PART I will compare more practical versions of astronomy with the Greek version. It will also discuss the relation of astronomy to morals.
PART II will present an overview of the Copernican Revolution. It will also discuss the basis for the Ptolemaic theory.
PART III will discuss Aristotle's physics and Ptolemy's defence of it. It will compare Copernicus' attack on it with Kepler's attack.
PART IV will discuss the propertie's of astronomy that make it a unique science. It will also discuss the interplay between mathematical discovery and empirical observation.
Astronomy could take its place in the Great Ideas on the ground that several of the great books are monuments of astronomical science.
They exemplify the imaginative and analytical powers of the human mind.
Its inclusion can also be justified by the way that astronomical speculation raises problems and suggests conclusions that have a bearing on all of philosophy.
Careful and precise astronomical observations antedate the birth of astronomy as a science.
The Egyptian priests noticed that the Dog Star was in the evening sky at the annual flooding of the Nile.
They did not, however, organize their observations or use them to formulate hypotheses.
They left this up to the Greeks.
Aristotle and Plato paid eloquent tribute to astronomy.
In the opening chapter of his Metaphysics, Aristotle associates astronomial inquiry with the birth of philosophy.
"Apart from usefulness," he says, "men delight in the sense of sight."
He adds, "It is owing to their wonder that men both now begin and at first began to philosophise."
A wider view of the importance of astronomy is taken by Plato.
In the Timaeus, he dwells on "the higher use and purpose for which God has given eyes to man . . . Had he never seen the stars, and the sun, and the heaven," Timaeus says, "none of the words about the universe would have ever been uttered . . . "
"God invented and gave us sight," he continues, "to the end that we might behold the courses of intelligence in the heaven, and apply them to the courses of our own intelligence which are akin to them, the unperturbed to the perturbed;"
"and that we, learning them and partaking of the natural truth of reason, might imitate the absolutely unerring course of God and regulate our own vagarities."
For Plato, then, mans intellectual relation to the heavens does more than imitate philosophy.
Mans self-rule, his purity and peace of soul, is at stake in that relation.
That is one reason why, in both the Republic and the Laws, Plato makes astronomy a required part of the curriculum for the education of rulers.
"He who has not contemplated the mind of nature which is said to exist in the stars . . . and seen the connection of music with these things, and harmonized them all with laws and institutions, is not able," the Athenian Stranger says in the Laws, "to give a reason for such things as have a reason."
Now we will consider the connection between astronomy and morals.
The issues raised by Plato concerning the importance of astronomy for purification and piety, for education and politics, run through the tradition of Western thought.
On one hand, astronomers like Ptolemy, Copernicus, and Kepler, for all their differences on points of scientific theory, seem to concur in affirming Platos conception of the bearing of their science on religion and morals.
Lucretius and Augustine, on the other hand, while not agreeing with each other, seem to disagree with Plato.
Lucretius hopes that astronomy may help free men from religious superstitions.
If when they "gaze on the heavenly quarters of the great upper world," and direct their thoughts "to the courses of the sun and moon," they do so with a "mind at peace" because they see only the workings of natural law and no evidence of a controlling power in the will of the gods, then men achieve the natural piety of the scientist different in the opinion of Lucretius from false worship which is based on fear.
Augustine dealt with the Manichean sect, studying their astronomy and how it related to their religious doctrine.
Augustine insisted that the teachings of religion in no way depend on astronomy.
Though a man does not know "even the circles of the Great Bear, yet it is folly to doubt," he writes, "that he is in a better state than one who can measure the heavens and number the stars, and poise the elements, yet neglecteth Thee who has made all things in number, weight, and measure."
When Faustus, the leader of the Manicheans, "was found out to have taught falsely of the heaven and stars, and of the motions of the sun and moon (although these things pertain not to the doctrine of religion)," his religious teachings, according to Augustine, inevitably suffered ridicule because of his pretention that they derived support from a science of the heavenly bodies.
Augustines position anticipated a position taken by Cardinal Barberini during the controversy over the Copernican hypothesis.
Barberini is reported to have told Galileo that astronomy and religion have separate tasks. One teaches how the heavens go; the other teaches how to go to heaven.
Thales of Miletus once was walking at night gazing at the heavens.
Since he was not watching where he was going, he fell into a well.
Taking a humanistic view of astronomy, Montaigne wrote, "I am very pleased with the Milesian girl who . . advised the philosopher Thales rather to look to himself than to gaze at the heavens."
Montaigne had a preference for the moral sciences over the natural sciences.
He regards astronomical inquiry as a prime example of mans "natural and original disease resumption."
Montaigne went further to say, "Being assaulted as I am by ambition, avarice, temerity, superstition, and having so many other enemies in life, shall I go cudgel my brains about the worlds revolutions?"
