Lesson 6: After Aristotle and Plato

One way to think of what happens to philosophy after Plato and Aristotle, in what can be called the Hellenistic Age, is to divide it into four major moments, Epicureanism, Stoicism, Skepticism and Neoplatonism.

The Epicureans

Epicurus flourished in the century after Plato and Aristotle, coming to Athens from his native island of Samos. He had studied under Platonists and Aristotelians, but later denied it, acquiring a reputation for arrogance. His school was still in existence in the third century of the Christian era.

Epicurus divided philosophy into three parts: Canonic, Physics, Ethics, to each of which he devoted at least one treatise.

Canonic deals with sensations, preconceptions and feelings as standards of truth. Simple sensations are devoid of error nor is one sense more authoritative than another. Reason depends on sensations, not vice versa. All sensory reports are true, but not all judgments based on them are. When I am dreaming I am truly dreaming but to judge that what I dream is really happening is something again. Preconceptions sound a good deal like Platonic Ideas. "We should not have given anything a name, if we had not first learnt its form by way of preconception." Call them innate ideas. Feelings -- pleasure and pain -- are also standards, and it is here that we find the source of the popular notion of Epicureanism.

Physics -- the natural doctrine of Epicureanism is summarized in a letter to Herodotus. He begins with the difficulty posed by Parmenides. "To begin with, nothing comes into being out of what is non-existent." A thing comes into being out of particular antecedents. Nor can anything be destroyed and become non-existent. The sum total of things has always been what it is now, for there is nothing into which it might change, there being nothing apart from the sum total of things. Epicurus' positive doctrine is a version of the atomism of Democritus. There are only bodies and space. Composite bodies are made up of indivisible and indestructible elements of which there is an infinite number. Soul like body is composed of them. Atoms possess only shape, weight and size. Mind automatically receives the data of sensation but then goes on to judge and assess, and in the latter error is possible.

Ethics -- this is the term of Epicurus' philosophy. Death is neither good nor evil, and should hold no terror for us anymore than life should.

Pleasure is the beginning and fulfillment of a happy life, but there is a calculus of pleasures and pains in the ethical life. This is hedonism but of a minimalist kind: we should be content with a minimum. Sensual pleasure is discounted -- so much for the popular notion of Epicure. Nature as he understands it, is for Epicurus the guide in ethics. Despite his atomism, his view is not fatalistic. The ultimate value is life, but death should not be feared. Epicurus would prefer the myths about the gods rather than a philosophical view that all is determined. The role of Physics is to remove the causes of man's fear.

The influence of Epicurus extended for centuries. Mention should be made of Lucretius and his De rerum natura (On the nature of things) published in 54 B.C. The final assault on Epicureanism came from Christianity which eventually brought to an end the school that had the longest and greatest impact on ancient times.

The Stoics

The school was founded on Cyprus by Zeno of Citium. Zeno was born in the middle of the 4th century and he came to Athens shortly after the death of Aristotle and was associated with Crates the Cynic. The school is named for the porch where Zeno taught. Most of our knowledge of Zeno is conjectural and secondhand. Cleanthes was succeeded as head of the school by Chrysippus, born in 280 BC, often called the second founder of Stoicism. He died in 206 BC. Eventually Stoicism was introduced into the Roman world.

The Stoics too divided philosophy in to three parts: Logic, Ethics and Physics. They are usually thought to have subordinated the other parts to ethics and to have opposed the Platonic and Aristotelian notion of contemplation. With interest in the logic of the Stoics in recent years, this picture has been altered somewhat. Since there were so many Stoics, it is not easy to formulate a common doctrine. Cicero gives a graphic description of Zeno's account of knowledge. Extending his right hand palm upwards, fingers extended, Zeno said: this is representation; bending the fingers, he said this is assent; making a fist, he said, this is comprehension; then smashing the fist into the palm of his other hand, he said, that is science. The comprehensive representation is produced by a real object and a real object is that gained by comprehensive representation. In a species of nominalism, the Stoics held that there are only individual facts and only statements with singular subjects can correspond with them. Logic is the study of the links and connectives between singular propositions.

The goal of ethics is harmony with nature. Happiness is gained by rational activity or virtue. Only virtue is good, only vice is evil. Virtue is in accord with the recognized course of the world, vice is disharmony. The gifts and blows of fortune must be risen above and happiness is immune to such influences. The Stoic ethics is thus an austere one. It was meant to arm a man in an unsure world by a kind of inner withdrawal from what might affect his equanimity. The link of Stoicism with suicide is noteworthy. The school cited various good reasons for ending one's own life -- poverty, illness, the weakening of the mind. Oddly such things should be, on the Stoic account, matters of indifference.

