Stoic Philosophy

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Zeno of Citium in Thomas
Stanley History of Philosophy
Zeno of Citium (335-263 B.C.) and the Stoics exalted reason, identified it with virtue, and counseled an ascetic disregard for misfortune. Building on the moral ideas of the Cynics, the Stoics placed great emphasis on goodness and peace of mind gained from living a life of Virtue in accordance with Nature. Stoicism was very popular, and gained a large following in the Hellenistic and Roman periods. The Stoics gave us the word “stoic,” meaning: enduring pain or hardship without showing feelings or complaining.

Massimo Pigliucci of the City University of New York (CUNY) wrote in the Internet Encyclopedia of Philosophy: “Stoicism originated as a Hellenistic philosophy, founded in Athens by Zeno of Citium (modern day Cyprus), c. 300 B.C.E. It was influenced by Socrates and the Cynics, and it engaged in vigorous debates with the Skeptics, the Academics, and the Epicureans.... Stoicism moved to Rome where it flourished during the period of the Empire, alternatively being persecuted by Emperors who disliked it (for example, Vespasian and Domitian) and openly embraced by Emperors who attempted to live by it (most prominently Marcus Aurelius).” [Source: Massimo Pigliucci, City University of New York (CUNY),Internet Encyclopedia of Philosophy (IEP) ]

“Stoicism “influenced Christianity, as well as a number of major philosophical figures throughout the ages (for example, Thomas More, Descartes, Spinoza), and in the early 21st century saw a revival as a practical philosophy associated with Cognitive Behavioral Therapy and similar approaches. Stoicism is a type of eudaimonic virtue ethics, asserting that the practice of virtue is both necessary and sufficient to achieve happiness (in the eudaimonic sense). However, the Stoics also recognized the existence of “indifferents” (to eudaimonia) that could nevertheless be preferred (for example, health, wealth, education) or dispreferred (for example, sickness, poverty, ignorance), because they had (respectively, positive or negative) planning value with respect to the ability to practice virtue. Stoicism was very much a philosophy meant to be applied to everyday living, focused on ethics (understood as the study of how to live one’s life), which was in turn informed by what the Stoics called “physics” (nowadays, a combination of natural science and metaphysics) and what they called “logic” (a combination of modern logic, epistemology, philosophy of language, and cognitive science).”

According to the Stanford Encyclopedia of Philosophy: The name stoicism “derives from the porch (stoa poikilê) in the Agora at Athens decorated with mural paintings, where the members of the school congregated, and their lectures were held. Unlike ‘epicurean,’ the sense of the English adjective ‘stoical’ is not utterly misleading with regard to its philosophical origins. The Stoics did, in fact, hold that emotions like fear or envy (or impassioned sexual attachments, or passionate love of anything whatsoever) either were, or arose from, false judgements and that the sage – a person who had attained moral and intellectual perfection – would not undergo them. The later Stoics of Roman Imperial times, Seneca and Epictetus, emphasise the doctrines (already central to the early Stoics’ teachings) that the sage is utterly immune to misfortune and that virtue is sufficient for happiness. [Stanford Encyclopedia of Philosophy, 1996, updated 2018 ]

“Our phrase ‘stoic calm’ perhaps encapsulates the general drift of these claims. It does not, however, hint at the even more radical ethical views which the Stoics defended, e.g. that only the sage is free while all others are slaves, or that all those who are morally vicious are equally so. (For other examples, see Cicero’s brief essay ‘Paradoxa Stoicorum’.) Though it seems clear that some Stoics took a kind of perverse joy in advocating views which seem so at odds with common sense, they did not do so simply to shock. Stoic ethics achieves a certain plausibility within the context of their physical theory and psychology, and within the framework of Greek ethical theory as that was handed down to them from Plato and Aristotle. It seems that they were well aware of the mutually interdependent nature of their philosophical views, likening philosophy itself to a living animal in which logic is bones and sinews; ethics and physics, the flesh and the soul respectively (another version reverses this assignment, making ethics the soul). Their views in logic and physics are no less distinctive and interesting than those in ethics itself.

Ancient Roman Government, Military, Infrastructure and Economics (42 articles);

Websites on Ancient Greece and Rome: Internet Encyclopedia of Philosophy; Stanford Encyclopedia of Philosophy; Internet Ancient History Sourcebook: Greece ; Internet Ancient History Sourcebook: Hellenistic World ; BBC Ancient Greeks; Canadian Museum of History; Perseus Project - Tufts University; ; ;; British Museum; Illustrated Greek History, Dr. Janice Siegel, Department of Classics, Hampden–Sydney College, Virginia ; The Greeks: Crucible of Civilization ; Oxford Classical Art Research Center: The Beazley Archive ;; Metropolitan Museum of Art; The Ancient City of Athens; The Internet Classics Archive ; Internet Ancient History Sourcebook: Rome ; Internet Ancient History Sourcebook: Late Antiquity ; Forum Romanum ; “Outlines of Roman History”; “The Private Life of the Romans”|; BBC Ancient Rome;
The Roman Empire in the 1st Century; The Internet Classics Archive ; Bryn Mawr Classical Review; De Imperatoribus Romanis: An Online Encyclopedia of Roman Emperors; Cambridge Classics External Gateway to Humanities Resources; Ancient Rome resources for students from the Courtenay Middle School Library ; History of ancient Rome OpenCourseWare from the University of Notre Dame / ; United Nations of Roma Victrix (UNRV) History

Historical Background of Stoicism

Massimo Pigliucci of CUNY wrote in the Internet Encyclopedia of Philosophy: “Classically, scholars recognize three major phases of ancient Stoicism (Sedley 2003): the early Stoa, from Zeno of Citium (the founder of the school, c. 300 B.C.E.) to the third head of the school, Chrysippus; the middle Stoa, including Panaetius and Posidonius (late II and I century B.C.E.); and the Roman Imperial period, or late Stoa, with Seneca, Musonius Rufus, Epictetus and Marcus Aurelius (I through II century C.E.). Of course, Stoicism itself originated as a modification from previous schools of thought (Schofield 2003), and its influence extended well beyond the formal closing of the ancient philosophical schools by the Byzantine Emperor Justinian I in 529 C.E. (Verbeke 1983; Colish 1985; Osler 1991). [Source: Massimo Pigliucci, City University of New York (CUNY), Internet Encyclopedia of Philosophy (IEP) ]

“Stoicism is a Hellenistic eudaimonic philosophy, which means that we can expect it to be influenced by its immediate predecessors and contemporaries, as well as to be in open critical dialogue with them. These includes Socratic thinking, as it has arrived to us mainly through the early Platonic dialogues; the Platonism of the Academic school, particularly in its Skeptical phase; Aristotelianism of the Peripatetic school; Cynicism; Skepticism; and Epicureanism. It is worth noting, in order to put things into context, that a quantitative study of extant records concerning known philosophers of the ancient Greco-Roman world (Goulet 2013) estimates that the leading schools of the time were, in descending order: Academics-Platonists (19 percent), Stoics (12 percent), Epicureans (8 percent), and Peripatetics-Aristotelians (6 percent).

“Eudaimonia was the term that meant a life worth living, often translated nowadays as “happiness” in the broad sense, or more appropriately, flourishing. For the Greco-Romans this often involved—but was not necessarily entirely defined by—excellence at moral virtues. The idea is therefore closely related to that of virtue ethics, an approach most famously associated with Aristotle and his Nicomachean Ethics (Broadie & Rowe 2002), and revived in modern times by a number of philosophers, including Philippa Foot (2001) and Alasdair MacIntyre (1981/2013).

“Stoicism is best understood in the context of the differences among some of the similar schools of the time. Socrates had argued—in the Euthydemus, for instance (McBrayer et al. 2010)—that virtue, and in particular the four cardinal virtues of wisdom, courage, justice and temperance, are the only good. Everything else is neither good nor bad in and of itself. By contrast, for Aristotle the virtues (of which he listed a whopping twelve) were necessary but not sufficient for eudaimonia. One also needed a certain degree of positive goods, such as health, wealth, education, and even a bit of good looks. In other words, Aristotle expounded the rather commonsensical notion that a flourishing life is part effort, because one can and ought to cultivate one’s character, and part luck, in the form of the physical and cultural conditions that affect and shape one’s life.

