Stoicism

• 1. Introduction

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  A dog is tied to the back of a cart. If it follows willingly, it moves with ease. If it resists, it is dragged along anyway, going wherever the cart goes. The Stoic philosopher Cleanthes used this image to describe the wicked person, compelled by fate. Stoicism is a philosophical movement and a practical guide to living, built on daily self-discipline and moral improvement. It began in the Hellenistic period of ancient Greece and lasted well into the Roman Imperial period. Its founder taught in the open air, on a painted porch beside the marketplace of Athens. Among those who later called themselves Stoics was a Roman emperor. How does a school that began with conversation under a colonnade end up shaping digital computers, Christian theology, and the modern therapist's couch? And what did these thinkers mean when they insisted that virtue is the only good, that everything else is merely material for virtue to act upon? The answers run through logic, through physics, through the control of fear, and through a man tied to a cart who chose, finally, to walk.

• 2. The Painted Porch

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  The Stoa Poikile gave Stoicism its name. The phrase means painted porch, a colonnade decorated with mythic and historical battle scenes on the north side of the Agora in Athens. There, near the end of the fourth century BCE, Zeno of Citium gathered with his followers to discuss their ideas. Zeno made a deliberate choice that set him apart. Unlike the Epicureans, he taught his philosophy in a public space, open to anyone who passed. The school was originally called Zenonism, after its founder. That name was soon dropped, probably because the Stoics did not consider their founders to be perfectly wise. Dropping the name also avoided the risk of the philosophy becoming a cult of personality. Zeno's ideas grew out of the Cynic tradition, brought to him by Crates of Thebes. The Cynics traced their founding to Antisthenes, who had been a disciple of Socrates. Zeno's most influential successor was Chrysippus, who followed Cleanthes as leader and molded what is now called Stoicism. The school became the foremost popular philosophy among the educated elite of the Hellenistic world and the Roman Empire. In the words of Gilbert Murray, nearly all the successors of Alexander professed themselves Stoics. Scholars usually split the school's history into three phases. The Early Stoa runs from Zeno's founding to Antipater. The Middle Stoa includes Panaetius and Posidonius. The Late Stoa includes Musonius Rufus, Seneca, Epictetus, and Marcus Aurelius. No complete works survived from the first two phases. Only the Roman texts of the Late Stoa came down to us intact.

• 3. The Logic Of Day And Night

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  If it is day, it is light. It is day. Therefore it is light. That small chain of statements is a typical Stoic syllogism, and it captures how the school treated reason itself as a discipline. For the Stoics, logic was the part of philosophy that examined reason, the logos. They held that an understanding of ethics was impossible without it. In the words of Inwood, logic helps a person see what is the case, reason effectively about practical affairs, stand his or her ground amid confusion, and differentiate the certain from the probable. The Stoic tradition of logic did not start with Zeno. It originated in the 4th-century BCE Megarian school, where two dialecticians, Diodorus Cronus and his pupil Philo, developed theories of modalities and conditional propositions. Zeno himself studied under the Megarians and was said to have been a fellow pupil with Philo. The outstanding figure was Chrysippus of Soli, who lived from about 279 to about 206 BCE and served as the third head of the school. Chrysippus built a system of propositional logic, analyzing whole statements rather than terms. His logical writings are almost entirely lost. His system has to be reconstructed from partial accounts preserved by later authors. The smallest unit in his logic is an assertible, a proposition that is either true or false. Examples include it is night, it is raining this afternoon, and no one is walking. A truth-value can shift with time, so it is night is true only at night. From these simple units, Chrysippus introduced three main connectives. The conditional joins statements with if. The conjunctive joins them with and. The disjunctive joins them with or. Their or was exclusive, unlike the inclusive or used in modern formal logic. Chrysippus listed five basic argument forms, called indemonstrables, to which all other arguments reduce. The first is modus ponens, the day-and-light chain. The second, modus tollens, runs if it is day it is light, it is not light, therefore it is not day. Three more handle the cases of not both and either or. He claimed that complex syllogisms could be reduced to these five through four ground rules called themata, of which only two survive. In the 2nd-century BCE, Antipater of Tarsus is said to have introduced a simpler method using fewer themata, though few details remain.

