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Stoicism was a philosophical movement founded in Athens in the late fourth century BCE by Zeno of Citium. Although Stoicism was shaped by many philosophical influences (including the thought of Heraclitus), it was throughout its history an essential part of the mainstream Socratic tradition of ancient philosophy. Inspired as well by the Cynics (Zeno was taught by Crates, a student of Diogenes of Sinope), Stoicism developed alongside and in competition with Platonism and Aristotelianism over the next 500 years. For centuries it was the main rival to Epicurean thought as well. Virtually no works survive from the early period of the school's history. Yet its doctrines have been reconstructed with a fair level of reliability on the basis of later accounts, critical discussions by non-Stoics, and the surviving works of later Stoic writers.


When Zeno arrived in Athens, attracted from his home on Cyprus by Socratic philosophy, Plato's Academy was led by Polemo and was soon to make its historic shift away from what we now recognize as Platonism toward a form of skepticism under the leadership of Arcesilaus. Aristotle's legacy was still in the hands of Theophrastus, head of the Lyceum, though in the third century BCE the school would decline in philosophical power as it concentrated on more narrowly scientific problems. Nevertheless, the Aristotelian drive for broad-based philosophical synthesis had an impact on the shape of Stoicism. A significant group of philosophers, forming no particular school but many coming from nearby Megara, concentrated on dialectic as their principal activity. These included Stilpo, also interested in ethics and metaphysics, and Diodorus Cronus, whose sharply formulated arguments provided powerful challenges in physics and metaphysics and challenged the Stoics to develop dialectic as a central part of their system. The Cynics in turn championed nature (as opposed to narrow polis-based social norms) as the foundation of ethics. All of this contributed to Zeno's formation of a powerful philosophical system whose internal articulation into three parts (logic, physics, ethics) was inspired by the Academic Xenocrates.

Stoicism was named for Zeno's favorite meeting place, the Painted Stoa in the Athenian marketplace. The movement was concentrated in a formal philosophical school in Athens for more than 200 years until political changes resulting from Rome's rise to power led prominent philosophers to spread out around the Mediterranean world, especially to Rhodes, Alexandria, and Rome itself. The climax of this process came when the Roman general Sulla sacked Athens in 86 BCE during the Mithridatic Wars. By the end of the first century BCE, Stoic activity was widely dispersed and had become a central part of intellectual culture in the Greco-Roman world. In the early second century CE, the emperor Hadrian founded a chair of Stoic philosophy in Rome (as well as chairs for the other major schools). With the rise of Neoplatonism, Stoicism gradually faded in prominence, though its influence persisted until the end of antiquity. Its impact on medieval philosophy was sporadic, but in the Renaissance it became an important part of the philosophical legacy of the ancient world to modern philosophy.

Principal Stoics and Their Works

The founder of the school, Zeno, was a prolific author whose best-known work was his utopian Republic, influenced by his Cynic teachers and by Plato's Republic. He wrote extensively on ethics and politics (e.g., On the Life according to Nature ; On Law ; On Human Nature ; On Passions ; On Greek Education ), on cosmology (On the Universe ), on poetry (Homeric Problems ; On Listening to Poetry ), and on dialectic (On Signs ; Refutations,; Solutions ). Of his many students, some (Persaeus and Sphaerus) also involved themselves in politics. Cleanthes was a highly prolific writer in the areas of cosmology, physics, ethics, and dialectic. He was also known for his poetry, especially the Hymn to Zeus (which has survived entire) and for his interest in Heraclitus. Cleanthes' contemporary Aristo of Chios favored the Cynic side of the school's heritage and rejected physics and dialectic in favor of a teaching based solely on ethics. Though eclipsed by Cleanthes (who succeeded Zeno as head of the school) and Chrysippus (the third head of the school), Aristo's influence continued to be felt at least until the first century CE.

