Copyright © 1996 R.J. Kilcullen
This lecture is a sketch of some of the Greek philosophical background to medieval thought. In this course I want you as far as possible to read the medieval philosophers themselves, not read about them in secondary works. But because medieval philosophy derived a lot of its questions and doctrines from ancient Greek philosophy, we must begin with a rapid survey of Greek philosophy. You'll have to be content here with second-hand knowledge.
The main schools of ancient Greek philosophy were the Academics (founder Plato), the Peripatetics (founder Aristotle, who had been for 20 years a member of Plato's Academy), the Stoics (founder Zeno), and the Epicureans (founder Epicurus). If you look at the illustration from Long and Sedley's Hellenistic Philosophers at the end of the printed introductory lecture (press the pause button while you find it) you can see how these schools were situated in Athens. The stoics met originally in a Stoa (i.e. a "porch") beside the Agora (the city square), the Epicurians met in a house with a garden, the Academics met in a "grove", i.e. a stand of trees, sacred to the memory of the hero Academos. The peripatetic or Aristotelian school met originally in a covered walkway (peripatos) in a garden called the Lyceum. In the Hellenistic period these schools came to have hundreds, perhaps thousands, of students from all parts of the Greek and Roman world. There was another "school", if it can be called that, the sceptics, or "seekers", who tried to suspend judgment, to balance argument on both sides. This school grew out of the Academic school - hence the connotations the word "academic" has today. The Athenian schools of philosophy lasted almost 1000 years. They were closed down by the Emperor Justinian in AD 529.
So those are the main schools of thought in ancient Greek philosophy - the Platonists, the Aristotelian, the Stoics, the Epicureans, the Sceptics. The Epicureans and Sceptics did not have much influence in medieval philosophy, so I'll concentrate on the other three, and especially on Plato. Plato, not, as you might have heard, Aristotle, was the main Greek influence in medieval Latin philosophy. Not much of what Plato wrote was available to them in Latin translation, but his ideas came to them indirectly through many sources.
Why did Plato use the dialogue form? Partly I suppose for literary reasons. Sometimes, especially in the later dialogues, the discussion is very laborious and unexciting, but some of the Socratic dialogues are brilliant pieces of dramatic literature - Symposium, Protagoras, Gorgias, Phaedo, Phaedrus, for example.
But there is also a philosophical reason. Plato believed that a person comes to see the truth - really see it - in conversation with another person. You can't take it in by passively listening or reading. In the Seventh Letter he says that his own philosophy is nowhere written down: no one really knows what he thinks except his friends, from conversation. So the dialogues are an attempt to produce in writing an imitation of conversation - it is not the real thing, and Plato tells us that we do not have his philosophy in writing, but this is a close as we can get.
These are among the convictions Plato seems to get from Socrates. Socrates (as we see him in Plato's Socratic dialogues) thinks that no one ever does the wrong thing knowing that it is wrong. When you do something, you think at the moment of action that it is a good thing to do. You may know that it is in some sense wrong - against the rules, likely to lead to evil later on, etc. - but at the time you believe that these drawbacks are outweighed by something good about it: even though it is in some way wrong it is still better to do it, so you think. So virtue consists in knowledge: not abstract theoretical remembered knowledge, but vivid knowledge at the moment of decision. Knowledge of what? Knowledge of good and evils and of the degree of goodness and evil: to know for example that undergoing death is not as evil as inflicting an injustice on another person. In the Gorgias Socrates maintains that it is better to suffer wrong than to inflict it. So this is the knowledge that constitutes virtue: real knowledge at the moment of decision of what is better and worse than what. (Plato came to think, and in this he was followed by Aristotle, that such knowledge is not sufficient for virtue - that it is possible to do what you know is wrong, even when in some sense you want to do what is good - "I do not do the good I want, but the evil I do not want is what I do", as St. Paul says in the letter to the Romans. But knowing what is good and what is evil, and the degrees of good and evil, is at any rate one of the conditions of acting well.
