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Philosophy of the Stoics

Introduction by Charles Siegel

Volume 1 of the Rediscovered Philosophers series

new material in this edition copyright © 2016

The philosophy of Stoicism was intended to provide peace of mind, like the philosophy of Epicureanism, which became popular at about the same time - though the Stoics' advice was very different from the Epicureans'.

Many of its doctrines seem strange unless we remember their purpose. Philosophy was considered a guide to living a good life, and many young people flocked to the schools of philosophy to learn the wisdom to live well. We tend to forget this now that philosophy has become primarily an intellectual pursuit for academic specialists.


The three branches of classical philosophy were ethics, natural philosophy (which included theology) and logic (which included epistemology). Of the three, ethics was the most important to the Stoics.
Stoic ethics begins with the idea that, by nature, all living things seek to survive and thrive. Plants seek the sunlight. Animals seek the food that nourishes them. People seek to thrive as animals do but also seek to thrive by gaining wealth, knowledge, health, physical strength, skill, and other natural advantages.

The virtues help us and others to gain these natural advantages, as we can see by looking at the four cardinal virtues, temperance, fortitude, prudence, and justice. Temperance helps us to protect our health. Fortitude and prudence help us to succeed at any endeavor. Justice implies that we should not pursue natural advantages for ourselves by sacrificing others: for example, we should not pursue wealth by stealing from or cheating others. Today, we generally think of ethics as a matter of acting altruistically or of treating others fairly, but to understand classical ethics, we must remember that the virtues were also means of living a successful and happy life.

The Stoics added this twist to virtue ethics: they said that only the virtues themselves were good. The natural advantages that the virtues aimed at were not good. They were indifferent, but they were "preferred" or "to be chosen" or "valuable."

Cicero sums up this idea very well in a passage based on the writing of the Stoic philosopher Diogenes of Babylon:

…this which we entitle preferred or superior is neither good nor evil; and accordingly we define it as being indifferent but possessed of a moderate value …. For in fact, it was inevitable that the class of intermediate things should contain some things that were either in accordance with nature, or the reverse, and this being so, that this class should include some things which possessed moderate value, and, granting this, that some things of this class should be ‘preferred.'

Sometimes the Stoics described these natural advantages as "preferred indifferents," which seems like a self-contradiction.

In fact, the theory is problematic: if the natural advantages are "valuable" and "to be chosen," then why not call them good? Diogenes of Babylon tried to explain it by saying:

It will be an error to infer that this view implies two Ultimate Goods. For though if a man were to make it his purpose to take a true aim with a spear or arrow at some mark, his ultimate end, corresponding to the ultimate good as we pronounce it, would be to do all he could to aim straight: the man in this illustration would have to do everything to aim straight, yet, although he did everything to attain his purpose, his ‘ultimate End,' so to speak, would be what corresponded to what we call the Chief Good in the conduct of life, whereas the actual hitting of the mark would be in our phrase ‘to be chosen' but not ‘to be desired.'

In other words, if you are practicing archery, your real goal is to be as skillful as possible at archery; hitting the target is not important in itself but is chosen to exercise your skill.

The flaw in this argument is that archery practice is a game with an arbitrary goal that you play to improve your skill. It is very different to seek some natural advantage. If a doctor tries his best to cure a patient but the patient dies anyway, would we say that it is not important whether the patient dies, because the doctor's goal is to behave virtuously? If a man tries his best to feed his family, would we say that it is not important whether the family starves, because the man's goal is to behave virtuously? These goals are natural advantages, given by nature, rather than being arbitrary.

If the virtues are aimed at gaining natural advantages, why should we say that the virtues are good but the goals they aim at are not good?

The Stoics made this distinction in order to put your happiness completely under your own control. A wise man is virtuous. Virtue is the only good and so is the only thing needed for happiness. Therefore, a wise man will be perfectly happy because of his virtue, regardless of his external conditions. Even if he is being tortured or even if he is starving to death, he will not lack any good thing and so will be perfectly happy.

It is logically problematic to say that the virtues are aimed at the goal of gaining practical advantages and that it does not matter whether they actually reach this goal, but it was psychologically helpful to the Stoics, helping them to achieve peace of mind.

Natural Philosophy and Theology

Natural philosophy (what we would now call attempts at science) and theology were considered a single subject in the three-fold Hellenistic division of philosophy. We should be able to see the connection by considering how scientific discoveries such as the theory of evolution have affected religious belief in our own time.

Stoicism also combined natural philosophy and theology in its key idea that all of nature has a mind, which governs the world for the benefit of all living things. Mind is made up of a fiery substance in early Stoicism and of a mixture of fire and air among later Stoics. This substance pervades the entire universe and gives it mind, just as it pervades our bodies and gives us mind.

