Thomas Samuel Kuhn (July 18, 1922June 17, 1996) was an American physicist, historian, and philosopher of science and who wrote extensively on the history of science and developed several important notions in the philosophy of science.


  • Only when they must choose between competing theories do scientists behave like philosophers.
    • Thomas Kuhn (1970) in Logic of Discovery or Psychology of Research?, edited by Imre Lakatos, Alan Musgrave (1970). Criticism and the growth of knowledge. Cambridge University Press. p. 7. ISBN 0521096235. 

The Structure of Scientific Revolutions (1962)

Thomas Kuhn. The Structure of Scientific Revolutions. University of Chicago Press, 1962; second edition, enlarged, 1970; third edition 1996; fourth edition 2012.


  • To my complete surprise, that exposure to out-of-date scientific theory and practice radically undermined some of my basic conceptions about the nature of science and the reasons for its special success.
    Those conceptions were ones I had previously drawn partly from scientific training itself and partly from a long-standing avocational interest in the philosophy of science. Somehow, whatever their pedagogic utility and their abstract plausibility, those notions did not at all fit the enterprise that historical study displayed. Yet they were and are fundamental to many discussions of science, and their failures of verisimilitude therefore seemed thoroughly worth pursuing. The result was a drastic shift in my career plans, a shift from physics to history of science and then, gradually, from relatively straightforward historical problems back to the more philosophical concerns that had initially led me to history.
  • Somehow, the practice of astronomy, physics, chemistry or biology normally fails to evoke the controversies over fundamentals that today seem endemic among, say, psychologists or sociologists. Attempting to discover the source of that difference led me to recognize the role in scientific research of what I have since called “paradigms.” These I take to be universally recognized scientific achievements that for a time provide model problems and solutions for a community of practitioners.
    • p. xiii (2012 ed.)

I. Introduction: A Role of History

  • History, if viewed as a repository for more than anecdote or chronology, could produce a decisive transformation in the image of science by which we are now possessed.
  • Out-of-date theories are not in principle unscientific because they have been discarded. That choice, however, makes it difficult to see scientific development as a process of accretion.
  • Normal science, the activity in which most scientists inevitably spend almost all their time, is predicated on the assumption that the scientific community knows what the world is like. Normal science often suppresses fundamental novelties because they are necessarily subversive of its basic commitments.
    • p. 5

II. The Route to Normal Science

  • "Normal science" means research firmly based upon one or more past scientific achievements, achievements that some particular scientific community acknowledges for a time as supplying the foundation for its further practice.
    • p. 10
  • Men whose research is based on shared paradigms are committed to the same rules and standards for scientific practice. That commitment and the apparent consensus it produces are prerequisites for normal science, i.e., for the genesis and continuation of a particular research tradition.
    • p. 11 (2012 ed.)
  • Ever since prehistoric antiquity one field of study after another has crossed the divide between what the historian might call its prehistory as a science and its history proper. These transitions to maturity have seldom been so sudden or so unequivocal as my necessarily schematic discussion may have implied. But neither have they been historically gradual, coextensive, that is to say, with the entire development of the fields within which they occurred.
    • p. 22 (2012 ed.)

III. The Nature of Normal Science

  • Few people who are not actually practitioners of a mature science realize how much mop-up work of this sort a paradigm leaves to be done or quite how fascinating such work can prove in the execution.
    • p. 24 (2012 ed.)
  • These three classes of problems—determination of significant fact, matching of facts with theory, and articulation of theory—exhaust, I think, the literature of normal science, both empirical and theoretical. They do not, of course, quite exhaust the entire literature of science. There are also extraordinary problems, and it may well be their resolution that makes the scientific enterprise as a whole so particularly worthwhile. But extraordinary problems are not to be had for the asking. They emerge only on special occasions prepared by the advance of normal research.
    • p. 34 (2012 ed.)

IV. Normal Science as Puzzle-solving

  • The scientific enterprise as a whole does from time to time prove useful, open up new territory, display order, and test long-accepted belief. Nevertheless, the individual engaged on a normal research problem is almost never doing any one of these things. Once engaged, his motivation is of a rather different sort. What then challenges him is the conviction that, if only he is skillful enough, he will succeed in solving a puzzle that no one before has solved or solved so well.
    • p. 38.