So knowledge is important. Knowledge is not the same as opinion: we often think that something is so, but discover later that we were wrong. Someone else might think that we were right the first time and were wrong to change our mind. Opinion or belief fluctuates: even when you happen to be right, you may abandon the belief. You may set out down the right road to Larissa, not knowing that it is the way but believing (perhaps because someone has given you directions), and if you keep going that way you'll get to Larissa: but on the way you may lose the belief (perhaps wondering whether the giver of directions really knew) and turn back. Knowledge is not merely true belief but true belief that is stable and unfluctuating, because it is tied down by reasons. (See Meno, 96e-98b.) But tied to what? What can give stability to belief?
So where are these forms? No where - they are not in space, in a place, because everything in space is always changing; and they are for the same reason not in time. We cannot see them through sensation - eyes, ears, touch, feel, etc. Yet they are real, and more real than the things we do sense. Thus in Plato's philosophy these are levels of reality, above this world a super-sensible world: of course "levels", "above" and "super" - are metaphors, since the forms are not in space. And our minds can know realities that our senses cannot detect: we can know what justice, goodness, etc. are even though we have never seen with our eyes anything that is a perfect realisation of these ideals. How can we know these realities if we never see adequate examples"? By remembering the forms which we did "see" in a previous existence, before our present life, as disembodied souls: our minds then "gazed" directly on justice itself, beauty itself, goodness itself, and so on. So we are our souls, souls exist before being embodied, and they continue to exist after the body dies. While we are in the body we cannot directly see the supreme realities, but what we do see with our eyes can remind us of what we almost completely forgot on being joined to a body. Teaching about these realities is reminding, learning is remembering.
One of Plato's virtues as a philosopher is that he is willing to suggest things he does not claim to be able to prove. Often the suggestions are made in the form of "myth". Mythos is just the Greek word for story; these stories have a philosophical point, they are vehicles for conveying something Plato thinks is true but does not have an argument to prove. The doctrines I have just been summarising about the soul are presented in this way, notably in the dialogue Phaedrus.
Plato has some argument for these suggestions. It does seem to be a fact that our minds apprehend ideals or standards which we have never seen with our eyes (or perceived with other senses) perfectly realised. Take the notion of equality, for instance. He suggests that we have never seen two things exactly equal, yet we have a notion of exact equality which enables us to judge that the near equals we see are not quite equal. Similarly with other standards such as justice; we can judge that all the arrangements we see around us are not perfectly just, so we must know what justice is in some other way than by looking around us.
According to Plato, progress toward a better life starts with conversion, i.e. with a turning round; instead of looking at the things of this world we must turn and look toward the forms. This is all metaphor; the forms are not in space so we can't literally turn toward them. Another metaphor: we must turn inward, and search our inner self for memories of the forms seen in our earlier existence.
In the Republic (514 ff) Socrates introduces the myth of the cave. We are like men held prisoner in a cave, watching flickering shadows cast on a wall and mistaking those shadows for reality. Perhaps with God's help one of the prisoners turns round, gets free, struggles up to the daylight and sees the real things and the light of the sun. If he comes back down into the cave to rescue the other prisoners they will think at first that he is talking nonsense - for them the shadows are the reality. Plato means of course that the things we think are real - the things we see and touch - are shadows, or as he says elsewhere reflections or imitations, of what is really real.
So there are levels of reality, and to come to know we must turn our minds to the higher levels; progress in knowledge and virtue is an ascent, a climb to the higher level out of the cave. By climbing we set our real self, the soul, free.
Among the forms there is also a hierarchy, an order, different levels: at the top is the idea of Good. We care about justice, beauty and other ideals because we think they are good. When we act we think that the action will achieve some good. The Good is like the sun in the real world above the cave: it gives intelligibility or meaning and reality to everything else. (On the Good as like the sun see Republic 508-9.)
The Forms mentioned so far relate to sensible things - i.e. to sense-perceptible things - as perfect to imperfect. Thus Justice itself is the perfect standard by reference to which we recognise the imperfection of the approximately just arrangements of this world; Beauty itself is the perfect standard, beautiful things are never perfectly beautiful. Besides this relation of perfect to imperfect Plato also speaks of a relation of one to many: Justice itself is one thing, the approximations to justice in this world are many. Thus Plato also postulates Forms which are not ideal perfections but simply the one character shared by many instances. There are many white things, one whiteness in which they all participate: whiteness is a form. There are many human beings, one humanity in which they all share. For every set of many things sharing the one characteristic there is one form of that characteristic, usually referred to by the abstract noun: many white things, one whiteness, many human beings, one humanity, many imperfectly just things, one Justice, and so on.