Kant was as critical as Montaigne of the frailty of human knowledge.
"The investigations and calculations of the astronomers, " he writes, have shown us "the abyss of our ignorance in relation to the universe."
But Kant astronomer himself as well as a moralist does not, therefore, advise us to forsake the study of the heavens.
On the contrary, he recommends it not only for its scientific value but so for its moral significance. "Two things," Kant declares in a passage which has become famous, "fill the mind with ever increasing admiration and awe, the oftener and more steadily we refect on them: the starry heavens above and the moral law within."
The two fit together to form a single effect. Astronomy with its view "of a countless multitude of worlds annihilates, as it were, my importance as an animal creature."Morality "elevates my worth as an intelligence by my personality, in which the moral law reveals to me a life independent of amimality, and even of the whole sensible world."
In one passage of Freud we find an almost complete return to the Platonic insight: "Order has been imitated from nature," he writes; "mans observations of the great astronomical periodicities not only furnished him with a model, but formed the ground plan of his first attempts to introduce order into his own life."
In PART II we will sketch out an overview of the Copernican Revolution. Also we will discuss the basis for Ptolemaic theory.
The Copernican Revolution represents one of the great crises, certainly one of the most dramatic turning points, in the development of astronomy, and of physical science and natural science generally.
When the Copernican hypothesis was formulated, it was nothing more than a mathematical alternative to the Ptolemaic hypothesis.
In the hands of Kepler, Galileo, and Newton, it became much more than that. While Ptolemy proposed that the earth was stationary with the heavens rotating around it, Copernicus proposed that the sun was stationary with the earth revolving around the sun.
The changes in the heavens are attributed to three types of motion of the earth. It spins on its axis, revolves around the sun, and varies the inclination of its axis relative to the sun.
The revolutionary part of this hypothesis is its effect on mans estimate of himself and his place in the universe. As Kant suggests, mans stature seems to shrink. He becomes "a mere speck in the universe" which has been enlarged to infinity, or at least to an unimaginable immensity.
He is displaced from its center and becomes a wanderer with his planet.
Humanitys self-esteem, according to Freud, was thus for the first time deeply wounded; He refers to the theory that "is associated in our minds with the name of Copernicus" as the "first great outrage" which humanity has had to endure from the hand of science.
In earlier centuries, when the Ptolemaic system prevailed, the appraisal of mans rank seemed to depend more on the position he occupied in Gods heirarchy (below the angels and above the brutes) than upon the motion of the earth.
Boethius, for example, finds the Ptolemaic universe large enough to remind man of the infimitesimal space he occupies. Kepler claims that the new hypothesis is more fitting for mans stature than the old one.
He declares, "it was not fitting that man, who was going to be the dweller in this world and its contemplator, should reside in one place as in a closed cubicle . . . "
"It was his office to move around in this very spacious edifice by means of the transportation of the Earth, his home."
In order to properly view and measure the parts of his world, the astronomer "needed to have the Earth a ship and its annual voyage around the sun." A certain disillusionment may result from the affirmation repeated by every schoolboy who is taught the Copernican system that, despite what we see, the sun does not move around the earth, and the earth both rotates and revolves.
It undermines the trust men placed in their senses and the belief that science would describe the world as they saw it. In order to "save the appearences," that is, to account for the phenomena, science might henceforth be expected to destroy any naive acceptance of them as reality.
Furthermore, though the Ptolemaic world was large, the Copernican universe was much larger. Whereas in the former the radius of the earth was deemed negligible in relation to the radius of the sphere of fixed stars, in the new universe, the earths orbit around the sun was negligible in relation to the same radius of the sphere of fixed stars.
It can hardly be doubted that this intensified mans sense of almost being lost in the abyss of infinity. "I see those frightful spaces of the universe that surround me," Pascal writes, "and I find myself tied to one corner of this expanse, without knowing why I am put in this place rather than another."
When he regards the worlds immensity as "the greatest sensible mark of the almighty power of God, " Pascal experiences an awe which for him is qualified by reverence. Other men may experience the same feeling, but less with reverence than with a gnawing loneliness, born of the doubt that so vast a cosmos of cosmos rather than chaos can have been beneficially designed as mans habitation.
Whatever the truth about the effect of the Copernican theory in the order of opinion, imagination, and feeling, it did produce a result in the intellectual plane. It, more than any other single factor, led to the overthrow of certain crucial doctrines which had been linked together in the physics and astronomy of Aristotle;
It thus radically changed the fundamental principles in terms of which man had understood the order and unity of nature. That scientific event deserves not only the name but also the fame of "The Copernican Revolution."
That Aristotles physics and cosmology lie at the very heart of the issue is confirmed by the way in which Kepler later argues for the Copernican theory against Ptolemy. He does not defend its truth on the ground that it accounts for observable facts which the Ptolemaic hypothesis cannot handle.