V. The Priority of Paradigms

  • Scientists work from models acquired through education and through subsequent exposure to the literature often without quite knowing or needing to know what characteristics have given these models the status of community paradigms
    • p. 46

VI. Anomaly and the Emergence of Scientific Discoveries

  • Normal science, the puzzle-solving activity we have just examined, is a highly cumulative enterprise, eminently successful in its aim, the steady extension of the scope and precision of scientific knowledge. In all these respects it fits with great precision the most usual image of scientific work. Yet one standard product of the scientific enterprise is missing. Normal science does not aim at novelties of fact or theory and, when successful, finds none.
    • p. 52
  • We must now ask how changes of this sort can come about, considering first discoveries, or novelties of fact, and then inventions, or novelties of theory. That distinction between discovery and invention or between fact and theory will, however, immediately prove to be exceedingly artificial.
    • p. 52 (2012 ed.)
  • In science, as in the playing card experiment, novelty emerges only with difficulty, manifested by resistance, against a background provided by expectation.
    • p. 64 (2012 ed.)
  • In the development of any science, the first received paradigm is usually felt to account quite successfully for most of the observations and experiments easily accessible to that science’s practitioners. Further development, therefore, ordinarily calls for the construction of elaborate equipment, the development of an esoteric vocabulary and skills, and a refinement of concepts that increasingly lessens their resemblance to their usual common-sense prototypes. That professionalization leads, on the one hand, to an immense restriction of the scientist’s vision and to a considerable resistance to paradigm change. The science has become increasingly rigid. On the other hand, within those areas to which the paradigm directs the attention of the group, normal science leads to a detail of information and to a precision of the observation-theory match that could be achieved in no other way.
    • p. 64 (2012 ed.)

VII. Crisis and the Emergence of Scientific Theories

  • Philosophers of science have repeatedly demonstrated that more than one theoretical construction can always be placed upon a given collection of data. History of science indicates that, particularly in the early developmental stages of a new paradigm, it is not even very difficult to invent such alternates. But that invention of alternates is just what scientists seldom undertake except during the pre-paradigm stage of their science’s development and at very special occasions during its subsequent evolution. So long as the tools a paradigm supplies continue to prove capable of solving the problems it defines, science moves fastest and penetrates most deeply through confident employment of those tools. The reason is clear. As in manufacture so in science—retooling is an extravagance to be reserved for the occasion that demands it. The significance of crises is the indication they provide that an occasion for retooling has arrived.
    • p. 76 (2012 ed.)
  • Scientific revolutions are inaugurated by a growing sense... that an existing paradigm has ceased to function adequately in the exploration of an aspect of nature to which that paradigm itself had previously led the way.
    • p. 91 (2012 ed.)

X. Revolutions as Changes of World View

The subject of a gestalt demonstration knows that his perception has shifted because he can make it shift back and forth repeatedly while he holds the same book or piece of paper in his hands...
  • The subject of a gestalt demonstration knows that his perception has shifted because he can make it shift back and forth repeatedly while he holds the same book or piece of paper in his hands. Aware that nothing in his environment has changed, he directs his attention increasingly not to the figure (duck or rabbit) but to the lines of the paper he is looking at. Ultimately he may even learn to see those lines without seeing either of the figures, and he may then say (what he could not legitimately have said earlier) that it is these lines that he really sees but that he sees them alternately as a duck and as a rabbit. ...As in all similar psychological experiments, the effectiveness of the demonstration depends upon its being analyzable in this way. Unless there were an external standard with respect to which a switch of vision could be demonstrated, no conclusion about alternate perceptual possibilities could be drawn.
    • p. 114 (3rd edn.)

XII. The Resolution of Revolutions

  • These examples point to the third and most fundamental aspect of the incommensurability of competing paradigms. In a sense that I am unable to explicate further, the proponents of competing paradigms practice their trades in different worlds. One contains constrained bodies that fall slowly, the other pendulums that repeat their motions again and again. In one, solutions are compounds, in the other mixtures. One is embedded in a flat, the other in a curved, matrix of space. Practicing in different worlds, the two groups of scientists see different things when they look from the same point in the same direction. Again, that is not to say that they can see anything they please. Both are looking at the world, and what they look at has not changed. But in some areas they see different things, and they see them in different relations one to the other. That is why a law that cannot even be demonstrated to one group of scientists may occasionally seem intuitively obvious to another.
    • p. 149

XIII. Progress Through Revolutions

  • We may, to be more precise, have to relinquish the notion, explicit or implicit, that changes of paradigm carry scientists and those who learn from them closer and closer to the truth
    • p. 170

Postscript (1969)

  • A scientific theory is usually felt to be better than its predecessors not only in the sense that it is a better instrument for discovering and solving puzzles but also because it is somehow a better representation of what nature is really like. One often hears that successive theories grow ever closer to, or approximate more and more closely to, the truth. Apparently generalizations like that refer not to the puzzle-solutions and the concrete predictions derived from a theory but rather to its ontology, to the match, that is, between the entities with which the theory populates nature and what is “really there.”
    Perhaps there is some other way of salvaging the notion of ‘truth’ for application to whole theories, but this one will not do. There is, I think, no theory-independent way to reconstruct phrases like ‘really there’; the notion of a match between the ontology of a theory and its “real” counterpart in nature now seems to me illusive in principle. Besides, as a historian, I am impressed with the implausability of the view. I do not doubt, for example, that Newton’s mechanics improves on Aristotle’s and that Einstein’s improves on Newton’s as instruments for puzzle-solving. But I can see in their succession no coherent direction of ontological development. On the contrary, in some important respects, though by no means in all, Einstein’s general theory of relativity is closer to Aristotle’s than either of them is to Newton’s.

