Program 07 - "Greek Philosophy in the Golden Age"

 

Music Hey.Huh?Hey, look what it says right here.Whaat?It says we owe a debt to the ancient Greeks.Why, did they pass down their national debt to us?No, the cultural heritage of science owes them a debt.What is that a charitable organization?What?That cultural heritage of science thing you were just talking about.

 

MusicSilico: "We're back with Science 122, The Nature of Physical Science,the telecourse that says, 'It's all Greek to me'This is Program 7, 'Athens and the Golden Age,' which correspondswith Lesson 1.7 in your Study Guide."Before we're done with this program we will have studiedthe greatest of all Greek philosophers of the Golden Age.We'll see how Plato combined the moral philosophy of Socrateswith Pythagorean mysticism and wound up asking a really important question.We will follow the contributions of Plato's two outstandingstudents, Euxodus and Aristotle, and we will see how Aristotlesolved the dilemma of circular perfection while synthesizinga system of the world in a web of unity which persisted for 2000 years.Be sure to read these objectives in the StudyGuide and refer to them as you study the lesson.Focussing on the Learning Objectives will help youto study and understand the important concepts.Compare the objectives with the study questions for this lessonto be sure that you have the concepts under control.

 

The Golden Age of Greece centered around the city of Athens,one of several flourishing city states which comprised the Greek republics.From the birth of Socrates in 470 B.C. to Aristotle's deathin 322 B.C., spans only a century and a half.That's a relatively short period of time for a culture,and it's a period during which much change tookplace in our ideas about the physical world.In today's program we'll examine the thread of thought whichculminated in Aristotle's system of the world.A system that was, for 2000 years, the paradigm whichguided the development of three differentcivilizations in Egypt, in the Middle East, and in Europe.So, our story begins with Socrates, the first of the greattrio of philosophers of the Golden Age.

 

The moral philosophy of Socrates marks the beginningof the middle or classical period of Greek philosophy.The Greek civilization centered in Athens.It was at it's peak in Socrates' time, but two generations later,ravaged by war and finally conquered,the Greek civilization had virtually fallen apart.For us, Socrates is important for his influence as Plato's mentor,but also for the tradition of moral philosophyand logical discourse which he began for us.So, have you heard of Socrates before?What can you tell me about him?What is he best known for?Well, his crime was corrupting the youth of Athens.Corrupting the youth.That sounds like a good 20th century sort of thing to do, doesn't it?You see Socrates died from a self administered potion of poisonhemlock having been condemned to death by the state for his crimes.It was basically a case of you're condemned to death.Do you want to do it, or do you want us to do it?Socrates, being a moral sort of guy, chose, basically to execute himself.He executed himself in the presence of his friends and his students.He drank the poisoned hemlock and they sat around while he wasdying with Socrates generating and carrying on a Socraticdialog with his friends and his students.

 

Picture this.I mean, this is really an amazing thing, if you think about it.The great Socrates dying while engagedin a Socratic dialog with his students and friends.If you haven't read this yet, it's in "Plato's Republic."I'll mention this a little bit later on.It's also in the Bibliography in your Study Guide.What Socrates taught was that there are moral principlesof behavior and government, and that governments which did notfollow them were unjust and doomed.You can sort of see why this might have been considered subversive.It's important for us at this time to put Socrates' ideas in context.During much of Socrates' lifetime, Athens was engaged in a seriesof devastating wars, the Peloponnesian warswith Sparta, which was a neighboring city state.Sort of like the United States in the Vietnam war where manypeople disagreed about the morality and about the continuation of the war.

 

History tells us in this case that Sparta was the aggressor.So, Athens and Socrates, were in the position of wondering hownot to make war with someone who keepsattacking you when you don't want to fight them.It's pretty clear that in the midst of such a social crisis thingslike understanding astronomy and the heavensmight lose a little bit of priority.In Socrates' view astronomy simply isn't important, what matters is morality.Out of this belief comes the conclusion that observingthe motions of the planets is a waste of time.Socrates thought that nothing can be learned of planetary motionswithout first knowing the underlying moral principles which govern their motion.In fact, Socrates taught that the physical world issecondary to fundamental moral principles.He asked questions like, "What is moral, and what's ethical?How do we decide what's moral and what's ethical?"The reason behind this was simple.Understanding what is moral and just allows us to be betterindividuals and if we're better individuals, then we make abetter society and the better individuals we are the bettergovern, if we happen to be in that business.

 

Socrates said, in fact, "Know thyself," believing that to bethe most basic kind of knowledge from which all morality was derived.He believed that all knowledge flows from moral principlesand since moral principles reveal knowledge, and knowledge seeks truth.Isn't that a wonderful synthesis?It's a synthesis forged entirely on logic without really any hard data.But, from these same moral principles, accordingto Socrates, we can extract methods for governing wiselyand morally, and we can ultimately achievethe perfect form of government.The trick is knowledge.Knowledge which is obtained through logical discourse.That is, to use principles of logic to draw conclusionsabout the nature of good and truth.Further understanding, according to Socrates,follows deductively from moral principles.Once the underlying principles have been discovered logically,the truth of things like arithmetic and geometryand astronomy will follow naturally.Now this sounds like a good idea when you read Socrates, or whenyou read Plato's dialogues of Socrates.It seems like Socrates had his act together pretty well.But we'll see as we go through the course that this exclusivereliance on deductive logic is a serious weakness in Socrates' argument.

