Customer Reviews (12) 
Excellent exposition, questionable interpretation
This is a great overview of the development of the Copernican system. The main text is very clear and readable and the "technical appendix" has good expositions of key mathematical arguments. Nevertheless, I think Kuhn's interpretation of "the Copernican revolution" has some shortcomings. Kuhn wishes the Copernican revolution to conform to his idea (as presented in his book The Structure of Scientific Revolutions) of a revolution brought on by a crisis: "[Copernicus'] famous preface still provides one of the classic descriptions of a crisis state" and "Ptolemaic astronomy had failed to solve its problems; the time had come to give a competitor a chance." But Kuhn does not support this position very well. For instance he writes: "When Copernicus listed the aspects of contemporary astronomy that had led him to consider his radical theory, he began, 'For, first, the mathematicians are so unsure of the movements of the Sun and the Moon that they cannot even explain or observe the constant length of the seasonal year.'" Here Kuhn is using a rather underhand trick. He is implying, of course, that this calendar issue was Copernicus' primary motivation, but fails to address two crucial counterarguments. First, Copernicus' preface is addressed to the Pope and he is clearly interested in emphasising that "my labors contribute somewhat even to the Commonwealth of the Church, of which your Holiness is now Prince," mentioning specifically how the calendar issue was a concern for Leo X, etc. Second, when Copernicus says "first...", he does not mean "first" as in "most important," for he continues with a "second" and then reaches "the chief point of all." This chief point of all is the fact that the Copernican model has a beautiful implication: the planetary distances. A geocentric model cannot give such information because we could scale the orbit of Saturn, say, to make it twice as big and it would still look exactly the same seen from earth. But in a heliocentric model the distances are determined because if we scaled the orbit of Saturn then it would look the same seen from the sun but different seen from earth. So with the earth in the center we cannot determine planetary distances because we are the center of scaling, but with the sun in the center we would notice scaling and thus the planetary distances are locked, or, as Copernicus puts it, "this correlation binds together so closely the order and the magnitudes of all the planets and of their spheres or orbital circles and the heavens themselves that nothing can be shifted around in any part of them without disrupting the remaining parts and the universe as a whole." Thus he can claim triumphantly that earlier astronomers "have not been able to discover or to infer the chief point of all, i.e., the form of the world and the certain commensurability of its parts. But they are in exactly the same fix as someone taking from different places hands, feet, head, and the other limbs---shaped very beautifully but not with reference to one body and without correspondence to one another---so that such parts made up a monster rather than a man." (I'm using the translation from Goldoni's excellent article in the Mathematical Intelligencer.) Kuhn admits that the Copernicus' determination of the planetary distances is "crucially important" but dismisses it as the main reason for the acceptance of the theory: "'Harmony' seems a strange basis on which to argue for the earth's motion... Copernicus' arguments are not pragmatic. They appeal, if at all, not to the utilitarian sense of the practising astronomer but to his aesthetic sense and to that alone. ... New harmonies did not increase accuracy or simplicity. Therefore they could and did appeal primarily to that limited and perhaps irrational subgroup of mathematical astronomers whose Neoplatonic ear for mathematical harmonies could not be obstructed by page after page of complex mathematics leading finally to numerical predictions scarcely better than those they had before." The correct reading---beauty before truth---is staring Kuhn in the face but he refuses to recognise it, opting instead to dismiss Copernicus as "strange" and Kepler as "irrational."
An idea that change the world
I asked my son when he was 4 years old why the Sun moved across the sky over the day. He answered me "because the earth turns". This seems like an obvious answer even for a 4 year old, but 400 years ago his response would be meet with ridicule and even worse would be considered heresy. Thomas S. Kuhn is able to beautifully and logically describe from a scientific perspective the ideas and discoveries through the ages that lead to the enormous conceptual leap from a geocentric to heliocentric world. This alone makes this book a great read. But what I valued more from the book is Kuhn's revealing of the impact of the "Copernican Revolution" outside the scientific world. It's influence on religion, society and the entire scientific process is still felt today. The idea of a heliocentric universe was not only a great scientific theory, it was really a turning point in the human race and how we see ourselves in the universe. I would also recommend "The book nobody read" and "Galileo's Daughter" as more modern follow ups to "The Copernican Revolution".
Case Study of a Scientific Revolution
"The Copernican Revolution" tells the epochal story of how the earth-centered cosmology of Ptolemy was replaced by the sun-centered cosmology of Copernicus and Kepler.The book is a classic.Kuhn understood how ideas influence each other and hang together in a system.He could write with equal erudition about observational astronomy, medieval theology, astrology, and Aristotelian physics.