Aristotle sometimes calls Plato's Forms "universals". By a universal Aristotle means something that can be predicated of many subjects. "Be predicated of" means: be the predicate of a statement about. Imagine a series of statements in which this, that and the other are all said to be white: then white is predicated of each of them. Any term that can be predicated of different subjects is a universal. "Socrates" and other proper names are not universals because they cannot be predicated of many different subjects - they are proper names, names proper to, in the sense of peculiar to, one individual. But "human being" is predicable of many - Socrates is a human being, Plato is a human being, etc. "Human being", "white", "just", "beautiful", etc. are universals. So you can see why Aristotle sometimes says that Plato's idea on forms are universals. But all the same this is misleading. Universals are terms found in statements, i.e. words or thoughts, whereas Forms are natures or characters that things have. "Human being", the phrase, is a term that can be predicated of many individuals, but humanity is the nature in which those individuals share. It is because they all share the same humanity that it is true to say of each, "This is a human being". We can, however, say that to every term (in words or thoughts) that Aristotle calls a universal there corresponds a Platonic form, existing not in language or thought but in reality, in a reality superior to that of the sensible world.
There are other souls also besides human souls: the gods are souls, the sun, moon and stars have divine souls: our soul is divine. Soul is another category of super-sensible being, i.e. another kind of reality at a higher level than the things we can perceive through our senses. I mentioned earlier that Plato takes mutability or change as the mark of an inferior degree of reality. The Forms are immutable and therefore more real. It would seem that it was only rather late in the development of his thought that Plato came to recognise that although souls change they are fully real. Change in a soul is self-initiated, and is the source of change in inferior realities. For example, you change when you make a decision, and then change other things when you carry out your decision. A sense-perceptible thing that is changed from outside by something else is at an inferior level of reality, but a soul that changes itself and then changes other things is at a higher level. The first dialogue in which this questions is discussed is the Sophist. In this dialogue the lead is not taken by Socrates but by a "stranger" (as if Plato wanted to be free to express thoughts that had not been Socrates'). Starting at Sophist 248a, the stranger criticises the "friends of the Forms" (the party to which Plato in his earlier writings belonged). They say that the powers of acting and being acted on do not belong to real being. The stranger comments: "Are we really to be so easily convinced that change, life, soul, understanding have no place in that which is perfectly real - that it has neither life nor thought, but stands immutable in solemn aloofness, devoid of intelligence?" The answer is no. But then, if it has intelligence and life it cannot be completely unchanging. This is an important development in Plato's thought. Later on those followers of Plato whom we call neo-Platonists, - Plotinus, Porphyry, Proclus and others - give intelligence and life an even higher place than the Ideas. The ideas or forms become part of the life of a supreme intelligence.
In Plato's last work, The Laws, there is another important passage on the place of souls at the highest level of reality. In Laws 890ff the Athenian stranger (who leads that discussion) sets out to refute atheism, to prove that there are gods. When we find one thing producing a change in another, and that in turn affecting something else, and so forth, there must be, in such sequence, an original cause of change - something that moves itself without being put into motion by anything else, which then moves other things. Something that moves itself without being moved by anything else is alive: the power to originate movement or change is soul. Soul is a divinity. The highest souls are those that cause the highest movements, i.e. the souls which carry the heavens on their course. They move the heavenly spheres. A sphere moves on itself always in the same place, around the same centre. The self-movement of these divine souls is therefore regular, uniform, always at the same point in space, around a fixed centre, in the same position relative to other objects.
These thoughts of Plato had great influence over later thinkers. Aristotle adopts a very similar picture of the universe. He distinguishes, however, between moving in the sense of being in motion, and moving in the sense of being the cause of movement in something else. A "mover" can mean either something that is in motion or something that causes motion. According to Aristotle anything that is able to be in motion must have parts spread out through space. Nothing really causes itself to be in motion: rather one part of it causes some other part to be in motion. According to Aristotle the divinities which move the heavenly spheres in their eternal revolutions are causes of motion not themselves in motion: they are unmoved movers. Except for this refinement, which Plato might well have accepted, the intelligences which in Aristotle's system move the heavenly spheres are like Plato's divine souls.