 

OK, so, Socrates was known, among other things, for the Socratic dialog.It's a way of teaching.Basically, Socrates would collect a bunchof students and just start asking questions.And when people would answer questions, he would ask otherquestions, and when someone else would ask questions, he wouldanswer questions with questions.So, the answering questions with questions is an important thingand you're often told not to do this."Don't answer questions with questions."But, it's a great way of probing, because as we'll see also, manytimes asking the right question is the greateststep in finding the right answer.The other thing Socrates would do was to provoke responses.He would often take a devil's advocate role.In leading discussions, and I already mentioned that he wentthrough the Socratic dialog on his deathbed dealingwith the nature of morality and death and that sort of thing.

 

 

 

Now, you're probably wondering at this point,what does all this have to do with physical science.I mean, well, one of the things we see already is that Socrateswithdrew from the physical world and was saying that the physicalworld is of secondary importance.Another reason that Socrates was so against the useof instruments and other tools such as those which might beused in observational astronomy was that the mechanical artswere thought by the Athenians to be fit onlyfor the lower classes and for slaves.Intellectuals and aristocrats were above doing such menial thingsas, you know, building instruments and that sort of thing.Now, if that seems a little strange to you, think of our own societytoday where we sort of have this division of laborinto blue collar and white collar.I think it's safe to say that most people, not everybody, wouldprefer to see their sons and daughters grow up to be lawyersor doctors or some professional or white collar worker than to planon a career digging ditches or a blue collar.Now this is changing, don't get me wrong.I'm not really placing a value on it.I'm simply saying that this is a carryover from the ancient Greeks.Now let's turn our attention to one of Socrates' pupils.That's Plato.

 

Now, we owe much to Plato's philosophy, probably more than to Socrates.In fact, his impact on physical science comes primarilyfrom three areas that we'll talk about today.One of these is his synthesis of a coherent and sensiblephilosophy which combined Pythagorean numerology and Socratic philosophy.The second thing is Plato's allegory of the cave whichprovides for us an interesting model of reality as well asdefining the role of the philosopher as theinterpreter of appearances.The third thing is what we refer to as Plato's question.This is probably the most important of all things.It was Plato's question that fixed the concept of the circularparadigm as the standard for heavenly motionsin Western philosophy for 2000 years.Plato, himself, was a bold and creative thinker.In fact, his intellect probably ranks amongst all genius of all times.He was a renaissance man and a mystic.He was interested in everything.In fact, he wrote about everything.He was not only a philosopher, he was also a teacher, a poet,a dramatist, a prophet, an aristocrat, and a mystic.When he wasn't writing about the nature of reality, or relatingthe dialogues of Socrates, he was writingabout political theory or some other thing.How brilliant he must have been to be able to find complementaryelements in the mysticism of Pythagoras and the moral philosophy of Socrates.

 

At first it might seem like these two things are not really reconcilable.Here's what Plato did:He popularized the ideas of Pythagoras and used those ideasto synthesize what we might call a mathematical philosophy,in which geometry played a central role.He generalized the idea of spherical perfectioninto a circular model of planetary motion, the first modelof anybody that was consistent with the facts.Plato thought that it was the small details which really heldthe truth, not general principles, and he also inheritedfrom Socrates a very low opinion of the physical world.He thought that reality is ideas, while the things that the ideasrepresent, are simply transitory.Plato popularized the ideas of the Pythagoreans concerning themystical and magical nature of numbers and shapes.The idea of perfection was a particularly appealing oneto Plato whether it be physical perfection or moral perfection.The Pythagorean ideals of the perfection of the polygonsstimulated Plato to extend the concept into three dimensionswith his discussion of what we now call the Platonic solids.These are shapes like the cube and the sphereand so on which are made out of the plane polygons.The sphere, for example, is made by rotating a circle, the cube ismade from six squares, joined at their edgeson three perpendicular planes.

 

We'll come back to this a little bit later on when we see therelevance of the Platonic solids in this Pythagorean mysticismthat shows up a little bit later on.So, it's with Plato that geometry truly enters science.The mystical nature of shapes and numbers which occupiedthe Pythagoreans had progressed by Plato's time to a desireto explain the common occurrence of thesegeometric shapes in nature.You recall from the Pythagoreans that they were fascinatedby the fact that numbers and geometry seem to crop upin all these different settings.Plato was really the first person to insist on the perfection of the heavens.

 

Now, a lot of this comes from the combination of the moralperfection of Socrates and the geometric perfection of the Pythagoreans.But at least Plato was the first person who had any intellectualclout who tried to put these together.Plato reasoned that the most perfect orbit of a planet wouldbe circular and it would be moving at a constant speed, like the stars.The constant speed idea comes from the fact that the perfectand unchanging heavens, if they were truly perfect,would not change speeds at all.Perfect also means unchanging, right?Well, Plato's model was the first model that wasconsistent with the facts at the time.Recall that the Pythagoreans had structuredthe universe into three concentric sections.Remember that?There was Uranos at the center and then Cosmosand then Olympos, the home of the gods.But in the Pythagorean model there was no hint at allabout how the planets might actually move within the cosmos.Pythagoreans had just said that the cosmos was wherethe planets were, but there was no hint about the structureof the cosmos, or about how the planets might actually move.

 

OK, so, that's the Pythagorean part.Socrates had linked the concepts of truth and good with his moralphilosophy which sought the truest and most just form of government.The best government was the truest government which wasthe most just and, therefore, contained the least evil.According to Plato truth could be attained only through longand arduous study by mastering all the available details.Remember Plato thought that the details were important.So, Plato inherited from Socrates a low opinion of the physicalworld as appealing to the senses and the senseswere considered to be ultimately corruptible.In other words, it's very easy to fool the senses.Plato, unlike Socrates, thought that you cannot ignore the physical world.Socrates, remember, had put no faith at all in the physical world.Plato recognized that you had to be able to incorporatethe physical world somehow into your philosophy.But, the physical world had somehow to be subservientto the ethical and physical world.In other words, the ethical and moral worlds were firstprinciples and the physical world were second principles,and therefore, following from those moral principles.According to Plato, ideas are the only true reality.