“Contrast this to the rather extreme (even for the time) take of the Cynics, who not only thought that virtue was the only good, like Socrates, but that the additional goods that Aristotle was worried about were actually distractions and needed to be positively avoided. Cynics like Diogenes of Sinope were famous for their ascetic and shall we say rather eclectic life style, as is epitomized by a story about him told by Diogenes Laertius (VI.37): “One day, observing a child drinking out of his hands, he cast away the cup from his wallet with the words, ‘A child has beaten me in plainness of living.’”

“One way to think of this is that the Aristotelian approach comes across as a bit too aristocratic: if one does not have certain privileges in life, one cannot achieve eudaimonia. By contrast, the Cynics were preaching a rather extremely minimalist life style, which is hard to practice for most human beings. What the Stoics tried to do, then, was to strike a balance in the middle, by endorsing the twin crucial ideas, on which I will elaborate later, that virtue is the only true good, in itself sufficient for eudaimonia regardless of one’s circumstances, but also that other things—like health, education, wealth—may be rationally preferred (Proēgmena) or “dispreferred” (Apoproēgmena), as in the case of sickness, ignorance, and poverty, as long as one did not confuse them for things with inherent value.

Greek Stoicism

Stoa Poikile at the Agora in Athens

Massimo Pigliucci of CUNY wrote in the Internet Encyclopedia of Philosophy: “The “Greek” phase of the Stoa covers the first and second periods, from the founding of the school by Zeno to the shifting of the center of gravity from Athens to Rome in the time of Posidonius in the I Century B.C.E., who became a friend of Cicero—not a Stoic himself, but one of our best indirect sources on early Stoicism. Stoicism was not just born, but flourished in Athens, even though most of its exponents originated from the Eastern Mediterranean: Zeno from Citium (modern Cyprus), Cleanthes from Assos (modern Western Turkey), and Chrysippus from Soli (modern Southern Turkey), among others. According to Medley (2003), this pattern is simply a reflection of the dominant cultural dynamics of the time, affected as they were by the conquests of Alexander. [Source: Massimo Pigliucci, City University of New York (CUNY), Internet Encyclopedia of Philosophy (IEP) ]

“From the beginning Stoicism was squarely a “Socratic” philosophy, and the Stoics themselves did not mind such a label. Zeno began his studies under the Cynic Crates, and Cynicism always had a strong influence on Stoicism, all the way to the later writings of Epictetus. But Zeno also counted among his teachers Polemo, the head of the Academy, and Stilpo, of the Megarian school founded by Euclid of Megaria, a pupil of Socrates. This is relevant because Zeno came to elaborate a philosophy that was both of clear Socratic inspiration (virtue is the Chief Good) and a compromise between Polemo’s and Stilpo’s positions, as the first one endorsed the idea that there are external goods—though they are of secondary importance—while the second one claimed that nothing external can be good or bad. That compromise consisted in the uniquely Stoic notion that external goods are of ethically neutral value, but are nonetheless the object of natural pursuit.

“Zeno established the tripartite study of Stoic philosophy (see the three topoi[[hyperlink]]) comprising ethics, physics and logic. The ethics was basically a moderate version of Cynicism; the physics was influenced by Plato’s Timaeus (Taran 1971) and encompassed a universe permeated by an active (that is, rational) and a passive principle, as well as a cosmic web of cause and effect; the logic included both what we today refer to as formal logic and epistemology, that is, a theory of knowledge, which for the Stoics was decidedly empiricist-naturalistic.

“The Stoics after Zeno disagreed on a number of issues, often interpreting Zeno’s teachings differently. Perhaps the most important example is provided by the dispute between Cleanthes and Chrysippus about the unity of the virtues: Zeno had talked about each virtue in turn being a kind of wisdom, which Cleanthes interpreted in a strict unitary sense (that is, all virtues are one: wisdom), while Chrysippus understood in a more pluralistic fashion (that is, each virtue is a “branch” of wisdom).

“The early Stoics could also be stubbornly anti-empirical in their apologetics of Zeno’s writings, as when Chrysippus insisted in defending the idea that the heart, not the brain, is the seat of intelligence. This went against pretty conclusive anatomical evidence that was already available in the Hellenistic period, and earned the Stoics the scorn of Galen (for example, Tieleman 2002), though later Stoics did update their beliefs on the matter.

“Despite this faux pas, Chrysippus was arguably the most influential Stoic thinker, responsible for an overhaul of the school, which had declined under the guidance of Cleanthes, a broad systematization of its teachings, and the introduction of a number of novel notions in logic—the aspect of Stoicism that has had the most technical philosophical impact in the long run. Famously, Diogenes Laertius (2015, VII.183) wrote that “But for Chrysippus, there had been no Porch.”

“In the six decades following Chrysippus there were just two heads of the Stoa, Zeno of Tarsus (south-central Turkey) and Diogenes of Babylon, whose contributions were rather less significant than those of Chrysippus himself. We have to wait until 155 B.C.E. for the next impactful event, when the heads of the three major schools in Athens—the Stoics, the Academics and the Peripatetics—were sent by the city to Rome in order to help with diplomatic efforts. (It is interesting to note, as does Sedley (2003) that the fourth large school, the Epicurean one, was missing, following their stance of political non-involvement.) The philosophers in question, including the Stoic Diogenes of Babylon, made a huge impression on the Roman public with their public performances (and, apparently, an equally worrisome one on the Roman elite, thus beginning a long tradition of tension between philosophers and high-level politicians that characterized especially the post-Republican empire), paving the road for the later shift of philosophy from Athens to Rome, as well as other centers of learning, like Alexandria.

“Beginning with Antipater of Tarsus, and then more obviously Panaetius (late II Century B.C.E.) and Posidonius (early I Century B.C.E.), the Stoics revisited their relationship with the Academy, especially in light of the above mentioned importance of the Timaeus for Stoic cosmology. Apparently, what particularly interested Posidonius was the fact that Plato’s main character in the dialogue is a Pythagorean, a school that Posidonius somewhat anachronistically managed to link to Stoicism.

“It appears that the broader project pursued by both Panaetius and Posidonius was one of seeking common ground (Sedley 2003 uses the term “syncretism”) among Academicism, Aristotelianism and Stoicism itself, that is, the three branches of Socratic philosophy. This process seems to have been in part responsible for the further success of Stoicism once the major philosophers of the various schools moved from Athens to Rome, after the diaspora of 88-86 B.C.E.

Roman Stoicism


Massimo Pigliucci of CUNY wrote: “If the visit to Rome by the head of various philosophical schools in 155 B.C.E. was crucial for bringing philosophy to the attention of the Romans, the political events of 88-86 B.C.E. changed the course of Western philosophy in general, and Stoicism in particular, for the remainder of antiquity. [Source: Massimo Pigliucci, City University of New York (CUNY), Internet Encyclopedia of Philosophy (IEP) ]

“At that time philosophers, particularly the Peripatetic Athenion and—surprisingly—the Epicurean Aristion, were politically in charge at Athens, and made the crucial mistake of siding with Mithridates against Rome (Bugh 1992). The defeat of the King of Pontus, and consequently of Athens, spelled disaster for the latter and led to a diaspora of philosophers throughout the Mediterranean.

“To be fair, we have no evidence of the continuation of the Stoa as an actual school in Athens after Panaetius (who often absented himself to Rome anyway), and we know that Posidonius taught in Rhodes, not Athens. However, according to Sedley (2003), it was the events of 88-86 B.C.E. that finally and permanently moved the center of gravity of Stoicism away from its Greek cradle to Rome, Rhodes (where an Epicurean school also flourished), and Tarsus, where a Stoic was at one point chosen by Augustus to govern the city.

“Most crucially, however, Stoicism became important in Rome during the fraught time of the transition between the late Republic and the Empire, with Cato the Younger eventually becoming a role model for later Stoics because of his political opposition to the “tyrant” Julius Caesar. Sedley highlights two Stoic philosophers of the late First Century B.C.E., Athenodorus of Tarsus and Arius Didymus, as precursors of one of the greatest and most controversial Stoic figures, Seneca. Both Athenodorus and Arius were personal counselors to the first emperor, Augustus, and Arius even wrote a letter of consolation to Livia, Augustus’ wife, addressing the death of her son, which Seneca later hailed as a reference work of emotional therapy, the sort of work he himself engaged in and became famous for.