The Road Since Structure (2002)

Thomas Kuhn, The Road since Structure: Philosophical Essays, 1970-1993, with an Autobiographical Interview, Edited by James F. Conant and John Haugeland, University of Chicago Press, 2002

  • I rapidly discovered that Aristotle had known almost no mechanics at all. ... How could his characteristic talents have deserted him so systematically when he turned to the study of motion and mechanics? Equally, if his talents had so deserted him, why had his writings in physics been taken so seriously for so many centuries after his death? ... I was sitting at my desk with the text of Aristotle's Physics open in front of me... 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.
    • p. 16-17; from "What Are Scientific Revolutions?" (1982)
  • By now it may be clear that the position I'm developing is a sort of post-Darwinian Kantianism.
    • p. 104; from "The Road since Structure" (1990)

Quotes about Thomas Kuhn

  • Kuhn’s treatment of philosophical ideas is neither systematic nor rigorous. He rarely engaged in the stock-in-trade of modern philosophers, the careful and precise analysis of the details of other philosophers’ views, and when he did so the results were not encouraging.
    • Alexander Bird, Thomas Kuhn (2000), Preface
  • Thomas Kuhn was undoubtedly the strongest influence on the philosophy of science in the last third of the twentieth century. Yet today, at the beginning of the twenty-first century it is unclear what his legacy really is. In the philosophy of science there is no characteristically Kuhnian school. This could be because we are all Kuhnians now. But it might also be because Kuhn's thought, although revolutionary in its time, has since been superseded. In a sense both may be true.
    • Alexander Bird, "Kuhn and Philosophy of Science in the Twentieth Century", Annals of the Japan Association for Philosophy of Science (2004)
  • Partly because he was an outsider to philosophy he was unable to appreciate that philosophy of science had gone beyond Kuhn in distancing itself from positivism. And thus when he rejected aspects of contemporary philosophy of science—notably referentialism and a realist conception of truth—he was unintentionally aligning himself more closely to positivism than to its opponents.
    • Alexander Bird, "Kuhn and Philosophy of Science in the Twentieth Century", Annals of the Japan Association for Philosophy of Science (2004)
  • To introduce my story, I take the reader back to 1962, when the academic world saw the publication of The Structure of Scientific Revolution, by Thomas Kuhn. … Most certainly, it upset my own Logical Empiricist assumptions. It had that effect for two reasons. The first was his claim, vividly documented, that past scientific revolutions were not the unambiguous expression of sheerly logical and experimental factors, rationally played out according to a well-defined methodology. Rather, they were the expression of a variety of nonlogical factors as well: social, psychological, metaphysical, technological, aesthetic, and personal. … The second reason for the ensuing controversy was his claim, also well-documented, that the unit of scientific understanding is not the sentence, or set of sentences, but rather the so-called "paradigm", or family of paradigms.
    • Paul Churchland, The Engine of Reason (1995), Chap. 10 : Language, Science, Politics and Art
  • In fact, Kuhn is decidedly conservative in his methodological impulses. If science is politics, then he is a staunch Tory, not an anything-goes radical. In fact, Kuhn was not attacking scientific standards. Rather, he was attacking a false and confabulatory theory about the nature of scientific standards, a worthy and nontrivial philosophical theory called Logical Empiricism, a theory that tried to capture all such standards in narrowly logical terms. If one already accepts that orthodox but confabulatory theory, as most philosophers did, then one is doomed to see an attack on it as an attack on scientific standards in general.
    But it needn't be so. Once we have seen that a scientific theory is much more than a set of sentences, then we can appreciate that its evaluation must encompass much more than mere logical relations among sentences. Once we are freed from the grip of the orthodox philosophical approach, we can pursue the question of theory evaluation with a fresh eye.
    • Paul Churchland, The Engine of Reason (1995), Chap. 10 : Language, Science, Politics and Art
  • Thomas Kuhn, in The Structure of Scientific Revolutions (1962), is the godfather of all the subsequent discussions, and it should be noted that Kuhn's book is perhaps the all-time champion in the category of Enthusiastically Misunderstood Classic. It's a wonderful book, in spite of all the misuse to which it's been put.
    • Daniel Dennett, Breaking the Spell (2006), Note 4 on Chapter 8. Belief in Belief
  • Kuhn’s book has been misread and misused in many quarters; Kuhn’s excellent points are not as radical as many like to believe.
    • Daniel Dennett, in "The Dan Schneider Interview 2: Daniel Dennett" (July 1, 2007)
  • How do scientists think?
    The short answer: very much like you or me.
    If that statement doesn’t raise any eyebrows today, it’s because of a college professor named Thomas Kuhn who died in 1996.
  • A lot of people have put Genealogy of Morals on their lists because Nietzsche was the first person they read who pointed out that morals might have an instrumental and particularistic motivation. I’m not sure Kuhn is completely correct in his vivisection of how science works, but it was only after reading this book that I began to recognize the instrumental, cognitive, and sociological dimensions of scientists.
  • A few years ago I happened to meet Kuhn at a scientific meeting and complained to him about the nonsense that had been attached to his name. He reacted angrily. In a voice loud enough to be heard by everyone in the hall, he shouted, "One thing you have to understand. I am not a Kuhnian." Kuhn never said that science is a political power struggle. If some of his followers claim that he denied the objective validity of science, it is only because he overemphasized the role of ideas and underemphasized the role of experimental facts in science.
    • Freeman Dyson, The Sun, The Genome, and The Internet: Tools of Scientific Revolutions (1999)