(For myths concerning the soul, see: Phaedrus, 245 ff Gorgias, 523 ff Republic 614 ff.)
In fact in this dialogue the Forms are themselves alive like soul: the maker looked to the ideas in making this world which is itself a living being with a soul: the ideas he "looked to" already constitute a living being. What was the living creature in whose likeness he framed the world? (Timaeus 30). "The world is like... that Living Being of which all other intelligible living beings [the Forms] are parts": the Forms are here intelligible living beings which are parts of a living being. The highest reality is alive. The maker wanted to make the world an image of this eternal living reality. The nearest creature equivalent of eternity is time. "Now the nature of that Living Being [the system of Forms] was eternal, and this character it was impossible to confer in full perfection upon the generated thing. But he took thought to make, as it were, a moving likeness of eternity; and at the same time that he ordered the heaven, he made, of eternity that abides in unity, an everlasting likeness moving according to number - that to which we have given the name time" (Tim.37).
Let me repeat the question the stranger asks in the Sophist of the "Friends of the Forms": "Are we really to believe that change, life, soul, understanding, have no place in that which is perfectly real - that it has neither life nor thought, but stands immutable in solemn aloofness, devoid of intelligence?" No: indeed the system of the Forms is, in Timaeus, a living and intelligent being. That which is perfectly real is immutable in the sense that nothing outside itself causes it to change, but it is alive, self-moving, a source of movement in lower levels of reality.
Let's turn now to the lower level of reality and consider what Plato came to think about that. In Timaeus Plato suggests that the mutable images of the eternal intelligible living being must exist in something. In the myth of the cave in Republic, where the prisoners watch shadows, the shadows are cast onto something, a wall. That is a point not made in Republic. But now in Timaeus Plato recognises a "receptacle", into which the images are received (Tim. 48ff). The receptacle is itself devoid of the qualities it will receive. The receptacle is empty space.
So, to sum up Plato's world picture, first there are the Forms, each being eternally just what it is - Beauty itself, Justice itself, Humanity itself - together in a systematic unity comprising an intelligible living being - intelligible, i.e. knowable by intellect, not by sense. Then there are the souls, realities that are the source of change in the universe. One is the demiurge, another is the world soul, others are our souls, and there are others. Then there is Space, into which souls (notably the demiurge) project images of the Forms, images perceptible to our senses, i.e. sensible things in space and time, always changing. The created universe is good because the demiurge looked to the supreme idea of The Good in making it - he made it as good as it could be; however, since it is only an image in space of the "intelligible living being" it cannot be perfectly good. In the neo-Platonic philosophers, Plotinus and the rest, the universe eternally emanates ("diffuses", another metaphor - like light shining) from a point source, the One = the Good, through various levels, including Intellect (equivalent to the intelligible living being of the Timaeus) and the World Soul down to material beings (matter equivalent to Plato's receptacle, which was not matter but space): The universe, since it emanates from the Good, is good; the principle of evil is matter, which is the outermost limit of reality, beyond which (to use a spatial metaphor) lies non-being.
As in Plato's ethical dialogues we are told we must turn our minds to higher realities, climb up out of the cave, look to the good, and love it, so in the neo-Platonic philosophies each level of being turns back in contemplation and love to the higher level which is its source, thereby achieving the unity and coherence which preserves and perfects its own existence. For some description of these neo-Platonic systems see the Encyclopedia Britannica article printed in Vol.2, Supplement, at the beginning; and see also p.92.
In this rapid survey I've given you of Plato's philosophy myth or story has figured more largely than argument. Philosophy is a matter of argument, and Plato's writings contain plenty of careful argument. I've been presenting just his conclusions and suggestions as a "world picture", with only a sketch of his reasons. As background to medieval philosophy this is appropriate, because a lot of medieval philosophy tries, by means of its own arguments, to establish conclusions like Plato's, and often assumes among its premises some part or parts of Plato's world picture.