Chrysippus, the great systematizer of the Stoic tradition, put the school's doctrines on a solid footing after a long period of debate and criticism, especially by the Academic Arcesilaus. Respected as a second founder of the school, he and his students dominated its leadership for many decades. He argued that Zeno's philosophy (as he interpreted it) was essentially correct and thereby stabilized the essential doctrines of the school, which nevertheless continued to be open to internal debate. A highly prolific author (more than 700 books are attributed to him and a partial catalog survives in book 7 of Diogenes' Lives ), Chrysippus revised and rounded out the areas of physics and ethics and put dialectic, especially the study of formal inference and the theory of language, on a new foundation. He wrote a work in defense of Zeno's Republic, evidently declining to abandon the school's Cynic roots, a large number of works on logic and dialectic (including Logical Investigations, of which a few fragments have survived among the Herculaneum papyri), and a nearly equal number on logic and physics. The best attested work is certainly his On Passions, from which Galen quotes many passages in the course of his criticism of Stoic views on psychology and ethics.

The next phase in the school's history came in the late second and early first centuries BCE, when Panaetius of Rhodes and subsequently Posidonius of Apamea adopted a more open stance toward Platonic and Aristotelian approaches than seems to have been characteristic of Chrysippus. There was, however, no dramatic departure from the earlier school. Prominent among later Stoics is Seneca the Younger, a Roman politician of the first century CE. Many of his works, including the Moral Epistles to Lucilius, were highly influential in the early modern period. Other works of Seneca's include On Benefits (which offers important arguments in ethics) and Natural Questions (on physics and meteorology). His works form the earliest corpus of Stoic writing that has survived to the modern era. Another Stoic was Epictetus, a prolific writer and teacher, mostly of ethics, in the late first century CE. He owed a great deal to Musonius Rufus, a Roman citizen from Etruria who wrote in Greek in the early first century CE. Epictetus's lectures were very influential in later antiquity and the early modern period; this is especially true of his Handbook, a compendium drawn from the Discourses, which in turn was compiled by his student Arrian from his lectures. The emperor Marcus Aurelius left a set of personal philosophical reflections, To Himself, more commonly titled Meditations. In no sense a professional philosopher, Marcus combines a profoundly Stoic point of view, deeply influenced by Epictetus, with a more generalized "philosophical" stance reflecting influences from many traditions.

Central Ideas

The concept of nature played a central role in Stoicism. The key to human fulfillment or happiness (eudaimonia ) is living according to nature, and Stoic philosophy was based on this conception of the goal of life. The study of the natural world, physics, was a major occupation of virtually all Stoics (Aristo of Chios being a notable early exception). Human nature for the Stoics is characterized by a rationality that, when fully developed, is divine in its perfection. A deep expression of our nature and of that of the cosmos is our capacity for logic. Nature was formally defined as "a craftsmanlike fire, proceeding methodically to creation (genesis )" (Diogenes 7.156). God, a fully rational and providential force causally responsible for the world and its orderliness, was equated with nature. Whereas the divine craftsman of Plato's Timaeus stood outside the physical cosmos, the rational creator god of Stoicism is completely immanent in the material world.

The Stoics, more than any other ancient school, emphasized the interdependence among the parts of philosophy. They used various similes to illustrate the point. Philosophy is like an animallogic is the bones and sinews; ethics the flesh; physics the soul. Or it is like an egglogic is the shell; ethics the white; physics the yolk. Or like agricultural landlogic is the wall around the field; ethics the fruit; physics the land or trees that bear the fruit. Ideas varied about the ordering and relative importance of the three parts and their subdivisions, but all agreed that philosophy, when properly taught, demanded an intimate blend of all three disciplines, regardless of the pedagogical order chosen (Diogenes 7.3941).

The Stoics based all areas of their thought on a rigorous metaphysical principle that sharply distinguished the corporeal and the incorporeal. The key to this distinction is the argument that only bodies can interact causally, an argument that seems to have emerged from a critique of Plato's metaphysics. Hence god, the soul, nature, and the principles that organize raw matter into intelligible natural kinds are all forms of matter for the Stoics. Even cognitive states such as knowledge are treated as corporeal dispositions of the material mind, since they have causal impact; so too for virtue and other dispositions. Their theory of perception similarly posits corporeal entities, lending weight to their essentially empiricist epistemology. The Stoics recognized only four incorporeal entities: void, space, time, and "sayables" (lekta, roughly, the meanings of thought and speech). Each of these incorporeal entities is parasitic on bodies, a necessary feature of the world but in itself causally inefficacious.