• 4. Paradox And Possibility

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  A man says he is lying. Is what he says true or false? Chrysippus studied this puzzle, known as the Liar paradox. If the man says something true, then he is lying. If he is lying, then he is not saying something true, and the contradiction loops without end. Another puzzle, the Sorites paradox or Heap, asked how many grains of wheat you need before you get a heap. It challenged the clean line between true and false by introducing vagueness. The Stoics did not collect these paradoxes for amusement. Mastering them was meant to sharpen rational powers, enable ethical reflection, and lead a person toward truth. The Megarian debate over what is possible drew Chrysippus into another fine distinction. Diodorus Cronus had defined the possible as that which either is or will be true, a view that pointed toward fatalism, since no possibility goes forever unrealised. His pupil Philo rejected this. Philo called possible whatever is capable of being true by the proposition's own nature, so a piece of wood that spends its whole existence at the bottom of the ocean can still, in principle, burn. Chrysippus took a middle position. He was a causal determinist, holding that true causes inevitably give rise to their effects. He was not a logical determinist, and he wanted to keep possible truths distinct from necessary ones. For him a possible assertible can become true and is not hindered by external things, while an impossible one cannot become true or is hindered from it. This care with what could and could not be otherwise pointed beyond logic toward a much larger claim. The Stoics believed the entire universe was itself a kind of reasoning substance.

• 5. A Reasoning Universe

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  The Universe, for the Stoics, was a material reasoning substance, the logos, divided into the active and the passive. The passive substance is matter itself. The active substance is an intelligent aether or primordial fire that acts on matter, pervading and animating everything. It was conceived as material and usually identified with God or Nature. The Stoics spoke of the seminal reason, the logos spermatikos, the law of generation working through inanimate matter. Each human being possesses a portion of this divine logos, the same fire and reason that controls and sustains the whole. Everything falls under the laws of Fate, for the Universe acts according to its own nature. This physics rests on an unusual claim about what exists. The Stoics held that all beings are material, though not all things are. Besides existing beings they admitted four incorporeals that merely subsist: time, place, void, and the sayable. They accepted Anaxagoras's idea that a hot object is hot because part of a universal heat body entered it, and they stretched the idea to cover every quality, so a red object is red because part of a universal red body entered it. They sorted reality into four categories. Substance is the formless matter that things are made of. Quality is the way matter is organized through pneuma, air or breath, into an individual object. The third is being somehow disposed, covering size, shape, action, and posture. The fourth is being somehow disposed in relation to something, covering position relative to other things. Jacques Brunschwig gives a plain example. I am a lump of matter, a substance; I am this individual man, qualified; I am sitting or standing, disposed in a certain way; I am the father of my children, disposed in a certain way in relation to something else. The Universe itself has no single beginning or end. The current Universe is one phase in a present cycle, preceded by an infinite number of Universes, each doomed to be destroyed in a conflagration called Ekpyrosis, then re-created, then followed by infinitely many more.

• 6. Virtue And The Passions

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  Virtue is the only good. That single claim sits at the center of Stoic ethics, the part of philosophy the school treated as central. The Stoics believed the practice of virtue is enough to achieve eudaimonia, a well-lived life. The path runs through four cardinal virtues practiced in everyday life: prudence, fortitude, temperance, and justice. External things like health, wealth, and pleasure are neither good nor bad in themselves. They are adiaphora, indifferent, with value only as material for virtue to act upon. Because virtue is sufficient for happiness, the sage stays emotionally resilient to misfortune. Epictetus captured this resilience in a striking list. The Stoic of virtue remains sick and yet happy, in peril and yet happy, dying and yet happy, in exile and happy, in disgrace and happy. The Stoics judged a person not by speech but by behavior, since the best indication of someone's philosophy is how the person acts. Destructive emotions, in this view, come from errors of judgment. For Chrysippus the passions are evaluative judgements, disturbing and misleading forces that arise from failing to reason correctly. The Stoics sorted them under four headings: distress, pleasure, fear, and lust. From the treatise On Passions, distress is an irrational contraction at something bad thought to be present. Fear is an irrational aversion to an expected danger. Lust is an irrational pursuit of an expected good that is in reality bad. Delight is an irrational swelling at something good thought to be present. Each heading branches further. Distress includes envy, jealousy, anxiety, mourning, and grief. Fear includes shame, fright, and timidity. Lust includes anger, rage, hatred, and greed. The wise person, the sophos, is free from the passions, a state called apatheia. The sage instead feels eupatheia, the clear-headed good feelings, sorted under joy, wish, and caution. These are not diminished emotions but the correct rational ones. Even death fell under this calculus. The Stoics considered suicide permissible for the wise person in circumstances that might prevent a virtuous life, such as severe pain or disease. Otherwise it was usually seen as a rejection of one's social duty. Plutarch reports that accepting life under tyranny would have compromised Cato's self-consistency as a Stoic and impaired his freedom to make honorable moral choices.

