Spielberg & Anderson 23-25; 29-30
Booth & Bloom 7-11
1. What are moral principles? Describe one.
2. Why did Socrates think astronomy was a waste of time?
3. According to the allegory of Plato's cave, what is the task of the philosopher?
4. What did Plato mean when he spoke of being 'reverse of blind'?
5. What did Plato mean by "saving the appearances?"
6. Why did the Greek philosophers insist that heavenly motions must be circular?
7. What is "Plato's Question" and why is it relevant the study of science?
8. What is the "Prime Mover?"
9. What were the four prime substances of Aristotle? What is quintessence?
10. How did Aristotle's system differ from Euxodos'
Here are the objectives for today's lesson.
Before you begin to study the lesson, take a few minutes to read the objectives and the study questions for this lesson. Try to connect the objective and the questions with ideas.
Look for key words and ideas as you read. Use the study guide and follow it as you watch the program.
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Be sure to read these objectives in the study guide and refer to them as you study the lesson.
Focusing on the learning objectives will help you to study and understand the important concepts.
Compare the objectives with the study questions for the lesson to be sure that you have the concepts under control.
I. Socrates and Moral Philosophy
II. Plato's Cave Allegory and Plato's Question
III. Euxodos and Homocentric Spheres
IV. The Philosophy of Aristotle
V. Aristotle's System of the World
Before we're done with this program we will have studied the greatest of all the Greek philosophers of the golden age. We'll see how Plato combined the moral philosophy of Socrates with Pythagorean mysticism and wound up asking a really important question. We will follow the contributions of Plato's two outstanding students, Euxodos and Aristotle. and we will see how Aristotle solved the dilemma of circular perfection while synthesizing a system of the world in a web of unity which persisted for two thousand years .
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 death in 322 B.C. spans a century and a half, a relative short period of time for any culture, and a period during which much change took place in our ideas about the physical world. In today's program we will examine the thread of thought which culminated in Aristotle's system of the world, a system that was, for two thousand years, the paradigm which guided the development of three different civilizations in Egypt, in the middle East, and in Europe.
Our story begins with Socrates, the first of the great trio of philosophers of the Golden Age.
The moral philosophy of Socrates marks the beginning of the middle or classical period of Greek philosophy. The Greek civilization centered in Athens was at its peak in Socrates' time, but two generations later, ravaged by war and finally conquered, had virtually fallen apart. For us Socrates is important for his influence as Plato's mentor but also for the tradition of moral philosophy and logical discourse which he began.
What can you tell me about Socrates? What is he best known for?
His crime was corrupting the youth of Athens. He was sentenced to death but given the choice of suicide or execution. He chose suicide.
Socrates was not a writer, in fact there are no known writings by Socrates at all. We know of him only through Plato's dialogues and other stories about him. He was famous for his teaching methods which involved dialogues of question and answer, with each answer leading to another question, eventually unfolding truth and instilling virtue in the student.
He was seen as a threat to the stable government of Athens for his opposition to war, and because of his teachings which advocated the overthrow of unjust governments. Socrates died from a self administered potion of poison hemlock having been condemned to death by the state for his crimes.
"You or us," was the sentence of death. Socrates chose to execute himself.
He carried on a Socratic dialogue with his friends and students after drinking the hemlock. This is reported by Plato in his dialogues and gives much insight into the character of Socrates.
Socrates taught that there were moral principles of behavior and government, and that governments which did not follow them were unjust and doomed.
It's important to put Socrates' ideas in context. During much of Socrates lifetime Athens was engaged in a series of devastating wars (the Peloponnesian wars) with Sparta, a neighboring city-state.
Like the United States in the Vietnam era, citizens disagreed about the morality and continuation of the war. History tells us that Sparta was the aggressor, so Athens, and Socrates, were in the position of wondering how to not make war with someone who keeps attacking you when you don't want to fight.
It is clear that in the midst of such a social crisis, things like understanding the heavens might lose priority.
In Socrates view, astronomy isn't important, what matters is morality. Out of this belief comes the conclusion that observing the motion of the planets is a waste of time. Nothing can be learned of planetary motions without first knowing the underlying moral principles which govern their motion.
Socrates taught that the physical world is secondary to fundamental moral principles.
What is moral and what is ethical? How do we know?
Understanding what is moral and just allows us to be better individuals which make a better society.
Socrates said "Know Thyself," believing that to be the most basic kind of knowledge.