In ethics the central concept was virtue, understood in a distinctively Stoic manner. Human life has a single goal (telos ): to live according to nature. Following Aristotle, the Stoics called achieving this goal "happiness" (eudaimonia ). Perfection of our intrinsically rational nature is the only way to do this. This perfection, which they called "virtue" (aretē ), is the necessary and sufficient condition for achieving our goal. This robust conception of virtue is at the center of Stoic thought and became the defining feature of the school.


Stoic logic has two parts: dialectic and rhetoric. Dialectic is broader in scope than logic in the modern sense. Yet the Stoics made crucial advances even in logic understood in the narrower modern sense.

Traditionally, rhetoric had been the art of persuasion through speech. As such it was either condemned, as by Plato, or reformed, as by Aristotle. The Stoics restricted rhetoric by insisting that it, like other crafts, must be conducted under norms of truth and virtue. Hence rhetoric became the art of persuading an audience of the truth through orderly discourse and argument, differing from dialectic only in form; rhetoric is merely a more expansive way of achieving such conviction. As Zeno said, rhetoric is an open hand, while dialectic is a closed fist (Sextus 1935, 2.7 [= Adv. Mathematicos 2.7]). Stoic ideas about rhetoric understandably had limited influence.

In contrast, their dialectic had considerable influence, since it aimed to be a comprehensive study of human discourse and its relation to truth about the world. It covered the content of discourse as well as the utterances that express that content, both what is signified and what does the signifying. The relationship between linguistic signifiers and their meaning lies at the heart of Stoic dialectic. Accordingly, dialectic covered much of what we classify as epistemology and philosophy of language (including semantics), as well as the study of propositions and their relations. But since what is signified by speech are incorporeal sayables, dialectic also included aspects of metaphysics and philosophy of mind. The broad Stoic conception of dialectic also covered what we would consider linguistics and grammar, the parts of speech and various forms of speech acts; their theories had great influence on the development of grammar as a discipline.

In perception, on the Stoic theory, we receive through the senses representations of objects and events. A rational animal becomes aware of this representational content by way of a sayable (usually a proposition [axiōma ], defined as what admits of being true or false), which is dependent on the physical change in the mind. We either assent to this proposition, reject it as being unrepresentative of its alleged correlate in the world, or suspend judgment about its truth. This is the heart of Stoic epistemology. Academic critics of the Stoic theory argued that no sensory representation could be satisfactorily reliable. In defending their theory (in part by positing self-verifying cataleptic representations) and in elaborating how perceptual experience formed the basis for concepts, memories, and the like, the Stoics expanded on the foundations for empirical epistemology that Aristotle had laid.

The most important aspect of Stoic logic is its study of the forms of argument, inference, and validity. Stoics undertook this to defend the truth of their substantive doctrines and to demonstrate the pervasiveness of rational structures in the world. Chrysippus went beyond that goal and plunged into had been the starting point, and the subject had been advanced by the development of challenging paradoxes and puzzles by Megarian and other dialecticians. Chrysippus made the logic of propositions and arguments into a discipline.

Stoic logic takes the proposition (axiōma, often symbolized by an ordinal number) as its basic unit of analysis and works with a small set of operators used to connect them: "if," "and," "not," and exclusive "or." Five basic inference forms were recognized; all valid arguments were supposed to be derivable from these indemonstrable arguments by purely logical means. Stoics attempted to prove this completeness claim with the aid of higher-order logical principles. The five indemonstrables are the following:

If the first, the second.
But the first.
Therefore, the second.

If the first, the second.
But not the second.
Therefore, not the first.

Not both the first and the second.
But the first.
Therefore, not the second.

Either the first or the second.
But the first.
Therefore, not the second.

Either the first or the second.
But not the second.
Therefore, the first.