  • Thomas Kuhn is the Thomas Hobbes of science, assuring us that unless there is an Absolute (conceptual) Sovereign, known as The Paradigm, all is chaos, and the life of cognitive ideas is solitary, poor, nasty, brutish and short.
    • Ernest Gellner, The Psychoanalytic Movement: The Cunning of Unreason (1985)
  • Without doubt, Kuhn's work was the single most influential force in creating the intersection of history, philosophy and sociology of science that became identified as 'science studies'. The irony and tragedy is that, in spite of official honours and genuine attempts at reconciliation by both Kuhn and others, he himself was never truly at home in any of these disciplines, nor in their intersection. The majority of historians and philosophers of science never permitted Kuhn to feel genuinely comfortable in their professional associations. The sociologists tried, but Kuhn himself was not comfortable in their company. He died professionally homeless.
    • Ronald N. Giere, "Kuhn's Legacy for North American Philosophy of Science", Social Studies of Science, Vol. 27, No. 3 (Jun., 1997)
  • So who cares? We should care. Kuhn's work supports the idea that science progresses from-what-we-know to what-we-know-next. This is in contrast with the Whig interpretation of science, which is the inevitable march from darkness to light, from confusion to clarity, from error to truth. Of course, there is nothing wrong with teaching physics by recounting its past successes, but that is not in fact how the dynamic of knowledge works.
  • Kuhn cannot take seriously that “there is some one full, objective, true account of nature.” Does this mean that he does not take truth seriously? Not at all. [...]
    Kuhn did reject a simple “correspondence theory” which says true statements correspond to facts about the world.[...]
    In the wave of skepticism that swept American scholarship at the end of the twentieth century, many influential intellectuals took Kuhn as an ally in their denials of truth as a virtue. I mean the thinkers of the sort that cannot write down or utter the word true except by literally or figuratively putting quotation marks around it—to indicate how they shudder at the very thought of so harmful a notion. Many reflective scientists, who admire much of what Kuhn says about the sciences, believe he encouraged deniers.
    It is true that Structure gave enormous impetus to sociological studies of science. Some of that work, with its emphasis on the idea that facts are “socially constructed” and apparent participation in the denial of “truth,” is exactly what conservative scientists protest against. Kuhn made plain that he himself detested that development of his work...
    • Ian Hacking (2012), Introductory Essay, in 50th anniversary edition of Thomas Kuhn's The Structure of Scientific Revolution
  • Notice that there is no sociology in the book. Scientific communities and their practices are, however, at its core, entering with paradigms, as we saw, at page 10 and continuing to the final page of the book. There had been sociology of scientific knowledge before Kuhn, but after Structure it burgeoned, leading to what is now called science studies. This is a self-generating field (with, of course, its own journals and societies) that includes some work in the history and the philosophy of sciences and technology, but whose emphasis is on sociological approaches of various kinds, some observational, some theoretical. Much, and perhaps most, of the really original thinking about the sciences after Kuhn has had a sociological bent.
    Kuhn was hostile to these developments. In the opinion of many younger workers, that is regrettable. Let us put it down to dissatisfaction with growing pains of the field, rather than venturing into tedious metaphors about fathers and sons. One of Kuhn’s marvelous legacies is science studies as we know it today.
    • Ian Hacking (2012), Introductory Essay, in 50th anniversary edition of Thomas Kuhn's The Structure of Scientific Revolution
  • Well, he wasn't a relativist. There's a long and complicated story of the rise of a desire for scientific relativism. Part of it may well be simply sort of rage against reason, the fear of the sciences and a kind of total dislike of the arrogance of a great many scientists who say we're finding out the truth about everything—and here [with Kuhn] there was a way to undermine that arrogance.
    • Ian Hacking, in Gary Stix, "A Q&A with Ian Hacking on Thomas Kuhn's Legacy as "The Paradigm Shift" Turns 50" (April 27, 2012)
  • Kuhn had the genius to find the words and sketch the concepts that made important old philosophical problems relevant to the public and newly discussable by philosophers. He had the strength of mind and commitment to lead the discussion. He could speak the truly incommensurable languages of physics, philosophy, and history, all necessary to frame and advance his epistemological quest. He wrote, as one of his admirers, Margaret Masterman, put it, in a "quasi-poetic style," sometimes veiled, sometimes with "rhetorical exaggeration," but always after careful and even painful thought. Or, to switch metaphors, he drew the portrait of science in the manner of the Impressionists. At a distance, where most viewers stand, the portrait appears illuminating, persuasive, and inspiring; close in, where historians and philosophers stare, it looks sketchy, puzzling, and richly challenging.
  • Kuhn's recognition that science might cease—leaving us with what Charles Sanders Peirce had defined as the "truth" about nature—made it even more imperative for Kuhn than for Popper to challenge science's authority, to deny that science can ever arrive at absolute truth. "The one thing I think you shouldn't say is that now we've found out what the world is really like," Kuhn said. "Because that's not what I think the game is about."
    • John Horgan, The End of Science (1996), Ch. 2 : The End of Philosophy
  • In Structure, the “third and most important aspect of […] incommensurability” is world change (p. 150)
    There have been several reactions to this claim:
    a. Dismissal because of idealism
    b. Defusing of world change by a metaphorical or psychological reading
    c. “Neo-Kantian” reading
  • World change, reaction a: dismissal