“Once we get to the Imperial period (Gill 2003), we see a decided shift away from the more theoretical aspects of Stoicism (the “physics” and “logic,” see below) and toward more practical treatments of the ethics. However, as Gill points out, this should not lead us to think that the vitality of Stoicism had taken a nose dive by then: we know of a number of new treatises produced by Stoic writers of that period, on everything ranging from ethics (Hierocles’ Elements of Ethics) to physics (Seneca’s Natural Questions), and the Summary of the Traditions of Greek Theology by Cornutus is one of a handful of complete Stoic treatises to survive from any period of the history of the school. Still, it is certainly the case that the best known Stoics of the time were either teachers like Musonius Rufus and Epictetus, or politically active, like Seneca and Marcus Aurelius, thus shaping our understanding of the period as a contrast to the foundational and more theoretical one of Zeno and Chrysippus.

“Importantly, it is from the late Republic and Empire that we also get some of the best indirect sources on Stoicism, particularly several books by Cicero (2014; for example., Paradox Stoicorum, De Finibus Bonorum et Malorum, Tusculanae Quaestiones, De Fato, Cato Maior de Senectute, Laelius de Amicitia, and De Officiis) and Diogenes Laertius’ Lives of the Eminent Philosophers (Book VII, 2015). And this literature went on to influence later writers well after the decline of Stoicism, particularly Plotinus (205-270 C.E.) and even the 6th Century C.E. Neoplatonist Simplicius.

medievel Plato, Seneca, Aristotle

“All of the above notwithstanding, what is most vital about Stoicism during the Roman Imperial period, however, is also what arguably made the philosophy’s impact reverberate throughout the centuries, eventually leading to two revivals, the so-called Neostoicism of the Renaissance, and the current “modern Stoicism” movement to which I will turn at the end of this essay. The sources of such vitality were fundamentally two: on the one hand charismatic teachers like Musonius and Epictetus, and on the other hand influential political figures like Seneca and Marcus. Indeed, Musonius was, in a sense, both: not only he was a member of the Roman “knight” class, and the teacher of Epictetus, he was also politically active, openly criticizing the policies of both Nero and Vespasian, and getting exiled twice as a result. Others were not so lucky: Stoic philosophers suffered a series of persecutions from displeased emperors, which resulted in murders or exile for a number of them, especially during the reigns of Nero, Vespasian and Domitian. Seneca famously had to commit suicide on Nero’s orders, and Epictetus was exiled to Greece (where he established his school at Nicopolis) by Domitian.

“It is also important to appreciate different “styles” of being Stoic among the major Roman figures. As Gill (2003) points out, Epictetus was rather strict, arching back to the Cynic model of quasi-asceticism (see, for instance, his “On Cynicism” in Discourses III.22). Musonius was a sometimes odd combination of “conservative” and “progressive” Stoic, advocating the importance of marriage and family, but also stating very clearly that women are just as capable of practicing virtue and philosophizing as men are, and moreover that it is hypocritical of men to consider their extramarital sexual activities differently from those of women! Seneca was not only more open to the pursuit of “preferred indifferents” (he was a wealthy Senator, but it seems unfair to accuse him of endorsing a simplistic self-serving philosophy: see the nuanced biographies by Romm 2014 and Wilson 2014), but explicitly stated that he was critical of some of the doctrines of the early Stoics, and that he was open to learn from other schools, including the Epicureans. Famously, Marcus Aurelius was open—one would almost want to say agnostic—about theology, at several points in the Meditations (1997) explicitly stating the two alternatives of “Providence” (Stoic doctrine) or “Atoms” (the Epicurean take), for instance: “Either there is a fatal necessity and invincible order, or a kind Providence, or a confusion without a purpose and without a director. If then there is an invincible necessity, why do you resist? But if there is a Providence that allows itself to be propitiated, make yourself worthy of the help of the divinity. But if there is a confusion without a governor, be content that in such a tempest you have yourself a certain ruling intelligence” (XII.14); or: “With respect to what may happen to you from without, consider that it happens either by chance or according to Providence, and you must neither blame chance nor accuse Providence” (XII.24). More is said about this specific topic in the section on Stoic metaphysics and teleology.

“There is ample evidence, then, that Stoicism was alive and well during the Roman period, although the emphasis did shift—somewhat naturally, one might add—from laying down the fundamental ideas to refining them and putting them into practice, both in personal and social life.

Debates Between Stoics and Other Philosophical Schools

Massimo Pigliucci of CUNY wrote: “One should understand the evolution of all Hellenistic schools of philosophy as being the result of continuous dialogue amongst themselves, a dialogue that often led to partial revisions of positions within any given school, or to the adoption of a modified notion borrowed from another school (Gill 2003). To have an idea of how this played out for Stoicism, let us briefly consider a few examples, related to the interactions between Stoicism and Epicureanism, Aristotelianism, and Platonism—without forgetting the direct influence that Cynicism had on the very birth of Stoicism and all the way to Epictetus. [Source: Massimo Pigliucci, City University of New York (CUNY), Internet Encyclopedia of Philosophy (IEP) ]

“Epictetus is pretty explicit about his—negative—opinions of the Epicureans, drawing as sharp a contrast as possible between the latter's concern with pleasure and pain and the Stoic focus on virtue and integrity of character. For example, Discourses I.23 is entitled “Against Epicurus,” and begins: “[1] Even Epicurus realizes that we are social creatures by nature, but once he has identified our good with the shell, he cannot say anything inconsistent with that. [2] For he further insists—rightly—that we must not respect or approve anything that does not share in the nature of what is good.” “The shell” here is the body, a reference to the Epicureans’ insistence on pleasure and the absence of pain as what leads to ataraxia, or tranquillity of mind—a term interestingly different from the one preferred by the Stoics, apatheia, or lack of disturbing emotions, as shall be seen below.

“A longer section, II.20, is entitled “Against the Epicureans and the Academics,” at the beginning of which Epictetus calls the bluff, in his mind, on the rivals’ theories, which he understands as clearly impractical and contrary to common sense: “[1] Even people who deny that statements can be valid or impressions clear [that is, the Skeptics] are obliged to make use of both. You might almost say that nothing proves the validity of a statement more than finding someone forced to use it while at the same time denying that it is sound.” Epictetus even goes so far as suggesting that Epicurus is incoherent, as he advises a life of retired tranquility away from society, and yet bothers to write books about it, thus showing himself to be concern about the welfare of society after all: “[15] What urged him to get out of bed and write the things he wrote was, of course, the strongest element in a human being—nature—which subjected him to her will despite his loud resistance.”

“Attacking the Skeptics among the Academics, Epictetus turns up the rhetoric significantly: “What a travesty! [28] What are you doing? You prove yourself wrong on a daily basis and still you won’t give up these idle efforts. When you eat, where do you bring your hand—to your mouth, or to your eye? What do you step into when you bathe? When did you ever mistake your saucepan for a dish, or your serving spoon for a skewer?” And he sees his invective as justified—in sure Stoic fashion—not on theoretical grounds, but on practical ones: “[35] We could give adulterers grounds for rationalizing their behavior; such arguments could provide pretexts to misappropriate state funds; a rebellious young man could be emboldened further to rebel against his parents. So what, according to you, is good or bad, virtuous or vicious—this or that?”

“Even so, not all Stoics rejected either Academic or Epicurean ideas altogether. I have mentioned Marcus Aurelius’ relative “agnosticism” about Providence vs. Atoms (though he clearly preferred the first option, in line with standard Stoic teaching), and Seneca is often sympathetic to Epicurean views, though, as Gill (2003, note 58) comments, this is in the spirit of showing that even some of the rival school’s ideas are congruent with Stoic ones. He very clearly states, however, in Natural Questions: “I do not agree with [all] the views of our school” (2014, VII.22.1).

