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Plato vs. Aristotle

Painting of Plato and Aristotle walking and talking, Plato pointing upwards and Aristotle hand spread level, with other philosophers on each side in the renaissance style.

The School of Athens, Raphael, 1509-1511

Socrates, Plato and Aristotle are perhaps the most famous of all Western philosophers and certainly the most famous Ancient Greek philosophers. Socrates taught Plato and other students, and Plato taught Aristotle and other students. For some years Aristotle was the tutor of Alexander the Great.

Socrates did not write anything down but taught through dialogues, typically asking questions. His teaching is known to us almost entirely through Plato. Many of Plato's works are the dialogues of Socrates with other people on particular topics. It can be difficult to differentiate the work of Plato and the work of Socrates. Plato was certainly not merely a scribe, though as his independent works, such as the Republic demonstrate.

Socrates taught in public places and was dedicated to truthfulness, often exposing hypocrisy and criticising Athenian people. He was condemned to death for allegedly 'corrupting youth' with his teaching.

Plato founded a school just outside of Athens called the Academy where many students were taught, Aristotle among them. The Academy persisted for a long time after his death being a centre for later Hellenistic philosophy and it is regarded as the fore runner to the Western University - hence the terms academics and academia.

Aristotle attended the Academy and later founded his own school in a part of Athens used for public philosophy and speaking called the Lyceum. His school came to be called 'the Lyceum' and also the 'peripatetic' school which means walking about, since Aristotle walked as he taught.

Both the Lyceum and the Academy were destroyed in 86 BC by the Sulla, a Roman, but their philosophies carried on.

It's Complicated

When learning about something or reading summaries and overviews we inevitably get an oversimplified view of ideas, and so can think something easy to dismiss that is not, or ridiculous when it's not so ridiculous when we see the chain of reasoning that got there. For example we might read that the difference between Plato and Aristotle is:

Plato believed in an ideal realm of 'forms', separate to this material world and the things in the world are as they are because they resemble, like poor copies or shadows, these perfect and eternal 'forms'.

Aristotle was much more down to earth and said the only reality is the world of matter or substance and if there are forms they are only secondary, not eternal, and are invented by our minds as generalisations we make about reality. We should try to understand the world around us first by observing it.

The works of philosophers fill books so, needless to say, these are always over simplifications. Reading a book, and reading it closely, gives a greater appreciation for the nuances, context and ramifications of someone's thought. The following provides some small examples of that. For example, the idea of 'forms' has implications across ethics, epistemology and politics. Aristotle and Plato are not necessarily in disagreement on all points, rather Aristotle accepts some of Plato's and Socrates arguments, but qualifies them and adds his own.


The method of Socrates, as it appears in Plato's books, which are dialogues between Socrates and others, is known as 'dialectic'. Here is an example from Gorgias:

Soc. Now I think, Gorgias, that you have very accurately explained what you conceive to be the art of rhetoric; and you mean to say, if I am not mistaken, that rhetoric is the artificer of persuasion, having this and no other business, and that this is her crown and end. Do you know any other effect of rhetoric over and above that of producing persuasion?

Gor. No: the definition seems to me very fair, Socrates; for persuasion is the chief end of rhetoric.

Soc. Then hear me, Gorgias, for I am quite sure that if there ever was a man who-entered on the discussion of a matter from a pure love of knowing the truth, I am such a one, and I should say the same of you.

Gor. What is coming, Socrates?

Soc. I will tell you: I am very well aware that do not know what, according to you, is the exact nature, or what are the topics of that persuasion of which you speak, and which is given by rhetoric; although I have a suspicion about both the one and the other. And I am going to ask-what is this power of persuasion which is given by rhetoric, and about what? But why, if I have a suspicion, do I ask instead of telling you? Not for your sake, but in order that the argument may proceed in such a manner as is most likely to set forth the truth.

Socrates here explains this method in a discussion about rhetoric with a famous sophist. He points out a difference between the rhetoric of the sophists, which intends only to persuade regardless of the truth, for example in order to win a case, and his own method which involves two people questioning each other with the intention of arriving at the truth.

Elsewhere, Socrates describes dialectic as a method of arguing backwards by questioning a premise to arrive at the truth, rather than forwards drawing conclusions from it. Knowledge is best derived from those truths and principles we have arrived at through dialectic.

For this to work we must be willing to change our views, rather than be intent on winning. It's important also that this is a dialogue. If we were alone there would be no way to test our theories, to expose weak arguments or raise to our awareness things we hadn't considered.


Aristotle includes dialectic but says that is only suitable for some situations and aims for a complete account of all things and all methods of reasoning for different situations and fields on knowledge.

Dialectic is one approach to knowledge among others. He builds on this with logic of various forms, categorisation, understanding of causation and rhetoric.

Aristotle builds on the work of his predecessors, accepting the parts that he finds valid and dismissing anything that doesn't stand up to criticism. Part of the method is to respect people who have thought a lot about it, but not uncritically.

In ancient greece episteme (knowledge) actually mean something including 'understanding' so an argument was thought necessary.

Some of the books where you can find these ways of reasoning discusses in detail are in a set called the 'Organon':

An important Aristotelian distinction is between demonstration and dialectic.

A demonstration is a reasoned argument (such as by syllogistic logic) based on premises that are known to be true in and of themself (eg: 1+1=2; or 'all unicorns have horns' because having a horn is entailed in the idea of what it means to be a unicorn - it is a necessary condition, or part of the definition.)

