A Mini-Course in The Course of Philosophy After Aristotle


These mini-courses study the growth of philosophy after its emergence in the early Greek Schools, and traces the development of philosophic thought from Socrates to its relatively full expression in the magnificent synthesis of Aristotle in the 4th century B.C. Also discussed is the retrogression of philosophy after Aristotle. Part I discusses the philosophy of Socrates and Plato. Part II discusses the philosophy of Aristotle. Part III discusses the course of philosophy after Aristotle.

Part III of The Development of Philosophy is divided into six Sections:

  • Section 1: The Later Greek Schools
  • Section 2: Greco-Jewish Philosophy
  • Section 3: Neoplatonism
  • Section 4: Gnosticism
  • Section 5: Manicheism
  • Section 6: Patristic Philosophy

Section 1. The Later Greek Schools

After Aristotle philosophy suffered a long period of retrogression. Ancient errors were revived. Chief of these were skepticism, which denies the ability of man to attain truth and certitude; materialism, which asserts that the bodily universe is the whole of reality; pantheism, which, in one way or another, identifies God with the material world.

The chief interest of the “schools” or groups of philosophers centered, at this time, upon the ethical question, the question of human happiness and the means of attaining it.

The most notable of the “schools” are here to be briefly considered. These were the Stoics, the Epicureans, the Skeptics, and the Eclectics.

(a) The Stoics — chief of whom were Zeno of Citium, Cleanthes of Assus, and Chrysippus of Soli — held that the material world is the only reality (cosmological materialism), and that God is the soul of the world; He is a kind of fire, and of this fire the human soul is, so to speak, a spark (pantheism). Everything exists and happens by fixed law and necessity; neither God nor man has any freedom (determinism). Man’s business is to find happiness. But, since man, like everything else, is subject to the sway and buffetings of changeless fate, the only way to happiness is that of stolid and passionless endurance. “Bear and forbear” is the Stoic motto. This motto is capable of a splendid and Christian interpretation, but, as is manifest, the Stoics did not understand it in any such light. Man, said the Stoics, must be apathetic, neither giving way to pleasure in the things of sense nor acknowledging the pressure of sorrow and pain.

  • More details about the Stoics and individual Stoic philosophers can be found in The Radical Academy HERE.

(b) The Epicureans — named for Epicurus, an Athenian philosopher — held that man can have no true intellectual knowledge, but only the knowledge that comes through the senses (sensism). The action of the senses, that is, sensation, is either pleasurable or painful. Man must avoid what is painful and indulge what is pleasurable. Yet man must not wallow in sense-pleasures, for excess is always productive of subsequent pain. Hence man must live with great moderation; he must hold desire in check; he must cast off all worry and all fear. Thus shall he achieve serenity of mind and heart, and this is the true pleasure for which man is made. All this amounts to hedonism, or quest of what is sweetly pleasing; and some pessimism or the conviction that the best life has to offer is the avoidance of pain. The Epicureans thought that the bodily world is a kind of cluster of particles, variously united by sheer chance to constitute the different things we see about us. Here we have materialistic atomism and casualism.

  • More details about Epicurus and the Epicureans can be found in The Radical Academy HERE.

(c) The Skeptics — variously classified as the Pyrrhonians, the Neo-Pyrrhonians, the Academians — held that man cannot attain to certain knowledge of anything; he cannot surely and positively know truth. Some skeptics admit the possibility of attaining probability, and some say that even this is beyond man’s powers. Hence philosophy and science are illusory. And no moral duties exist, for if man can know nothing for certain, how can he know that any duty certainly binds him? The best a man can do is to seek quietness and imperturbability of mind; in this lies his happiness. It is manifest that the view of the skeptics is pessimistic, amoral, and stoical.

  • More details about the Skeptics can be found in The Radical Academy HERE.

(d) The Eclectics — named from the Greek eklegein which means “to choose out” — thought that true philosophy is scattered piecemeal throughout all existing theories, and it is the business of the philosopher to sift it out. The “test” for the authentic philosophy is, according to the Greek Eclectics, a person’s direct experience plus a kind of “inner voice” or instinct which proclaims truth or indicates its presence.

  • More details about the Eclectics can be found in The Radical Academy HERE.

It is manifest that these later Greek schools worked a damage to philosophy. They represent a “throw back” to crass materialism and pantheism. Despite the doctrine of moderation which they generally recommend, they represent a surrender to sensualism. Their ignoring or denial of philosophical certitude is the suicide of thought; they make all science and all philosophy utterly impossible.