“Cicero, in Book III of De Finibus, provides us with some glimpses of the disagreement between Stoics and Aristotelians, by way of his imaginary dialogue with Cato the Younger. At [41] he writes: “Carneades never ceased to contend that on the whole so-called ‘problem of good and evil,’ there was no disagreement as to facts between the Stoics and the Peripatetics, but only as to terms. For my part, however, nothing seems to me more manifest than that there is more of a real than a verbal difference of opinion between those philosophers on these points.” He continues: “The Peripatetics say that all the things which under their system are called goods contribute to happiness; whereas our school does not believe that total happiness comprises everything that deserves to have a certain amount of value attached to it,” referring to the different treatment of “external goods” between Aristotelians and Stoics.

“There are well documented examples of Stoic opinions changing in direct response to challenges from other schools, for instance the modified position on determinism that was adopted by Philopator (80-140 C.E.), a result of criticism from both the Peripatetic and the Middle Platonist philosophers. We also have clear instances of Stoic ideas being incorporated by other schools, as in the case of Antiochus of Ascalon (130-69 B.C.E.), who introduced Stoic notions in his revision of Platonism, justifying the move by claiming that Zeno (and Aristotle, for that matter) developed ideas that were implicit in Plato (Gill 2003). Finally, Stoicism found its way into Christianity via Middle Platonism, at the least since Clement of Alexandria (150-215 C.E.).”

Stoic Philosophy and Ideas

According to the Stanford Encyclopedia of Philosophy: “When considering the doctrines of the Stoics, it is important to remember that they think of philosophy not as an interesting pastime or even a particular body of knowledge, but as a way of life. They define philosophy as a kind of practice or exercise (askêsis) in the expertise concerning what is beneficial (Aetius, 26A). Once we come to know what we and the world around us are really like, and especially the nature of value, we will be utterly transformed. This therapeutic aspect is common to their main competitors, the Epicureans, and perhaps helps to explain why both were eventually eclipsed by Christianity. [Stanford Encyclopedia of Philosophy, 1996, updated 2018 ]

Aetius wrote (1.7.33L): "The Stoics make god out to be intelligent, a designing fire which methodically proceeds towards creation of the world, and encompasses all the seminal principles" [Source: CSUN]

Diogenes Laertius wrote (7. 135-6): "God, Intelligence, Fate, and Zeus are all one, and many other names are applied to him. In the beginning, all by himself, he turned the entire substance through air into water. Just as the sperm is enveloped in the seminal fluid, so god, who is the seminal principle of the world, stays behind as such in the moisture, making matter serviceable to himself for the successive stages of creation. he then creates first of all the Four Elements: fire, water, air, earth."

Stobaeus wrote (1.213. 15-21): “Zeno says that the sun and the moon and each of the other stars are intelligent and prudent and have the fieriness of designing fire. For there are two kinds of fire: one is undesigning and converts fuel into itself; the other is designing, causing growth and preservation, as is the case in plants and animals where it is physique and soul respectively. Such is the fire which constitutes the substance of the stars."

Plutarch wrote in “On Stoic self-contradictions” (1052 c-d): “In Chrysippus' On Providence Book I, he says that Zeus continues to grow until he has used up everything on himself: "For since death is the separation of the soul from the body, and the soul of the world is not separated but grows continuously until it has completely used up its matter on itself, the world must be said to die..."

Eusebius wrote in “Praeparatio evangelica (15.14.2), quoting Aristocles: “At certain fated times the entire world is subject to conflagration, and then is reconstituted afresh. But the primary fire is as it were a sperm which possesses the principles (logoi) of all things and the causes of past, present, and future events. The nexus and succession of these is Fate, Knowledge, Truth, and an inevitable and inescapable Law of what exists. In this way, everything in the world is excellently organized as in a perfectly ordered society."

Sextus Empiricus wrote in “Against the Professors (7.234): “Some of the Stoics say that the soul has two meanings: that which sustains the whole compound; and in particular the commanding faculty. For when we say that man is a compound of soul and body, or that death is separation of soul and body, we are referring particularly to the commanding-faculty."

Aetius wrote (4.21.1-4): “The Stoics say that the commanding-faculty is the soul's highest part, which produces impressions, assents, perceptions and impulses. They also call it the REASONING FACULTY. From the commanding-faculty there are seven parts of the soul which grow out and stretch out into the body, like the tentacles of an octopus. Five of these are the senses: sight, sound, smell, taste, and touch. ... Of the remainder, one is called SEED, and this is breath extending from the commanding-faculty to the genitals. The other ... which they call UTTERANCE, is breath extending from the commanding-faculty to the pharynx, tongue, and appropriate organs...."

Plutarch wrote in “On Stoic self-contradictions” (1057a.): “"What is the subject most argued about by Chrysippus himself and Antipater in their disputes with the Academics? The doctrine that without ASSENT there is neither action nor impulsion, and that they are talking nonsense and empty assumptions who claim that, when an appropriate impulsion occurs, impulsion ensues at once without people first having yielded or given their assent." Eusebius wrote in “Praeparatio evangelica” (15.20.6): "The Stoics say that the SOUL is subject to generation and destruction. When separated from the body, however, it does not perish at once, but survives on its own for certain times, the soul of the virtuous up to the dissolution of everything into fire, that of fools only for certain definite times. By the survival of souls they mean that we ourselves survive as souls separated from bodies and changed into the lesser substance of the soul, while the should of non-rational animals perish along with their bodies..."

Stoic Divisions

Diogenes Laërtius wrote: “The Stoics divide reason according to philosophy, into three parts; and say that one part relates to natural philosophy, one to ethics, and one to logic. And Zeno, the Cittiaean, was the first who made this division, in his treatise on Reason; and he was followed in it by Chrysippus, in the first book of his treatise on Reason, and in the first book of his treatise on Natural Philosophy; and also by Apollodorus and by Syllus, in the first book of his Introduction to the Doctrines of the Stoics; and by Eudromus, in his Ethical Elements; and by Diogenes, the Babylonian; and Posidorus, Now these divisions are called topics by Apollodorus, species by Chrysippus and Eudromus, and genera by all the rest. And they compare philosophy to an animal, likening logic to the bones and sinews, natural philosophy to the fleshy parts, and ethical philosophy to the soul. Again, they compare it to an egg; calling logic the shell, and ethics the white, and natural philosophy the yolk. Also to a fertile field; in which logic is the fence which goes round it, ethics are the fruit, and natural philosophy the soil, or the fruit-trees. Again, they compare it to a city fortified by walls, and regulated by reason; and then, as some of them say, no one part is preferred to another, but they are all combined and united inseparably; and so they treat of them all in combination. But others class logic first, natural philosophy second, and ethics third as Zeno does in his treatise on Reason, and in this he is followed by Chrysippus, and Archidemus, and Eudromus. [Source: Diogenes Laërtius: “The Lives and Opinions of Eminent Philosophers Book VII: The Stoics”, A.D. early 3rd century, translated by C.D. Yonge (London: George Bell & Sons, 1895)]

“For Diogenes of Ptolemais begins with ethics; but Apollodorus places ethics second; and Panaetius and Posidonius begin with natural philosophy, as Phanias, the friend of Posidonius asserts, in the first book of his treatise on the School of Posidonius. But Cleanthes says, that there are six divisions of reason according to philosophy: dialectics, rhetoric, ethics, politics physics, and theology; but others assert that these are not divisions of reason, but of philosophy itself; and this is the opinion advanced by Zeno, of Tarsus, among others.

“Some again say, that the logical division is properly subdivided into two sciences, namely, rhetoric and dialectics; and some divide it also into definitive species, which is coversant with rules and tests; while others deny the propriety of this last division altogether, and argue that the object of rules and tests is the discovery of the truth; for it is in this division that they explain the differences of representations. They also argue that, on the other side, the science of definitions has equally for its object the discovery of truth, since we only know things by the intervention of ideas. They also call rhetoric a science conversant about speaking well concerning matters which admit of a detailed narrative; and dialectics they call the science of arguing correctly in discussions which can be carried on by question and answer; on which account they define it thus: a knowledge of what is true, and false, and neither one thing nor the other.

