Stoicism one of the three leading movements constituting Hellenistic philosophy. Its founder was Zeno of Citium (334–262 B.C.), who was succeeded as school head by Cleanthes (331– 232). But the third head, Chrysippus (c.280– c.206), was its greatest exponent and most voluminous writer. These three are the leading representatives of Early Stoicism. No work by any early Stoic survives intact, except Cleanthes’ short ‘Hymn to Zeus.’ Otherwise we are dependent on doxography, on isolated quotations, and on secondary sources, most of them hostile. Nevertheless, a remarkably coherent account of the system can be assembled. The Stoic world is an ideally good organism, all of whose parts interact for the benefit of the whole. It is imbued with divine reason (logos), its entire development providentially ordained by fate and repeated identically from one world phase to the next in a never-ending cycle, each phase ending with a conflagration (ekpyrosis). Only bodies strictly ‘exist’ and can interact. Body is infinitely divisible, and contains no void. At the lowest level, the world is analyzed into an active principle, god, and a passive principle, matter, both probably corporeal. Out of these are generated, at a higher level, the four elements air, fire, earth, and water, whose own interaction is analogous to that of god and matter: air and fire, severally or conjointly, are an active rational force called breath (Greek pneuma, Latin spiritus), while earth and water constitute the passive substrate on which these act, totally interpenetrating each other thanks to the non-particulate structure of body and its capacity to be mixed ‘through and through.’ Most physical analysis is conducted at this higher level, and pneuma becomes a key concept in physics and biology. A thing’s qualities are constituted by its pneuma, which has the additional role of giving it cohesion and thus an essential identity. In inanimate objects this unifying pneuma is called a hexis (state); in plants it is called physis (nature); and in animals ‘soul.’ Even qualities of soul, e.g. justice, are portions of pneuma, and they too are therefore bodies: only thus could they have their evident causal efficacy. Four incorporeals are admitted: place, void (which surrounds the world), time, and lekta (see below); these do not strictly ‘exist’ – they lack the corporeal power of interaction – but as items with some objective standing in the world they are, at least, ‘somethings.’ Universals, identified with Plato’s Forms, are treated as concepts (ennoemata), convenient fictions that do not even earn the status of ‘somethings.’
Stoic ethics is founded on the principle that only virtue is good, only vice bad. Other things conventionally assigned a value are ‘indifferent’ (adiaphora), although some, e.g., health, wealth, and honor, are naturally ‘preferred’ (proegmena), while their opposites are ‘dispreferred’ (apoproegmena). Even though their possession is irrelevant to happiness, from birth these indifferents serve as the appropriate subject matter of our choices, each correct choice being a ‘proper function’ (kathekon) – not yet a morally good act, but a step toward our eventual end (telos) of ‘living in accordance with nature.’ As we develop our rationality, the appropriate choices become more complex, less intuitive. For example, it may sometimes be more in accordance with nature’s plan to sacrifice your wealth or health, in which case it becomes your ‘proper function’ to do so. You have a specific role to play in the world plan, and moral progress (prokope) consists in learning it. This progress involves widening your natural ‘affinity’ (oikeiosis): an initial concern for yourself and your parts is later extended to those close to you, and eventually to all mankind. That is the Stoic route toward justice. However, justice and the other virtues are actually found only in the sage, an idealized perfectly rational person totally in tune with the divine cosmic plan. The Stoics doubted whether any sages existed, although there was a tendency to treat at least Socrates as having been one. The sage is totally good, everyone else totally bad, on the paradoxical Stoic principle that all sins are equal. The sage’s actions, however similar externally to mere ‘proper functions,’ have an entirely distinct character: they are renamed ‘right actions’ (katorthomata). Acting purely from ‘right reason,’ he is distinguished by his ‘freedom from passion’ (apatheia): morally wrong impulses, or passions, are at root intellectual errors of mistaking what is indifferent for good or bad, whereas the sage’s evaluations are always correct. The sage alone is happy and truly free, living in perfect harmony with the divine plan. All human lives are predetermined by the providentially designed, all-embracing causal nexus of fate; yet being the principal causes of their actions, the good and the bad alike are responsible for them: determinism and morality are fully compatible. Stoic epistemology defends the existence of cognitive certainty against the attacks of the New Academy. Belief is described as assent (synkatathesis) to an impression (phantasia), i.e. taking as true the propositional content of some perceptual or reflective impression. Certainty comes through the ‘cognitive impression’ (phantasia kataleptike), a self-certifying perceptual representation of external fact, claimed to be commonplace. Out of sets of such impressions we acquire generic conceptions (prolepseis) and become rational. The highest intellectual state, knowledge (episteme), in which all cognitions become mutually supporting and hence ‘unshakable by reason,’ is the prerogative of the wise. Everyone else is in a state of mere opinion (doxa) or of ignorance. Nevertheless, the cognitive impression serves as a ‘criterion of truth’ for all. A further important criterion is prolepseis, also called common conceptions and common notions (koinai ennoiai), often appealed to in philosophical argument. Although officially dependent on experience, they often sound more like innate intuitions, purportedly indubitable. Stoic logic is propositional, by contrast with Aristotle’s logic of terms. The basic unit is the simple proposition (axioma), the primary bearer of truth and falsehood. Syllogistic also employs complex propositions – conditional, conjunctive, and disjunctive – and rests on five ‘indemonstrable’ inference schemata (to which others can be reduced with the aid of four rules called themata). All these items belong to the class of lekta – ‘sayables’ or ‘expressibles.’ Words are bodies (vibrating portions of air), as are external objects, but predicates like that expressed by ‘ . . . walks’, and the meanings of whole sentences, e.g., ‘Socrates walks’, are incorporeal lekta. The structure and content of both thoughts and sentences are analyzed by mapping them onto lekta, but the lekta are themselves causally inert. Conventionally, a second phase of the school is distinguished as Middle Stoicism. It developed largely at Rhodes under Panaetius and Posidonius, both of whom influenced the presentation of Stoicism in Cicero’s influential philosophical treatises (mid-first century B.C.). Panaetius (c.185–c.110) softened some classical Stoic positions, his ethics being more pragmatic and less concerned with the idealized sage. Posidonius (c.135–c.50) made Stoicism more open to Platonic and Aristotelian ideas, reviving Plato’s inclusion of irrational components in the soul.
A third phase, Roman Stoicism, is the only Stoic era whose writings have survived in quantity. It is represented especially by the younger Seneca (A.D. c.1–65), Epictetus (A.D. c.55–c.135), and Marcus Aurelius (A.D. 121–80). It continued the trend set by Panaetius, with a strong primary focus on practical and personal ethics. Many prominent Roman political figures were Stoics.
After the second century A.D. Stoicism as a system fell from prominence, but its terminology and concepts had by then become an ineradicable part of ancient thought. Through the writings of Cicero and Seneca, its impact on the moral and political thought of the Renaissance was immense.
See also CICERO, DOXOGRAPHERS , HEL- LENISTIC PHILOSOPH. D.N.S.