Nor does he prefer it merely because it is mathematically the simpler hypothesis. On the contrary, he specifically notes that anything which can be claimed on mathematical grounds for Copernicus over Ptolemy can be equally claimed for Tycho Brahe over Ptolemy.
Brahes theory was that while the other planets revolve around the sun, the sun, with its planets, revolves around a stationary earth. According to Kepler, the truth of these theories must be judged physically, not mathematically, and when the question is put that way, as it is not by Copernicus himself; Copernicans, like Kepler, Galileo, and Newton take issue with what has been associated with Ptolemaic theory逆he physics of Aristotle.
In PART III we will discuss Aristotles physics and Ptolemys defence of it. We will compare Copernicus attack on it with Keplers attack on it.
Just as Ptolemys astronomy conforms to what we see as we look at the heavens, so Aristotles physics represents a too simple conformity with everyday sense-experience. We observe fire rising and stones falling. Mix earth, air, and water in a closed container, and air bubbles will rise to the top while particles of earth will sink to the bottom.
To cover a multitude of similar observations, Aristotle develops the theory of the natural motions and places of the four terrestrial elements earth, air, fire, and water.
Since bodies move naturally only to attain their proper places, the great body which is the earth, already at the bottom of all things, need not move at all. Being in its proper place, it is by nature stationary. Celestial bodies differ from terrestrial bodies in two ways.
In the first place, they neither come into being nor cease to exist. They are eternal. In the second place, their motion is not linear rising or falling). It is circular.
Summarizing Aristotles doctrine, Aquinas writes, "Plato, and all who preceded Aristotle, held that all bodies are of the nature of the four elements," and consequently, "that the matter of all bodies is the same.
"But the fact of the incorruptibility of some bodies was ascribed by Plato, not to the condition of matter, but to the will of the artificer, God . . . " "This theory," Aquinas continues, "Aristotle disproves by the natural movements of bodies." "For since he says that the heavenly bodies have a natural movement, different from that of the elements, it follows that they have a different nature from them."
"For movement in a circle, which is proper to the heavenly bodies is not by contraries, whereas the movements of the elements are mutually opposite, one tending upwards, another downwards . . . "
"And as generation and corruption are from contraries, it follows that, whereas the elements are corruptible, the heavenly bodies are incorruptible." When Kepler prepares his attack on Aristotles physics he lines up the same points.
"By what arguments did the ancients establish their opinion which is opposite of yours?" he asks. "By four arguments in especial: (1) From the nature of moveable bodies. (2) From the nature of the motor virtue. (3) From the nature of the place in which the movement occurs. (4) From the perfection of a circle.
In the attack on Pttolemaic astronomy, Copernicus meets Ptolemy on his own terms, while Kepler goes outside his tems. Ptolemys universe, as complicated as a Swiss watch, grates against Aristotles love of simplicity.
In the thirteenth and last book of The Almagest, Ptolemy writes, "Let no one, seeing the difficulty of our devices, find troublesome such hypotheses . . . "
"It is proper to try and fit as far as possible the simpler hypotheses to the movements of the heavens;" "and if this does not succeed, then any hypothesis possible." "Once all the appearances are saved by the consequences of the hypotheses, why should it seem strange that such complications can come about in the movements of heavenly things?"
"We ought not to judge the simplicity of heavenly things by comparison with what seems simple in the explanation of earthly phenomena." "We should instead judge their simplicity from the unchangableness of the natures in the heavens and their movements."
"For thus they would all appear simple, more than the things which seem so here with us." Ignoring the supposition that simplicity must be judged differently in different spheres, Copernicus challenges Ptolemy on his own ground."
He proposes "simpler hypotheses" to fit "the movements of the heavens."
In doing so, he seems to adopt the traditional view of the mathematical character of astronomical hypotheses. What distinguishes Kepler from both Ptolemy and Copernicus is the way in which he is concerned with the truth of alternative hypothesis in astronomy.
He looks upon the truth of an hypothesis as something to be judged not merely in mathematical terms according to the adequacy and simplicity of a calculating device, but to be measured by its conformity to all the physical realities.
At the very beginning of his "Epitome of Copernican Astronomy," he flatly declares that "astronomy is a part of physics." And in the opening pages of his fourth book, he insists that astronomy has not one, but "two ends: to save the appearances and to contemplate the true form of the edifice of the World."
He follows this immediately by observing that, if astronomy had only the first end, Tycho Brahes theory would be as satisfactory as that of Copernicus. "You must seek the foundations of your astronomy," he tells his fellow scientists, "in a more elevated science, I mean in physics or metaphysics."