There is a dead and pessimistic sameness in these schools. This is due to the fact that their ethical theory is wholly divorced from reality. Ethics, as a human science, is the fruit of the sound philosophy of reality, indeed of true metaphysics. When it is severed from this true source or principle, ethics becomes a subjective theory of flabby sentimentalism and invariably degenerates (as history shows) into dull and dreary pessimism.

Section 2: Greco-Jewish Philosophy

The so-called Greco-Jewish philosophy was the result of an attempt to draw into a harmonious system the Greek philosophy (especially that of Plato) and the Old Testament Scriptures. The effort was made by certain Jews of Alexandria in Egypt, chiefly by Aristobulus (2nd century B.C.) and Philo (born about 25 B.C.).

Aristobulus is notable as the inaugurator of the system. Philo is the one great name associated with this syncretizing or amalgamating effort.

Philo was a contemporary of Jesus Christ. He was known as an eminent scholar with an unbounded love for the philosophy of Pythagoras and of Plato. Like Aristobulus, Philo was convinced of two things: first, that Holy Scripture is the source of all truth; true philosophy derives from Scripture, and therefore the function of the philosopher is the interpreting of Holy Writ; second, the Greek philosophy is the best that man has done in his quest for wisdom; it is the true philosophy, therefore, it must be fundamentally at one with Scripture and indeed, rightly understood, must be seen as something derived from Scripture. Philo sets to work to harmonize and unify philosophy and revelation.

Philo teaches that God is an inexpressibly perfect Being. God begets the Logos or Word which contains in Itself patterns of all creatable things as well as the power to produce them and to interpenetrate them as their soul. The Logos does Its work by impressing forms upon matter. Matter is wholly imperfect; it exists eternally; it is independent of God. The soul of men existed before their bodies, and were imprisoned in bodies in consequence of some offense. Release from the body-prison is achieved by conquest of fleshly tendencies and cultivation of serene contemplation of God. Unless a man take the one means of release, his soul passes from body to body in a continuous transmigration which is the only hell. The study of philosophy is a splendid aid in quelling passion and setting up the spirit of contemplation.

Philo is manifestly eclectic in tendency, for he “picks and chooses” the elements of his doctrine from Greek philosophy and Holy Writ. He is, in many points, Platonic; thus he holds to the subsistent forms of things resident in the Logos; to the pre-existence of human souls; to the transmigration of souls (although his transmigration is ever from one human body to another and never downward through animals to plants, as in Plato); to the merely accidental union of man’s soul and body. We notice, too, that Philo adopts the Stoical idea of a world-soul. And he borrows (as the Greeks had borrowed before him) the ancient oriental notion of rapt contemplation or ecstatic absorption in God.

Like the later Greek school just discussed, Philo represents a retrogression in philosophy, not an advance. His system is more Greek than biblical. It contains deeply erroneous doctrines on the theological question, the psychological question, the cosmology question, and the ethical question. Based as it is on the gratuitous assumption of Scripture as the only source of knowledge, it also errs on the critical question. Throughout, Philo makes Scripture conform to his conception of Greek philosophy; he seldom, if ever, puts pressure on his philosophy to bring it into line with Scripture. His system is, among other things, materialistic, pantheistic, and pessimistic.

Section 3: Neoplatonism

Neoplatonism, like the Greco-Jewish philosophy, is an attempt at “blending.” It is an amalgam of Plato’s philosophy and ancient oriental doctrines; with these are mingled some almost forgotten doctrines of the earliest Greeks. Neoplatonism is not a single or clear-cut system; various Neoplatonist theories were taught at Alexandria, at Athens, and in Syria. The Athenian “school” of Neoplatonism was the most worthy of note because it had the one philosopher of importance whose name is associated with this syncretizing and eclectic movement. This was Plotinus (204-269).

Plotinus taught that there is a formless Supreme Being. This being he calls The One. From this Being emerges mind or intelligence; that is, Nous. From Nous come The World-Soul. Here we have indubitably a pagan’s mistaken interpretation of the Christian doctrine of The Trinity. The human soul, while radically identified with The One, with Nous, and with World-Soul, is nevertheless a sort of individual; it existed before it had a body, in which it is unhappily and unnaturally enmeshed; it is immortal. The soul must struggle to be free of the trammels of the flesh and to rise to contemplation of The One in conscious union with Nous and World-Soul. Perfect attainment of this glorious contemplation (which is one of direct or intuitive vision) is only to be attained in the life to come. Souls that fail to free themselves of subjection to the body will have to endure a succession of transmigrations until they have finally attained to purification.