 

On earlier programs we talked about some of the pre-Socraticphilosophers and their concepts of ideas and we'll see how thischanges as we get into Aristotle and subsequentscientists throughout the program.Ideas, according to Plato, are the one true reality.Things come and go.He'd give an example, for example, a particular animal, like a cat,is here for a while and then it's gone.It goes through its life stage and it dies.But the concept of "cat" persists in spite of the birthand death of individuals which that classification fits.Now I want to turn attention to the Allegory of Plato's Cave.From this allegory we begin to get a fairly good idea of whatrelevance Plato really had in this scheme or this thread of ideas.It's in book VII of "The Republic," that Plato relates this allegorywhich defines the relationship between perception and reality,very similar to what we covered in Program 3.The story's come to be known as the Allegoryof the Cave, or simply as The Cave.I want to take a few minutes, a few secondshere to discuss the concept of an allegory first.Then I'll tell you the story.After that we'll look at Plato's analysis of the story whichincludes the dilemma of the philosopher and the heresy of new ideas.So, what is an allegory, exactly?This would be a good word for you to look up in the dictionary,if you don't know what an allegory is already.

 

Let me just leave it at this,and you can research this for yourself.An allegory is a metaphorical story which contains a moral message.In other words, it's a story with a larger meaning.I'm sure you know some of these already.You know the term, "sour grapes," comesfrom the story of the fox and the grapes.You know, the fox can't get the grapes and the bird gets thegrapes, and the fox says, "I didn't want them, they were sour, anyway."Get the moral of the story and so on.The tortoise and the hare is another exampleof an allegory, with a little moral behind it.So, both of these are examples of stories, allegories, which have alarger meaning and from which we can derive some sort of a moral principle.OK, so, here's the story of Plato's Cave.

 

Now, I'm not going to try to relate this exactly the way Plato did,but the situation was that Plato was talking to Socrates,and he was talking about the, trying to define the roleof the philosopher, and he used this Allegory of the Cave as away of getting at the task of the philosopher, or what a philosopher really was.So, it goes something like this:Now, keep in mind, this is an allegory.All parts of this won't necessarily ring completely true to you.But it goes like this:Once upon a time, you have to start all these storieswith "once upon a time," there was a bunchof slaves who were chained in a cave.They were chained in a cave.In fact, they were the third or fourth generation of slavesand they spent their entire life in this cave.Their only contact with reality, the outdoor reality,was through lights which defused into the cave from an openingwhich they could not see because they were chainedwith their backs to that light, staring at a wall on whichthe light from outside defused, coming in through the openingwould occasionally project shadows.The shadows would move and they would appear to movealong the side of the cave wall.The slaves, of course, would sit there with nothing better to doand what do you think they did when they looked at the shadows?Well, we know what we do when we look at clouds and when welook at other patterns in tea leaves and that sort of thing.

 

We try to imagine what those patterns mean.Right?So over the years, over the generations, this groupof slaves had built up an entire idea, an entire paradigm,if you like, about what these shadows meantand about what the outside world was like.You see what we're getting at here?What they had built was a cultural paradigm based upon theirknowledge of the outside world based upon theirinterpretations of these shadows.So then Plato speculates on what might happen if oneof the slaves should, for some reason or another, break freefrom the rest and be able to go out to the outside world.What do you think would happen?Well, here's what Plato talked about.The first thing that happens is, keep in mind the slavesare in the dark in this cave.What happens when you leave a dark room and walk into the light?Sure, you're blinded by the light.The light hurts your eyes and you have to squint for a whileand eventually you can open your eyes and you begin to see in the light.At first the philosopher sees only sort of the guywho escapes sees only these vague images.Eventually he can see in the light, and what he sees is acompletely different reality from anything he has ever imagined.In fact, it's a reality very different from anything thatthe cave dwellers had ever imagined.

 

Now what he's seeing, of course, is those things which make the shadows.So, now we come to the dilemma.What is the dilemma?Suppose you were in this situation.What would you do?You've just escaped from a life in the dark cave.You've seen the light.You now understand things that no one else around you has ever seen before.What do you do?Well, the escapee feels a moral obligation to return to the caveto share his knowledge with the others.Now this is a real dilemma, right?Because on one hand you could say, the slave could escape.He could live the good life.He could incorporate himself into this world.On the other hand, if he did that, he'd be abandoning his fellows back in the cave.So, he knows very well that if he goes back to the cave and tellspeople what he's seen, that they are not going to believe him,because they, after all, have this entire world built up.Not only that, but he knows that if he returns back to the cave,that he'll be immediately rechained and will neverhave the opportunity to escape again.You see the moral dilemma.

 

This bring to mind Socrates, of course, who Plato washaving a dialog with in the first place.But Socrates would be later in life compelled to reveal a truthwhich he had discovered despite the fact that it was necessarilywhat people of the time wanted to hear.So, Plato goes on then to elaborate on the duty of the philosopherto enlighten his fellows even at the risk of one's own safety.And recall, once again, that Socrates lived up to his ownideals and eventually died for them.So, there are several messages here.What are the moral messages?Well, there are several things.One of the things that Plato relates.He tells Socrates, and this is a quote, "Bewildermentsof the eyes are of two kinds, and arise from two causes,either coming out of the light or from going into the light,which is true of the mind's eye, quite as much as of the bodily eye."The first thing that happens when the philosopher goesback into the cave is that he can't see.