3.5.1. all knowledge flows from moral principles
He believed that all knowledge flows from moral principles since moral principles reveal truth and knowledge seeks truth. This is a brilliant synthesis forged of logic, and optimism. Unfortunately for Socrates it was not very popular.
3.5.2. knowledge is necessary to govern wisely, morally
From these same moral principles we can, according to Socrates, extract methods for governing wisely and morally and can ultimately achieve the perfect form of government. The trick is knowledge, which comes from discourse through question and answer, the Socratic method.
Ethically and morally speaking, goodness equals truth. According to Socrates, truths are obtained through the use of logic to draw conclusions about the nature of good and truth.
Further understanding, according to Socrates, follows deductively from moral principles once they have been discovered through logical discourse.
Once the underlying principles have been discovered logically, the truth of arithmetic, geometry, and astronomy will follow naturally. This is why astronomy and the other sciences were considered to be a waste of time.
Another reason Socrates was so against the use of instruments and other tools such as might be used in observational astronomy was that the mechanical arts were thought by Athenians to be fit only for the lower classes and slaves. Intellectuals and aristocrats were above doing such menial things.
If this seems a little strange, we still carry this with us today twenty-five hundred years later. Think of our division of labor today into white and blue collar work.
Plato was a student of Socrates. He is responsible for nearly all of our knowledge of Socrates. Much of Plato's writings consist of dialogues with Socrates. They dialogues themselves may be fiction, but there is little doubt that they reflect Socrates' ideas and not Plato's.
Although we owe much to Plato's philosophy, his impact on physical science came primarily from three areas. One is the synthesis of a coherent and sensible philosophy which combined Pythagorean numerology and Socratic philosophy. Second is the allegory of the cave which provides an interesting model of reality and defines the role of the philosopher as interpreter of appearances. The third is what we refer to as Plato's question, which fixed the circular paradigm as the standard for heavenly motion in western philosophy for two thousand years.
Plato himself was a bold, creative thinker. His intellect ranks among greatest geniuses of all time
He was a a renaissance man and a mystic. He was interested in everything, and wrote about it. He was not only a philosopher, but also a teacher, poet, dramatist, prophet, aristocrat, and mystic. When he wasn't writing about the nature of reality, or relating the dialogues of Socrates, he was writing about political theory or some other subject.
4.1.1. philosopher, teacher, poet, dramatist, prophet, aristocrat, mystic
How brilliant to have been able to find complementary elements is the mysticism of Pythagoras and the moral philosophy of Socrates. Here's what Plato did:
He popularized the ideas of Pythagoras and used that to synthesize a mathematical philosophy in which geometry played a central role. He generalized the idea of spherical perfection into a circular model of planetary motion, the first model that was consistent with facts.
Plato thought that it was details which held the truth, not general principles and inherited a low opinion of the physical world from Socrates.
He thought that reality is ideas, while the things that the ideas represent are transitory. A particular object, like a chair, is built, used, and eventually falls apart. Meanwhile the concept or idea of a chair exists containing the set of all possible chairs. Therefore, according to Plato, the idea represents the greater reality while individual chairs are only transitory objects and serve to illustrate examples of the category, chair.
4.2.1. popularized ideas of Pythagoras
Plato popularized the ideas of the Pythagoreans concerning the mystical nature of numbers and shapes. Because of his association with Socrates and his moral philosophy, the idea of perfection was a particularly appealing one to Plato whether it be physical or moral perfection. The Pythagorean ideals and the perfection of the polygons stimulated Plato to extend the concept into three dimensions with his discussion of what we now call the Platonic solids. These are shapes such as the sphere and cube which are made out of the plane polygons. The sphere is made by rotating a circle, the cube is made from six squares, joined at their edges on three perpendicular planes. These platonic solids will return to play a role in Kepler's analysis of planetary motion in the seventeenth century, more than two millennia later.
4.2.2. created "mathematical philosophy"
Plato adopted the Pythagorean ideas and ideals, but took it quite a bit further, introducing what might be called a mathematical philosophy. Combining the logical discourse and moral philosophy of Socrates with the mathematical mysticism of the Pythagoreans created for Plato a new world view, more encompassing than ever before.
4.2.3. geometry enters science
It is with Plato that geometry truly enters science. The mystical nature of shapes and numbers which occupied the Pythagoreans had progressed by Plato's time to a desire to explain the common occurrence of geometric shapes in nature. Questions such as, "Why do numbers have certain properties," and "Why does nature mimic geometric shapes," were answered by Plato in moral terms by applying the Pythagorean concept of perfection.