    Israel Scheffler in Science and Subjectivity, 1967, p. 19: “I cannot, myself, believe that this bleak picture, representing an extravagant idealism, is true.”
    The full argument contains four premises and one conclusion (this is for the philosophers):
    P1: Incommensurability encompasses world change
    P2: World change (in revolutions) implies idealism.
    P3: Idealism is bullshit.
    P4: Bullshit can be dismissed.
    Conclusion: Incommensurability can be dismissed.
    Ad P2: Yes, perhaps, but what sort of idealism?
    Ad P3: The high-school version of idealism is certainly very questionable: “What reality is depends on how you think of it” – period
    Was this Kuhn’s view?

  • World change, reaction c: “Neo-Kantian”

    From 1979 onward, Kuhn described his position as Kantian with “temporally mutable categories” (or in Peter Lipson’s words: Kuhn’s position is “Kant on wheels”)
    Note first that this cannot be entirely correct because

    • Kant’s forms of intuition and forms of thought (categories) are responsible for the constitution of what physical things in general, i.e. spatio-temporal things, are: Kant’s forms of intuition and thought are constitutibe of “thinghood”
    • By contrast, Kuhn’s world change does (usually) not affect thinghood itself, it only affects the existence, the qualities, and the relations of specific things.
However, Kuhn’s spirit is the same as Kant’s:
What we correctly take as objective reality is nevertheless somehow shaped by genetically subject-sided components.
  • Kuhn as does Popper rejects the idea that science grows by accumulation of eternal truths.. But while according to Popper science is ‘revolution in permanence’, and criticism the heart of the scientific enterprise, according to Kuhn revolution is exceptional and, indeed, extra-scientific, and criticism is, in ‘normal’ times, anathema... The clash between Popper and Kuhn is not about a mere technical point in epistemology. It concerns our central intellectual values, and has implications not only for theoretical physics but also for the underdeveloped social sciences and even for moral and political philosophy. If even in science there is no other way of judging a theory but by assessing the number, faith and vocal energy of its supporters, then this must be even more so in the social sciences: truth lies in power. Thus Kuhn’s position would vindicate, no doubt, unintentionally, the basic political credo of contemporary religious maniacs (‘student revolutionaries’).
  • What, then, is the hallmark of science? Do we have to capitulate and agree that a scientific revolution is just an irrational change in commitment, that it is a religious conversion? Tom Kuhn, a distinguished American philosopher of science, arrived at this conclusion after discovering the naivety of Popper’s falsificationism. But if Kuhn is right, then there is no explicit demarcation between science and pseudoscience, no distinction between scientific progress and intellectual decay, there is no objective standard of honesty.
  • What truth is not, according to Kuhn, is an accurate representation of the world as it is in itself. Scientific theories represent a world, but one partially constituted by the cognitive activities of the scientists themselves. This is not a commonsensical view, but it has a distinguished philosophical pedigree, associated most strongly with Kant. The Kantian view is that the truths we can know are truths about a ‘phenomenal’ world that is the joint product of the ‘things in themselves’ and the organising, conceptual activity of the human mind.
    Kuhn, however, is Kant on wheels. Where Kant held that the human contribution to the phenomenal world is invariant, Kuhn’s view is that it changes fundamentally across a scientific revolution. This is what he means by his notorious statement that, after a scientific revolution, ‘the world changes’. This is neither the trivial claim that scientists’ beliefs about the world change, nor the crazy claim that scientists can change the things in themselves simply by changing their beliefs. It is the claim that the phenomenal world changes because the human contribution to it changes.
    • Peter Lipton, "Kant on Wheels", London Review of Books (19 July 2001)
  • The Structure of Scientific Revolutions contains some nice observations on the nature of what Kuhn calls “normal science”, which makes it out to have none of the heroic aspects that Popper insisted on. But when Kuhn goes beyond normal science to “revolutionary science” the book is a disaster. It promotes an irrationalist view of scientific revolutions that is both false and pernicious. The Copernican Revolution is a lovely book, much needed at the time. Planck and the Black Body Discontinuity is a mixed bag: some good historiography and some poor analysis.
  • Kuhn's description of how scientific revolutions happen does not apply to any biological revolution. To be very frank, I cannot understand how this book could have been such a success. The general thesis was not new, and when he did assert specific claims he was almost always wrong!
    Kuhn's book mainly appealed to historians and social scientists. It was they who built it up into a big thing. It was vague, and vagueness always appeals to historians and social scientists.
  • Much of what Kuhn says about great theoretical shifts, and the inertial role of long-established scientific paradigms and their cultural entrenchment in resisting recalcitrant evidence until it becomes overwhelming, is entirely reasonable, but it is also entirely compatible with the conception of science as seeking, and sometimes finding, objective truth about the world. What has made him a relativist hero is the addition of provocative remarks to the effect that Newton and Einstein, or Ptolemy and Galileo, live in "different worlds," that the paradigms of different scientific periods are "incommensurable," and that it is a mistake to think of the progress of science over time as bringing us closer to the truth about how the world really is.
    • Thomas Nagel, "The Sleep of Reason", The New Republic, October 12, 1998
  • This brutal summary of the revolutionary process does not do justice to the complexity and subtlety of Kuhn's thinking. To appreciate these, you have to read his book. But it does perhaps indicate why Structure… came as such a bombshell to the philosophers and historians who had pieced together the Whig interpretation of scientific progress.