Dialectic is a reasoned argument (such as by syllogistic logic) based on premises that are accepted to be true by anyone participating in the debate (eg: we might be talking to a group of people, and start by saying, "Ok, so I think we can all agree that apples are healthy. So if all apples are healthy..."

Note that the word 'dialectic' is defined differently in the works of Plato and Aristotle. I'm not sure if this is a problem with translation, or if they both simply use the word differently. Socrates starts with an agreed premise but doesn't accept it as true without questioning. By contrast Aristotle describes dialectic as arguing from an accepted premise. Note that a 'demonstration' in Aristotle's terminology would be coming from the result of Platonic (Socratic) dialectic.

Now reasoning is an argument in which, certain things being laid down, something other than these necessarily comes about through them. (a) It is a 'demonstration', when the premises from which the reasoning starts are true and primary, or are such that our knowledge of them has originally come through premisses which are primary and true: (b) reasoning, on the other hand, is 'dialectical', if it reasons from opinions that are believed on the strength not of anything else but of themselves: for in regard to the first principles of science it is improper to ask any further for the why ans wherefore of them; each of the first principles shoudl command belief in and by itself. On the other hand, those opinions are 'generally accepted' which are accepted by every one or by the majority, or by the philosophers - ie by all, or by a majority, or by the most notable and illustrious of them. Again (c), reasoning is 'contentious' if it starts from opinions that seem to be generally accepted, but are not really such, or again if it merely seems to reason from opinions that are or seem to be generally accepted. For not every opinion that seems to be generally accepted actually is generally accepted... Further (d), besides all the reasonings we have mentioned there are the mis-reasonings that start from the premises peculiar to the special sciences..." Topics p188 (first page of Topics)

Note that these last two are about false reasoning, so not part of Aristotle's method per se. Aristotle is stating these as species of reasoning we might encounter and have to respond to with in the world.

Much of Aristotle's work is about methods for valid reasoning so we can't cover it all here. He is noted for formalising 'syllogisms' which remain one of the foundations of logic. These are statements such as 'If all A are B and C is A then C is B' and similar. They can be a bit dry to study, but there are only a small number of them and are an extremely powerful thing to know. We use them a lot in our arguments and reasoning without even knowing. Aristotle has a very thorough approach, breaking things into categories. For example, to make or refute an argument he says we may consider it in terms of 'definition', 'property', 'genus', and 'accident', and also types of 'predicates' that we can consider: essence, quantity, quality, relation, place, time, position, state, activity, passivity. We will look at these in the next session on logic an rhetoric, which will focus on Aristotle and classical rhetoricians such as Cicero.

Aristotle's view is that the aim of philosophy is towards the most general knowledge of first principles. This will apply to most things, and will enable us to draw the most conclusions:

"Such and so many are the notions, then, which we have about Wisdom and the wise. Now of these characteristics that of knowing all things must belong to him who has in the highest degree universal knowledge; for he knows in a sense all the instances that fall under the universal. And these things, the most universal, are on the whole the hardest for men to know; for they are farthest from the senses. And the most exact of the sciences are those which deal most with first principles; for those which involve fewer principles are more exact than those which involve additional principles, e.g. arithmetic than geometry. But the science which investigates causes is also instructive, in a higher degree, for the people who instruct us are those who tell the causes of each thing. And understanding and knowledge pursued for their own sake are found most in the knowledge of that which is most knowable (for he who chooses to know for the sake of knowing will choose most readily that which is most truly knowledge, and such is the knowledge of that which is most knowable); and the first principles and the causes are most knowable; for by reason of these, and from these, all other things come to be known, and not these by means of the things subordinate to them. And the science which knows to what end each thing must be done is the most authoritative of the sciences, and more authoritative than any ancillary science; and this end is the good of that thing, and in general the supreme good in the whole of nature. Judged by all the tests we have mentioned, then, the name in question falls to the same science; this must be a science that investigates the first principles and causes; for the good, i.e. the end, is one of the causes.

Indonesian Wayang Kulit shadow puppets projected on a screen.

Indonesian Wayang Kulit shadow puppets. (They are the 5 Pandava brothers from The Mahabharata, from the left, Bima, Arjuna, Yudhistra, Nakula and Sahadeva.)

The parable of the cave in Plato's Republic

One of the things Plato is most famous for is the theory of the forms. No orange is an exact sphere, so where does this sphericality come from? It comes from another reality of ideas, of forms, which our minds have access to when we think. Our thought of a perfect sphere is not something in the world that changes, decays and ceases to exist, but is outside of time, it is something we can all access in our minds. Plato calls this the 'form' of a sphere and it is only in imperfect, transient resemblance to this perfect eternal ideal 'form' of a sphere that we can say that the orange is spherical.

References to this theory occur throughout Plato's dialogues with some aspects touched on in different ways in different dialogues but perhaps the most thorough account, and the most famous is in Plato's Republic, around the allegory of the cave.

Setting up the dialogue

Socrates starts a new topic for dialogue by asking Glaucon to accept that an understanding of 'the good' is one of the most important things we might be able to have knowledge of. There is nothing worth having that is not good.

“...For you have often heard272 that the greatest thing to learn is the idea of good273 by reference to which274 just things275 and all the rest become useful and beneficial. And now I am almost sure you know that this is what I am going to speak of and to say further that we have no adequate knowledge of it. And if we do not know it, then, even if without the knowledge of this we should know all other things never so well, you are aware that it would avail us nothing, [505b] just as no possession either is of any avail276 without the possession of the good. Or do you think there is any profit277 in possessing everything except that which is good, or in understanding all things else apart from the good while understanding and knowing nothing that is fair and good278?” “No, by Zeus, I do not,” he said.