“Again, rhetoric itself they divide into three kinds; for one description they say is concerning about giving advice, another is forensic, and the third encomiastic; and it is also divided into several parts, one relating to the discovery of arguments, one to style, one to the arrangement of arguments, and the other to the delivery of the speech. And a rhetorical oration they divide into the exordium, the narration, the reply to the statements of the adverse party, and the peroration.

Stoic Physical Theory

According to the Stanford Encyclopedia of Philosophy: “An examination of Stoic ontology might profitably begin with a passage from Plato’s Sophist (cf. Brunschwig 1994). There (247d-e), Plato asks for a mark or indication of what is real or what has being. One answer which is mooted is that the capacity to act or be acted upon is the distinctive mark of real existence or ‘that which is.’ The Stoics accept this criterion and add the rider that only bodies can act or be acted upon. Thus, only bodies exist. So there is a sense in which the Stoics are materialists or – perhaps more accurately, given their understanding of matter as the passive principle (see below) – ‘corporealists’. However, they also hold that there are other ways of appearing in the complete inventory of the world than by virtue of existing. Incorporeal things like time, place or sayables (lekta, see below) are ‘subsistent’ (huphestos, Galen 27G) – as are imaginary things like centaurs. The distinction between the subsistent and the existent somewhat complicates the easy assimilation of Stoicism to modern materialism. It’s not wrong to say that all existent things are corporeal according to the Stoics, but one needs to add that existent things don’t exhaust their ontology. All existent things are, in addition, particulars. The Stoics call universals ‘figments of the mind’. Platonic Forms, in particular, are rejected as ‘not somethings’ which lack even the subsistent status of incorporeals like time, place or sayables (Alexander, 30D). The Stoics’ positive nominalist alternative is harder to interpret. Some texts suggest that they offered a conceptualist treatment akin to Locke’s, treating an apparent predication like “man is a rational, mortal animal” as the disguised conditional, “if something is a man, then it is a rational mortal animal” (Sextus Empiricus, 30I). But there may well have been development within the school from this conceptualist view toward a form of predicate nominalism. See Caston (1999). [Stanford Encyclopedia of Philosophy, 1996, updated 2018 ]

“In accord with this ontology, the Stoics, like the Epicureans, make God a corporeal entity, though not (as with the Epicureans) one made of everyday matter. But while the Epicureans think the gods are too busy being blessed and happy to be bothered with the governance of the universe (Epicurus, Letter to Menoeceus 123–4), the Stoic God is immanent throughout the whole of creation and directs its development down to the smallest detail. The governing metaphor for Stoic cosmology is biological, in contrast to the fundamentally mechanical conception of the Epicureans. The entire cosmos is a living thing and God stands to the cosmos as an animal’s life force stands to the animal’s body, enlivening, moving and directing it by its presence throughout. The Stoics insistence that only bodies are capable of causing anything, however, guarantees that this cosmic life force must be conceived of as somehow corporeal.

“More specifically, God is identical with one of the two ungenerated and indestructible first principles (archai) of the universe. One principle is matter which they regard as utterly unqualified and inert. It is that which is acted upon. God is identified with an eternal reason (logos, Diog. Laert. 44B ) or intelligent designing fire or a breath (pneuma) which structures matter in accordance with Its plan (Aetius, 46A). The designing fire is likened to sperm or seed which contains the first principles or directions of all the things which will subsequently develop (Aristocles in Eusebius, 46G). The biological conception of God as a kind of living heat or seed from which things grow seems to be fully intended. The further identification of God with pneuma or breath may have its origins in medical theories of the Hellenistic period. See Baltzly (2003). On the entire issue of God and its relation to the cosmos in Stoicism, see the essays in Salles (2009).

“Just as living things have a life-cycle that is witnessed in parents and then again in their off-spring, so too the universe has a life cycle that is repeated. This life cycle is guided by, or equivalent to, a developmental plan that is identified with God. There is a cycle of endless recurrence, beginning from a state in which all is fire, through the generation of the elements, to the creation of the world we are familiar with, and eventually back to the state of pure designing fire called ‘the conflagration’ (Nemesius, 52C). This idea of world-cycles punctuated by conflagrations raised a number of questions. Will there be another you reading this encyclopedia entry in the next world cycle? Or merely someone exactly similar to you? Different sources attribute different answers to the Stoics on these questions. (For sameness of person, see Alexander (52F). For someone indistinguishable, but not not identical, see Origen (52G).) The doctrine of eternal recurrence also raises interesting questions about the Stoic view of time. Did they suppose that the moment in the next world cycle at which you (or someone indistinguishable from you) reads this entry is a moment in the future (so time is linear) or the very same moment (with some notion of circular time)? The Stoic definition of time as the ‘dimension (diastêma) of motion’ or ‘of the world’s motion’ (Simplicius, 51A) hardly seems to settle the question. For a clear exchange on the issue, see Long (1985) and Hudson (1990).

Elements and Pneuma

According to the Stanford Encyclopedia of Philosophy: “The first things to develop from the conflagration are the elements. Of the four elements, the Stoics identify two as active (fire and air) and two as passive (water and earth). The active elements, or at least the principles of hot and cold, combine to form breath or pneuma. Pneuma, in turn, is the ‘sustaining cause’ (causa continens, synektikon aition) of all existing bodies and guides the growth and development of animate bodies. What is a sustaining cause? The Stoics think that the universe is a plenum. Like Aristotle, they reject the existence of empty space or void (except that the universe as a whole is surrounded by it). Thus, one might reasonably ask, ‘What marks any one object off from others surrounding it?’ or, ‘What keeps an object from constantly falling apart as it rubs elbows with other things in the crowd?’. The answer is: pneuma. [Stanford Encyclopedia of Philosophy, 1996, updated 2018 ]


“Pneuma, by its nature, has a simultaneous movement inward and outward which constitutes its inherent ‘tensility.’ (Perhaps this was suggested by the expansion and contraction associated with heat and cold.) Pneuma passes through all (other) bodies; in its outward motion it gives them the qualities that they have, and in its inward motion makes them unified objects (Nemesius, 47J). In this latter respect, pneuma plays something like one of the roles of substantial form in Aristotle for this too makes the thing of which it is the form ‘some this,’ i.e. an individual (Metaph. VII, 17). Because pneuma acts, it must be a body and it appears that the Stoics stressed the fact that its blending with the passive elements is ‘through and through’ (Galen 47H, Alex. Aph. 48C). Perhaps as a result of this, they developed a theory of mixture which allowed for two bodies to be in the same place at the same time. It should be noted, however, that some scholars (e.g. Sorabji, 1988) think that the claim that pneuma is blended through the totality of matter is a conclusion that the Stoics’ critics adversely drew about what some of their statements committed them to. Perhaps instead they proposed merely that pneuma is the matter of a body at a different level of description.

“Pneuma comes in gradations and endows the bodies which it pervades with different qualities as a result. The pneuma which sustains an inanimate object is (LS) a ‘tenor’ (hexis, lit. a holding). Pneuma in plants is, in addition, (LS) physique (phusis, lit. ‘nature’). In animals, pneuma is soul (psychê) and in rational animals pneuma is, besides, the commanding faculty (hêgemonikon) (Diog. Laert. 47O, Philo 47P) – that is responsible for thinking, planning, deciding. The Stoics assign to ‘physique’ or ‘nature’ all the purely physiological life functions of a human animal (such as digestion, breathing, growth etc.) – self-movement from place to place is due to soul.

