Aristotelian physics

"[T]he Aristotelian doctrine of inertia was a doctrine of rest—it was motion, not rest, that always required to be explained."

"[T]he peculiar character of that Aristotelian universe... things... in motion had to be accompanied by a mover all of the time. A universe... [that] had the door half-way open for spirits...unseen hands had to be in constant operation... sublime Intelligences had to roll the planetary spheres... Alternatively, bodies had to be endowed with souls and aspirations... [M]atter itself seemed to possess mystical qualities."

"When mons. Descartes's philosophical Romance, by the Elegance of its Style and the plausible Accounts of natural Phænomena, had overthrown the Aristotelian Physics, the World received but little Advantage by the Change: For instead of a few Pedants, who, most of them, being conscious of their Ignorance, concealed it with hard Words and pompous Terms; a new Set of Philosophers started up, whose lazy Disposition easily fell in with a Philosophy, that required no Mathematicks to understand it, and who taking a few Principles for granted, without examining their Reality or Consistence with each other, fancied they could solve all Appearances mechanically by Matter and Motion; and, in their smattering Way, pretended to demonstrate such things, as perhaps Cartesius himself never believed; his Philosophy (if he bad been in earnest) being unable to stand the test of the Geometry which he was Master of."

"With the discovery of the law of inertia and the subsequent downfall of the Aristotelian theory of motion on which Kepler had based his work, his physical theories soon became outmoded and were then rendered obsolete by Newton's work. Yet Kepler's laws of planetary motion remained, so that Edmond Halley could write in his review of Newton's Principia that the first eleven propositions were found to agree with the phenomena of celestial motions, as discovered by the great sagacity and diligence of Kepler."

"Gaukroger believes that contemporary physicists concern themselves with a kind of mathematical knowledge that“ is clearly not the same as that derived by abstraction from individual cases.” Indeed, he goes goes so far as to claim that true scientific knowledge, “cannot be attained, at least in [Aristotelian] physics and cosmology."

"Let it be conceived that the [or a] particle acquires a tendency to move, and that nevertheless it does not move. It is then in a condition totally different from that in which it was at first. A cause competent to produce motion is operating upon it, but for some reason or other, is unable to give rise to motion. If the obstacle is removed, the energy which was there, but could not manifest itself, at once gives rise to motion. While the restraint lasts, the energy of the particle is merely potential; and the case supposed illustrates what is meant by potential energy. In this contrast of the potential with the actual, modern physics is turning to account the most familiar of Aristotelian distinctions—that between δύναμιζ [potential] and ένέργεια [action, effect, entelechy, power or energy]."

"[An] example of the hubris of contemporary science is the rigorous banishment of the word "purpose" from its vocabulary. This is probably an aftermath of the reaction against the animism of Aristotelian physics, where stones accelerated their fall because of their impatience to get home, and against a teleological world-view in which the purpose of the stars was to serve as chronometers for man's profit. From Galileo onward, "final causes" were relegated into the realm of superstition, mechanical causality reigned supreme. ...The mechanistic universe gradually disintegrated, but the mechanistic notion of causality survived until Heisenberg's indeterminacy principle proved its untenability."

"I could easily believe that Aristotle had stumbled, but not that, on entering physics, he had totally collapsed. Might not the fault be mine rather than Aristotle's, I asked myself. Perhaps his words had not always meant to him and his contemporaries quite what they meant to me and mine. Feeling that way, I continued to puzzle over the text, and my suspicions ultimately proved well-founded. I was sitting at my desk with the text of Aristotle's Physics open in front of me and with a four-colored pencil in my hand. Looking up, I gazed abstractedly out the window of my room -- the visual image is one I still retain. Suddenly the fragments in my head sorted themselves out in a new way, and fell into place together. My jaw dropped, for all at once Aristotle seemed a very good physicist indeed, but of a sort I'd never dreamed possible. Now I could understand why he had said what he'd said, and what his authority had been. Statements that had previously seemed egregious mistakes, now seemed at worst near misses within a powerful and generally successful tradition. That sort of experience -- the pieces suddenly sorting themselves out and coming together in a new way -- is the first general characteristic of revolutionary change that I shall be singling out after further consideration of examples. Though scientific revolutions leave much piecemeal mopping up to do, the central change cannot be experienced piecemenal, one step at a time. Instead, it involves some relatively sudden and unstructured transformation in which some part of the flux of experience sorts itself out differently and displays patterns that were not visible before."