Socrates points out common misconceptions and bad arguments about the 'Good'. Most people say 'the good' is pleasure, but contradict themselves when they admit that bad things can be pleasurable. More sophisticated people say that 'knowledge' is the good, but when questioned about what this knowledge is of, they end up saying 'knowledge of the good' and so have a circular argument (It is good to have knowledge. Knowledge of what? Knowledge of what is good.)

But, furthermore, you know this too, that the multitude believe pleasure279 to be the good, and the finer280 spirits intelligence or knowledge.281” “Certainly.” “And you are also aware, my friend, that those who hold this latter view are not able to point out what knowledge282 it is but are finally compelled to say that it is the knowledge of the good.” “Most absurdly,” he said. “Is it not absurd,” [505c] said I, “if while taunting us with our ignorance of the good they turn about and talk to us as if we knew it? For they say it is the knowledge of the good,283 as if we understood their meaning when they utter284 the word ‘good.'” “Most true,” he said. “Well, are those who define the good as pleasure infected with any less confusion285 of thought than the others? Or are not they in like manner286 compelled to admit that there are bad pleasures287?”

Socrates backs away from saying what the good is, claiming (pretending) that he hasn't yet attained that height of understanding, then starts using similes and parables to explain his point of view:

The Sun

Socrates describes how vision requires not only the thing seen and the eye, but also light.

“Well, look at it thus. Do hearing and voice stand in need of another medium315 so that the one may hear and the other be heard, [507d] in the absence of which third element the one will not hear and the other not be heard?” “They need nothing,” he said. “Neither, I fancy,” said I,” do many others, not to say that none require anything of the sort. Or do you know of any?” “Not I,” he said. “But do you not observe that vision and the visible do have this further need?” “How?” “Though vision may be in the eyes and its possessor may try to use it, and though color be present, yet without [507e] the presence of a third thing316 specifically and naturally adapted to this purpose, you are aware that vision will see nothing and the colors will remain invisible.317” “What318 is this thing of which you speak?” he said. “The thing,” I said, “that you call light.”

Socrates points out that the Sun can't be looked at directly, but illumines everything else clearly.

“Is it not also true that the sun is not vision, yet as being the cause thereof is beheld by vision itself?” “That is so,” he said. “This, then, you must understand that I meant by the offspring of the good323 which the good [508c] begot to stand in a proportion324 with itself: as the good is in the intelligible region to reason and the objects of reason, so is this in the visible world to vision and the objects of vision.” “How is that?” he said; “explain further.” “You are aware,” I said, “that when the eyes are no longer turned upon objects upon whose colors the light of day falls but that of the dim luminaries of night, their edge is blunted and they appear almost blind, as if pure vision did not dwell in them.” “Yes, indeed,” he said. “But when, I take it, [508d] they are directed upon objects illumined by the sun, they see clearly, and vision appears to reside in these same eyes.”

Socrates says that the form of 'The Good' is like the sun. Difficult to understand directly, but 'the good' is what enables us to 'see' or understand what is knowable and pleasurable.

“This reality, then, that gives their truth to the objects of knowledge and the power of knowing to the knower, you must say is the idea326 of good, and you must conceive it as being the cause of knowledge, and of truth in so far as known.327 Yet fair as they both are, knowledge and truth, in supposing it to be something fairer still328 than these you will think rightly of it. But as for knowledge and truth, even as in our illustration [509a] it is right to deem light and vision sunlike, but never to think that they are the sun, so here it is right to consider these two their counterparts, as being like the good or boniform,329 but to think that either of them is the good330 is not right.

The Line

Socrates then describes a line divided into knowledge and opinion, with opinion divided into illusion and belief, and knowledge divided into mathematical reasoning and dialectical reasoning. Socrates draws a distinction between dialectic which starts from some premise and questions it to find truths and principles and the sciences about the world and of mathematics which draw conclusions from some initial assumption. These two kinds of reasoning go in opposite directions. One questions assumptions to find knowledge, while the other reasons from assumptions to find knowledge.

“Understand then,” said I, “that by the other section of the intelligible I mean that which the reason353 itself lays hold of by the power of dialectics,354 treating its assumptions not as absolute beginnings but literally as hypotheses,355 underpinnings, footings,356 and springboards so to speak, to enable it to rise to that which requires no assumption and is the starting-point of all,357 and after attaining to that again taking hold of the first dependencies from it, so to proceed downward to the conclusion, [511c] making no use whatever of any object of sense358 but only of pure ideas moving on through ideas to ideas and ending with ideas.359”

Plato Republic Book 6

The Cave

The allegory of the cave is perhaps the most famous passage in Plato's works.

“Next,” said I, “compare our nature in respect of education and its lack to such an experience as this. Picture men dwelling in a sort of subterranean cavern1 with a long entrance open2 to the light on its entire width. Conceive them as having their legs and necks fettered3 from childhood, so that they remain in the same spot, [514b] able to look forward only, and prevented by the fetters from turning their heads. Picture further the light from a fire burning higher up and at a distance behind them, and between the fire and the prisoners and above them a road along which a low wall has been built, as the exhibitors of puppet-shows4 have partitions before the men themselves, above which they show the puppets.” “All that I see,” he said. “See also, then, men carrying5 past the wall [514c] implements of all kinds that rise above the wall, and human images [515a] and shapes of animals as well, wrought in stone and wood and every material, some of these bearers presumably speaking and others silent.” “A strange image you speak of,” he said, “and strange prisoners.” “Like to us,” I said;

Plato Republic Book 6

Plato develops this allegory throughout Book 6 using it to demonstrate many points. In the allegory someone escapes the cave and sees the road above, the real things in the sunlight. Through question and answer Socrates shows this person would be at first confused, and then come to understand the truth about reality. They would still find it difficult to look at the sun. http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.01.0168%3Abook%3D6&force=y

- They would not wish to return.
- If they returned, nobody would believe them, and even be angry at them for telling lies (reference to Socrates)
- Yet if anyone knew overall, they would urge the philosopher to return and explain, and those in the cave would want to learn the truth.
- So the metaphysical view of 'form's relates to morality and politics.