Plotinus borrows from strangely assorted sources. From the Christian faith he takes (and distorts) the notion of the Trinity, and the doctrine of the Beatific Vision. From Pythagoras (and Plato) he takes transmigration, and from Plato he takes the pre-existence of human souls. From the old Ionians he borrow the notion of a living world (for World-Soul, or Demiurge, makes the world a living thing); and the notion of a world-soul itself is borrowed from the Stoics.

Plotinus is pantheistic, hylozoistic, and materialistic. It is interesting to note in passing that Henri Bergson (1859-1940), a French Jew who came to recognize the truth of the Catholic religion although he never became a Catholic, considered his appreciation of Christianity to be the fruit of his devoted study of Plotinus.

Section 4: Gnosticism

Certain heretics of early Christian times called themselves by the Greek name of gnostikoi or ” the enlightened ones.” These folk are known in history as the Gnostics, and their doctrine is Gnosticism.

The Gnostics claimed to have a special divine illumination (or gnosis “knowledge” or “enlightenment”) which is denied to ordinary men. By aid of the gnosis they claimed to understand all fundamental truths. Their doctrine is a sad mixture of Neoplatonism, badly twisted Christian doctrine, and plain paganism.

The Gnostics taught that God cannot come into contact with matter, for matter is wholly vile and God is all-perfect. God created spiritual beings; these created others less perfect than themselves; these created others still less perfect, and so on until the least perfect spiritual beings created the bodily world.

Matter, or bodiliness, is the source of all evil. The human body is the source of evil in man. Man must free the soul from the influence of the body which imprisons it so that death may restore it to its pure and pristine state.

Among the spiritual beings that intervene between God and the material world is one called Christ. Another is Jesus. These are two beings, not one. Jesus assumed an apparent human body and Christ was united with Him at the baptism by John in the Jordan. Jesus and Christ, in union, worked for the deliverance of mankind from pains. At the Crucifixion, Christ withdrew from Jesus, and Jesus suffered the pain and death in His apparent human body.

Gnosticism is an example of what prideful ignorance can do. As philosophy it is meaningless, for it is wholly gratuitous, baseless, and grotesque. It died quickly; by the end of the 3rd century it was extinct. But something like Gnosticism is always recurring in the world, and notably in times of intellectual exhaustion or decadence.

Valentinus, Marcion of Sinope, and Basilides of Alexandria — all of the 2nd century — were notable Gnostics.

Section 5: Manicheism

Manes or Mani, whose name is Latinized as Manichaeus, was a Persian reformer of the 3rd century. He taught a mixture of doctrines taken from Zoroaster, the Neoplatonists, the Gnostics, and the Christians.

Manicheism holds the theory of two first principles, one of goodness and light, the other of evil and darkness. These are God and Satan. Each produced creatures of his own, and the world is made up of these; hence the world is a mixture of good and evil. Each human being is also a mixture of good and evil. Man must seek to make the good in him triumph over the evil that is there. He achieves this victory by contemplation of the truth and by bodily austerities. Still, since the average man is very weak and consequently unable to wage the constant exacting warfare against evil, he need not concern himself too much about the effort.

Manicheism, like all decadent philosophies, is full of a great weariness together with a wistful longing for ideals and a pathetic half-attempt to set forth a system of guiding truths.

Section 6: Patristic Philosophy

The Fathers of the Church (that is, Patres Ecclesiae, whence comes the adjective Patristic) were those holy and leaned men of the first Christian centuries who wrote notable treatises in explanation or defense of the Catholic faith. In their work of uprooting heresy and planting true doctrine, the Fathers came constantly upon false philosophical theories which had to be met and answered on philosophical grounds. Thus many of the Fathers were, perforce, philosophers. Among these we must mention St. Clement of Alexandria (2nd & 3rd century); Origen (3rd century); Minucius Felix (2nd century); Tertullian (2nd & 3rd century); Lactantius (3rd century); Arnobius (4th century). [More information about Patristic Philosophy in The Radical Academy can be found HERE.]