Stoic physics was, in its day, the most up-to-date and influential version of the nonatomistic physics pioneered by Empedocles and developed by Aristotle. Stoics posited a geocentric cosmos made up of earth, air, fire, and water arranged in four roughly concentric spheres. Although the cosmos has no void within it, it is surrounded by an indefinitely large void, which provides room for expansion when the cosmos reaches the end of its finite life span. The Stoics held that the cosmos was generated by the creative intelligence of Zeus and eventually ends by returning to the fire from which it was born. This process repeats itself forevera doctrine that responds in part to Aristotle's arguments for the eternity of the cosmos. Since things expand when heated, the conflagration that occurs at the end of each cycle requires that there be empty space outside the physical world.

Zeus is a craftsman-god modeled on the creator god of Plato's Timaeus and initially identified with a kind of fire. Cosmogony begins when this fire transforms itself in a quasi-biological process that generates the four elements that are the stuff of the world. Fire has a dual role, both as the original divine source and as one of the four elements. Each element is analyzable into two principles, the active and the passive, but these principles are themselves corporeal. The active principle (like Aristotelian form) is immanent everywhere and is responsible for the structure and comprehensibility of things; hence it is often identified as god and reason, a creative form of fire that embodies a divine plan for every aspect of the physical world. This emphasis on unified and immanent divine power made the Stoics pioneers for later forms of pantheism.

Later Stoics (including Chrysippus) revised the role of fire and claimed that the immanent shaping power was better understood as pneuma, a unique blend of fire and air with an optimal combination of fluidity and tensile strength. Pneuma gives order and shape to things in varying degrees. In lifeless things like rocks it is a disposition (hexis ), giving them coherence and shape. In plants it is their "nature" (phusis ) and accounts for their ability to grow and change. In animals it accounts for the full range of dynamic attributes, including perception and desire; hence it is there called "soul" (psuchē ). In humans and gods this divine shaping power is labeled "reason" (logos ). These various forms of a single power unite all entities into a single order, the cosmos. Since both the active shaping power and the passive component of a thing are corporeal, the Stoics had to give an account of how two such bodies could be fused into a perfect mixture. Their sophisticated theory of "total blending" was frequently criticized, but the concept of pneuma itself had considerable influence in later centuries.

The Stoics analyzed each individual entity by means of a complex theory that today would fall under the heading of metaphysics. They posit four "genera" or kinds (less helpfully, "categories"), all of which apply to every object. First, each object can be treated as a "substrate"; this merely asserts that it is a material object, a being, without specifying its attributes. Second, each object is "qualified," endowed (by the active principle or by pneuma ) with structure sufficient to make it a definite thing. Qualities are either common (making the object a kind of thing, such as a human) or peculiar (making it a unique individual, such as Socrates). The third genus specifies dispositions or conditions of an entity (Socrates may be courageous or have frost-bitten feet), while the fourth is termed "relative disposition" and picks out relations such as being the father of someone or being on the right of someone. Though we cannot be certain of all its details, this theory clearly provided the analytical framework for Stoic corporealist physics.

Since the cosmos is a whole united by reason (i.e., the pneuma that pervades it), it can be regarded as a single living entity. In this perspective, everything else is a part of the whole, even humans, whose reason is the same in nature as that of Zeus. Hence humans are uniquely situated in the world, subordinate to it as parts but able to understand in principle the unified plan determining all that happens.

From a theological perspective, this plan appears as a providential divine arrangement, but in Stoic physics, it is actually a mere consequence of Stoic causal determinism. There are no uncaused events, so all that happens is determined by antecedent events and states of affairs in the world. The world, then, is a network of causal relationships capable in principle of being explained. If this were not the case, there would be uncaused events, which Stoics thought unacceptable; even the principle of bivalence (the claim that every proposition is either true or false) would be threatened, and Chrysippus (contrary to Aristotle and Epicurus) held that this logical principle obtains even for future-tense propositions.

Human thoughts, actions, and decisions are a part of this causally deterministic system, but moral responsibility is not threatened (according to the Stoics), since the decisive causal factor is the character and disposition of the agent as he or she reacts to the world. Critics in the ancient world argued that causal determinism jeopardized moral accountability, but Chrysippus stoutly maintained a distinction between being caused (as human actions are) and being necessitated by factors wholly external to the agent. Stoic compatibilism still seems reasonable to many philosophers, but it remained contentious in the ancient world.