4.2.4. spherical perfection --> circular orbits
Plato was really the first to insist on the perfection of the heavens. At least he was the first to leave massive written records that had intellectual clout.
Plato reasoned that the most perfect orbit of a planet would be circular and at a constant speed, like the stars. The constant speed idea comes from the idea that motion is a constant, while change in motion is not constant.; unchanging heavens would not change speeds.
4.2.5. first model consistent with facts
Plato's model of the heavens was the first that was consistent with the facts known at that time, and also consistent with the moral principles of Socrates. Recall that although the Pythagoreans had structured the universe into three concentric spherical sections, there was no hint in that model as to how the planets might actually move within the cosmos, nor that the motions of the planets themselves were circular and perfect.
4.2.6. knowledge attained by long and arduous study through mastery of details
Socrates had linked the concepts of truth and good with his moral philosophy which sought the most just and therefore truest form of government. The best government was the truest government which was most just and therefore contained the least evil.
According to Plato truth could only be attained through long and arduous study by mastering all the available details through repeated questions and answers in the Socratic tradition.
4.2.7. low opinion of physical world
Plato inherited from Socrates a low opinion of the physical world, known as natural philosophy, as appealing to the senses which are ultimately corruptible.
One can't ignore the physical world as Socrates thought, but should be subservient to the moral world, since physical world is not a first principle but rather is derived from moral principles.
4.2.8. ideas are eternal, reality; things are come and go
According to Plato, ideas are the one true reality because they persist, while things come and go. For example, an animal like a cat is here for awhile and then is gone. But the concept of "cat" persists in spite of the birth and death of individuals within the classification we call cat.
In book VII of The Republic, Plato relates an allegory which defines a relationship between perception and reality similar to that which we covered in program 3. The story has come to be known as the Allegory of the Cave, or simply as The Cave.
Read about The Cave in Speilberg & Anderson, p. 18 and listen to the story on the video program. You may also want to read the original (in translation). You should find The Republic in the library.
Do you know what an allegory is? This would be a good word to look up in the dictionary.
An allegory is a metaphorical story which contains a moral message, a story with a larger meaning.
The story of the fox and the grapes, or the tortoise and the hare are two examples of allegories from which we can derive a moral principle.
126.96.36.199. moral message in metaphor
188.8.131.52. story with larger meaning
184.108.40.206. sour grapes, tortoise and the hare
4.3.2. The Cave Story
220.127.116.11. slaves chained in cave, see only shadows of reality
A group of slaves are chained in a cave facing a wall with their backs to the cave entrance, having lived there their whole lives with no hope of ever escaping and seeing the world beyond. They can not see out of the cave but can see shadows cast on the wall by movements outside.
They have developed a culture complete with myths about what the shadows mean and what sorts of activities they represent.
18.104.22.168. one slave escapes, sees reality
Plato speculates on what might happen if one of the slaves could escape and visit the outer world, the method of his escape is irrelevant. What would be the reaction to suddenly gaining access to the information behind the myths?
22.214.171.124. the light hurts his eyes
The light hurts his eyes at first and he can see only shadows. Eventually his eyes adjust and he can see. In the bright light he sees a completely different reality, quite different from that he and his fellow cave dwellers had imagined from the shadows.
4.3.3. The Dilemma
Now what happens. Is the slave happy in his new found enlightenment. Does he want to stay and experience the wonders of this previously unimagined world. Of course he does. But he can't do it.
126.96.36.199. sense of duty compels his return
The escapee feels a moral obligation to return to the cave to share his knowledge with the others although he knows that they will not easily accept what he knows, and knowing that he will be rechained and will probably never have another opportunity to escape.
This brings to mind Socrates, who likewise would be compelled to reveal a truth he had discovered despite the fact that it was not the what people wanted to hear. Recall that Socrates would later stand up for his own ideas, and would eventually died for them.
188.8.131.52. duty to society emphasized above fear
Plato goes on to elaborate on the duty of the philosopher to enlighten even at the risk of one's own safety. In fact, Plato says, it is not just the philosopher, but each and every one of us who has an obligation to share our own enlightenment with our peers.
184.108.40.206. two kinds of blindness
In the dialogue, Plato tells Socrates that "bewilderments of 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." Which reality should be adopt, that seen with the dark eyes or with the light eyes.
He goes on to caution Socrates that it is good to know which kind of blindness we are dealing with
4.3.4. The Heresy
220.127.116.11. relates things never seen by others
When the escapee tells the others what he has seen they think that he damaged his eyes in the light and can no longer see clearly, and that his mind might have become a little tainted by the experience.