 

You know, when you're in the dark and you come back into light,you come back into the dark room, it takes your eyes a while to adjust.So Plato's getting at the point here that when you see thingswith different eyes, you see them from different perspectives.He goes on to caution Socrates that when we are blinded,it's a good idea to know which kind of blindness we're dealingwith, whether we're dealing with coming out of the darkinto the light, or coming out of the light into the dark.Doesn't this sound quite a bit to you like our modernview on paradigms and perceptions?Like we talked about last time?We might paraphrase the statement simply by sayingthat there are two different kinds of blindness,and we have to know which one we're dealing with.Well, here's the gist of the story now.When this philosopher gets back into the cave, he relatesto the other slaves who were chained there.Well, of course, first.

 

First, of course.I can't say this.At first, of course, that's easy for you to say, he's rechained and shackled.He then relates to the other fellows what he had seen.What do you think their reaction is?Think they said, "Oh, wow, a whole new world out there!"No, of course not.The first thing they say is that he's eyes have been damagedby the light and he's having hallucinations. Because, of course, this disagrees entirely with what they believe.After he's able to convince them that he really saw the thingsthat he saw, then they feel threatened.His ideas, in fact, are seen as disruptive to the society,they're heretical and they're threatening.And, in fact, the others say that they would just as soon killhim as risk the opportunity of going out into the lightand having suffered what he suffered.You see the message here.In Plato's philosophy the philosopher has this moralobligation to tell people what he's discovered even knowing thatthey will not like it and that they might not agree with it.(Crunch.)It's time for another "Food for Thought."Are truth and reality the same thing?Suppose we speculate as food for thought that truth is what webelieve, while reality is what is.What do you think about this?Can you write about it?Imagine the situation where you're writing a letter to your bestfriend about another friend whose life is a littlemessed up right now because of this confusion.

 

After the story of the Allegory of the Cave,Plato and Socrates go on to discuss the meaning of it.What emerges from that dialog is a working definition of what itis that makes a philosopher a philosopher.In Plato's words, "It's to determine the truth behind the appearances."You see, once you have the distinction between truthand reality under control, then comes the problem of findingthe relationship between the shapes or the shadowsor between the reality and the truth.Plato called this the truth behind the appearances.Here's the shadows, for an example.Suppose you see a shape on the wall which looks like a rabbit's head.Does this necessarily mean there's a rabbit nearby?No, I don't think so.It might be someone doing shadow tricks with their hands.We've all done this.So, even though the appearance is that of a rabbit, the truth behindthe appearances is that there are other shapeswhich can cast shadows that look like rabbits.So when we speak of "saving the appearances" we mean, simplyto understand what we perceive by somehow transforming itinto what we know to be true while at the same timenot violating any known principles.

 

Now this is pretty easy to do for the rabbit's shadowbecause we know how it's done.In fact, we have to know how it's done in order to do it in the first place.With the physical universe it's a different story.With the physical universe we're seeing the shadow first,and then trying to figure out how it's done.It does kind of seem like magic, doesn't it?Now a good magic trick is really just an illusion which isimpossible to figure out, but reasonably simple to perform.Now in the case of planetary motion, any geometric modelof perfection must somehow yield the motions thatwe see against the celestial sphere.According to Plato, we must know it by using logical arguments,and those logical arguments must be basedupon geometry, logic, and moral principles.

 

The motion of the planets in this context now presents a problem.Here's why.On one hand, the planets are heavenly and, therefore, they're perfect.On the other hand, they move in uneven paths across the fixedstar background, occasionally doing these irregular retrograde loops.Not perfect.So how do you explain that perfect things likethe planets behave in this imperfect way.Plato referred to this as "an offense that must be explained away."I want to point out here that the Pythagorean truth of perfectcircles is not simply taken for granted in Plato's philosophy.It was derived by discourse just as Socrates thought him to do.Like Socrates, Plato also believed that truth could be obtainedby logic, but he added the idea of reality of geometry and numbers.So, here's the logic, in somewhat condensed form that leadsto the concept of the truth of uniform circular motion in the heavens.This is an important concept because the circular modelfor planetary motion is something's that stayed around for a long time.

 

OK.Here's the way it goes.Since perfect numbers and mystical relationships areknown to exist, and polygons form the basis for all shapes,and polygons have certain hints of perfection in their symmetry,and the circle is the most perfect polygon,it seems only logical to conclude that if numbers in geometryare perfect and reality is geometry and numbers, then reality must be perfect.One more time.If numbers in geometry are perfect, and reality is geometryin numbers, then reality must be perfect.So, Plato's logic led him to the idea that as the Pythagoreansbelieved, the heavens are perfect.So, now we have this situation.Although the planets move erratically in retrogrademotion, they are, nonetheless, perfect.This is a major problem and we'll come back to it in a few minutes.As far as imperfection here on earth and how that fitsinto a perfect universe, we'll save that problem for Aristotle to solve.He solved it very well, but in the process he createdprobably more problems than he solved.But, there I go, getting ahead of things again.