The Roman Stoics extended the influence of the school. Seneca was born about 4 BC in Cordoba, Spain, came to Rome and died by his own hand at the command of Nero in 65 AD. The discrepancy between the Stoic precepts he espoused and his own life has fascinated students of Seneca. He has been called the favorite pagan of the Christian Church and was alleged to have been a correspondent of St. Paul. Epictetus (50-138 AD) and Marcus Aurelius, Emperor from 161-180 AD, concentrated on ethics, Marcus Aurelius writing his Meditations in Greek. Mind is the spark of divinity in us but it will be consumed in the conflagration that ends the cosmos.

The Skeptics

Pyrrho of Elis, born about 365 BC, is said to have accompanied Alexander the Great on his campaigns. He founded his school at Elis in 330 BC when he was thirty-five (he died in 275 BC). He wrote nothing. His approach was to doubt everything, to withdraw from all assertions into apathy and a suspension of judgment and commitment. Pyrrho thus taught an attitude which is summed up in ataraxy -- expect nothing and you will not be disappointed. The term Skeptic acquired its negative meaning slowly, much as the term Sophist had.

With Carneades, skepticism entered the Academy. On a visit to Rome, he is said to have presented the Platonic, Aristotelian and Stoic conceptions of justice, and then refuted them all. It sounds like Philosophy 101. There is no certain knowledge, there is no criterion of truth, judgment is to be suspended in a epoche. But Skeptics had a theory of probability and indeed of degrees of probability. The main target of Carneades was Stoicism because of its influential positive doctrine. With Carneades, the decline of the Academy from the golden period under its founder Plato is well under way.

An influential Skeptic was Sextus Empiricus whose works are attacks and refutations. His Outlines of Pyrrohonism and Against the Mathematicians have come down to us.


There is a vast number of thinkers to which the label Neoplatonist is applied. None is more important than Plotinus who was born in Egypt in the third century of the Christian era, studied at Alexandria and came to Rome at the age of forty, where his teaching knew phenomenal success. Porphyry became his student when Plotinus was sixty, and it is to Porphyry that we owe the edition of Plotinus' Enneads. The writings of the master are divided into six groups each containing nine tractates (from which the work takes its name). There is no reference to Christianity in Plotinus but Porphyry became a dedicated foe of the new religion.

In the Enneads, Plotinus sets forth the structure of the world and our place in that structure, the manner in which all things proceed from the One and return once more to it. The unity of reality follows from its emanation from the One and its destiny to return whence it came. The procession of all things from the One is both necessary and graded -- the One, Nous and Soul. The Nous or Mind receives the light of the One and passes it on to Soul. These are the three so-called hypostases that form the hierarchy of the universe, and the human task is to retrace that order to the source of all. Thus we begin with Soul, go on to Nous and then to the One.

Soul is the nexus of the world with Nous, organizing it. The Soul's connection with bodies, from which we are urged to turn away, forms a tension. Soul is not for Plotinus, as it is for Aristotle, the entelechy or form of bodies, however. "The substantial existence of the soul, then, does not depend upon its serving as form to anything: it is an essence which does not come into being by finding a seat in body; it exists before it becomes the soul of some particular..." The downward motion of soul produces the different powers. Soul has at least four meanings for Plotinus. It is one of the hypostases, there is also the soul of the visible world which in its totality is a living creature. The human soul has a superior and an inferior part. The soul is by nature divine, and evil is the effect of the corporeal on it. It is by reflecting on itself that soul discovers the order of the universe. If the One is the good, then Nous may be called beauty as the reflection of the One. The One is beyond, ineffable while Nous is its articulation into Ideas. Nous is a god but not the highest god, being an offspring of the One.

The One is the most important element in Plotinus' teaching and the most difficult to grasp. It is described in terms of the lower, as being beyond them and their source. Oddly, the One is said to be above Being. Strictly speaking it cannot be named, it is ineffable. It eludes our knowledge and is at best approximated from what emanates from it. The ultimate stage for us is a vision of the One that goes beyond understanding and speech. Porphyry said that the whole of Aristotle's Metaphysics is to be found compressed in the Enneads. The One is identical with its essence and its existence.

The detail of the Enneads is such that it is impossible to resume it. The overall effect of Plotinus' thought is to urge on us what might be called a spiritual life, a striving for union with that from which we and all things have come. God is the term of human striving but he must be approached via the intermediate stages. Matter is the ultimate emanation from the One, most distant from it, but Plotinus does not regard matter itself as evil. The sensible world shares in goodness and beauty and is thus a sign of what lies beyond. The striving is guided more by love than knowledge and thus the ultimate task cannot really be conveyed by a philosophical doctrine. It is not a matter of knowing as terminal, but knowing triggering off an ascent on the wings of love. The ultimate goal is ecstasy and union.

The Neoplatonic school extends well into the Christian era. Blending and altering elements from Plato and Aristotle, it was both the alternative to Christianity and an influence on it. The school at Alexandria, where Boethius may have studied, represents the last great stage of Greek philosophy.

Writing Assignment

Briefly compare the Skeptics and Plotinus.

Midterm Paper

Write a five page paper comparing Plato and Aristotle on the role of sensible things in human knowledge.


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