  • When Thomas Kuhn talked about paradigm shifts within science, he defined a paradigm as a disciplinary matrix, which included not just the dominant theoretical framework within a given science (say, quantum mechanics in modern fundamental physics), but also the vocabulary and methods accepted within the community, the range of questions deemed interesting, as well as the textbooks and other training tools for the next generation of scientists. In a very real sense, then, physics, biology, analytical philosophy, continental philosophy, and so forth are indeed “traditions,” and the best (if not the only) way to learn them is not just by reading books at home, but by engaging in personal training over a number of years. That’s one reason why lone individuals who style themselves as revolutionary geniuses and who are convinced to have discovered proof that, for instance, general relativity is flawed are (much) more likely to be cranks than anything else. And that is also why, again in part, pseudoscience has a very different character from the genuine article.
  • Kuhn’s (and Feyerabend’s) account of the historical development of science threatens inductivist and hypothetico-deductivist methodologies in a straightforward and dramatic way. When we look at what past scientists do, their work does not seem to fit the methods described by either inductivists or hypothetico-deductivists. Scientists engaged in normal science are pursuing neither confirmations nor refutations of their theory. They are engaged in an activity that Kuhn calls articulating the paradigm, which as we have seen involves many things other than theory testing.
    That is an important negative conclusion, and the method of arriving at it should appeal to the naturalist. The argument is essentially an empirical one. The history of science refutes (or at least shows the inadequacy of) the most popular methodologies of science. But Kuhn’s and Feyerabend’s description of scientific revolutions also presents two problems for the naturalist. First, since both claim that there is never a compelling reason to change from one paradigm to another, their accounts of science threaten to make scientific change look irrational. If that story is right, it should shake the naturalists’ conviction that science is to be admired as much as they think. Secondly, even if we could retell the story of scientific progress to remove some of the arbitrariness that Kuhn and Feyerabend claim exists; even if we could explain why scientists have changed paradigms and thereby methods from one period to the next, then we shall still have to confront another issue. If the methods of science have changed through history, that means there is no such thing as the scientific method, and so obviously no way to make use of the methods of science in philosophy.
    • Jack Ritchie, Understanding Naturalism (2008), Ch. 4 : Naturalized philosophy of science
  • Up until the publication of Thomas Kuhn's The Structure of Scientific Revolutions in 1962, the history, philosophy, and sociology of science maintained an internalist approach to scientific knowledge claims. Science was seen as somehow above any social, political, or cultural influences, and therefore, the examinations of scientific knowledge focused on areas such as 'discoveries,' 'famous men,' and 'the scientific revolution in the West.' When Kuhn opened the door to the possibility that external factors were involved in the development of scientific paradigms, science studies assumed a more critical tone.
    • Diane M. Rodgers (2009) "Debugging the Link Between Social Theory and Social Insects".
  • Whatever Kuhn’s intentions, I believe that his effect on general culture, though not on the practices of real scientists, has been unfortunate, because it has served to “demythologize” science, to “debunk” it, to prove that it is not what ordinary people have supposed it to be. Kuhn paved the way for the even more radical skeptical view of Paul Feyerabend, who argued that as far as giving us truths about the world, science is no better than witchcraft.
    • John Searle, “Philosophy in a new century,” in Philosophy in America at the Turn of the Century, APA Centennial Supplement, Journal of Philosophical Research (2003)
  • Finally, by the early 1960s, Thomas Kuhn’s picture of “normal science” portrayed scientific activity not as an open-minded philosophical quest but as puzzle-solving—the extension and application of existing paradigms. To the shock and indignation of some, Kuhn argued that being a scientist involved obedience to “dogma” and a narrowing of perception. Science remained, of course, the most reliable knowledge we had, but whatever moral authority might follow from regarding science as uniquely free of prejudice was—for those persuaded by Kuhn—no longer available.
  • To put the mater simply, I think that Kuhn might have vastly overemphasized the role of scientific revolutions. I also don’t believe that an evolutionary view can be compatible with Kuhnian discontinuities.
    • Eric Scerri, A Tale of Seven Scientists and a New Philosophy of Science (2016), Chap. 9 : Bringing Things Together
  • Not long after publication of my first article on the subject, I was given a book called The Structure of Scientific Revolutions written by the philosopher of science Thomas Kuhn. This book deals with the process by which scientific paradigms are produced and replaced. I warmly endorse this book because I have lived through several of the stages described in the book.
    • Dan Shechtman, "Quasi-Periodic Crystals—The Long Road from Discovery to Acceptance", Rambam Maimonides Medical Journal (2013)
  • I’m one of the few physicists I know who likes Thomas Kuhn. He was partly a historian of science, partly a sociologist. He got the basic idea right of what happens when the scientific paradigm shifts. A radical change of perspective suddenly occurs. Wholly new ideas, concepts, abstractions and pictures become relevant. Relativity was a big paradigm shift. Quantum mechanics was a big paradigm shift. So we keep on inventing new realisms. They never completely replace the old ideas, but they do largely replace them with concepts that work better, that describe nature better, that are often very unfamiliar, that make people question what is meant by “reality.” Then the next thing comes along and turns that on its head. And we are always surprised that the old ways of thinking, the wiring that we have or the mathematical wiring that we may have created, simply fail us.
    • Leonard Susskind, in "Bad Boy of Physics", Interview by Peter Byrne, Scientific American (July 2011)
  • Although Kuhn's emphasis on revolutionary change was an antidote to the simplistic models of the logical empiricists, a finer-grained theory of revolutionary change than Kuhn presented need not succumb to irrationalism. To develop such a theory, however, we need tools different from both the formal ones of the logical empiricists and the vague historical ones of Kuhn.
    • Paul Thagard, Conceptual Revolutions (1992), Chap. 1 : The Problem of Revolutionary Conceptual Change