 

OK.So, if the heavens are perfect and the circle is perfect,then the logical conclusion is that the heavens are circular.That make sense?So, if we accept, for whatever reason, Plato's logic that theheavens must be circular, then we have the problem of explainingaway the irregular motions of the planets.Plato, himself, could not explain away this offense.He simply recognized that it needed to be solved in orderto have a logically integrated universe.So how might we explain away this quandary?How do you take perfect things like planets and make them behave imperfectly?Consider shadows, like those seen by the slaves in the cave.Isn't it possible that shadows of perfect things might bestretched out of proportion in the right light?The shadow of a sphere need not be a circle.In fact, you can try this with a flashlight and a marble.Cast the shadow of the marble, and what shapes do you see?Certainly only under certain circumstances do you see circles.

So, from our perspective, in this case, seeing both the marbleand the flashlight, we can easily see how the shadow tells usthe shape of the object, only if we understandthe concept of the shadow, but not before.Suppose we saw only the shadow of the marble and knew nothingat all of the shape of a sphere or the properties of light?So, although Plato could not solve the problem, he did pose thequestion in a way which might lead to an answer.And this, again, is often one of the most important steps in solvinga problem, simply posing the problem in such as way that it does lead to an answer.

 

We will call this particular question, Plato's question.The search for a solution to this problem by Plato's students,Euxodus and Aristotle, established the circular paradigm.Although the reasons for the circular paradigm were longforgotten or at least ignored by Ptolemy's time, three or fourhundred years later, in the second century A.D., the magicof the circle continued to influence the cosmologyof Western thought until the 16th century.Breaking the circular paradigm was even more difficult thanabandoning the idea of geocentrism.So, here is Plato's question."What uniform and ordered circular motion must beassumed for each of the planets to accountfor its apparently irregular yearly path?"Now this question, I'm going to repeat it again in a minute.But this question influenced Western thinking and physicalscience probably more than any single ideauntil Newton's theory of gravity in the 17th century.Ok, here's the question again.What uniform and ordered circular motion must be assumedfor each of the planets to account for its apparently irregular yearly paths?Plato's question.

 

Now it seems like such a simple question, and it really is.But simple questions do not always have simple answers.In fact, the best simple questions are those which strike somefundamental cord and drive the questioning of human minds for millennia.Plato's question is one of those.Although Plato couldn't solve this problem,he did set forth the charge for astronomers.Charge for astronomers is simply to explain the motionof the planets as we observe them from earth in termsof perfect circles at uniform speed.The uniform speed's important, right?Because if something is changing speed, then it's not perfect.

 

One of Plato's students named Euxodus, around 400 B.C.,used his skills with geometry to envision a model which couldexplain the erratic motions of the planets while still allowingfor perfectly uniform and circular motion.When we talk about Euxodus building a model, it's importantto keep in mind here that this was a mental model.Good well education Athenians would never think of goingwith their hands and actually constructing a physical model.I think you've got to appreciate the level of mathematic abilityand mathematical reasoning that goes into evena simple solution like that of Euxodus.Euxodus' model was homocentric and concentric.Homocentric means spheres sharing a common center.Concentric means spheres inside one another.So, we have spheres inside spheres sharing a common center.And in Euxodus' scheme the center was earth.OK, it was a geocentric scheme.

 

The model, you see a picture on the screen now, consistedof circles which could rotate, sort of like a coinspinning upright on a table.Each of the circles in Euxodus' system fitsinside another, but it was free to spin on an axis thatcould be oriented in any direction.So that by combining the motions of the various spinning circlesand by putting planets on some of the circles which werethemselves also on circles, Euxodus could roughly recreatethe apparent motions of the plants as seen from earth.As it turns out, it's possible to create just about any kindof motion using homocentric spheres like this.Euxodus was really the first person to recognize this.The interesting thing about the model is that it took 27 spheresto describe the motions of five planets.Did I say five planets?It's actually seven planets if you count the sun and the moon in there.Not all of the spheres obviously contain planets.Some of them were simply used as rotational devicesto keep the other planets moving.

 

So, are you having trouble visualizing this?Even with the picture, it's pretty difficult, isn't it?So, again, you have to appreciate the mind of Euxodus who wasable to take basically the shadows, the motionsof the planets and build this model which savesthe appearances in the best platonic way possible. In fact, the model predicted the actual positions of the planetsto an accuracy as good as anyone could attain in thatday without instruments or telescopes.And keep in mind that those things, instrumentsand telescopes, weren't invented for hundreds of years.In the case of the telescope, it was almost 2000 years.So, the spheres of Euxodus were importantto our journey down the river of time for two reasons.First, it represents the first explanation which considers themotions of the heavens as purely mechanical and geometricwith no mysticism or myth involved.Second, it's reductionistic because it separates the conceptof motion from the cause and removes the causein order to understand the shapes.Separating the two concepts, that is, the principles and the shapesand the cause, marks a major change in the perceptionof the heavens and in the perception of physical science in general.

 

Of all the classical Greek philosophers of the Golden Age,none has had more influence on the developmentof physical science than Aristotle.Aristotle was a student of Plato.He was also the tutor of Alexander the Great, who becameKing of Macedonia when he was only 20 years oldand in the 13 year reign extended his influence allover the known world all the way to India.Alexander's father was Phillip of Macedon who invadedand subsequently united the Greek city states.I hate to say this, but it was largely responsiblefor the demise for the Greek culture, although the stateshad been at war with each other for many years.Somehow the invasion just put the final cap on it.The effect was devastating, and Phillip's empire literally fellapart after Alexander's death in his early 20s.See, Alexander was a great conqueror and a great soldier,but he was a really lousy administrator, and he didn'treally have that tight a hold on the empire to begin with.But we're getting a little bit ahead of things here.But a glimpse into the crystal ball like this convinces us that thismarked the end of the Golden Age with the deathof Aristotle and with the death of Alexander.