The mind of the universe is god, and its benevolent government of the universe is providence. Whenever there is suffering or imperfection in the universe, it is because providence directs the universe for the benefit of the whole and sometimes must sacrifice a part for the sake of the whole. The Stoics also believed that the stars were guided by intelligences and were gods, and that the traditional Greek and Roman gods were allegories representing abstractions or forces of nature.

This view of nature is deterministic. Providence governs the universe through a chain of causes and effects, with the causes inevitably producing the effects. The Stoics (with the exception of Panaetius) also believed in divination: as part of its care for us, providence gives us messages about the future, for example, in dreams. Divination requires determinism, since providence can tell us which future events will happen only if those events are bound to happen.

People have two choices. The wise man accepts everything that will happen to him as part of the providential government of the universe, realizing that even things that cause him pain are necessary for the good of the universe as a whole, and so he has peace of mind. The foolish man tries to resist providence, fails, and so he can never have peace of mind. As the Stoics said, "Man is like a dog tied to a cart; if he does not walk along, he will pulled along." We are not in control of events, but we are in control of our attitude toward events, and we can make ourselves happy by accepting providence rather than resisting it and being pulled along against our wills.

Like the Stoic view of virtue, this theory is meant to give us peace of mind and is logically problematic.

If we can choose our attitude, deciding either to "walk along" or "be pulled along," then we have some freedom of choice. But if our minds are fiery matter, and if the behavior of matter is determined by inevitable chains of cause and effect, then our attitude is determined, like everything else.
Different Stoic philosophers dealt with this contradiction in different ways.

Chrysippus said that our behavior is determined both by external events, which are their proximate cause, and by our character, which is their basic cause. By analogy, if someone pushes a cylinder and it rolls down hill, its motion has two causes: the proximate cause is someone pushing it, but the primary cause of its rolling is its own form as a cylinder. He said that our freedom is limited only if we are compelled to act by external causes, but the primary cause of a wise man's action is his own character.

Chrysippus' claim that only one of the two causes matters is not convincing. The cylinder rolls both because of its shape and because it is pushed, and there is no good reason to say that the pushing is unimportant.

More fundamentally, Chrysippus just pushes the question back a step by claiming that that we are free if our actions are determined by our character. We still have to ask how we got our character. The cylinder got its shape because someone designed and produced it: it is problematic to say that its behavior is determined by its own shape and not by external causes, because its shape itself was determined by external causes. Likewise, it would be problematic to say that the wise man's behavior is not determined by external causes but by his character, if his character has been molded by external causes rather than his own free choices.

By contrast, the Stoic philosopher Cleanthes seems to reject the idea that providence determines all events that occur. In his Hymn to Zeus, where he praises Zeus as an allegorical representation of providence, he wrote:

No work is wrought apart from Thee, O God,
Or in the world, or in the heaven above,
Or on the deep, save only what is done
By sinners in their folly.

Thou hast fitted things
Together, good and evil, that there reigns
One everlasting Reason in them all.

Here, Cleanthes preserves our freedom by saying that providence controls everything except moral choice: you are a sinner because you made this choice yourself, not because providence made you a sinner. Cleanthes' poem is reminiscent of the Christian view, where God gives us free will rather than determining our actions but governs the world so that even evil choices ultimately produce good. But the Stoics did not believe in an afterlife, so they did not have the Christians' consolation that the good will be rewarded and the wicked punished after death.

If we accept Cleanthes' idea of free will, we lose the Stoic consolation that all the evils that we face are caused by a wise providence because they are necessary to benefit the whole. If I am being tortured, my suffering is caused by the wickedness of the torturer. Even though providence will ultimately direct it to good ends, my suffering is not caused by providence; and my suffering is not necessary for the good of the universe as a whole, since the universe as a whole would be even better if the person torturing me were wise rather than evil.

Despite its logical difficulties, this doctrine seems to have been psychologically useful to the Stoics. They accepted the hardships they faced, which they believed were caused by a wise providence. They also exercised their free will in constant efforts to be virtuous. Their determinism gave them the strength to face hardships, and their belief in their own free will let them make the effort to improve themselves, regardless of the contradiction between the two.


The Stoics needed an epistemology that let them claim they had certain knowledge, but the exact form of the Stoics' epistemology was not essential to their goal of gaining peace of mind.
Stoic epistemology is based on the idea that some perceptions are evidently true, which they called phantasia katalêptikê. Phantasia means "perception" or "sense impression." Katalêpsis means "comprehension." Phantasia katalêptikê can be translated as "comprehensible impression" and has also been translated as "recognizable impression" or "cognitive impression." Because it is a technical term and translations differ, many scholars adapt the Greek term and say "cataleptic perception" or "cataleptic impression."

