Thomas Kuhn

"If a demarcation criterion exists (we must not, I think, seek a sharp or decisive one), it may lie just in that part of science which Sir Karl ignores."

"Only when they must choose between competing theories do scientists behave like philosophers."

"I suggest that scientific knowledge, though logically more articulate and far more complex, is of this sort. The books and teachers from whom it is acquired present concrete examples together with a multitude of theoretical generalizations. Both are essential carriers of knowledge, and it is therefore Pickwickian to seek a methodological criterion that supposes the scientist can specify in advance whether each imaginable instance fits or would falsify his theory."

"To my complete surprise, that exposure to out-of-date scientific theory and practice radically undermined some of my basic conceptions about the nature of science and the reasons for its special success.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."

"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"Out-of-date theories are not in principle unscientific because they have been discarded.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."

""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."

"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."

"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."

"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."

"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."

"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."

"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"

"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."

"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."

"In science, as in the playing card experiment, novelty emerges only with difficulty, manifested by resistance, against a background provided by expectation."

"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."

"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."

"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."

"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."

"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."

"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"

"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."

"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."

"By now it may be clear that the position I'm developing is a sort of post-Darwinian Kantianism."

"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."

"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."

"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."

"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."

"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."

"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."

"Kuhn’s book has been misread and misused in many quarters; Kuhn’s excellent points are not as radical as many like to believe."

"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."

"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."

"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."

"I did learn from Kuhn that he was very dissatisfied with the way in which his earlier book, Structure of Scientific Revolutions, was being transformed into an anti-science post-modern diatribe by many academics. He taught me that there is nothing post-modern whatever about his theory of scientific change. I never forgot the lesson."

"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..."

"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."

"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."

"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.""

"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: dismissalIsrael 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 b: metaphorical/psychological[...] The metaphorical/psychological reading of world change does not capture Kuhn’s intentions."

"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"