 

Aristotle was not only a philosopher, he was anobserver as well as a thinker.Unlike Socrates and Plato before him who found observationsto be unreliable and deceptive, Aristotle saw great valuein observing and understanding the behavior of matter both hereon earth and in the heavens, although he still subscribedto the moral philosophy of Socrates and the logical reality of Plato.Unlike his predecessors Aristotle insisted on a unified universe.The word, universe, means unified.One reason that Aristotle became the ultimate authorityon everything was that he was prolific.He wrote a lot of books.Many copies were lost, but many copies also survivedto be rediscovered in Europe a thousand years later and reread.We'll have more on this later.

 

See, Aristotle wrote on just about everything.Like Plato, except he was more physical.Aristotle wrote treatises and essays on just about every topicyou can think of, physics, chemistry, biology,meteorology, logic, metaphysics,mathematics, ethics, politics, poetry, you name it.Someone said that Aristotle may have been the last,if not the only, person whoever completelyunderstood the world he lived in.What do you suppose that means?Do you think any of us really understands the world that we live in, completely?The word here is "completely."Aristotle made a lot of errors and one of the greatest errors thathe made was the assumption that biology is the most basic science.

 

Now today we believe that biology, that biological processes obeythe laws of chemistry and physics, and many biological processescan be explained using the models of the physical sciences,things like genetics, biochemical reactions, use the ideasof physics, specifically those of atoms and the entities of energy.Aristotle argued, on the other hand, that physical and chemicalprocesses obeyed the laws of biology.He just wasn't clear on what those laws of biology were.There's an interesting twist on the paradigm,because today we consider physics and chemistry to be the most basic sciences.Plato's other student, Euxodus, had proposed this model,the homocentric model, which answered Plato's Question,it was not a totally satisfying modelto Aristotle because it was incomplete.Euxodus' model had no explanation for the causeof motion and no connection between the motion of one planet and another.Aristotle's refined version of Euxodus' spheres connected themotions of the planets to one another, just like a gear train.The whole system was driven by what Aristotle called "imponderable" which he called the Prime Mover,meaning the first principle of motion.

 

So, what exactly does it mean to be imponderable?Why don't you ponder that for a few minutes and I'll come back to it later.So, the idea here is that in order to produce the right motions,using the homocentric spheres of Euxodus, but also connecting allthose motions together, Aristotle had to add extra spheresof different sizes, turning at different speeds,sometimes even turning in different directions.In fact, Aristotle's system required a total of 56 spheresto account for the motion of seven heavenly objects,the sun and the moon and five planets.That's about eight spheres per planet.Now this doesn't really seem like a simple model.Eight spheres per planet?Fifty six to describe the whole thing?If the idea's simplicity?Try to imagine the mind required to see this,this whole connected thing, in a way that made senseto Aristotle, and then imagine trying to explain it in writingso that others could make any sense out of it.

 

 

Now try to imagine doing this without ever really buildinga physical model, and without a calculator, or for that matter,without the use of numbers as we know them today.It didn't come around until very late in the mid 500s or so.So, I want to take a minute here.I used the word Aristotle became the final "authority" a few minutes ago.What does it mean to be an "authority?"Some people would say that authority has to do with power.But what's the difference between power and authority?Does it mean like the authority you said ordered an evacuation?But see, authority can also mean that you no longer have to thinkbecause someone has already made decisions for youand decreed what you're supposed to think.It often happens when social order breaks down,and a certain idea becomes the authority.The person or persons who are responsible to do theinterpretations of the meaning and make judgmentsabout the compliance and so forth of rules, become the authoritiesbecause they are linked with this political power.And we'll see that Aristotle's authority, indeed, becamelinked with the political power of the Church which provided avery strong hold on people's minds and on social order and that sort of thing.

 

OK.So, Aristotle introduced a concept of a world system whereeverything is linked to everything else.In Aristotle's world view there were no separate areasof knowledge and no separate sciences.Everything had to be connected to everything else.He built a world, in fact, which was in harmony with every other part.Harmony is a nice Pythagorean word.He took the elements of earlier ideas and synthesized aremarkably consistent, coherent and unified system.He defined matter as the true reality in a universe of fiveelements in concentric spheres modeledafter the Pythagorean model of the universe.Aristotle's model had the five planets moving in homocentricharmony like the gears in a giant machine, made of substanceswhose souls determine their behavior.He gave us theories of motion which explains why planetsmove and why rocks fall and why fire rises.Although his system does contain many weaknesses and manyerrors it's the most detailed synthesis ever completedand became THE world view of Western civilization,influencing the growth and development of three separatecultures over more than 2000 years.That's quite a statement, I think.It gives us an idea of how powerful Aristotle's ideas must have been.

 

 

So, in Aristotle's universe there's a sharpdistinction between the earthly and heavenly realms.It differed in this way from the Pythagoreans.The Pythagorean universe had no cause, no properties and no connections.It simply had a structure.In Aristotle's scheme the heavenly and earthlyrealms were different from one another.In fact, they contained different kinds of matter.The heavenly realm was perfect and unchanging,except for its circular motion which is appropriately perfect.But the sublunar realm, that's between the earth, I should say,under the moon, was corruptible, was imperfect.Here change took place in an attempt to gain perfectionaccording to the qualities and desires of different substancesto attain the concentric and perfect circular symmetryof the rest of the universe.