“Their account of the human soul (mind) is strongly monistic. Though they speak of the soul’s faculties, these are parts of the commanding faculty associated with the physical sense organs (Aetius, 53H). Unlike the Platonic tri-partite soul, all impulses or desires are direct functions of the rational, commanding faculty. This strongly monistic conception of the human soul has serious implications for Stoic epistemology and ethics. In the first case, our impressions of sense are affections of the commanding faculty. In mature rational animals, these impressions are thoughts, or representations with propositional content. Though a person may have no choice about whether she has a particular rational impression, there is another power of the commanding faculty which the Stoics call ‘assent’ and whether one assents to a rational impression is a matter of volition. To assent to an impression is to take its content as true. To withhold assent is to suspend judgement about whether it is true. Because both impression and assent are part of one and the same commanding faculty, there can be no conflict between separate and distinct rational and nonrational elements within oneself – a fight which reason might lose. Compare this situation with Plato’s description of the conflict between the inferior soul within us which is taken in by sensory illusions and the calculating part which is not (Rep. X, 602e). There is no reason to think that the calculating part can always win the epistemological civil war which Plato imagines to take place within us. But because the impression and assent are both aspects of one and the same commanding faculty according to the Stoics, they think that we can always avoid falling into error if only our reason is sufficiently disciplined. In a similar fashion, impulses or desires are movements of the soul toward something. In a rational creature, these are exercises of the rational faculty which do not arise without assent. Thus, a movement of the soul toward X is not automatically consequent upon the impression that X is desirable. This is what the Stoics’ opponents, the Academic Skeptics, argue against them is possible (Plutarch, 69A.) The Stoics, however, claim that there will be no impulse toward X – much less an action – unless one assents to the impression (Plutarch, 53S). The upshot of this is that all desires are not only (at least potentially) under the control of reason, they are acts of reason. Thus there could be no gap between forming the decisive judgement that one ought to do X and an effective impulse to do X.

“Since pneuma is corporeal, there is a sense in which the Stoics have a theory of mind that would be called ‘materialist’ in the modern sense (cf. Annas 2009). The pneuma which is a person’s soul is subject to generation and destruction (Plutarch 53 C, Eusebius 53W). Unlike for the Epicureans, however, it does not follow from this that my soul will be utterly destroyed at the time at which my body dies. Chrysippus alleged that the souls of the wise would not perish until the next conflagration (Diog. Laert. 7.157=SVF 2.811, not in LS). Is this simply a failure of nerve on the part of an otherwise thorough-going materialist? Recall that the distinctive movement of pneuma is its simultaneous inward and outward motion. It is this which makes it tensile and capable of preserving, organising and, in some cases, animating the bodies which it interpenetrates. The Stoics equate virtue with wisdom and both with a kind of firmness or tensile strength within the commanding faculty of the soul (Arius Didymus 41H, Plutarch 61B, Galen 65T). Perhaps the thought was that the souls of the wise had a sufficient tensile strength that they could continue to exist as a distinct body on their own. Later Stoics like Panaetius (2nd c. B.C.) and Posidonius (first half 1st c. B.C.) may have abandoned this view of Chrysippus’.

Stoic Logic

According to the Stanford Encyclopedia of Philosophy: “The scope of what the Stoics called ‘logic’ (logikê, i.e. knowledge of the functions of logos or reason) was very wide, including not only the analysis of argument forms, but also rhetoric, grammar, the theories of concepts, propositions, perception, and thought. Thus Stoic logikê included not only what we would call logic, but also philosophy of language and epistemology. [Stanford Encyclopedia of Philosophy, 1996, updated 2018 ]

“In philosophy of language, their most noted innovation was their theory of ‘sayables’ or lekta. The Stoics distinguish between the signification, the signifier and the name-bearer. Two of these are bodies: the signifier which is the utterance and the name-bearer which is what gets signified. The signification, however, is an incorporeal thing called a lekton, or ‘sayable,’ and it, and neither of the other two, is what is true or false (Sextus Empiricus, 33B). They define a sayable as “that which subsists in accordance with a rational impression.” Rational impressions are those alterations of the commanding faculty or rational mind whose content can be exhibited in language. Presumably ‘graphei Sôkratês’ and ‘Socrates writes’ exhibit the contents of one and the same rational impression in different languages. “At first glance, this looks very like a modern theory of propositions and indeed propositions (axiômata) are one subspecies of Stoic sayables. But it would be a mistake to assimilate this sub-class of sayables too closely to modern theories of propositions. Modern theories tend to treat propositions as untensed and time-indexed. When I utter the words “It’s warm in Hobart today” I express the proposition that it is warm in Hobart on 25 February 2018. That’s a different proposition from the one I would express with the use of those same words tomorrow. If, as is all too often the case, it is cold tomorrow and what I say by means of the words “It is warm in Hobart today” is false, then the proposition did not change its truth value. The tenseless and time-indexed propositions we express with our words have their truth values eternally. Stoic axiômata are crucially different in this respect. The Stoic theory holds invariant the identity of the sayable corresponding to my utterances on the different occasions, but allows its truth value to change (Diog. Laert., 34E). In addition to these axiômata, the class of so-called ‘complete sayables’ included questions and commands, as well as syllogisms (Diog. Laert., 33F).

“In the category of sayables called ‘incomplete,’ the Stoics included predicates and, as in the case of propositions, these are the meanings which we can express through the use of different languages. So the utterance ‘graphei’ in Greek presumably corresponds to the same incomplete sayable as ‘___ writes’ in English. Like some modern theories of predicates, these incomplete lekta are hungry for arguments or what the Stoics would call a nominative case (ptôsis, Diog. Laert., 33G). Curiously the Stoics distinguished between examples where the filling in of the subject that yields a complete sayable happens by means of a referring term (as in ‘Socrates writes’ and cases involving ostensive reference like ‘this one writes’. ‘This one writes’ was called ‘definite’, while ‘Socrates writes’ was predicative or middle – the latter in order to distinguish it from an indefinite predication like ‘someone writes’. The isolation of ostensive reference as a special case gives rise to another odd feature of the Stoic account of meanings and propositions. Standing in the presence of Socrates’ corpse, you can utter the words ‘Socrates is dead’ and your words correspond to a complete lekton (and one that is true at that time). But point to the body and say ‘This one is dead’ and the Stoics seem to have supposed the reference failed in such a way that the sayable ‘is destroyed’ (Alexander, 38F). This odd feature of sayables looms large in the Stoic response to competing accounts of modality.

“The examples dealt with so far are examples of simple, complete sayables or propositions. The Stoics also developed an account of non-simple propositions. This interest in non-simple propositions and their logical relations was shared with philosophers in the Megarian or Dialectical school. It set the philosophers of the Hellenistic period on the pathway to surpass Aristotle’s progress in logic. His logic was ‘a logic of terms’. To put the matter very briefly and far too crudely, Aristotle had developed an account of a limited range of kinds statements (e.g. All A are B, or Some A are B, or No A are B). His theory of the syllogism sought to systematically investigate all the ways of combining pairs of such statements and to identify the combinations where the first two (the premises) entail a third statement (the conclusion) of same sort purely as a result of the form of the premises rather than their content. Focused on the connections between predicate and subject terms in such statements, it had little to say about complex statements that had complete statements as parts. The Stoics, by contrast, made progress in what we now call propositional logic. They developed accounts of propositional negation (‘it is not the case that p’), conjunction (‘p and q’), disjunction (‘p or q’) and entered the on-going debate over the correct understanding of conditionals (‘if p, then q’). Their accounts of the connectives joining simple propositions into complex ones also led them into questions about modal concepts (possibility, impossibility, necessity and contingency). One of the accounts they offer of the validity of arguments is that an argument is valid if, through the use of certain ground rules (themata), it is possible to reduce it to one of the five indemonstrable forms (Diog. Laert., 36A). These five indemonstrables are argument forms that should be familiar to anyone who has taken an introductory logic class:

“if p then q; p; therefore q (modus ponens); if p then q; not q; therefore not-p (modus tollens); it is not the case that both p and q; p; therefore not-q; either p or q; p; therefore not-q; either p or q; not p; therefore q

“Stoic contributions to logic and philosophy of language, as well as the backdrop of Aristotelian and Megarian views in the Hellenistic period, are thoroughly surveyed in a 100 page entry on the subject by Barnes, Bobzien and Mignucci in The Cambridge History of Hellenistic Philosophy (Algra et al, 1999). An abbreviated and more digestible version of this material by Bobzien appears in Inwood (2003).

“Though these and other developments in logic are interesting in their own right, the Stoic treatment of certain problems about modality and bivalence are more significant for the shape of Stoicism as a whole. Chrysippus in particular was convinced that bivalence and the law of excluded middle apply even to contingent statements about particular future events or states of affairs.

