Stoicism
Authors: Sedley David 
Published: September 2018

Stoicism is the Greek philosophical system founded by Zeno of Citium c.300 bc and developed by him and his successors into the most influential philosophy of the Hellenistic age. It views the world as permeated by rationality and divinely planned as the best possible organization of matter. Moral goodness and happiness are achieved, if at all, by replicating that perfect rationality in oneself, and by finding out and enacting one’s own assigned role in the cosmic scheme of things.
The leading figures in classical, or early, Stoicism are the school’s first three heads: Zeno of Citium, Cleanthes and Chrysippus. It is above all the brilliant and indefatigable Chrysippus who can be credited with building Stoicism up into a truly comprehensive system. ‘Early Stoicism’ – the main topic of this entry – is in effect largely identical with his philosophy.
No formal philosophical writings of the early Stoics survives intact. We are mainly dependent on isolated quotations and secondary reports, many of them hostile. Nevertheless, the system has been reconstructed in great detail, and, despite gaps and uncertainties, it does live up to its own self-description as a unified whole. It is divided into three main parts: physics, logic and ethics.
The world is an ideally good organism, whose own rational soul governs it for the best. Any impression of imperfection arises from misleadingly viewing its parts (including ourselves) in isolation, as if one were to consider the interests of the foot in isolation from the needs of the whole body. The entire sequence of cosmic events is pre-ordained in every detail. Being the best possible sequence, it is repeated identically from one world phase to the next, with each phase ending in a conflagration followed by cosmic renewal. The causal nexus of ‘fate’ does not, however, pre-empt our individual responsibility for our actions. These remain ‘in our power’, because we, rather than external circumstances, are their principal causes, and in some appropriate sense it is ‘possible’ for us to do otherwise, even though it is predetermined that we will not.
At the lowest level of physical analysis, the world and its contents consist of two coextensive principles: passive ‘matter’ and active ‘god’. At the lowest observable level, however, these are already constituted into the four elements earth, water, air and fire. Air and fire form an active and pervasive life force called pneuma or ‘breath’, which constitutes the qualities of all bodies and, in an especially rarefied form, serves as the souls of living things.
‘Being’ is a property of bodies alone, but most things are analysed as bodies – even moral qualities, sounds, seasons and so forth – since only bodies can causally interact. For example, justice is the soul in a certain condition, the soul itself being pneuma and hence a body. A scheme of four ontological categories is used to aid this kind of analysis. In addition, four incorporeals are acknowledged: place, void, time and the lekton (roughly, the expressed content of a sentence or predicate). Universals are sidelined as fictional thought constructs, albeit rather useful ones.
The world is a physical continuum, infinitely divisible and unpunctuated by any void, although surrounded by an infinite void. Its perfect rationality, and hence the existence of an immanent god, are defended by various versions of the Argument from Design, with apparent imperfections explained away, for example, as blessings in disguise or unavoidable concomitants of the best possible structure.
‘Logic’ includes not only dialectic, which is the science of argument and hence logic in its modern sense, but also theory of knowledge, as well as primarily linguistic disciplines like rhetoric and grammar. Stoic inferential logic takes as its basic units not individual terms, as in Aristotelian logic, but whole propositions. Simple propositions are classified into types, and organized into complex propositions (for example, conditionals) and complete arguments. All arguments conform to, or are reducible to, five basic ‘indemonstrable’ argument formats. The study of logical puzzles is another central area of Stoic research.
The Stoics doggedly defended, against attacks from the sceptical Academy, the conviction that cognitive certainty is achieved through ordinary sensory encounters, provided an entirely clear impression (phantasia) is attained. This, the ‘cognitive impression’ (phantasia katalēptikē), is one of such a nature that the information it conveys could not be false. These self-certifying impressions, along with the natural ‘preconceptions’ (prolēpseis) which constitute human reason, are criteria of truth, on which fully scientific knowledge (epistēmē) – possessed only by the wise – can eventually be built.
Stoic ethics starts from oikeiōsis, our natural ‘appropriation’ first of ourselves and later of those around us, which makes other-concern integral to human nature. Certain conventionally prized items, like honour and health, are commended by nature and should be sought, but not for their own sake. They are instrumentally preferable, because learning to choose rationally between them is a step towards the eventual goal of ‘living in agreement with nature’. It is the coherence of one’s choices, not the attainment of their objects, that matters. The patterns of action which promote such a life were systematically codified as kathēkonta, ‘proper functions’.
Virtue and vice are intellectual states. Vice is founded on ‘passions’: these are at root false value judgments, in which we lose rational control by overvaluing things which are in fact indifferent. Virtue, a set of sciences governing moral choice, is the one thing of intrinsic worth and therefore genuinely ‘good’. The wise are not only the sole possessors of virtue and happiness, but also, paradoxically, of the things people conventionally value – beauty, freedom, power, and so on. However geographically scattered, the wise form a true community or ‘city’, governed by natural law.
The school’s later phases are the ‘middle Stoicism’ of Panaetius and Posidonius (second to first century bc) and the ‘Roman’ period (first to second century ad) represented for us by the predominantly ethical writings of Seneca, Epictetus and Marcus Aurelius.