Historians described Kepler and Galileo as "realistic Copernicans."Galileos astronomy as well as his terrestrial mechanics served to confirm the Copernican hypothesis by physics. Newton was the third member of this triumvirate of "realistic Copernicans."
Newton took Keplers Three Laws and deduced them in terms of Galileos laws of motion in the dynamics of bodies falling on the earths surface. The very posing of the problem itself depended on the insight that terrestrial and celestial mechanics can proceed according to the same principles and laws.
That insight entailed the complete overthrow physics, with its division of the universe into two distinct parts, having different kinds of matter and different laws of motion.
In PART IV we will discuss properties of astronomy as opposed to other sciences. Also we will cover the interplay between mathematical discovery and empirical observation. We will add a new word to your vocabulary: "consilience."
Astronomy is one of the natural sciences that comes under the classification of "mathematical physics." Thought that phrase may be modern, the ancients recognized the special character of sciences which apply mathematics to nature and which consult experience to choose among hypotheses arising from different mathematical formulations.
Outlining a curriculum or liberal education, Plato, in -The Republic , groups music and astronomy along with arithmetic and geometry as mathematical arts or sciences. Astronomy is no more concerned with the visible heavens than music is with audible tones.
Music is rather the arithmetic of harmonies, astronomy the geometry of motions. But, in the -Timaeus , Plato turns mathematical formulae and calculations to use in telling what he calls "a likely story" concerning the formation and structure of the sensible world of becoming.
Here, rather than in -The Republic , we have, according to Whitehead, the initial conception of mathematical physics as well as deep insight into its nature and pattern. The development of astronomy from Plato and Aristotle through Ptolemy, Copernicus, and Kepler to Galileo and Newton constitutes an extraordinary set of "case histories" for the study of what J.B. Conant calls the "tactics and strategy" of science, especially mathematical physics.
Astronomy has one particular feature that distinguishes it from other branches of mathematical physics. It is not an experimental sceince, it is an empirical science. The astronomer does not, like the physicist, chemist, or physiologist; produce an isolated system of events by means of laboratory arts.
Since the invention of the telescope, the astronomer has had instruments of all sorts to increase the range and accuracy of his observations; But the fact that the place where he uses such apparatus is called an observatory rather than a laboratory indicates that these instruments do not make astronomy an experimental science.
Defending psychoanalysis against attack "on the ground that it admits of no experimental proof," Freud points out that his critics "might have raised the same objection against astronomy; experimentation with the heavenly boides is, after all, exceedingly difficult. There one has to rely on observation."
Because it is a mixed science, both empirical and mathematical, astronomy advances not only with the improvement and enlargement of observation, but also with the new insights or developments in mathematics.
Kant gives us striking examples of how the work of pure mathematicians contributes to the advance of physics or astronomy. Their discoveries are often made without any knowledge of their application to natural phenomena.
"They investigated the properties of a parabola," he writes, "in ignorance of the laws of terrestrial graviatation, which would have shown them its application to the trajectory of heavy bodies . . . "
"So again they investigated the properties of the ellipse without a suspicion that a gravitation was also discoverable in celestial bodies, and without knowing the law that governs it as the distance from the point of attraction varies, and that makes the bodies describe this curve in free motion."
So amazing are such mathematical anticipations that Kant thinks Plato may be pardoned for supposing that pure mathematics "could dispense with all experience" in discovering the constitution of things. This twofold relationship between mathematical discovery and empirical observation is present throughout the development of the physical sciences.
When an hypothesis is tested, the hypothesis (in the language used ever since Simplicicus) must "save the appearances." Then the choice between them becomes a matter of the greater mathematical elegance of one than the other.
This does not, however, give the mathematically superior theory a greater claim to truth. As far as reality is concerned, it is only, in Platos words "a likely story." They have explanatory power with the range of phenomena they were designed to fit. But only one of them may have the quite amazing virtue of fitting other sets of observations not originally thought to be related to the phenomena for which the hypothesis was devised.
The word consilience has been used to name the property of an hyothesis which, in addition to saving a limited field of appearances, succeeds in fitting many other phenomena which seem to have become related逆o have -jumped together under its covering explanation.
The heliocentric hypothesis, as developed by Newtons laws of motion and thoery of gravitation, certainly has this property of consilience to a high degree, for it covers both celestial and terrestrial phenomena, and a wide variety of the latter.
Is the heliocentric hypothesis true, then? The property of consilience may be grounds for rejecting the Ptolemaic hypothesis, but is it grounds for accepting the heliocentric hypothesis?
Is our judgment comparative or absolute?
If one hypothesis is better than another at doing what hypotheses do, can we regard its success as a sign of exclusive truth?
Or are we restricted to the more modest claim that a better hypothesis tells a more likely story?
Source: Philosophy-irc.org