It is tempting to suppose that for the Stoics ethics is the most important branch of philosophy, subserved by logic and physics. But of all the similes used to described the relationship among the parts of philosophy, only two support this claim: Posidonius's assertion that ethics is like the soul of an animal (Sextus 1935, 1..19 [= Adv. Mathematicos 7.19]) and the claim that ethics is like fruit on the trees (Diogenes 7.3941). Other Stoics make physics the culmination of philosophical activity. Three factors incline us to regard ethics as the core of Stoic thought: the pattern of ancient philosophical controversy, the accidental bias of the surviving sources, and the fact that Stoic physics is today more obviously obsolete than Stoic ethics. To yield to this tendency is to take sides in a debate within the ancient school, to support the Socratic mission of Aristo of Chios against, for example, Chrysippus, who regarded theology (part of physics) as the culmination of philosophy (Plutarch 1035a).

Philosophy is a craft for living (technē tou biou ). As a craft, it is based on a body of knowledge, consists in a stable disposition of a rational agent, and has a determinate function (ergon ) and goal (telos ). Stoicism is firmly embedded in the eudaimonistic tradition of ancient ethics, where the goal is eudaimonia, conventionally translated as "happiness." For Stoics, the goal is to live in accordance with nature, and their claim is that this consists in living in accordance with virtue, since human virtue is the excellence of our nature. But our nature is fundamentally rational. Hence perfection of human reason is another summary expression of the goal. This remains a merely formal account until substantive Stoic views about human nature are considered. In contrast to Plato and Aristotle, Stoics denied that the mature human soul contains essentially irrational components. In Stoic thought, there is no lower part of the soul to be tamed and managed by reason; rather, our rational faculties have an affective component, and so emotion and desire are features of some of our cognitive processes. Further, the Stoics held that our rational nature is qualitatively the same as the divine reason embedded in nature, so that our goal requires living in accordance with both human nature and cosmic nature (Diogenes 7.88).

Like all living things, humans are shaped by a fundamental drive to preserve and enhance their nature, a drive visible even in infants but taking on its characteristic form when they mature. This basic drive involves a commitment to pursue the good, understood as what is truly beneficial. Stoics accept the Socratic argument that only virtue is consistently and genuinely beneficial, since an excellence cannot be misused. Other advantageous things (health, pleasure, social standing, etc.) admit of misuse, so their value is merely provisional. They are preferred but not good. There is a similar account of vice (the only truly bad thing) and disadvantageous things like disease and poverty, which are dispreferred but not genuinely bad. This basic duality in Stoic value theory is a central feature of Stoic ethics. Though it is rational to avoid dispreferred things and embrace preferred things in the course of a well-planned human life, only genuine goods demand unconditional commitment.

This is the basis for the notorious Stoic rejection of passions, which are understood as unreasonable and excessive reactions to preferred and dispreferred things. If sickness and poverty are not bad but merely dispreferred, we should not grieve over them (but, of course, we should do our best to avoid them). If wealth is not a strict good, we should not be elated at achieving it (though there is nothing wrong with enjoying it). If a favorable reputation in our community is not an unconditional good, then we need not fear losing it. If romantic attachments are worth having but are not the sine qua non of human flourishing, then we should pursue potential partners without obsession. And so forth. Life according to our purely rational nature will be free of passions, but not devoid of affect. For in a life of virtuous choices and actions, there will be many things to want, to shun, and to rejoice over. Such positive affective states were called eupatheiai.

Most Stoics accepted the doctrine of the unity of virtues, though there was serious debate about the nature of that unity. But all Stoics held that virtuous action was limited to the sagea normative ideal of perfected virtue used as a benchmark for good action. The Stoics distinguished between appropriate actions (kathēkonta ), which can be determined by the proper application of moral guidelines and maxims, and genuinely good actions (katorthōmata ), which are appropriate actions performed from the perfected disposition of a sage. Nonsages may have little real chance to attain wisdom, but their constant striving to determine the appropriate thing and to do is guided by the ideal of the sage. Stoic recommendations for appropriate actions (such as participation in civic life, unless it is hopelessly corrupt) are routinely presented as descriptions of what the sage will do, yet Stoicism does not categorically prescribe any particular actions. Only the commands to follow (or accommodate oneself to) nature and to act virtuously are unconditional.