18.104.22.168. ideas are heretical, seen as threat
His ideas are seen as disruptive, heretical, threatening, and dangerous to the stability of the society. The others express their sympathy for the trauma he has suffered and would kill him if he tried to drag them into the light to experience the horror that he has known.
Are truth and reality the same thing? Suppose we say, as food for thought, that truth is what is, while reality is what we believe to be true.
What do you think about this? Write about it. Imagine a situation where you are writing a letter to your best friend about another friend whose life is a little messed up right now because this confusion between truth and reality.
Using the cave allegory, Plato and Socrates go on to discuss the meaning of it. What emerges from the dialogue is a working definition of what it is that makes a philosopher a philosopher, a politician a politician, and how it is the duty of every philosopher to become a politician in order to change society and government for the better.
Do you see in these arguments any parallels between the classical Greek culture and our own ideals, as expressed in the United States Constitution?
4.5.1. Determine Truth Behind Appearances
The Truth Behind Appearances
The true shape of the scupture is hidden in its shadow.
Once you have the distinction between truth and reality under control, then comes the problem of finding the relationship between the shapes and the shadows, or between reality and truth.
Plato called this the "truth behind the appearances."
Using the shadows as an example, suppose you look at shape on the wall which looks like a rabbits's head. Does this mean there is a rabbit nearby?
Not necessarily. It might be someone doing shadow tricks with their hands. We've all done it.
So the appearance is that of a rabbit, the truth behind the appearances is that there are other shapes which can cast shadows that look like rabbits.
22.214.171.124. "Save the Appearances"
When Plato speaks of "saving the appearances" he means to understand our perceptions of reality by somehow transforming it into what we know to be true without violating any known principles. What we know to be true has been discovered by the Socratic method. So the job of the philosopher is to save the appearances by logically connecting reality with truth.
This is easy for the case of the rabbit shadow because we have to know how its done before we can do it. Unlike shadow figures, as far as the physical universe is concerned, we are seeing the shadow first and trying to figure out what it really is a shadow of. Keep in mind, in the case of the rabbit shadow, there might be many different objects which could cast a shadow which looks like a rabbit.
It does seem like magic, doesn't it. A good magic trick is an illusion which is impossible to figure out but reasonably simple to perform. The reality is what we observe to happen, the truth is the way the trick is performed.
126.96.36.199. model of perfection must somehow yield what we observe to be true
In the case of planetary motion, any geometrical model of perfection must somehow yield the motions that we see against the celestial sphere. Reality is the motions of the heavenly objects. The diurnal motion of the stars, the daily and monthly movements of the moon, the daily and yearly motions of the sun, and the erratic retrograde motions of the planets. The truth behind the appearances must be circular motion at a constant speed which is forever unchanging.
According to Plato, we must know truth by using logical arguments based upon the reality of planetary motions, geometry, logic, and moral principles.
He differs from Socrates in assigning equal importance to the observed motions. In Plato's view the senses cannot be completely ignored. Although unreliable and not very accurate, they certainly are registering some aspect of the truth.
4.5.2. APPEARANCE: erratic motions of sun, moon and planets are less than perfect
In this scheme, the motion of the planets presents a problem.
On one hand they are heavenly and therefore must be perfect.
On the other hand they move in uneven paths across the fixed star background, occasionally doing irregular and nonrepeating retrograde loops. So how do you explain that perfect things like planets behave imperfectly?
Plato thought this to be "an offense that must be explained away" by saving the appearance through discourse and logic.
188.8.131.52. do not move at a constant rate
184.108.40.206. irregular retrograde loops
220.127.116.11. "an offense that must be explained away"
4.5.3. TRUTH: true motions of sun, moon, and planets is uniform and circular
The Pythagorean truth of perfect circles is not simply taken for granted by Plato. He derived it by discourse just as Socrates taught. Like Socrates, Plato also believed, that truth could be attained by logic, but he added the idea of the reality of geometry and numbers, and the reality of the observed planetary motions. Here is an outline of the logic, in condensed form, that leads to this concept of the truth of uniform circular motion in the heavens.
18.104.22.168. reality is geometry and numbers
The logical steps that follow have more to do with truth than with reality, but it is truth (what we believe) that is attainable. Reality is geometry and numbers if you are a Pythagorean like Plato. It doesn't take much observation to see that relationships do exist between number and between numbers and shapes. Likewise the appearance of the common geometric forms in everything from crystals to spider webs guarantees they they play some important role.