We must also mention the great Greek and Latin Fathers who flourished after the Council of Nice (A.D. 325). The “Big Four” among the Greek Fathers were John Chrysostom, Athanasius, Gregory of Nazianzen, and Basis. Among the Latin Fathers, the “Big Four” were Jerome, Ambrose, Gregory the Great, and Augustine. Of all the Fathers, by far the most notable in philosophy was the illustrious African, Aurelius Augustinus, whom we know as St. Augustine of Hippo.

St. Augustine (354-430) was not only a great philosopher; he was one of the very greatest that the world has ever known. To a genius approaching, if not equaling, that of Plato or even that of Aristotle, he joined the light of knowledge that comes with the Christian faith. In the cast of his philosophy he is Platonian rather than Aristotelian, for in his day Plato was universally regarded as the king of philosophers. Aristotle was not recognized at his true worth until a much later day, although he was always held in reverent esteem. It was left for two great Dominicans, William of Moerbeke and St. Thomas Aquinas — the former by a pure translation and the latter by his interpretation and application of Aristotelian philosophy — to bring Aristotle to his true place as far and away the greatest philosopher of ancient times, and indeed of all times.

St. Augustine taught that the mind of man is adequate to attain to truth with certitude; he held that the mind is much aided in its work by endeavoring to have as clear an idea of God as it is possible to achieve; for to know God is to have some concomitant knowledge of God’s creatures and of all knowable things.

St. Augustine proves the existence of God from the contingency of the world; from the nature of the human soul; and from the character of human knowledge. He shows that God is infinite, eternal, changeless, and absolutely free; that God creates in goodness, unimpelled by any stress or necessity. He says that, in the beginning, God made all living bodily creatures (excepting man) in germ; that is, God gave to certain particles of matter a kind of see-force (or ratio seminalis) to develop into determinate plants and animals at a time set beforehand by God. Man, however, is not explained by this theory of rationes seminales. Man’s soul is a spiritual and immortal substance, wholly present in every part of the living human body. As to the origin of the soul, St. Augustine felt that the inheritance of Original Sin indicates the fact that the soul is somehow drawn from the souls of parents (traducianism).

Man, says St. Augustine, is endowed with free-will. He tends of necessity towards beatitude or happiness, but he freely chooses the means whereby he seeks to attain this beatitude. Man’s freedom of choice is in no way hindered or hampered by God’s foreknowledge of human acts. The object that will perfectly fill up man’s capacity for happiness is God alone; St. Augustine cites and interprets Plato in proof of this truth. God is to be known, loved, and served in this life, and He is to be possessed in heaven by an immediate intuition or direct vision of the Divine Essence (the Beatific Vision).

The law or norm of morality for man is the Eternal Law. The Eternal Law is God Himself inasmuch as He ordains the order He has set up in nature to be conserved and forbids it to be disturbed (the natural law). Man’s normal and natural grasp of the natural law is effected by reason, that is, by the thinking mind, and in this service reason is sometimes called conscience.

God is in no sense the cause of moral evil or sin. Sin is possible because of the abuse of free-will by man, and God, having bestowed free-will, does not take it away again even when it is abused. In His loving Providence, God draws good out of evil, even of moral evil. God may be called the cause per accidens (that is, the accidental cause) of physical evils in the world; yet these evils, rightly undergone, prove to be blessings to man.

Summary of Part III of The Development of Philosophy

We have briefly discussed, in Part III, the more notable expressions of the philosophy of times following the Golden Age of Greek achievement.

The Later Greek Schools, and the syncretizing systems (Greco-Jewish philosophy, Neoplatonism, Gnosticism, and Manicheism) have nothing whatever in the way of solid or original thought to offer; their borrowings from many sources are, for the most part, set forth as gratuitous assertions.

The decadence of philosophy represented in these schools and systems was checked at last by the emergence of the perennial philosophy as developed by philosophers such as St. Augustine.

Our vocabulary of philosophical terms and phrases has been enriched as we learned the meaning of:

  • skepticism
  • materialism
  • pantheism
  • cosmological materialism
  • soul-of-the-world theory
  • Stoicism
  • Epicureanism
  • Eclecticism
  • determinism
  • sensism
  • materialistic atomism
  • casualism
  • hedonism
  • Manicheism
  • Gnosticism
  • Neoplatonism
  • traducianism
  • creationism (with reference to the soul)
  • theory of “rationes seminales”
  • the natural law
  • the Eternal Law
  • the Beatific Vision
  • reason
  • conscience
  • cause per accidens