Stoic Epistemic Criteria

Jeremy Kirby of Albion College wrote in the Internet Encyclopedia of Philosophy: “How does the ruling element of the soul distinguish a real presentation from a mere figment? According to Diogenes Laertius, the Stoics maintained the following (Lives 155): “With respect to presentations, on the one hand there is the cataleptic, and on the other there is the non-cataleptic. The cataleptic, which they say is the criterion of things, is that which comes to be from an existent object, agrees with the real object itself, having been stamped and imprinted. The non-cataleptic does not come to be from the existent object, or if it does, fails to accord with that which exists; it is neither clear nor distinct. [Source: Jeremy Kirby, Albion College, Internet Encyclopedia of Philosophy (IEP) ]

“A cataleptic (“apprehending” or “grasping”) presentation (i) comes from a real object (ii) accurately corresponds to that object, (iii) is imprinted on the sense faculty, and, as we might add, (iv) is clear and distinct. The Stoics, moreover, take the cataleptic impression to be the criterion by means of which one may discern fact from fiction. Needless to say, the Skeptics were eager to ask how it is that one may discern the cataleptic from the non-cataleptic. The conceptual landscape here is filled out aptly by Cicero in his Academica (2.83):

“There are four headings to prove there is nothing that can be known, cognized, or grasped, which is the subject of this whole controversy. The first of these is that (i) some false impression does exist. The second is that (ii) it is not cognitive. The third is that (iii) impressions between which there is no difference cannot be such that some are cognitive and others not. The fourth is that (iv) no true impression arises from sensation that does not have alongside it another impression, no different from it, that is not cognitive. Everyone accepts the second and third of these. Epicurus does not grant the first, but you…[Stoics], with whom we are dealing, admit that one. The entire battle is about the fourth.

“The Stoics seemed to have denied that a true and a false impression might nevertheless be qualitatively indistinguishable. But, as Cicero goes on to ask, what mark (notum) of a cataleptic impression might one have such that it could not be false? In response to Cicero’s question, the Stoics developed several strategies (Lives 162):

“The standard of truth they claim is the cataleptic presentation, i.e., that which comes to be from a real object, according to Chrysippus in the twelfth book of his Physics, and to Antipater and Apollodorus. Boëthus, however, admits a plurality of standards, namely intelligence, sense-perception, appetency, and knowledge. But Chrysippus contradicts himself…and says that the criterion is sensation and preconception (prolepsis). And preconception is a natural concept of the universal. Again, certain others of the older Stoics make orthos logos the criterion; so also does Posidonius in his treatise On the Criterion.

“The pivotal question for understanding Chrysippus’ epistemology seems to concern the meaning he attaches to prolepsis. On one reading, these preconceptions might be considered innate concepts. This reading, however, rings inconsonant with the empiricist leanings associated with the Stoics (SVF 2.83): ‘The Stoics say that whenever a person is born, the hegemonic part of his soul is like a sheet prepared to be written upon. Upon this he writes each one of his conceptions. The first method of inscription is via the senses. For by perceiving something, e.g., white, they have a memory of it when it has departed. And when many memories of a similar kind have occurred, we then say we have experience. For the plurality of similar experiences is experience. Some conceptions arise naturally in the previously mentioned ways without deliberation, others by means of our own instruction and attention. The latter are called merely conceptions. The former are called preconceptions (prolepseis) as well. Reason, for (possessing) which we are called rational, is said to be completed by means of our preconceptions during our first seven years.

“The above passage suggests that Stoics viewed the mind as a tabula rasa. Concepts, or prolepseis, are acquired causally by the repetition of similar presentations. (See Aristotle’s Posteria Analytica II.9) Chrysippus seems to have thought that one might compare a given token presentation with the concept one has of the type thereof. When, for example, the sage rejects the presentation of a dragoness, one may note that the dragoness does not match the prolepsis one has of females. If this is his line of thinking, it is fair to say that Chrysippus is sanguine indeed with respect to the reliability of the cognitive mechanism responsible for the acquisition of prolepseis. Optimism at this level, however, accords well with the Stoic view that the world is constructed in accordance with reason (Lives VII.134): “[The Stoics] think that there are two principles of the universe—that which acts, and that which is acted upon. That which is acted upon is unqualified substance, i.e. matter; that which acts is the reason (logos) in it, i.e. god.

“Understood in this way, Chrysippus’s view seems to share certain features with those more contemporary epistemologists who are keen to emphasize the proper function of one’s cognitive abilities—more so than one’s subjective relationship to a belief—in the production of beliefs that meet the requirements for warrant or knowledge. The Stoics saw the presence of the divine in terrestrial things. The epistemic faculties, like other faculties, are there for a reason.

Stoic Dialectics

Diogenes Laërtius wrote: “Dialectics, they say, is divided into two parts; one of which has reference to the things signified, the other to the expression. That which has reference to the things signified or spoken of, they divide again into the topic of things conceived in the fancy, and into those of axioms, of perfect determinations, of predicaments, of things alike, whether upright or prostrate, of tropes, of syllogisms, and of sophisms, which are derived either from the voice or from the things. And these sophisms are of various kinds; there is the false one, the one which states facts, the negative, the sorites, and others like these; the imperfect one, the inexplicable one, the conclusive one, the veiled one, the horned one, the nobody, and the mower. [Source: Diogenes Laërtius: “The Lives and Opinions of Eminent Philosophers Book VII: The Stoics”, A.D. early 3rd century, translated by C.D. Yonge (London: George Bell & Sons, 1895)]

“In the second part of dialectics, that which has for its object the expression, they treat of written language, of the different parts of a discourse, of solecism and barbarism, of poetical forms of expression, of ambiguity, of a melodious voice, of music; and some even add definitions, divisions, and diction. [after 276] They say that the most useful of these parts is the consideration of syllogisms; for that they show us what are the things which are capable of demonstration, and that contributes much to the formation of our judgment, and their arrangement and memory give a scientific character to our knowledge. They define reasoning to be a system composed of assumptions and conclusions; and syllogism is a syllogistic argument proceeding on them. Demonstration they define to be a method by which one proceeds from that which is more known to that which is less. Perception, again, is an impression produced on the mind, its name being appropriately borrowed from impressions on wax made by a seal; and perception they divide into, comprehensible and incomprehensible: Comprehensible, which they call the criterion of facts, and which is produced by a real object, and is, therefore, at the same time conformable to that object; Incomprehensible, which has no relation to any real object, or else, if it has any such relation, does not correspond to it, being but a vague and indistinct representation.

“Dialectics itself they pronounce to be a necessary science, and a virtue which comprehends several other virtues under its species. And the disposition not to take up one side of an argument hastily, they defined to be a knowledge by which we are taught when we ought to agree to a statement, and when we ought to withhold our agreement. Discretion they consider to be a powerful reason, having reference to what is becoming, so as to prevent our yielding to an irrelevant argument. Irrefutability they define to be a power in an argument, which prevents one from being drawn from it to its opposite. Freedom from vanity, according to them, is a habit which refers the perceptions back to right reason.”

Stoics on Perception

Diogenes Laërtius wrote: “Again, they define knowledge itself as an assertion or safe comprehension, or habit, which, in the perception of what is seen, never deviates from the truth. And they say further, that without dialectic speculation, the wise man cannot be free from all error in his reasoning. For that that is what distinguishes what is true from what is false, and which easily detects those arguments which are only plausible, and those which depend upon an ambiguity of language. And without dialectics they say it is not possible to ask or answer questions correctly. They also add, that precipitation in denials extends to those things which are done, so that those [after 277] who have not properly exercised their perceptions fall into irregularity and thoughtlessness. Again, without dialectics, the wise man cannot be acute, and ingenious, and wary, and altogether dangerous as an arguer. For that it belongs to the same man to speak correctly and to reason correctly, and to discuss properly those subjects which are proposed to him, and to answer readily whatever questions are put to him, all which qualities belong to a man who is skilful in dialectics. This then is a brief summary of their opinions on logic. [Source: Diogenes Laërtius: “The Lives and Opinions of Eminent Philosophers Book VII: The Stoics”, A.D. early 3rd century, translated by C.D. Yonge (London: George Bell & Sons, 1895)]

“And, that we may also enter into some more minute details respecting them, we will subjoin what refers to what they call their introductory science, as it is stated by Diocles, of Magnesia, in his Excursion of Philosophers, where he speaks as follows, and we will give his account word for word.