 

Now, in Aristotle's view, that perfection was never attainedhere in the earthly realm, but changes were constantly takingplace to try to attain this sort of perfection.So, in Aristotle's scheme the planets moved in the Cosmosaccording to the geometry of Euxodus.He modified this to allow for the connection, but the idea wasbasically the same, with the addition of the conceptof the Prime Mover, the first cause, or the cause or motion.In Aristotle's scheme, it's the properties of substances whichdetermine their behavior and their motion.Rocks fall through air because they contain a high percentageof earth and so they move toward their rightfulplace of earthly things at the center.Air bubbles rise through water because they want to attaintheir place in the sphere of air which lies above the sphere of water.And for the same reason, fire rises through the air to attainits natural place in thisfour-tiered structure, earthat the center, then water, then air and then fire, and finally,the moon and beyond that the Cosmos.Consider combustion.I mean, this really makes good sense.Combustion is a type of change which we would call today a chemical change.And it took place in Aristotle's view because the elementswhich made up the substance that was combining or combustingwere simply trying to escape and attain this universal perfection,a state of perfection and purity, if you like.This makes good sense, though, doesn't it?I mean, it's amazing to me that anyone, Aristotle or anyoneelse, could think through such a consistent and logical systembased on so real little knowledgeof the world.

 

So let's look at combustion again now.What exactly is combustion?In modern terms we would say that what happensduring combustion is that molecules of carbonand hydrogen and other volatile substances combinewith oxygen and form new substances like water and carbon dioxide.How would Aristotle view this?Well, Aristotle would say that the combustion is a breakdownof the wood into its constituent elements.In other words, the wood is releasing its constituent elements.Fire, of course, is given off when the wood burns,leaving behind ashes which represent the earth.Not a pure form of earth because purity, complete purity never happens.But, also, the smoke is given off.Smoke is, in Aristotle's view, sort of imperfect airand sure enough, the smoke will dissipate into the airand eventually become visible.The water particles is a little harder to see, but you do knowthat if you breathe on your eye glasses or if you breatheon a glass, or if you hold something cold like porcelainor glass over a fire, water vapor will condense on it.

 

OK.So, we'll study Aristotle's theories on motionin much more detail later on in the course.But we need to get a brief overview now of how this works.We also can begin to get a glimpse of how well Aristotlesynthesized and integrated this remarkably consistent world view.So, Aristotle's world view combined, then, elementsof Pythagorean Mysticism, Milesian views on matter,the moral philosophy of Socrates and Plato's mathematical philosophy.Like the Milesians before him, notably Thales and Anaxagoras,Aristotle considered that matter was the true reality of the universe.This is opposed to Plato who thought ideas were realand Socrates who thought that morality was real,and other people who thought that other things were real.Aristotle noticed as many of us have that the dominantthing in the universe is matter.This approach to the nature of reality was a radical departurefrom Socrates and from Plato, and marks one of the, I guess youmight say, Aristotle's preference for bringingthe physical back into the world.

 

So, Aristotle adopted the ideas and suggestionsof the early Milesian philosophers that the basic stuff of matterwere the four elements, earth, air, fire and water.But, to this he added a fifth element, which he called quintessence.Because, after all, if you have a universe in which the imperfectstuff lies in one place and the perfect stuff lives in anotherplace, then the perfect stuff has to be different from the imperfect stuff.So quintessence comes from the word "quint" which means five,and "essence" which means essence.So, in essence, the quintessence was the fifth element.So, not only were there these four elements, earth, air, fireand water, but in Aristotle's scheme there were also qualities of matter.Things like hot, dry, wet and cold, which determinedthe actual nature of a particular substance.For example, in Aristotle's scheme, fire was consideredto be the ideal combination, or the ideal manifestationof the qualities of hot and dry.And by adding, Aristotle said, by adding wetness, for example,to fire you might create something which is little more watery,and eventually, when you reach something that's wet and cold,then you wind up with the substance called water.

 

We'll return to this concept a little bit later in the coursewhen we study the chemical properties of matter.But, you see, the whole idea is that chemical reactionsand matter, changes in matter which take place here on earthare all striving to gain this universal perfection whichexists, according to Aristotle, every place in the world exceptright here in this sublunar realm.So, in Aristotle's scheme, you see, things never are completelyseparated, so things also means slightly imperfect, so there'salways some motivation for change to keep on occurring till the end of time.The physical structure of Aristotle's universe wasslightly different from, but derived from the Pythagoreanspheres, Uranos, Cosmos and Olympos.

 

The structure seemed ready made for Uranos, that's the earthlyrealm in the Pythagorean scheme, to be divided further into thesesmaller spheres, one for each of the four elements.So, Aristotle's realm was also concentric, but the earthlyrealm consisted of four layers instead of onlyone, one each for the four elements.And then the heavenly realm contained the five planetsmoving in the spheres like Euxodus' spheres that Aristotle had modified.OK.In Aristotle's view, motion of any kind required a motivational cause.And again, we'll discuss these in somewhat moredetail when we get into Galileo up in Section 3.Things do not move without reason or cause.Think about this.You're sitting at home alone, late at night.It's very quiet and the room is dark.Suddenly, a chair across the room starts rattlingand sliding slowly across the floor.

 

So what do you think?You say, "Oh, there's a chair moving across the floor allby itself, nothing pushing it, OK."Well, probably not.You probably would expect that if the chair ismoving, then something is moving it.In fact, if furniture suddenly starts to move itselfspontaneously around the house, most of us would startthinking there's something really weird going on.So, it takes something to cause motion and, in our experience,if you do push a chair across the floor, it stops movingafter you stop pushing on it.Its cause of motion having been removed.So, according to Aristotle, motion in nature, such as when thingsfall to the earth, is caused by the desire of each substance to findits natural place in the universe, the place where it belongs.This is intimately tied in with the moral philosophy of Socratesand Aristotle's own explanation about the nature of matter beingcomposed of four earthly and one celestial substance.