22.214.171.124. numbers and geometry are perfect
Since perfect numbers and mystical relationships are known to exist, and the polygons form the basis for all shapes, and they have certain hints of perfection in their symmetry, and the circle is the perfect polygon, it seems only logical to conclude that if numbers and geometry are perfect and truth is geometry and numbers, then truth must be perfect.
126.96.36.199.1. if mathematics is perfect and truth is mathematics then truth must be perfect
188.8.131.52. heavens are perfect
So the heavens are perfect, as the Pythagoreans believed. Although the planets appear to move erratically in retrograde motion, they are nonetheless perfect. This was a major problem, and we'll come back to it in a few minutes.
As for imperfection here on earth and how that fits into a perfect universe, we'll save the problem of imperfection here on earth for Aristotle to solve. He solved it very well, but with his solution he created just a few more small problems.
184.108.40.206. circle is most perfect shape
If the heavens are perfect, and the circle is perfect, then the logical conclusion is that the heavens are circular.
220.127.116.11.1. if heavens are perfect and the circle is perfect then heavens are circular
18.104.22.168. heavens are circular
So if the heavens are somehow circular because they are perfect, then their motion must also be unchanging and circular.
Plato himself could not explain away the offense and save the appearances. He simply recognized that it needed to be in order to have a logically integrated universe and left it to his students and posterity to reconcile. Here we see an excellent example of the power of an idea. With virtually no evidence in support of his ideas, other than the logic of discourse. Plato influenced a hundred generations of scholars, thinkers, and philosophers.
How might we explain away this quandary? How do perfect things be made to behave imperfectly. Consider shadows, like those seen by the slave in the cave. Isn't it possible that shadows of perfect things might be stretched out of proportion in the right light? The shadow of a sphere need not be a circle. Try it with a flashlight and a marble. What do you see?
So seeing both the marble and the flashlight we can easily see how the shadow tells us the shape of the object only after we understand the concept of the shadow and the light, but not before. But suppose we saw only the shadow and knew nothing of the shape of a sphere or the properties of light?
That is the position that we find ourselves in here on earth starting out at the blackness of space and the pinpoints of light we know as the stars and planets.
4.6.1. Plato could not solve the problem.
Although Plato could not solve the problem, he did pose the question in a way which might lead to an answer. We will call this Plato's question. The search for a solution to this problem by Plato's students Euxodos and Aristotle established the circular paradigm as the world view of the West. Although the reasons were forgotten or ignored by Ptolemy's time in the second century A. D., the magic of the circle continued to influence the cosmology of Western thought until the sixteenth century. It will turn out that breaking the circular paradigm was even more difficult than abandoning geocentrism.
4.6.2. PLATO'S QUESTION: What uniform and ordered circular motion must be assumed for each of the planets to account for its apparently irregular yearly paths?
Here is the question which influenced Western thinking and physical science probably more than any single idea until Newton's gravity.:
What uniform and ordered circular motion must be assumed for each of the planets to account for its apparently irregular yearly paths?
This seems like such a simple question, and it is really. But simple questions do not always have simple answers. In fact, the best questions, like the best answers, are those which strike some fundamental chord and drive the questioning of human minds for millennia.
Plato's question is one of them.
Although Plato could not solve the problem, one of his students could, and did.
Euxodos, around 400 B.C. used his skills with geometry to envision a model which could explain the erratic motions of the planets while still allowing for perfectly uniform and circular motion.
Euxodos' model was homocentric and concentric. Spheres inside spheres sharing a common center. The center was earth.
The model consisted of circles which could rotate like a coin spinning upright on a table. Each circle fit inside another, but was free to spin on an axis that was oriented in any direction.
View a movie of homocentric spheres (404K).
By combining the motions of the various spinning circles, and by putting planets on circles which were themselves on circles, Euxodos could roughly recreate the apparent motion of the planets as seen from earth.
In fact, it is possible to create just about any kind of motion using homocentric spheres.
22.214.171.124. not all spheres contained planets
The model predicted the actual positions of the planets to an accuracy as good as anyone could attain without instruments or telescopes. Those things weren't invented for hundreds of years.
The spheres of Euxodos are important to our journey down the river of time for two reasons.
First, this represents the first explanation which considers the motions of the heavens purely mechanical and geometric grounds alone with no mysticism or myth.
Second, it is reductionistic because it separates the concept of motion from the cause and removes the cause in order to understand the shape. Separating the two concepts marks a major change in the perception of the heavens.