Aristotle has quite a bit to say about moving causes: see Metaphysics, 1013 a25 ff, in Supplement, p.118 (pause the tape while you read it); also about matter, form, and about the chain of moving causes going back to original unmoved (i.e. not in motion) movers. This is the subject matter of his Physics (Nature), one of his longest and most elaborate works. Just one more point before I leave it: According to Aristotle, Nature is eternal. It never began, it will never end, there always have been brass spheres and human beings, and fish and whatever other kinds of things there are; and there always will be. There is nothing in his philosophy corresponding to Plato's myth of creation by the demiurge - the world was never brought into existence. The neo-Platonists followed Aristotle here: the world emanates eternally from the One.
According to Aristotle the soul is the form of a body potentially alive: the moving cause that begets a living thing does something exactly like the cause that shapes brass into a sphere. The shape or form in this case is not just on the surface; it is the deep and complex dynamic structure of a living organism. The soul does not pre-exist the living organism, any more than the sphere pre-exists the brass. Plants and animals have souls, because they are alive. The human soul has plant and animal functions (growth and reproduction; sensation); it also has some functions or activities that do not seem to be acts of anything bodily, especially reason and intelligence. So it seems possible that the human soul or part of it might survive the body. Aristotle never says so and probably did not think so. Some later Aristotelians interpreted some obscure remarks of his to mean that the whole human species has a single intelligence, which is, like the human spheres and the rest of the world, eternal, but is not particularly yours or mine. Our minds are mere receivers of its thoughts. Besides plant and animal souls Aristotle postulated beings that Plato would have called souls, though Aristotle calls them intelligences: the intelligences that move the heavenly spheres. If there is a single intellect for the whole human species then it takes its place among these cosmic intelligences. The highest unmoving mover is God, an intelligence who or which has no other fitting object for his thought than himself: he is eternally rapt in self-contemplation.
In ethics Aristotle has no use for the idea of the Good, or for any ideas, since there are none, or for any turning of the mind to the ideas. The good life for Aristotle consists in activity in accordance with the virtues. There are many virtues, including courage and justice, which perfect political action, and wisdom and science which perfect intellectual activity. The good life requires an appropriate mix of these various sorts of activities done "virtuously", i.e. as well as possible. It also needs, though in a much lower degree of necessity, various worldly goods such as money, good health, friends, leisure, freedom and so on. You can't engage in the activities in which the good life mainly consists without leisure and material means.
In logic the Stoics included not only what we now call logic, to which they made valuable contributions, but also what we call epistemology, the theory of knowledge. They searched for a criterion to distinguish between real knowledge and mere fluctuating opinion. Their criterion was sense perception, when that is at its best, not misleading. This led the Stoics into controversy with the sceptics, who urged that we can never be sure that a given sense perception is not an illusion: there is no criterion, we may have no knowledge at all, none we can recognise as such - and knowledge must be recognised as such or it is not knowledge.
In ethics the Stoics built on Socrates' thesis (Gorgias) that it is better to suffer wrong than to do wrong - that wrongdoing is the worst evil. In fact the Stoics went further: wrongdoing is the only evil, virtuous action the only good. Other things are to be sought or avoided but don't count as goods and evils. This seems paradoxical and controversial: Cicero's De finibus is a good presentation of Stoic ethics with criticism from an Aristotelian point of view. Aristotle, you will remember, said that virtuous action is by far the most important element in the good life, but the good life also needs - though in a much lower degree of necessity - wealth, health, freedom, leisure etc. The Stoics said that for the good life such things are not needed at all: even a slave can live the good life. But then why say that other things are to be sought or avoided, though not as goods or evils? I think the point was to make sure that there could be no question of "trading off" between virtues and these other things. The virtuous man does not have a price, any price: no amount of threatened penalty or promised reward will make him do what is wrong or fail to do what is right. Whatever the philosophic merits of this doctrine it certainly made the Stoics formidable participants in Roman politics: they stood up to emperors and accepted death rather than take part in anything they regarded as wrong. The ethical theories of the Stoics were taken up by the neo-Platonists and by many of the Church fathers and thus became part of the medieval Christian ethical tradition. Readers of Boethius' Consolation of Philosophy imbibed a good deal of Stoic ethics.
Return to Teaching
Materials on Medieval Philosophy
Return to home page