Aristotle's discussion of predication and substance relates to Plato's Theaetetus. We won't discuss it, due to time, but here it is as it's wroth a look if you have the time for a little contemplation of form, substance and the nature of reality.


For I must repeat what I said before, that neither the agent nor patient have any absolute existence, but when they come together and generate sensations and their objects, the one becomes a thing of a certain quality, and the other a percipient. ...

But now, since not even white continues to flow white, and whiteness itself is a flux or change which is passing into another colour, and is never to be caught standing still, can the name of any colour be rightly used at all? ...

But if nothing is at rest, every answer upon whatever subject is equally right: you may say that a thing is or is not thus; ...

And you would admit that what you perceive through one faculty you cannot perceive through another; the objects of hearing, for example, cannot be perceived through sight, or the objects of sight through hearing? ...

SOCRATES: Very good; and now tell me what is the power which discerns, not only in sensible objects, but in all things, universal notions, such as those which are called being and not-being, and those others about which we were just asking--what organs will you assign for the perception of these notions?

THEAETETUS: You are thinking of being and not being, likeness and unlikeness, sameness and difference, and also of unity and other numbers which are applied to objects of sense; and you mean to ask, through what bodily organ the soul perceives odd and even numbers and other arithmetical conceptions.

SOCRATES: You follow me excellently, Theaetetus; that is precisely what I am asking.

THEAETETUS: Indeed, Socrates, I cannot answer; my only notion is, that these, unlike objects of sense, have no separate organ, but that the mind, by a power of her own, contemplates the universals in all things. ...

SOCRATES: The simple sensations which reach the soul through the body are given at birth to men and animals by nature, but their reflections on the being and use of them are slowly and hardly gained, if they are ever gained, by education and long experience.

THEAETETUS: Assuredly.

SOCRATES: And can a man attain truth who fails of attaining being?

THEAETETUS: Impossible.

SOCRATES: And can he who misses the truth of anything, have a knowledge of that thing?

THEAETETUS: He cannot.

SOCRATES: Then knowledge does not consist in impressions of sense, but in reasoning about them; in that only, and not in the mere impression, truth and being can be attained?


SOCRATES: And would you call the two processes by the same name, when there is so great a difference between them?

THEAETETUS: That would certainly not be right.

SOCRATES: And what name would you give to seeing, hearing, smelling, being cold and being hot?

THEAETETUS: I should call all of them perceiving--what other name could be given to them?

SOCRATES: Perception would be the collective name of them?

THEAETETUS: Certainly.

SOCRATES: Which, as we say, has no part in the attainment of truth any more than of being?

THEAETETUS: Certainly not.3

SOCRATES: And therefore not in science or knowledge?


SOCRATES: Then perception, Theaetetus, can never be the same as knowledge or science?

THEAETETUS: Clearly not, Socrates; and knowledge has now been most distinctly proved to be different from perception.

SOCRATES: But the original aim of our discussion was to find out rather what knowledge is than what it is not; at the same time we have made some progress, for we no longer seek for knowledge in perception at all, but in that other process, however called, in which the mind is alone and engaged with being.

Angular line diagram of a chair from side on. Curvy red plastic modern chair.

Aristotle's view of substance is described mainly in Categories and Metaphysics.

"Again, colour is present in body, therefore in individual bodies, for if there were no individual body in which it was present, it could not be present in body at all. Thus everything except primary substances is either predicated of primary substances, or is present in them, and if these last did not exist, it would be impossible for anything else to exist." Categories p9

"The most distinctive mark of substance appears to be that, while remaining numerically one and the same, it is capable of admitting contrary qualities. From among things other than substance, we should find ourselves unable to bring forward any which possessed this mark. Thus, one and the same colour cannot be white and black. Nor can the same one action be good and bad: this law holds good with everything that is not substance. But one and the self-same substance, while retaining its identity, is yet capable of admitting contrary qualities." p13 Categories.

The terms 'substance' is a translation of 'ousia' in ancient Greek, which means 'a being' - a noun form from the verb 'to be'. It refers to the thing which is, so has also been translated as 'essence', as it is not necessarily 'material' which is implied by the word 'substance'. (It is debatable and there has been much critique over whether such an 'essence' exists - what we interpret as a single entity (such as this cat called 'Snoops') with properties attached to it, such as whiskers, the ability to purr, a tortoiseshell pattern), it doesn't necessarily follow that there is a real thing to which these are attached. There may only be a collection, an aggregate, of properties.)

Note Aristotle's method of drawing distinctions, echoed in Avicenna, to then reason about them, and understand their relationships. For Aristotle there are things which are predicated and things which aren't.