5.4.1. mythical explanations put aside
5.4.2. cause of motion ignored
Of all of the classical Greek philosophers, none has had more influence on the development of physical science than Aristotle.
Aristotle was a student of Plato. He was also the tutor of Alexander the Great, who became King of Macedonia when he was twenty years old and in a thirteen year reign extended his influence all the way to India.
6.1.1. Alexander's father (Phillip of Macedon) united Greek city states in 338 B.C.
Alexander's father was Phillip of Macedon who invaded and subsequently united the Greek city states. This was largely responsible for the demise of the Greek culture, although the states had been at war with one another for many years.
6.1.2. empire fell apart after Alexander's death
The effect was devastating and Phillips empire literally fell apart after Alexander's death in his early twenties.
We're getting a little bit ahead, but a glimpse through the crystal ball convinces us that this was the end of the Golden Age.
Aristotle was an observer as well as a thinker. Unlike Socrates and Plato before him who found observation to be unreliable and deceptive, Aristotle saw great value in understanding the behavior of matter both here on earth and in the heavens, although he still subscribed to the moral philosophy of Socrates and the logical reality of Plato.
Unlike his predecessors Aristotle insisted on a unified universe.
6.2.1. reacted against efforts of Socrates and Plato to formulate laws without facts
One reason that Aristotle became the authority on everything was that he was prolific, he wrote a lot of books. Many copies survived the centuries to be reread more than a thousand years later.
Aristotle wrote treatises and essay on just about every topic there was. Physics, chemistry, biology, meteorology. logic, metaphysics, mathematics. ethics, politics, poetry, you name it.
Someone said the Aristotle may have been the last, if not the only, person who completely understood the world he lived in. What do you suppose that means?
6.3.1. much of it lost during Middle Ages
6.3.2. physical and biological, logic and metaphysics, ethics, politics, poetry
One of Aristotle's greatest errors was the assumption that biology is the most basic science. Today we believe that biological processes obey the laws of physics and chemistry, and many biological processes can be explained using the models of the physical sciences, such as atoms and energy.
Aristotle argued that physical and chemical processes obeyed the laws of biology.
It's an interesting twist on the paradigm.
Although Euxodos had proposed a model which answered Plato's Question, it was not totally satisfying to Aristotle because it was incomplete.
Euxodos' model had no explanation for the cause of the motion, and no connection between the motion of one planet and another.
6.5.1. connected motions of spheres like gears
Aristotle's refined version connected the motions of the planets to one another, like a gear train.
6.5.2. driven by "imponderable" prime mover
The whole system was driven by an what Aristotle called an "imponderable" which he called the Prime Mover, the first principle of motion.
What does it mean to be imponderable? Think about that for a few minutes and we'll come back to it.
6.5.3. counteracting spheres to cancel irregularities
To produce the right motions, Aristotle had to add extra spheres of different sizes and turning at different speeds.
6.5.4. 56 spheres total to describe system
Aristotle's system required a total of 56 spheres to account for the motion of 7 heavenly objects.
(Sun, moon, and five planets)
That's about eight spheres per planet, and not a simple mode.
Try to imagine the mind required to see this in a way that made sense to them, then explain it in writing so that others could understand it. Now imagine doing this without actually building a physical model, and without calculator, or for that matter without the use of numbers as we know them today.
What does it mean to be an authority?
Power, maybe, but in what sense. Like 'the authorities have ordered evacuation . . .'
Authority can also mean that you don't have to think anymore because someone has already decided and decreed what you are supposed to think.
It often happens when social order breaks down, and a certain idea becomes the authority. The person or persons who do the interpret of the meaning and make judgments about compliance and so forth become the authorities because they are linked with political power.
So don't interpret the sense of this word in meaning too narrow.
This would make a good topic to explore in a short essay.
Aristotle introduced the concept of a world system where everything is linked to everything else. There were no separate areas of knowledge and no separate sciences.
Aristotle's world combined elements of Pythagorean Mysticism, Milesian views on matter, Socrates' moral philosophy, Plato's mathematical philosophy.
Like the Milesians, Thales and Anaxagoras, Aristotle considered that matter was the true reality of the universe, having noticed that it dominates the universe. This approach to the nature of reality was a radical departure from Socrates who thought matter to be superficial and subservient to morality, and from Plato who considered the physical world somewhat important, but secondary to ideas.
