Chrysippus of Soli (c. 280–c. 207 BCE) was the third scholarch (head) of the Stoic school in Athens and is considered, alongside Zeno of Citium, the second founder of Stoicism. While Zeno founded the school and established its fundamental theses, it was Chrysippus who systematically elaborated Stoic logic, physics, and ethics, producing a monumental body of work that ancient tradition estimated at over 700 titles — almost all now lost. What we know of his thought comes from secondary sources: Diogenes Laërtius, Plutarch, Cicero, Sextus Empiricus, and Epictetus.
Key Concepts
Stoic Propositional Logic: Chrysippus’s greatest logical contribution. While Aristotle had developed term logic (syllogistic), Chrysippus developed the first systematic propositional logic in history. The five indemonstrables (basic argument schemas that require no proof) constitute the basis of all inference. Stoic logic was rediscovered as relevant in the 20th century when logicians recognised its affinity with modern propositional calculus.
Compatibilism — Fate and Moral Responsibility: Chrysippus argued that universal determination by logos/fate is compatible with moral responsibility. The famous cylinder argument (transmitted by Cicero in De Fato): when someone pushes a cylinder, the external impulse is necessary to initiate the motion, but the nature of the cylinder (its roundness) determines how it moves. Likewise, external circumstances can trigger our impressions, but the response — assent or refusal (synkatathesis) — is determined by our character. Virtue and vice are therefore genuinely ours, even in a determined world.
The Hegemonikon and Assent: Chrysippus’s Stoicism locates the seat of reason and soul in the hegemonikon (the directive part of the soul), identified with the heart. Representations (phantasiai) arrive from outside; the moral question is the assent (synkatathesis) we give to them. Only cognitive representations (phantasia kataleptike) merit assent; the Stoic sage assents only to these.
Pneuma and Stoic Physics: Stoicism is a materialist monism: everything that exists is body. The pneuma (literally: breath, spirit) is the active principle that structures passive matter. Different degrees of pneuma constitute different types of entities: hexis (cohesion) in stones, physis (growth) in plants, psychē (soul) in animals, logos (reason) in humans. The pneuma of the universe is the divine logos itself.
Ethics and the Passions: Chrysippus distinguished legitimate affective states (eupatheiai: joy, caution, will) from irrational passions (pathē: pleasure, pain, desire, fear). The passions are erroneous judgements — fear is a judgement that something bad is imminent, when nothing other than vice is genuinely bad. Philosophical therapy consists in correcting judgements. Apatheia (freedom from irrational passions) is the condition of the sage — not emotional coldness, but freedom from the disturbances caused by false judgements.
Oikeiōsis (Appropriation / Natural Affinity): All living beings have a natural tendency to care for themselves and identify with what is their own. For humans, this impulse expands: from self-affinity to care for children, family, fellow-citizens, and finally all humanity. The Stoic ethics of cosmopolitanism has its natural foundation here.
Influenced by
- Zeno of Citium — founder of Stoicism
- Cleanthes of Assos (c. 330–c. 230 BCE) — second scholarch; Hymn to Zeus
- Aristotle — logic (radically transformed)
- Heraclitus — logos and unity of opposites
Influenced
- Seneca, Epictetus, Marcus Aurelius — Imperial Stoicism
- Cicero — Latin adaptation of Stoicism
- Stoicism as a philosophical movement generally
- Modern propositional logic (affinity recognised by Łukasiewicz and others)
Works
(Almost all lost.) According to Diogenes Laërtius, he wrote on logic, physics, ethics, and rhetoric. Titles mentioned include: On Reason (Peri logou), On Propositions (Peri axiomaton), On Fate (Peri heimarmenes), On the Passions (Peri pathon), among many others.
See also
Hellenistic Philosophy
Recommended books:
The Stoics — F.H. Sandbach
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Hellenistic Philosophy — A.A. Long
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