The term 'predicate' is grammatical but is applicable to logic, and also to the world that we are talking about when we use grammar and logic to talk about the world. A sentence is made up of a subject and a predicate. In the sentence, 'The chair is green.' The chair is the subject and whatever we may say about it is the predicate. Note that the chair is not necessarily green. It could be red, yellow, purple, etc. In the following sentences Helen is the subject and the rest are predicates: "Helen is a woman.", "Helen is beautiful.", "Helen went to Troy." etc.

Forms are predicated so cannot exist without substance.

If there is change, there is a change from one 'form' to another. So from 'sad' to 'happy', from 'green' to 'yellow', from 'walking' to 'running'. There must be something which this change happens to. Something which changes from one emotion, colour or movement to another. It is this which provides continuity of identity across time. This is the 'thing' to which things happen, or 'substance'. It is the 'form' or those things which are 'predicated' that change while the 'substance' or 'essence' or we might say, 'object' or 'thing', persists.

This 'substance' does not require those things which are predicated on it in order to exist. Rather those things which are predicated on it require that substance to exist. I can exist without necessarily being one colour or another, without necessarily being happy or sad. I could walk, run, sit, or something else. Whereas these properties, or 'forms' which are predicated do require something to be instantiated in, in order to exist. There cannot be 'yellow' without there being something that is yellow. There can't be 'happiness' without there being something that is happy. For Aristotle then, the most fundamental 'being', the being which is real, is 'substance' or 'essence', 'ousia'. These is no need to resort to abstract ideal ideas to account for what exists.

This is in direct contrast to Plato and Socrates, who argued that because things in the world change they have less reality than those ideas which are perfect and eternal.

To look at it more abstractly consider a sphere and an orange. Plato would say, no orange is an exact sphere, so where does this sphericality come from? It comes from our minds. Our thought of a perfect sphere is not something in the world that changes, decays and ceases to exist, but is outside of time, it is something we can all access in our minds. Plato calls this the 'form' of a sphere and it is only in imperfect, transient resemblance to this perfect eternal ideal 'form' of a sphere that we can say that the orange is spherical.

Aristotle, in contrast to Plato and Socrates, says that there is no need to invent another reality to which we have access. It is only because of our experiences of oranges and other roughly spherical things that our minds gradually create a general idea of a perfect circle. However the circle cannot really exist except in substances, like oranges. The only real things are the individual particulars. These are prior, and our thoughts about them, such as the idea of a sphere, are posterior - derived from them. A sphere is predicated on an actual orange - eg: 'This orange is spherical'. (Ok, now if you are thinking, 'This sphere is orange.' you are of course just talking about the colour, not this piece of fruit. However, couldn't we say, "This sphere is imperfect like a fruit"? Aristotle is making a statement not just about grammatical construction but about the real world. He is asserting that mental ideals or 'forms' are secondary to substance which we can generally understand as 'matter'.)

Aristotle notes that some predicates are special cases, particularly species and genera. A 'species' is a type of thing. Genera is a more general category of species. These Aristotle refers to as 'secondary substances' because although they are not the individual man, they still exist materially. In the statement, "Odysseus is a man." the predicate is a species and refers to material substantial men, not just a property that a man might have. Similarly with the genera 'animal'. What is true of the species is true of the individual and what is true of the genera is true of the species.

One of the main arguments Aristotle provides for substance and not forms as primary and real is causation. He describes four causes: material, formal, efficient, final.

Incidentally, bearing these in mind is helpful in problem solving - when looking at a problem, you can ask, what is the cause of this? Material, formal, efficient, final?

Now that we have established these distinctions, we must proceed to consider causes, their character and number. Knowledge is the object of our inquiry, and men do not think they know a thing till they have grasped the 'why' of (which is to grasp its primary cause). So clearly we too must do this as regards both coming to be and passing away and every kind of physical change, in order that, knowing their principles, we may try to refer to these principles each of our problems.

In one sense, then, (1) that out of which a thing comes to be and which persists, is called 'cause', e.g. the bronze of the statue, the silver of the bowl, and the genera of which the bronze and the silver are species.

In another sense (2) the form or the archetype, i.e. the statement of the essence, and its genera, are called 'causes' (e.g. of the octave the relation of 2:1, and generally number), and the parts in the definition.

Again (3) the primary source of the change or coming to rest; e.g. the man who gave advice is a cause, the father is cause of the child, and generally what makes of what is made and what causes change of what is changed.

Again (4) in the sense of end or 'that for the sake of which' a thing is done, e.g. health is the cause of walking about. ('Why is he walking about?' we say. 'To be healthy', and, having said that, we think we have assigned the cause.) The same is true also of all the intermediate steps which are brought about through the action of something else as means towards the end, e.g. reduction of flesh, purging, drugs, or surgical instruments are means towards health. All these things are 'for the sake of' the end, though they differ from one another in that some are activities, others instruments.

This then perhaps exhausts the number of ways in which the term 'cause' is used.

Aristotle, Physics, Book II, Part 3

Here we see Aristotle state that knowledge requires that we are able to explain, 'why'. This is in agreement with Plato and Socrates.

Next he describes the 4 causes, another key aspect of Aristotle's philosophy. A consideration of causation and predication is what leads Aristotle to the conclusion, against Plato and Socrates, that the primary and real existents are substantial, or material, not Platonic forms. If forms such as whiteness, are predicates, they are accidental and changeable, so they can't be the cause, but must be instead something which is causes. They must be a change which is caused to happen to something - the substance.