Aristotle adopted the suggestions of the earlier Milesian philosophers that the basic stuff of material existence were the four elements, earth, air, fire, and water. To this he added a fifth element which he called quintessence (quint =5, essence = essence). In addition the four qualities hot, cold, wet, and dry, determined the characteristics of the elements.
We will return to this concept later in the course when we begin our study of the properties of matter.
8.2.1. no pure elements
According to Aristotle, we never see perfectly pure elements here in the earthly realm. All the substances we see are slightly impure. Thus there is always motivation for change to occur.
8.3.1. Aristotle's Universe
Like the Pythagoreans', Aristotle's universe was also concentric, but the earthly realm consisted of four layers, one for each of the four elements. The heavenly realm contained the planets moving in homocentric spheres like those of Euxodos.
8.3.2. sharp distinction between earthly (sublunar) vs. heavenly realms
Aristotle's universe differed from the Pythagoreans. The Pythagorean universe had no cause, no properties and no connections. In Aristotle's scheme the heavenly and earthly realms were very different. They contained different kinds of matter. The heavenly realm was perfect and unchanging, except for its circular motion, which was appropriately perfect.
The sublunar (below the moon) realm was corruptible, imperfect. Here change took place in an attempt to gain perfection according to the qualities and desires of the different substances to attain the concentric and perfect circular symmetry of the rest of the universe.
That perfection was never attained in the earthly realm, but changes were constantly taking place to increase the perfection.
Planets move according to the geometry of Euxodos as modified by Aristotle to allow for the connections between the motions of the various planets and the necessity to be driven by the Prime Mover.
It is the properties of substance which determine their behavior and their motion, in Aristotle's scheme. Rocks fall through air because they contain a high percentage of earth and so move towards the rightful place of earthy things at the center. Air bubbles rise through water and fire rises through air to attain their natural place in the four tiered structure of the earthly realm.
Combustion and other types of changes which we would today call chemical changes, took place in Aristotle's view because the various elements were trying to separate and attain a state of perfection and purity.
This makes good sense, doesn't it. It is amazing to me that anyone could think through such a consistent and logical system based on so little knowledge.
Consider combustion. Today we would say that certain molecules that make up the wood combine with oxygen from the air and release heat as they combine.
Aristotle would say that the combustion is a breakdown of the wood into its constituent elements. Fire escapes, leaving behind ashes (earth) while also giving off smoke (air) and vapor (water) which condenses on cold objects (like porcelain)
We'll study Aristotle's theories on motion in more detail later in the course, but we need to get an overview now. You can look ahead to see Aristotle's views on the properties of motion or his description of four different kinds of motion. We can also begin to get a glimpse of how well Aristotle synthesized and integrated a remarkably consistent world view.
8.6.1. motion of any kind required a motivation
In Aristotle's view, motion of any kind required a motivation or a cause. Things do not move without reason or cause. Think about it. You are sitting home alone late at night and it's very quiet and the room is dark. Suddenly a chair across the room starts rattling and sliding slowly across the floor.
What do you think, Oh there's a chair sliding across the floor, nothing pushing it, that's OK.
Probably not because you would expect that if the chair moves then something is moving it. And if you do push a chair across the floor, it stops moving after you stop pushing on it, its cause of motion having been removed.
8.6.2. natural motion caused by "desire" of each element to attain its natural place depending on its lightness or heaviness
Motion in nature, such as when things fall to the earth, is caused by the desire of each substance to find a place in the universe which it belongs. This is intimately tied in with the moral philosophy of Socrates and Aristotle's own explanation about the nature of matter being composed of four earthly and one celestial substance.
Disorder and chaos in the sublunar realm represent the imperfection of man. Natural motion takes place so that the elements can attain their rightful locations in the concentric spheres.
The difference here is that Aristotle reasoned that in the perfect universe, earth would be at the center, then water, then, air, then fire. It makes a lot of sense, and is actually a very good theory. Aristotle's elements were never actually seen in the pure state, but were always combined into imperfect mixed substances. That was the fate of the sublunar realm. We might strive for perfection, but will never reach it whether we are human or inanimate.
8.6.3. celestial motion caused by Prime Mover
Since the planets and other heavenly objects were perfect, they could not be composed of the same base matter that made up the sublunar realm, but even they required a cause to remain in motions. Aristotle assumed that there existed an imponderable Prime Mover who moved the heavens along through a series of mechanical linkages which we as mortals were incapable of understanding and so therefore should not even try. That's why it was imponderable.
A cop out? Yeah, I think so.
The image comes to mind of a Supreme Being turning a crank perpetually.