"The Copernican Revolution" is a trove of historical and intellectual insights.Perhaps the main lesson is that scientific progress is not a simple matter of theory being adapted to observation.Multiple theories can account for the same observations, theories have complex non-observational bases of support, and extra-theoretical assumptions provided by "common sense" (such as the immobility of the earth) can be highly contingent products of a culture.Scientific progress is never guaranteed.Erroneous theories -- such as the theory placing the earth at the center of the universe -- can hold sway for centuries and generate a vast body of supporting evidence, only to fall out of sync with new observations and a new climate of opinion -- at which point they can hang on tenaciously, or collapse "suddenly" over the course of a generation or two.It all comes down to history.
Kuhn's great contribution to thought was to situate the history of science within the history of ideas -- he treated scientific theories as the products of cultures, institutions, and sheer accidents, not as deliverances of pure logic."The Copernican Revolution" is fantastic and should be ready by anyone who enjoyed and learned from "The Structure of Scientific Revolutions."It's become fashionable to bash Kuhn lately but his books have a secure place in the canon of history and philosophy of science.Six stars!
How a world-view changed
The Sun and the planets and all the stars revolve around the Earth, which is itself at the center of the universe. Beyond the sphere of the fixed stars is nothing; there is no void or matter or anything, as voids cannot exist in nature. All these celestial bodies that do exist revolve in nice perfect circles. All these statements were once common knowledge to anyone with a smattering of education, even though astronomers were known to make slight variations on the concepts of circular motion. But today every single one of these concepts is demolished, and only fools believe in the Earth centered universe. Why was there a change? It certainly wasn't because of a mass of new information. The old geocentric universe was rejected long before anyone put up satellites and space probes to go zipping around the solar system. Even the invention of the telescope only provided the final blow to the old system. It was a fundamental change in thinking that made up the subject of The Copernican Revolution, Thomas Kuhn's look at the break between ancient and modern thinking on the subject.
Copernicus himself made no observations. He worked only with acquired data and ancient texts. What system did he start out with? This is important, as we can't understand what changed without knowing what was. Kuhn traces the nature of the Ptolemaic system with diagrams but virtually no equations (until the technical appendix at the end) to give the reader an understanding of what sorts of phenomena caught the eyes of ancient astronomers. The Sun and Moon and stars move in their own peculiar manners, and the planets, the wandering stars, behaved in the most peculiar manner of all. The ancients developed rather sophisticated methods to track and predict these movements using their own location as a reasonable starting point. Yet Copernicus had the idea that this starting point was not properly speaking the actual center of the universe. He developed a Sun centered system that qualitatively explained many phenomena (such as retrograde motion of the planets, a notable improvement) without some of the mathematical oddities of the old system, but required so many of its own modifications for accuracy that the final system was no neater than the original.
Yet some astronomers preferred the new to the old. This was, all myth busting aside, still a dangerous idea to advocate in the midst of the Reformation. There was a subtle distinction between advocating a mathematical model and advocating a statement of physical reality. There were many reasons to reject Copernicus, and Kuhn covers them here. There are two main themes: the first is that ancient astronomy was bound up with ancient physics and with theology, and rejecting one introduced many awkward questions about the rest that intellectually honest scholars couldn't ignore. The second is political. Most people know something of the story of Galileo and his confrontations with the Inquisition. It didn't help him that he was arrogant, that he mocked powerful people he called friends, and that politically it was a bad time to make waves. This is also touched upon briefly in Kuhn, but the focus remains on the intellectual revolution, and there Galileo had much to contribute in his new observations. Ultimately, the revolution was as much about insight and vision as about calculations and observations.
Readers more familiar with Kuhn from his later The Structure of Scientific Revolutions will find some of his discussion taking a familiar tone. Indeed, the Copernican revolution fits well with that model; it was a revolutionary idea that marked a turning point in Western science, straddling both the ancient and modern viewpoints. For the reader who is willing to visualize the issues and absorb the history, Kuhn has provided the most succinct and clear explanation of Copernicus's contribution to the Western world likely to be found anywhere.
Outstanding Elucidation
This book, written before his Structures, is condensed, well written and, for me at any rate, highly entertaining. No one with a casual understanding of the history of astronomy can read this and not be surprised. Of special interest is the illumination of the fact that at the time Copernicus offered his Helio-centric cosmology there was no good, scientific reason for accepting it - it being a geometric inversion of the Ptolemaic system and thus inheriting exactly all of the Ptolemaic deficiencies. Kuhn explores the reason for the gradual shift to Copernicanism and the effects a moving earth had on other sciences.
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why science isn't so scientific