  • [The Structure of Scientific Revolutions] was hugely influential, especially on the liberal arts, giving them ammunition to suggest that science was no better way of knowing the truth than any other way of investigating. It made a huge case of scientists gathering around one truth, and then there’s a tipping point and everyone moves away from that truth to gather around another truth. Hence the title of the book. And this left people with the sense that science is just whatever is in fashion. Kuhn used, as his best example of this, Copernicus. That’s half his book ... almost half of that book describes the Copernican Revolution as an example of the way science works. But that’s not how science works. It’s just not. It’s how things happened until 1600.
  • In his celebrated book The Structure of Scientific Revolutions Thomas Kuhn went a step further and argued that in scientific revolutions the standards (or “paradigms”) by which scientists judge theories change, so that the new theories simply cannot be judged by the prerevolutionary standards. There is much in Kuhn’s book that fits my own experience in science. But in the last chapter Kuhn tentatively attacked the view that science makes progress toward objective truths: “We may, to be more precise, have to relinquish the notion, explicit or implicit, that changes of paradigm carry scientists and those who learn from them closer and closer to the truth.” Kuhn’s book lately seems to have become read (or at least quoted) as a manifesto for a general attack on the presumed objectivity of science.
    • Steven Weinberg, Dreams of a Final Theory (1992), Ch. 7 : Against Philosophy
  • The changes in the way we judge our theories have bothered philosophers and historians of science. Thomas Kuhn’s early book, The Structure of Scientific Revolutions, emphasized this process of change in our scientific standards. I think Kuhn went overboard in concluding that there was a complete incommensurability between present and past standards, but it is correct that there is a qualitative change in the kind of scientific theory we want to develop that has taken place at various times in the history of science. But Kuhn then proceeded to the fallacy—much clearer in what he has written recently—that in science we are not in fact moving toward objective truth. I call this a fallacy because it seems to me a simple non sequitur. I do not see why the fact that we are discovering not only the laws of nature in detail, but what kinds of laws are worth discovering, should mean that we are not making objective progress.
    • Steven Weinberg, "The Methods of Science ... and Those by Which We Live" (1995)
  • By the way, in this respect my friend Thomas Kuhn has a lot to answer for. He distances himself from the postmoderns and the social constructivists, but he is endlessly quoted by them. He distances himself in saying that there is a place for evidence and reason in the scientific process—good to hear—but he attacks the idea that we are moving toward objective truth. As far as I can tell from one of his recent articles, his reason for rejecting the idea that science moves toward objective truth is that he and other philosophers have not succeeded in defining truth—and he cannot say what truth would be. This seems a bit like saying that because farmers cannot define cows or the difference between cows and, say, buffaloes, one should doubt the objective existence of cows. I would argue that it’s not the job of farmers to define cows; that’s the job of zoologists. Likewise, it’s not the job of physicists or other scientists to define truth; that’s the job of philosophers. If they haven’t done that job, too bad for them. But just as the farmer generally knows cows when he sees them, we scientists usually know truth when we see it.
  • Now, that really was a paradigm shift. For Kuhn it seems to have been the paradigm of paradigm shifts, which set a pattern into which he tried to shoehorn every other scientific revolution. It really does fit Kuhn's description of paradigm shifts: it is extraordinarily difficult for a modern scientist to get into the frame of mind of Aristotelian physics, and Kuhn's statement that all previous views of reality have proved false, though not true of Newtonian mechanics or Maxwellian electrodynamics, certainly does apply to Aristotelian physics.
    Revolutions in science seem to fit Kuhn's description only to the extent that they mark a shift in understanding some aspect of nature from pre-science to modern science. The birth of Newtonian physics was a mega-paradigm shift, but nothing that has happened in our understanding of motion since then—not the transition from Newtonian to Einsteinian mechanics, or from classical to quantum physics—fits Kuhn's description of a paradigm shift.
  • Kuhn rejected our old metaphysics—consciousness consists of an inner representation of an outer reality—as incoherent, impossible, and fundamentally inhuman. That's why he begins SSR by invoking history not as a discipline that can be applied to science, but as a necessary part of scientific understanding. … The problems that dominated Kuhn's life after his great moment of insight arose not because Kuhn wasn't brilliant enough. Rather, they arose and persist because while we increasingly understand that the old metaphysical paradigm has failed, for several generations now we have not found our new paradigm.
  • The Road since Structure is a collection of essays by Kuhn along with a lengthy interview with him conducted in 1995 by Aristide Baltas, Kostas Gavroglu, and Vassiliki Kindi. The essays form part of Kuhn’s thirty-year effort to clarify the contrast between paradigm shifts and normal science, with a focus on philosophical issues. For example, Kuhn alarmed many scientists with his claim that, while science makes progress, this progress is not towards truth but rather involves never-ending change through paradigm shifts. But the scientists have not realized that Kuhn’s claim is based on a philosopher’s definition of “truth,” which is not achieved (if ever) until there is exact knowledge of the ultimate constituents of matter on the quantum-gravity scale. Scientists use a less demanding definition for the word “truth,” in which measured parameters can be subject to nonzero error bars.
  • Thomas Kuhn believed that a science has to become a "paradigm", with a shared technical language that excludes outsiders, before it can get any real work done. In the formative stages of a science, according to Kuhn, the adherents go to great pains to make their work comprehensible to outside academics. But (according to Kuhn) a science can only make real progress as a technical discipline once it abandons the requirement of outside accessibility, and scientists working in the paradigm assume familiarity with large cores of technical material in their communications. This sounds cynical, relative to what is usually said about public understanding of science, but I can definitely see a core of truth here.

