Empiricus
Wikimedia Commons

Sextus Empiricus

Systematized ancient Skepticism; our fullest source on it.

Skepticism (Pyrrhonism)RomanAncient Greek160–210 CE◦ uncertain (possibly Alexandria or Athens)2nd century CE

Overview

A physician and philosopher, Sextus Empiricus wrote the most complete surviving account of Pyrrhonian skepticism. Where earlier skeptics left little in writing, he set out the skeptic's 'modes' — systematic ways of generating opposing arguments to induce suspension of judgement (epochē) and thereby tranquillity (ataraxia). He carefully distinguished Pyrrhonism from the 'negative dogmatism' of those who assert that nothing can be known. His works were rediscovered in the Renaissance and reshaped early modern philosophy.

What they supported — and why

The modes of suspension

SupportedSets of argument-patterns (the Ten Modes, Five Modes) show that for every claim there is an equally strong opposing one.

WhyBy balancing arguments on both sides, the skeptic is led to suspend judgement rather than dogmatically assert or deny.

Skepticism is a practice, not a doctrine

SupportedThe skeptic asserts nothing as true, not even that nothing is knowable; they merely report how things appear and suspend judgement.

WhyAsserting 'nothing can be known' would itself be a dogma; genuine skepticism withholds even that, avoiding self-refutation.

Tranquillity through epochē

SupportedSuspending judgement about how things really are brings the calm that dogmatists vainly seek.

WhyAnxiety comes from believing things are good or bad by nature; the skeptic, holding no such beliefs, finds peace.

Causes championed

  • Freedom from dogmatism
  • Peace of mind
  • Careful distinction of skeptical positions

Issues wrestled with

  • Is knowledge possible?
  • How can a skeptic live and act?
  • What is the difference between doubt and denial?

Hurdles faced

  • The ancient charge that skepticism makes life unlivable
  • Almost nothing is known of his own life

Works & books

2 catalogued. Status shows how much survives to today.

Outlines of Pyrrhonism

Survives

Pyrrōneioi Hypotypōseis

A systematic three-book handbook of skeptical method — the classic statement of Pyrrhonism.

Against the Mathematicians (Adversus Mathematicos)

Survives

Extended skeptical critiques of the dogmatists across logic, physics, ethics, and the liberal arts.

Read the texts free

Their works online — Open Library catalogues 0 works & editions.

Influenced by

PyrrhoAenesidemusAgrippa

Influenced

MontaigneDescartes (as target)Humemodern epistemology

In their words

“To every argument an equal argument is opposed.”

— Outlines of Pyrrhonism

Legacy

As the sole full source on ancient skepticism, his rediscovery in the 1500s helped ignite the modern debate about the possibility of knowledge.

Further reading

Cross-checked against these authoritative references.

Authority records

Linked into the wider knowledge graph via Wikidata — the stable spine other sources hang off.