"For Aristotelian physics the membership of an object in a given class was of critical importance, because for Aristotle the class defined the essence or essential nature of the object, and thus determined its behavior in both positive and negative respects."

"The attitude of Aristotelian physics toward lawfulness takes a new direction. So long as lawfulness remained limited to such processes as occurred repeatedly in the same way, it is evident, not only that the young physics still lacked the courage to extend the principle to all physical phenomena, but also that the concept of lawfulness still had a fundamentally historic, a temporally particular, significance. Stress was laid not upon the “general validity” which modem physics understands by lawfulness, but upon the events in the historically given world which displayed the required stability. The highest degree of lawfulness, beyond mere frequency, was characterized by the idea of the always eternal."

"Galileo's comprehension of the concept of acceleration, which he defined as a change of velocity either in magnitude or direction... was an abstract idea that no one seems to have thought much about before. And in using it to test the still accepted Aristotelian precept that a moving object requires a force to maintain it, Galileo easily demonstrated that it is not motion but rather acceleration which cannot occur without an external force. Deliberately rejecting common sense as a prejudiced witness, he let nature herself speak in the form of a "hard, smooth and very round ball" rolling down a "very straight" ideal groove lined with polished parchment, and then rolling up another groove, clocking each roll "hundreds or times"... he showed that, while downward motion (helped by gravity force) makes speed increase and upward motion (hindered by gravity force) makes speed decrease, there is always a "boundary case" in between... where speed remains constant (without any appreciable force)—and that, by reducing friction, this boundary case can be made to approach a horizontal level where gravity has no effect. Similarly testing... he also drafted a law of falling bodies: "that the distances traversed, during equal intervals of time... stand to one another in the same ratio as the odd numbers beginning with unity." And his beautiful analysis of a cannonball's trajectory into horizontal and vertical components... was one day to be of enormous help to Isaac Newton in solving the riddle of gravity."

"The victory of orthodox Christian doctrine over classical thought was to some extent a , for the theology that triumphed over Greek philosophy has continued to be shaped ever since by the language and the thought of classical metaphysics. For example, the Fourth Lateran Council in 1215 decreed that "in the sacrament of the altar... the bread is transubstantiated into the body [of Christ]." ...Most of the theological expositions of the term "" have interpreted "substance" [according] to the meaning given this term ...in the fifth book of Aristotle's Metaphysics; transubstantiation, then, would appear to be tied to the acceptance of Aristotelian metaphysics or even of Aristotelian physics. ...Transubstantiation is an individual instance of what has been called the problem of "the hellenization of Christianity.""

"The medieval theologians would not be surprised at a prerequisite of a degree in physics for a degree in theology. In their time, the highest degree in philosophy—which included the most advanced knowledge of physics of the day—was a prerequisite before a student was permitted to begin study for a degree in theology ...Kenny has shown the Aquinas' Five Ways—his five proofs of God's existence—are absolutely dependent on Aristotelian physics... Aquinas... was one of the leading scholars of Aristotelian physics... and... was primarily responsible for... [its] general acceptance throughout Europe. We could call Aquinas a great physicist as well as a great theologian, for, although Aristotelian physics was wrong, it was an essential precursor of modern physics."

"It is said, that Alexander the Great wrote to his former tutor to this effect; "You have not done well in publishing these lectures; for how shall we, your pupils, excel other men, if you make that public to all, which we learnt from you." To this Aristotle is said to have replied; "My Lectures are published and not published; they will be intelligible to those who heard them, and to none beside." This may very easily be a story invented and circulated among those who found the work beyond their comprehension; and it cannot be denied, that to make out the meaning and reasoning of every part, would be a task very laborious and difficult, if not impossible."