"After the systems we have named came the philosophy of Plato, which in most respects followed these thinkers, but had pecullarities that distinguished it from the philosophy of the Italians. For, having in his youth first become familiar with Cratylus and with the Heraclitean doctrines (that all sensible things are ever in a state of flux and there is no knowledge about them), these views he held even in later years. Socrates, however, was busying himself about ethical matters and neglecting the world of nature as a whole but seeking the universal in these ethical matters, and fixed thought for the first time on definitions; Plato accepted his teaching, but held that the problem applied not to sensible things but to entities of another kind-for this reason, that the common definition could not be a definition of any sensible thing, as they were always changing. Things of this other sort, then, he called Ideas, and sensible things, he said, were all named after these, and in virtue of a relation to these; for the many existed by participation in the Ideas that have the same name as they. Only the name 'participation' was new; for the Pythagoreans say that things exist by 'imitation' of numbers, and Plato says they exist by participation, changing the name. But what the participation or the imitation of the Forms could be they left an open question.

"Further, besides sensible things and Forms he says there are the objects of mathematics, which occupy an intermediate position, differing from sensible things in being eternal and unchangeable, from Forms in that there are many alike, while the Form itself is in each case unique.

"Since the Forms were the causes of all other things, he thought their elements were the elements of all things. As matter, the great and the small were principles; as essential reality, the One; for from the great and the small, by participation in the One, come the Numbers.

"But he agreed with the Pythagoreans in saying that the One is substance and not a predicate of something else; and in saying that the Numbers are the causes of the reality of other things he agreed with them; but positing a dyad and constructing the infinite out of great and small, instead of treating the infinite as one, is peculiar to him; and so is his view that the Numbers exist apart from sensible things, while they say that the things themselves are Numbers, and do not place the objects of mathematics between Forms and sensible things. His divergence from the Pythagoreans in making the One and the Numbers separate from things, and his introduction of the Forms, were due to his inquiries in the region of definitions (for the earlier thinkers had no tincture of dialectic), and his making the other entity besides the One a dyad was due to the belief that the numbers, except those which were prime, could be neatly produced out of the dyad as out of some plastic material. Yet what happens is the contrary; the theory is not a reasonable one. For they make many things out of the matter, and the form generates only once, but what we observe is that one table is made from one matter, while the man who applies the form, though he is one, makes many tables. And the relation of the male to the female is similar; for the latter is impregnated by one copulation, but the male impregnates many females; yet these are analogues of those first principles.

"Plato, then, declared himself thus on the points in question; it is evident from what has been said that he has used only two causes, that of the essence and the material cause (for the Forms are the causes of the essence of all other things, and the One is the cause of the essence of the Forms); and it is evident what the underlying matter is, of which the Forms are predicated in the case of sensible things, and the One in the case of Forms, viz. that this is a dyad, the great and the small. Further, he has assigned the cause of good and that of evil to the elements, one to each of the two, as we say some of his predecessors sought to do, e.g. Empedocles and Anaxagoras.

Aristotle, Metaphysics, Book I, Part 6

"Our review of those who have spoken about first principles and reality and of the way in which they have spoken, has been concise and summary; but yet we have learnt this much from them, that of those who speak about 'principle' and 'cause' no one has mentioned any principle except those which have been distinguished in our work on nature, but all evidently have some inkling of them, though only vaguely. For some speak of the first principle as matter, whether they suppose one or more first principles, and whether they suppose this to be a body or to be incorporeal; e.g. Plato spoke of the great and the small, the Italians of the infinite, Empedocles of fire, earth, water, and air, Anaxagoras of the infinity of things composed of similar parts. These, then, have all had a notion of this kind of cause, and so have all who speak of air or fire or water, or something denser than fire and rarer than air; for some have said the prime element is of this kind.

"These thinkers grasped this cause only; but certain others have mentioned the source of movement, e.g. those who make friendship and strife, or reason, or love, a principle.

"The essence, i.e. the substantial reality, no one has expressed distinctly. It is hinted at chiefly by those who believe in the Forms; for they do not suppose either that the Forms are the matter of sensible things, and the One the matter of the Forms, or that they are the source of movement (for they say these are causes rather of immobility and of being at rest), but they furnish the Forms as the essence of every other thing, and the One as the essence of the Forms.

"That for whose sake actions and changes and movements take place, they assert to be a cause in a way, but not in this way, i.e. not in the way in which it is its nature to be a cause. For those who speak of reason or friendship class these causes as goods; they do not speak, however, as if anything that exists either existed or came into being for the sake of these, but as if movements started from these. In the same way those who say the One or the existent is the good, say that it is the cause of substance, but not that substance either is or comes to be for the sake of this. Therefore it turns out that in a sense they both say and do not say the good is a cause; for they do not call it a cause qua good but only incidentally.

"All these thinkers then, as they cannot pitch on another cause, seem to testify that we have determined rightly both how many and of what sort the causes are. Besides this it is plain that when the causes are being looked for, either all four must be sought thus or they must be sought in one of these four ways. Let us next discuss the possible difficulties with regard to the way in which each of these thinkers has spoken, and with regard to his situation relatively to the first principles

Aristotle, Metaphysics, Book I, Part 7

"Let us leave the Pythagoreans for the present; for it is enough to have touched on them as much as we have done. But as for those who posit the Ideas as causes, firstly, in seeking to grasp the causes of the things around us, they introduced others equal in number to these, as if a man who wanted to count things thought he would not be able to do it while they were few, but tried to count them when he had added to their number. For the Forms are practically equal to-or not fewer than-the things, in trying to explain which these thinkers proceeded from them to the Forms. For to each thing there answers an entity which has the same name and exists apart from the substances, and so also in the case of all other groups there is a one over many, whether the many are in this world or are eternal.