 

You see, in Socrates' system men, by knowing moral principles,could gradually work on themselves to become more perfect.And in coming more perfect, they would help to create a more perfect universe.So don't you see that in Aristotle's idea here?He's taking the same sorts of ideas and saying that thephysical universe operates on the same principles.But the physical universe also tries to attain,due to the nature of the souls of the substances,tries to attain this type of perfection.So, in the scheme, disorder and chaos in the sublunar realmrepresents, in Aristotle's view, the imperfection of man.I mean, after all, we know that people are imperfect, right?So, again, there's a connection betweenthe moral aspects of man and the desires of the objects.Natural emotion, in Aristotle's scheme, takes place so thatthe elements can attain their rightful locations in the concentric spheres.The difference is that in Aristotle's scheme, the perfectuniverse, earth would be at the center, then water, then air and fire.You know, this makes a lot of sense.And it's really, really a very good theory.And again, Aristotle's elements were never seen in their purestate, but always combined into imperfect mixed substances.That's the fate of the sublunar realm.Just like people, we might strive for perfection, but will neverreach it whether we're human or inanimate.

 

So, the idea of quintessence was necessary, obviously,since the planets and other heavenly objects were perfect,they could not be composed of the base matter that madeup the sublunar realm, but even they required a cause to remain in motion.Aristotle assumed that there existed this imponderablePrime Mover, that I mentioned earlier, who moved the heavensalong though a series of mechanical linkages whichwe as mortals were incapableof understanding,and so, therefore, should not even try.That's why it was imponderable.Is that a cop out?Yeah, I think it is.I think, you know, you get to the point where the ideas are justtoo complicated and you need this thing so you just say, "OK,

 

 

 

I'm going to call this imponderable, we're going to assume it exists,and we're not going to think about it any more."And I think this is sort of like painting yourself into an intellectual corner.But, you know, what comes to mind to me is the imageof a Supreme Being, this god-like creature standing up there,the Prime Mover, turning a crank, perpetually, turning the crank.Which is kind of interesting, you know, because in the Athenianscheme of things, things like turning cranks were consideredto be menial tasks, even beneath the dignityof an educated, aristocratic Athenian.So it seems kind of funny that Aristotle would give you thisvision of the Supreme Being, the Prime Mover, engaging in this blue collar activity.I think you can see that, or you can anticipate that in the Christianworld, this is not a very nice model of God.The idea that the Christian God has to spend the entire eternity turning the crank.I mean, you know, couldn't he find some lesser creature to do that?Well, we'll get into that.Again, I'm getting ahead of things a little bit.So, in Aristotle's scheme, then, other types of motion weredifferent from planetary or natural motion.We will return to a study of those a little bit later in the course.You know, it seems almost impossible to us,from this platform of high technology that we have,that someone did not see through Aristotle'serrors and his weaknesses sooner.But remember, a paradigm partly determines truth.

 

A paradigm influences what we see.We are more likely to expect what we expect to see, I should say,we are more likely to see what we expect to seethan what we do not expect to see.So, when this whole model of circular perfection and all thisbecame ingrained so deeply into the culture,that people just simply could not see through it.Though there are many weaknesses to Aristotle's model that we cannote with the 20/20 vision of our two millennia hindsight,we won't take the time to detail them all, but you might wantto take a few minutes to look over them.It's not really the weaknesses that we want to concentrate on.What we're interested in is the fact that even with thoseweaknesses, and some are significant, Aristotle's theoryhad such power and carried such weight in resolving questionsabout the nature of physical reality.In fact, the underlying assumptions behind the theoriesand their philosophical justifications were all but lostby the beginning of the Christian era, 300 years after Aristotle.This, in part, is due to the rapid decline of the Greek culture,at least the Greek culture in Greece, following the deathof Alexander, and the death, less than a year later of the teacher, Aristotle.

 

So, despite the obvious weaknesses, Aristotle's ideasnot only survived, but became a THE system of the worldand influenced development of three separate cultures over 2000 years.We can only speculate on what might have happened had thetraditions of the Golden Age of Greece continued into subsequent generations.But, it didn't happen that way.As it was, the intellectual center of the Western world shiftedto Alexandria, across the Mediterranean, the newcity of the future built by Alexander.In honor of himself, actually.So, here, for another 400 years, Greek science evolved whilethe ideals of morality in the Golden Age faded into the memories of the past.

 

So, our next program is about the Hellenistic period of Greekculture in Alexandria and the change in Greek science during those times.Well, you know, Aristotle's ideas were full of a lotof misconceptions, and even though they influenceddevelopment, he painted himself into lots of philosophicalcorners, and sometimes gave reasons like imponderableswhich were cop outs, or which seem almost in desperation.

 

So, in this program, we've seen how the ideas of Pythagoras,Socrates, Plato and Euxodus were synthesizedinto a unified system of the world by Aristotle.Using the idea of concentric circles and homocentric spheresalong with the theory of motion with the attainmentof perfection as motivating force, Aristotle's theory of everythingserved as a model for understanding the universe for 2000 years.Well, there are many questions posed in this program,in this lesson, that's fuel for your writing efforts.So, sit down now and write out some of your thoughts.Submit something to us within one week of viewing the programto earn points toward the course grade.Well, I guess that's it.Time has run out on another program, so remember,when it comes to science, get physical.Bye.You know you've been really very quiet.Are you OK?You haven't said anything the entire program.Silico: "I'm awake, but this stuff is all Greek to me."Music