See also

Philosophy of science
ConceptsAnalysisA priori and a posterioriCausalityDemarcation problemFactInductive reasoningInquiryNatureObjectivityObservationParadigmProblem of inductionScientific methodScientific revolutionScientific theory
Related topicsAlchemyEpistemologyHistory of scienceLogicMetaphysicsPseudoscienceRelationship between religion and scienceSociology of scientific knowledge
Philosophers of science PlatoAristotleStoicism
AverroesAvicennaRoger BaconWilliam of Ockham
Francis BaconThomas HobbesRené DescartesGalileo GalileiPierre GassendiIsaac NewtonDavid Hume
Immanuel KantFriedrich SchellingWilliam WhewellAuguste ComteJohn Stuart MillHerbert SpencerWilhelm WundtCharles Sanders PeirceHenri PoincaréPierre DuhemRudolf SteinerKarl Pearson
Alfred North WhiteheadBertrand RussellAlbert EinsteinOtto NeurathC. D. BroadMichael PolanyiHans ReichenbachRudolf CarnapKarl PopperW. V. O. QuineThomas KuhnImre LakatosPaul FeyerabendJürgen HabermasIan HackingBas van FraassenLarry LaudanDaniel Dennett
  • Thomas Kuhn entry by Alexander Bird in the Stanford Encyclopedia of Philosophy
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