"Further, of the ways in which we prove that the Forms exist, none is convincing; for from some no inference necessarily follows, and from some arise Forms even of things of which we think there are no Forms. For according to the arguments from the existence of the sciences there will be Forms of all things of which there are sciences and according to the 'one over many' argument there will be Forms even of negations, and according to the argument that there is an object for thought even when the thing has perished, there will be Forms of perishable things; for we have an image of these. Further, of the more accurate arguments, some lead to Ideas of relations, of which we say there is no independent class, and others introduce the 'third man'.

"And in general the arguments for the Forms destroy the things for whose existence we are more zealous than for the existence of the Ideas; for it follows that not the dyad but number is first, i.e. that the relative is prior to the absolute,-besides all the other points on which certain people by following out the opinions held about the Ideas have come into conflict with the principles of the theory.

"Further, according to the assumption on which our belief in the Ideas rests, there will be Forms not only of substances but also of many other things (for the concept is single not only in the case of substances but also in the other cases, and there are sciences not only of substance but also of other things, and a thousand other such difficulties confront them). But according to the necessities of the case and the opinions held about the Forms, if Forms can be shared in there must be Ideas of substances only. For they are not shared in incidentally, but a thing must share in its Form as in something not predicated of a subject (by 'being shared in incidentally' I mean that e.g. if a thing shares in 'double itself', it shares also in 'eternal', but incidentally; for 'eternal' happens to be predicable of the 'double'). Therefore the Forms will be substance; but the same terms indicate substance in this and in the ideal world (or what will be the meaning of saying that there is something apart from the particulars-the one over many?). And if the Ideas and the particulars that share in them have the same form, there will be something common to these; for why should '2' be one and the same in the perishable 2's or in those which are many but eternal, and not the same in the '2' itself' as in the particular 2? But if they have not the same form, they must have only the name in common, and it is as if one were to call both Callias and a wooden image a 'man', without observing any community between them.

"Above all one might discuss the question what on earth the Forms contribute to sensible things, either to those that are eternal or to those that come into being and cease to be. For they cause neither movement nor any change in them. But again they help in no wise either towards the knowledge of the other things (for they are not even the substance of these, else they would have been in them), or towards their being, if they are not in the particulars which share in them; though if they were, they might be thought to be causes, as white causes whiteness in a white object by entering into its composition. But this argument, which first Anaxagoras and later Eudoxus and certain others used, is very easily upset; for it is not difficult to collect many insuperable objections to such a view.

"But, further, all other things cannot come from the Forms in any of the usual senses of 'from'. And to say that they are patterns and the other things share in them is to use empty words and poetical metaphors. For what is it that works, looking to the Ideas? And anything can either be, or become, like another without being copied from it, so that whether Socrates or not a man Socrates like might come to be; and evidently this might be so even if Socrates were eternal. And there will be several patterns of the same thing, and therefore several Forms; e.g. 'animal' and 'two-footed' and also 'man himself' will be Forms of man. Again, the Forms are patterns not only sensible things, but of Forms themselves also; i.e. the genus, as genus of various species, will be so; therefore the same thing will be pattern and copy.

"Again, it would seem impossible that the substance and that of which it is the substance should exist apart; how, therefore, could the Ideas, being the substances of things, exist apart? In the Phaedo' the case is stated in this way-that the Forms are causes both of being and of becoming; yet when the Forms exist, still the things that share in them do not come into being, unless there is something to originate movement; and many other things come into being (e.g. a house or a ring) of which we say there are no Forms. Clearly, therefore, even the other things can both be and come into being owing to such causes as produce the things just mentioned.

"Again, if the Forms are numbers, how can they be causes? Is it because existing things are other numbers, e.g. one number is man, another is Socrates, another Callias? Why then are the one set of numbers causes of the other set? It will not make any difference even if the former are eternal and the latter are not. But if it is because things in this sensible world (e.g. harmony) are ratios of numbers, evidently the things between which they are ratios are some one class of things. If, then, this--the matter--is some definite thing, evidently the numbers themselves too will be ratios of something to something else. E.g. if Callias is a numerical ratio between fire and earth and water and air, his Idea also will be a number of certain other underlying things; and man himself, whether it is a number in a sense or not, will still be a numerical ratio of certain things and not a number proper, nor will it be a of number merely because it is a numerical ratio.

"Again, from many numbers one number is produced, but how can one Form come from many Forms? And if the number comes not from the many numbers themselves but from the units in them, e.g. in 10,000, how is it with the units? If they are specifically alike, numerous absurdities will follow, and also if they are not alike (neither the units in one number being themselves like one another nor those in other numbers being all like to all); for in what will they differ, as they are without quality? This is not a plausible view, nor is it consistent with our thought on the matter.

"Further, they must set up a second kind of number (with which arithmetic deals), and all the objects which are called 'intermediate' by some thinkers; and how do these exist or from what principles do they proceed? Or why must they be intermediate between the things in this sensible world and the things-themselves?

"Further, the units in must each come from a prior but this is impossible.

"Further, why is a number, when taken all together, one?

"Again, besides what has been said, if the units are diverse the Platonists should have spoken like those who say there are four, or two, elements; for each of these thinkers gives the name of element not to that which is common, e.g. to body, but to fire and earth, whether there is something common to them, viz. body, or not. But in fact the Platonists speak as if the One were homogeneous like fire or water; and if this is so, the numbers will not be substances. Evidently, if there is a One itself and this is a first principle, 'one' is being used in more than one sense; for otherwise the theory is impossible.