Stoic ethics is often portrayed as mired in paradox, but we can make better sense of the persistent philosophical appeal of Stoicism if we focus instead on Stoics' stringent and carefully formulated theories in all branches of philosophy and their insistence that these parts should fit together into a coordinated whole, that they should combine the best understanding of the natural world available in their day with a deep commitment to the exercise of human reason as the key to human fulfillment.

See also Arcesilaus; Aristotelianism; Chrysippus; Cleanthes; Cynics; Diodorus Cronus; Epictetus; Epicureanism and the Epicurean School; Greek Academy; Heraclitus of Ephesus; Marcus Aurelius Antoninus; Musonius Rufus; Panaetius of Rhodes; Posidonius; Seneca, Lucius Annaeus; Zeno of Citium.


works by stoics

Diogenes Laertius. Lives of Eminent Philosophers. Translated by R. D. Hicks. Cambridge, MA: Harvard University Press, 1972.

Epictetus. The Discourses of Epictetus. London: J. M. Dent, 1995.

Epictetus. Handbook of Epictetus. Translated by Nicholas P. White. Indianapolis, IN: Hackett, 1983.

Marcus Aurelius. Meditations. Translated by A. S. L. Farquharson. New York: Knopf, 1992.

Plutarch. "On Stoic Self-Contradictions." In his Moralia. Vol. 13, Pt. 2: Stoic Essays, translated by Harold Cherniss. Cambridge, MA: Harvard University Press, 1976.

Seneca, Lucius Annaeus. Seneca's Letters to Lucilius. Translated by E. Phillips Barker. Oxford, U.K.: Clarendon Press, 1932.

Sextus Empiricus. Against the Logicians. Translated by R. G. Bury. Cambridge, MA: Harvard University Press, 1935.

Sextus Empiricus. Against the Physicists. Against the Ethicists. Translated by R. G. Bury. Cambridge, MA: Harvard University Press, 1936.

Sextus Empiricus. Against the Professors. Translated by R. G. Bury. Cambridge, MA: Harvard University Press, 1949.

Sextus Empiricus. The Skeptic Way: Sextus Empiricus's "Outlines of Pyrrhonism." Translated by Benson Mates. New York: Oxford University Press, 1996.

works on stoic philosophy

Algra, Keimpe, et al. Cambridge History of Hellenistic Philosophy. Cambridge, U.K.: Cambridge University Press, 1999.

Becker, Lawrence C. A New Stoicism. Princeton, NJ: Princeton University Press, 1998.

Bobzien, Susanne. Determinism and Freedom in Stoic Philosophy. Oxford, U.K.: Clarendon Press, 1998.

Frede, Michael. Die stoische Logik. Göttingen, Germany: Vandenhoeck und Ruprecht, 1974.

Hahm, David E. The Origins of Stoic Cosmology. Columbus: Ohio State University Press, 1977.

Inwood, Brad, ed. The Cambridge Companion to the Stoics. Cambridge, U.K.: Cambridge University Press, 2003.

Inwood, Brad. Ethics and Human Action in Early Stoicism. Oxford: Clarendon Press, 1985.

Long, A. A., ed. Problems in Stoicism. London: Athlone Press, 1971.

Long, A. A., and D. N. Sedley. The Hellenistic Philosophers. Chaps. 2667. Cambridge, U.K.: Cambridge University Press, 1987.

Mates, Benson. Stoic Logic. Berkeley: University of California Press, 1953.

Rist, John M., ed. The Stoics. Berkeley: University of California Press, 1978.

Sandbach, F. H. The Stoics. London: Chatto and Windus, 1975.

Striker, Gisela. "Following Nature: A Study in Stoic Ethics." Oxford Studies in Ancient Philosophy 10 (1996): 173.

Brad Inwood (2005)

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