• 7. The Long Afterlife

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  For around five hundred years, Stoic logic was one of the two great systems of logic in the classical world, discussed alongside Aristotle's. It may well have been more prominent, since Stoicism was the dominant philosophical school. Then the school declined after Christianity became the state religion in the 4th century CE. The last pagan philosophical school, the Neoplatonists, adopted Aristotle's logic instead. Plotinus had criticized both Aristotle's Categories and those of the Stoics. His student Porphyry defended Aristotle's scheme, and Boethius' acceptance of that defense carried it into Scholastic philosophy. As a result the Stoic writings on logic did not survive. Only confused fragments reached the Middle Ages through Boethius and other commentators. Propositional logic was redeveloped by Peter Abelard in the 12th century. By the mid-15th century the only logic being studied was a simplified Aristotle. Stoicism left deep marks elsewhere. The Fathers of the Church called it a pagan philosophy, yet early Christian writers borrowed its central concepts, including logos, virtue, Spirit, and conscience. Stoic influence appears in the works of Ambrose of Milan, Marcus Minucius Felix, and Tertullian. Both traditions taught inner freedom before the external world and equanimity toward the passions. The Renaissance brought a fresh revival. Neostoicism arose in the late 16th century from the works of the humanist Justus Lipsius, who tried to combine Stoicism and Christianity into a secular ethics based on Roman Stoic philosophy. Guillaume du Vair's Traite de la Constance of 1594 was another important influence, emphasizing Epictetus where Lipsius had leaned on Seneca. Pierre Charron, shaped by the French Wars of Religion, made a complete separation of morality and religion.

• 8. From The Stoa To The Circuit

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  Logic has not been able to advance a single step since Aristotle, Immanuel Kant declared in the 18th century, calling it a closed and complete body of doctrine. The 19th century treated Stoic logic with open contempt. Carl Prantl called it dullness, triviality, and scholastic quibbling, and welcomed the fact that the works of Chrysippus were no longer extant. The rescue came later. Modern developments paralleling Stoic logic began in the middle of the 19th century with George Boole and Augustus De Morgan. Stoic logic itself was reappraised only in the 20th century, starting with the Polish logician Jan Lukasiewicz and with Benson Mates. Susanne Bobzien observed that the close similarities between Chrysippus' logic and that of Gottlob Frege are especially striking. The same source draws a line from a colonnade to a machine. Boole aimed to codify the relations studied much earlier by Chrysippus, who labored long ago under an old Athenian stoa, and later generations built the logic of digital computers on those insights. The everyday meaning of the word drifted too. Contemporary usage defines a stoic as a person who represses feelings or endures patiently. The Stanford Encyclopedia of Philosophy notes that the sense of the English adjective stoical is not utterly misleading with regard to its philosophical origins. In the early 21st century a modern Stoicism movement emerged, promoting practical application through academic research, public conferences, and educational initiatives. One initiative is Stoic Week, an annual international event encouraging participants to practice Stoic exercises. The revival traces to the publication of Problems in Stoicism by A. A. Long in 1971, and figures such as Massimo Pigliucci have helped popularize it for modern audiences. According to Pierre Hadot, philosophy for a Stoic is not a set of beliefs but a way of life, an active process of constant practice and self-reminder called askesis. Perhaps the most concrete legacy is clinical. Stoic philosophy was the original inspiration for modern cognitive psychotherapy, mediated by Albert Ellis' rational emotive behavior therapy, the major precursor of cognitive behavioral therapy. The treatment manual for depression by Aaron T. Beck traces the philosophical origins of cognitive therapy to the Stoic philosophers. Ellis taught most clients a line from the Enchiridion of Epictetus in their first session: it is not the events that upset us, but our judgments about the events.