Not a very distinguished image for a Supreme Being, especially considering the low value placed on mechanical labor by the Athenians.
We will see that Aristotle's views on motion are among the less well argued of his ideas. Eighteen centuries later Galileo would recognize that Aristotle had painted himself into an intellectual corner from which he would not escape.
8.6.4. other types of motion were different from planetary or natural motion
Other types of motion, such as freefall and horizontal motion were different from planetary or natural motion in Aristotle's world view. We'll return to study these in greater detail later in the course.
It seems rather incredible to us from our high tech perspective that someone didn't see through Aristotle's errors sooner. But remember, the paradigm strongly influences truth. We are more likely to see what we expect to see than what we do not expect to see, and we are likely not to see things that we do not expect to see.
There are many weaknesses to Aristotle's model than we can note with the twenty twenty vision of our two millennia of hindsight. We won't take the time to detail them, but you might want to take a few minutes to look over them.
It is not the weaknesses that we want to concentrate on. What we are interested in is the fact that even with these weaknesses, and some are significant, Aristotle's theories had such power and carried such weight in resolving questions about the nature of physical reality.
In fact, the underlying assumptions behind the theories and their philosophical justifications were all but lost by the beginning of the Christian era.
That is due in part to the rapid decline of the Greek culture, at least in Greece following the death of Alexander, and the death, less than one year later of his teacher, Aristotle.
8.7.1. motion theory doesn't make sense
8.7.2. bad observational precision is ambiguous
8.7.3. doesn't account for variation in the size size of the moon (about 10%)
8.7.4. brightness of planets varies too much
8.7.5. Alexander's conquest brought Babylonian data that didn't fit
Despite the obvious weaknesses, Aristotle's ideas not only survived, but became THE system of the world and influenced development of three separate cultures over two thousand years.
We can only speculate on what might have happened had the traditions of the Golden Age of Greece continued into subsequent generations.
As it was, the intellectual center of the western world shifted to Alexandria, across the Mediterranean , the new city of the future built by Alexander. Here, for another four hundred years, Greek science evolved while the ideals and morality of the Golden faded into the past.
The Hellenistic period of the Greek culture in Alexandria is the topic of the next program.
8.8.1. Basis for a paradigm
Aristotle's ideas influenced development of three separate cultures over two thousand years. The impact his writings have had on the world is remarkable. There was the Arab empire to the east, the Byzantine to the north of them, and the remains of Roman domination over Europe.
His ideas became shaped to the various cultures which encountered them. Aristotle's world view, in greatly modified form, became the basis for the Ptolemaic system which became the official Church doctrine. Overall Aristotle's writing were the authority on everything for more than two thousand years.
They are for the most part, good ideas. But they are full of confusing and childish misconceptions, reflecting the ignorance of his times rather than a lack of intellect on Aristotle's part. He often painted himself into a logical corner, and sometimes grasped at ideas in desperation. One way out was the concept of an imponderable.
126.96.36.199. modified over several hundred years
188.8.131.52. basis for Ptolemaic system
184.108.40.206. ideas lasted 2000 years with little refutation
220.127.116.11. full of confusing misconceptions
Imponderables are those things which, according to Aristotle, are just too complex for our minds to understand. They are beyond comprehension, beyond pondering.
They are also cop outs.
18.104.22.168. writings preserved in middle Eastern civilization
Following the destruction of the Library of Alexandria over five hundred years in the early centuries of the Christian era, the most abundant repository of Aristotle's writings was the Arabic and Byzantine empires. Here, in what we now call the Middle East, civilization flourished while the ravages of the Roman Empire regrouped their civilization in Europe during the dark ages.
22.214.171.124. rediscovered and integrated into Church doctrine in 1100s
These writings would work their way back into Europe beginning in the twelfth century. By then they will have been modified and several different versions of the same works will conflict with one another on certain key points.
126.96.36.199. adopted as authority on everything by Church
Even with the contradictions, Aristotle's works became the official guide of the Church concerning cosmology and natural philosophy. Once that happened the paradigm was set firmly in place by the bureaucracy of the Church.
In this program we have seen how the ideas of the Pythagoreans, Socrates, Plato, and Euxodos were synthesized into a unified system of the world.
Using the idea of concentric and homocentric spheres along with a theory of motion with the attainment of perfection as motivating force, Aristotle's theory of everything served of a model for understanding the universe for two thousand years.
We have posed many questions in this program as fuel for your writing efforts. So sit down now and write down your thoughts. Submit something to us within one week of viewing this program to earn points towards the course grade.