The Stoics believed that all of our ideas were based on sense impression. When we are born, our minds are a blank slate (as Locke said). We form ideas by comparing multiple sense impressions. These ideas may be true or false, because our sense impressions may be true or false. For example, dreams and hallucinations are false.

But cataleptic impressions are true. They are defined as impressions that are caused by an outside object, are represented in our minds in a way that conforms to this object, and cannot come from anything else except this object. Cicero tells us that Zeno, the founder of Stoicism, defined a cataleptic impression by saying "That it was such as is impressed and stamped upon and figured in us, according to and conformably to something which exists."

The Academic skeptics argued that there was no such thing as a cataleptic perception. For example, if you see two identical objects, you get the same sense impression from them both, contrary to the Stoics' belief that a cataleptic impression conforms to an existing object and cannot come from anything else but that object. Nothing in your sense impressions tells you that they come from two different objects with identical appearance rather than from one object. To defend themselves against this argument, the Stoics were reduced to claiming that no two objects in the world were identical - hard for us to believe in our age of mass production.

This epistemology seems naive to us today. In the seventeenth century, as modern physics learned more about the nature of matter, philosophers realized that the ideas in our minds are qualitatively different from the physical objects that cause these ideas. For example, our perception of redness is qualitatively different from electromagnetic radiation with a wavelength of 650 nm, which causes this perception. This difference has been a central theme of philosophy since the time of Locke, Berkeley, and Hume, but most Hellenistic philosophy misses this issue completely. Aristotle dealt with it; it seems plausible that his Peripatetic followers also dealt with it, though not enough of their work remains for us to know; but mainstream Hellenistic philosophy ignored it.

Stoic epistemology was important historically, because it seems to have been the main or only epistemology used in Hellenistic times to claim that we can have knowledge. It was the epistemology that the Stoics developed to defend their beliefs, that the skeptics attacked to show we could have no knowledge, and that Antiochus of Ascalon adopted to defend his synthesis of Stoic, Peripatetic, and old Academic philosophy.

Stoicism as Wisdom Tradition

Though its philosophical ideas were problematic, Stoicism was a successful wisdom tradition. The idea that the virtues aim at natural advantages but that it makes absolutely no difference whether you get these natural advantages is problematic, but it apparently did help people to bear up under disappointments and failures. The idea that the universe is deterministic but that we should freely choose to follow the dictates of providence is problematic, but it apparently did help people to accept their lots in life.

Stoicism lasted longer as a wisdom tradition than as an abstract philosophy.

The early Stoa of Zeno of Citium, Cleanthes, Chrysippus, and Diogenes of Babylon held the beliefs described in this introduction. These beliefs were quite stable from about 300 to 120 BC, with some changes, such as the shift from Zeno's idea that mind is a fiery substance to Chrysippus' idea that mind is fire and air. Diogenes of Babylon is the only early Stoic whose writing is included in this book, though it also includes descriptions of the ideas of Zeno and Chrysippus.

The middle Stoa of Panaetius and Posidonius was more eclectic, willing to modify Stoic beliefs and accept some beliefs from other sources, such as Aristotle. It extends from 120 BC, when Panaetius became scholarch, to 51 BC, when Posidonius died. This book includes a number of selections from Panaetius and Posidonius.

The late Stoa of Epictetus, Seneca, and Marcus Aurelius preserved the Stoic wisdom tradition but did not worry much about its philosophical ideas. You can see it in the Meditations of Marcus Aurelius, written in about 170 AD, almost 500 years after Zeno:

Begin the morning by saying to thyself, I shall meet with the busy-body, the ungrateful, arrogant, deceitful, envious, unsocial. All these things happen to them by reason of their ignorance of what is good and evil. But I who have seen the nature of the good that it is beautiful, and of the bad that it is ugly, and the nature of him who does wrong, that it is akin to me, not only of the same blood or seed, but that it participates in the same intelligence and the same portion of the divinity, I can neither be injured by any of them, for no one can fix on me what is ugly, nor can I be angry with my kinsman, nor hate him….

Stoicism leads Marcus Aurelius and other late Stoics to make intensive moral demands on themselves but to accept other people's flaws as if they were not responsible for them. The writing of the late Stoa is readily available, though none is included in this book.

Though it was most successful as a wisdom tradition, Stoicism also had important philosophical influences. For example, Stoics invented the ideas of cosmopolitanism and of natural law, which have been important to our civilization ever since. Their ethical theory is also important because it had a strong influence on Antiochus of Ascalon, who was a major philosopher though he not well known today; his works can be found in the book Philosophy of the Syncretic Academy.

This internet preview does not include footnotes.