“The Stoics have chosen to treat, in the first place, of perception and sensation, because the criterion by which the truth of facts is ascertained is a kind of perception, and because the judgment which expresses the belief, and the comprehension, and the understanding of a thing, a judgment which precedes all others, cannot exist without perception. For perception leads the way; and then thought, finding vent in expressions, explains in words the feelings which it derives from perception. But there is a difference between phantasia and phantasma. For phantasma is a conception of the intellect, such as takes place in sleep; but phantasia is an impression, tupôsis, produced on the mind, that is to say, an alteration, alloiôsis, as Chrysippus states in the twelfth book of his treatise on the Soul. For we must not take this impression to resemble that made by a seal, since it is impossible to conceive that there should be many impressions made at the same time on the same thing. But phantasia is understood to be that which is impressed, and formed, and imprinted by a real object, according to a real object, in such a way as it could not be by any other than a real object; and, according to their ideas of the phantasiai, some are sensible, and some are not. Those they call sensible, which are derived by us from some one or more senses; and those they call not sensible, which emanate directly from the thought, as for instance, those which relate to incorporeal objects, or any others which are embraced by reason. Again, those which are sensible, are produced by a [after 278] real object, which imposes itself on the intelligence, and compels its acquiescence; and there are also some others, which are simply apparent, mere shadows, which resemble those which are produced by real objects. “Again, these phantasiai are divided into rational and irrational; those which are rational belong to animals capable of reason; those which are irrational to animals destitute of reason. Those which are rational are thoughts; those which are irrational have no name; but are again subdivided into artificial and not artificial. At all events, an image is contemplated in a different light by a man skilful in art, from that in which it is viewed by a man ignorant of art.

“By sensation, the Stoics understand a species of breath which proceeds from the dominant portion of the soul to the senses, whether it be a sensible perception, or an organic disposition, which, according to the notions of some of them, is crippled and vicious. They also call sensation the energy, or active exercise, of the sense. According to them, it is to sensation that we owe our comprehension of white and black, and rough and smooth: from reason, that we derive the notions which result from a demonstration, those for instance which have for their object the existence of Gods, and of Divine Providence. For all our thoughts are formed either by indirect perception, or by similarity, or analogy, or transposition, or combination, or opposition. By a direct perception, we perceive those things which are the objects of sense; by similarity, those which start from some point present to our senses; as, for instance, we form an idea of Socrates from his likeness. We draw our conclusions by analogy, adopting either an increased idea of the thing, as of Tityus, or the Cyclops; or a diminished idea, as of a pigmy. So, too, the idea of the centre of the world was one derived by analogy from what we perceived to be the case of the smaller spheres. We use transposition when we fancy eyes in a man‘s breast; combination, when we take in the idea of a Centaur; opposition, when we turn our thoughts to death. Some ideas we also derive from comparison, for instance, from a comparison of words and places.

“There is also nature; as by nature we comprehend what is just and good. And privation, when for instance, we form a notion of a man without hands. Such are the doctrines of the Stoics, on the subject of phantasia, and sensation, and thought.”

Stoic ideas of Phantasia and Logical Speculation

Diogenes Laërtius wrote: “They say that the proper criterion of truth is the comprehension, phantasia; that is to say, one which is derived from a real object, as Chrysippus asserts in the twelfth book of his Physics; and he is followed by Antipater and Apollodorus. For Boethius leaves a great many criteria, such as intellect, sensation, appetite, and knowledge; but Chrysippus dissents from his view, and in the first book of his treatise on Reason, says, that sensation and preconception are the only criteria. And preconception is, according to him, a comprehensive physical notion of general principles. But others of the earlier Stoics admit right reason as one criterion of the truth; for instance, this is the opinion of Posidonius, and is advanced by him in his essay on Criteria. [Source: Diogenes Laërtius: “The Lives and Opinions of Eminent Philosophers Book VII: The Stoics”, A.D. early 3rd century, translated by C.D. Yonge (London: George Bell & Sons, 1895)]

On the subject of logical speculation, there appears to be a great unanimity among the greater part of the Stoics, in beginning with the topic of the voice. Now voice is a percussion of the air; or, as Diogenes the Babylonian, defines it, in his essay on the Voice, a sensation peculiar to the hearing. The voice of a beast is a mere percussion of the air by some impetus: but the voice of a man is articulate, and is emitted by intellect, as Diogenes lays it down, and is not brought to perfection in a shorter period than fourteen years. And the voice is a body according to the Stoics; for so it is laid down by Archidemus, in his book on the Voice, and by Diogenes, and Antipater, and also by Chrysippus, in the second volume of his Physics. For everything which makes anything, is a body; and the voice makes something when it proceeds to those who hear from those who speak.

“A word (lexis), again, is, according to Diogenes, a voice consisting of letters, as "Day." A sentence (logos) is a significant voice, sent out by the intellect, as for instance, "It is day;" but dialect is a peculiar style imprinted on the utterance of nations, according to their race; and causes varieties in the Greek language, being a sort of local habit, as for instance, the Attics say thalatta, and the lonians say hêmerê. The elements of words are the twenty-four letters and the word letter is used in a triple division of sense, meaning the element itself, the graphical sign of the element, and the name, as Alpha. There are seven vowels, a, e, ê, i, o, u, ô; six mutes, b, g, d, k, p, t. But voice is different from a word, because voice is a sound; but a word is an articulate sound. And a word differs from a sentence, because a sentence is always significative of something, but a word by itself has no signification, as for instance, blitri:. But this is not the case with a sentence. Again, there is a difference between speaking and pronouncing; the sounds are pronounced, but what are spoken are things which are capable of being spoken of.

“Now of sentences there are five parts, as Diogenes tells us in his treatise on Voice; and he is followed by Chrysippus. There is the noun, the common noun, the verb, the conjunction, and the article. Antipater adds also quality, in his treatise upon Words and the things expressed by them. And a common noun (prosêgoria) is, according to Diogenes, a part of a sentence signifying a common quality, as for instance, man, horse. But a noun is a part of a sentence signifying a peculiar quality, such as Diogenes, Socrates. A verb is a part of a sentence signifying an uncombined categorem, as Diogenes (ho Diogenês) or, as others define it, an element of a sentence, devoid of case, signifying something compound in reference to some person or persons, as, "I write," "I say." A conjunction is a part of a sentence destitute of case, uniting the divisions of the sentence. An article is an element of a sentence, having cases, defining the genders of nouns and their numbers; as ho, hê, to, hoi, hai, ta.

“The excellences of a sentence are five,—good Greek, clearness, conciseness, suitableness, elegance. Good Greek (Hellênismos) is a correct style, according to art, keeping aloof from any vulgar form of expression; clearness is a style which states that which is conceived in the mind in such a way that it is easily known: conciseness is a style which embraces all that is necessary to the clear explanation of the subject under. discussion; suitableness is a style suited to the subject; elegance is a style which avoids all peculiarity of expression. Of the vices of a sentence, on the other hand, barbarism is a use of words contrary to that in vogue among the well-educated Greeks; solecism is a sentence incongruously put together.

Image Sources: Wikimedia Commons

Text Sources: Stanford Encyclopedia of Philosophy /, Internet Encyclopedia of Philosophy; Internet Ancient History Sourcebook: Greece ; Internet Ancient History Sourcebook: Hellenistic World ; BBC Ancient Greeks ; Canadian Museum of History ; Perseus Project - Tufts University; ; MIT, Online Library of Liberty, ; Metropolitan Museum of Art, National Geographic, Smithsonian magazine, New York Times, Washington Post, Los Angeles Times, Live Science, Discover magazine, Times of London, Natural History magazine, Archaeology magazine, The New Yorker, Encyclopædia Britannica, "The Discoverers" [∞] and "The Creators" [μ]" by Daniel Boorstin. "Greek and Roman Life" by Ian Jenkins from the British Museum.Time, Newsweek, Wikipedia, Reuters, Associated Press, The Guardian, and various books and other publications.

Last updated October 2018

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