Quotes from book
The Structure of Scientific Revolutions

Thomas Kuhn

The Structure of Scientific Revolutions is a book about the history of science by the philosopher Thomas S. Kuhn. Its publication was a landmark event in the history, philosophy, and sociology of scientific knowledge. Kuhn challenged the then prevailing view of progress in "normal science". Normal scientific progress was viewed as "development-by-accumulation" of accepted facts and theories. Kuhn argued for an episodic model in which periods of such conceptual continuity in normal science were interrupted by periods of revolutionary science. The discovery of "anomalies" during revolutions in science leads to new paradigms. New paradigms then ask new questions of old data, move beyond the mere "puzzle-solving" of the previous paradigm, change the rules of the game and the "map" directing new research.For example, Kuhn's analysis of the Copernican Revolution emphasized that, in its beginning, it did not offer more accurate predictions of celestial events, such as planetary positions, than the Ptolemaic system, but instead appealed to some practitioners based on a promise of better, simpler solutions that might be developed at some point in the future. Kuhn called the core concepts of an ascendant revolution its "paradigms" and thereby launched this word into widespread analogical use in the second half of the 20th century. Kuhn's insistence that a paradigm shift was a mélange of sociology, enthusiasm and scientific promise, but not a logically determinate procedure, caused an uproar in reaction to his work. Kuhn addressed concerns in the 1969 postscript to the second edition. For some commentators The Structure of Scientific Revolutions introduced a realistic humanism into the core of science, while for others the nobility of science was tarnished by Kuhn's introduction of an irrational element into the heart of its greatest achievements.

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

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), VI. Anomaly and the Emergence of Scientific Discoveries, p. 64 (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.”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), VII. Crisis and the Emergence of Scientific Theories, p. 91 (2012 ed.)

“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.”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), II. The Route to Normal Science, p. 11 (2012 ed.)

“"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”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), II. The Route to Normal Science, p. 10

“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.”

Thomas Kuhn book The Structure of Scientific Revolutions

The Structure of Scientific Revolutions (1962), Preface

“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.”

Thomas Kuhn book The Structure of Scientific Revolutions

The Structure of Scientific Revolutions (1962), I. Introduction: A Role of 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.”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), Preface, p. xiii (2012 ed.)

“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.”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), XII. The Resolution of Revolutions, p. 149

“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.”

Thomas Kuhn book The Structure of Scientific Revolutions

The Structure of Scientific Revolutions (1962), I. Introduction: A Role of History

“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.”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), II. The Route to Normal Science, p. 22 (2012 ed.)

“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.”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), VII. Crisis and the Emergence of Scientific Theories, p. 76 (2012 ed.)

“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.”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), III. The Nature of Normal Science, p. 24 (2012 ed.)

“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.”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), I. Introduction: A Role of History, p. 5

“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.”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), VI. Anomaly and the Emergence of Scientific Discoveries, p. 52 (2012 ed.)

“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.”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), X. Revolutions as Changes of World View, p. 114 (3rd edn.)

“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.”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), VI. Anomaly and the Emergence of Scientific Discoveries, p. 52

“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”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), XIII. Progress Through Revolutions, p. 170

“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.”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), III. The Nature of Normal Science, p. 34 (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.”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), VI. Anomaly and the Emergence of Scientific Discoveries, p. 64 (2012 ed.)

“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”

Thomas Kuhn book The Structure of Scientific Revolutions

Source: The Structure of Scientific Revolutions (1962), V. The Priority of Paradigms, p. 46

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