"When we wish to reduce substances to their principles, we state that lines come from the short and long (i.e. from a kind of small and great), and the plane from the broad and narrow, and body from the deep and shallow. Yet how then can either the plane contain a line, or the solid a line or a plane? For the broad and narrow is a different class from the deep and shallow. Therefore, just as number is not present in these, because the many and few are different from these, evidently no other of the higher classes will be present in the lower. But again the broad is not a genus which includes the deep, for then the solid would have been a species of plane. Further, from what principle will the presence of the points in the line be derived? Plato even used to object to this class of things as being a geometrical fiction. He gave the name of principle of the line-and this he often posited-to the indivisible lines. Yet these must have a limit; therefore the argument from which the existence of the line follows proves also the existence of the point.

"In general, though philosophy seeks the cause of perceptible things, we have given this up (for we say nothing of the cause from which change takes its start), but while we fancy we are stating the substance of perceptible things, we assert the existence of a second class of substances, while our account of the way in which they are the substances of perceptible things is empty talk; for 'sharing', as we said before, means nothing.

"Nor have the Forms any connexion with what we see to be the cause in the case of the arts, that for whose sake both all mind and the whole of nature are operative,-with this cause which we assert to be one of the first principles; but mathematics has come to be identical with philosophy for modern thinkers, though they say that it should be studied for the sake of other things. Further, one might suppose that the substance which according to them underlies as matter is too mathematical, and is a predicate and differentia of the substance, ie. of the matter, rather than matter itself; i.e. the great and the small are like the rare and the dense which the physical philosophers speak of, calling these the primary differentiae of the substratum; for these are a kind of excess and defect. And regarding movement, if the great and the small are to he movement, evidently the Forms will be moved; but if they are not to be movement, whence did movement come? The whole study of nature has been annihilated.

"And what is thought to be easy-to show that all things are one-is not done; for what is proved by the method of setting out instances is not that all things are one but that there is a One itself,-if we grant all the assumptions. And not even this follows, if we do not grant that the universal is a genus; and this in some cases it cannot be.

"Nor can it be explained either how the lines and planes and solids that come after the numbers exist or can exist, or what significance they have; for these can neither be Forms (for they are not numbers), nor the intermediates (for those are the objects of mathematics), nor the perishable things. This is evidently a distinct fourth class.

"In general, if we search for the elements of existing things without distinguishing the many senses in which things are said to exist, we cannot find them, especially if the search for the elements of which things are made is conducted in this manner. For it is surely impossible to discover what 'acting' or 'being acted on', or 'the straight', is made of, but if elements can be discovered at all, it is only the elements of substances; therefore either to seek the elements of all existing things or to think one has them is incorrect.

"And how could we learn the elements of all things? Evidently we cannot start by knowing anything before. For as he who is learning geometry, though he may know other things before, knows none of the things with which the science deals and about which he is to learn, so is it in all other cases. Therefore if there is a science of all things, such as some assert to exist, he who is learning this will know nothing before. Yet all learning is by means of premisses which are (either all or some of them) known before,-whether the learning be by demonstration or by definitions; for the elements of the definition must be known before and be familiar; and learning by induction proceeds similarly. But again, if the science were actually innate, it were strange that we are unaware of our possession of the greatest of sciences.

"Again, how is one to come to know what all things are made of, and how is this to be made evident? This also affords a difficulty; for there might be a conflict of opinion, as there is about certain syllables; some say za is made out of s and d and a, while others say it is a distinct sound and none of those that are familiar.

"Further, how could we know the objects of sense without having the sense in question? Yet we ought to, if the elements of which all things consist, as complex sounds consist of the clements proper to sound, are the same.

Aristotle, Metaphysics, Book I, Part 9

TBC - out of time :(

Meno for virtue as knowledge, and circular reasoning, start with definition, JTB, also Theatetus.

Aristotle Bk 1 Ethics, dismissing Plato's Good. Aristotle - good at it's purpose, but drawing on Plato, the analogy of a good knife being one that is good at cutting is from Plato's Republic. So, learning how to be who they are as best they can. Note that this is a lesson from Bhagavad Gita.

Living well, having pleasure is good, and to do this requires wisdom/knowledge. Epistemology and ethics are bound up - the purpose of knowledge is to be good at living well. This becomes a definition??? what knowledge is is what makes us better at living well.

TBC - out of time :(

Plato, equality, disinterested philosopher king. An early description of a utopian vision that would require revolutionary change. Aristotle, more conservative.

The English poet Coleridge famously said, "Every man is born an Aristotelian or a Platonist." He meant that there are two types of people in the world, broadly matching the general attitudes of Plato and Aristotle - some of us always look to some pure ideal place separate to the earth for answers, while others don't trust anything to be real unless they can kick it's tyres.

After their deaths Plato's academy and Aristotle's Lyceum continued under different heads of school with debate continuing alongside other schools of philosophy. Neoplatonism was popular in the late Roman Empire. Aristotle was a major source for Islamic philosophy, and so the development of Natural Philosophy or 'Science' as we know it today, given the focus on method and a full, well reasoned, often causal explanation of the material world.

In Europe the works of Aristotle became available to late Medieval universities through the works of Ibn Sina (Avicenna) and Ibn Rushd (Averroes) who argued for the preservation of philosophical enquiry against religious dogma. Aristotelianism became the standard attitude in European universities until the Renaissance when the Medici family in Florence sponsored a revival of neo-Platonism.

The contrast between the two is reflected in the enlightenment debate between rationalism (Plato) and empiricism (Aristotle).