Outlines of Scepticism

Overview

About two hundred and fifty pages, the fullest surviving account of ancient Pyrrhonian scepticism, written by Sextus Empiricus around 200 CE, in three books. The first explains what scepticism is, the ability to set appearances and arguments against one another so that the mind suspends judgement and tranquillity follows, and lays out the ten modes of Aenesidemus and the five modes of Agrippa for producing that suspension.

Books two and three apply the method to the logic, physics and ethics of the dogmatic schools, arguing against criteria of truth, proof, causes, gods and the existence of anything good or bad by nature.

What happens

Defining scepticism. Sextus opens by defining scepticism as the ability to set appearances and arguments against one another so that the mind suspends judgement, establishing this active method as his treatise’s foundational technique.

Tranquillity following suspension. Sextus argues that tranquillity follows from this suspension of judgment, inverting the usual assumption that settled belief, rather than continued uncertainty, produces genuine peace of mind.

The ten modes of Aenesidemus. Sextus lays out the ten modes of Aenesidemus, specific argumentative patterns for producing suspension of judgment by exposing how appearances vary according to circumstance and perspective.

The five modes of Agrippa. Sextus presents the five modes of Agrippa as further systematic technique, giving Pyrrhonism a genuinely comprehensive and teachable methodological apparatus beyond the earlier ten modes alone.

Applying the method to logic and physics. Books two and three apply the sceptical method to the logic and physics of the dogmatic schools, arguing against their claimed criteria of truth, proof and causes.

Applying the method to ethics. Sextus extends the method to ethics specifically, arguing against the existence of anything good or bad by nature, challenging even moral certainty other ancient schools had typically left unquestioned.

How to read it

Read Sextus’s definition of scepticism as the ability to set appearances and arguments against one another so the mind suspends judgement as giving ancient skepticism a genuinely active, practiced method rather than mere passive absence of belief.

Pay close attention to how the claim that tranquillity actually follows from this suspension inverts the usual assumption that settled belief produces peace of mind, insisting continued uncertainty, properly cultivated, delivers genuine psychological calm.

Notice how the ten modes of Aenesidemus and five modes of Agrippa give Pyrrhonism a genuinely systematic technical apparatus, transforming skeptical practice from loose general attitude into methodical, teachable philosophical technique.

Consider how systematically applying this method against the dogmatic schools’ criteria of truth, proof, causes, gods and the existence of anything good or bad by nature makes this the fullest surviving account of ancient Pyrrhonian scepticism.

Descartes’s own Meditations offers a revealing contrast to set beside this treatise: where Sextus pursues doubt as a permanent, tranquillity-producing suspension of judgment, Descartes deploys comparable doubt only temporarily, as a tool for eventually reaching certain foundational knowledge.

Questions it raises

• Does Sextus’s definition of scepticism as an active method for producing suspension of judgment successfully distinguish Pyrrhonism from simple ignorance or indecision, or does this framework risk collapsing back into a more passive failure to reach any genuine conclusion?
• How persuasive is the claim that tranquillity actually follows from suspended judgment rather than from settled belief? Does continued uncertainty genuinely produce the psychological calm Sextus describes, or would most people find sustained doubt more anxiety-producing than reassuring?
• What do the ten modes of Aenesidemus and five modes of Agrippa accomplish as systematic technique that looser skeptical attitude could not? Does this methodological apparatus successfully generalize across different specific dogmatic claims it might be applied against?
• How does extending the sceptical method into ethics, arguing against anything being good or bad by nature, complicate practical action? Does Pyrrhonism offer any guidance for actually living, or does thoroughgoing suspension of judgment leave practical decision-making unaddressed?
• Given that this represents the fullest surviving account of ancient Pyrrhonian scepticism, what does its preservation and transmission suggest about how selectively ancient philosophical texts survived, and what might have been lost from other skeptical writers whose work did not survive comparably intact?
• What does this treatise’s continued relevance to epistemology suggest about ancient skepticism’s durability as philosophical resource? Do Sextus’s specific modes and arguments still offer useful tools for contemporary discussions of knowledge, certainty and belief’s proper foundations?