Thomas Kuhn quotations

This material is the copyright property of the University of Chicago Press 1970, 1996


From Thomas Kuhn's "The Structure of Scientific Revolutions" (an excellent read)

(Nb, have written to a number of people to seek permission to reproduce these snippets at this web site. No one seems sure exactly who owns the copyright but all seem to think there would not likely be an objection. So, in exasperation, I have simply reproduced them here as an advert to read his book. I think all scientists should be aware of its conclusions. I will remove this section if requested to do so.

". . . we must recognise how very limited in both scope and precision a paradigm can be at the time of its first appearance." (p23)

". . . the enterprise seems (to be) an attempt to force nature into the preformed and relatively inflexible box that the paradigm supplies." (p24)

"Nor do scientists normally aim to invent new theories, and they are often intolerant of those invented by others."

"Perhaps the most striking feature of the normal research problems we have encountered is how little they aim to produce major novelties, conceptual or phenomenal." (p35)

"Yet even in cases like these the range of anticipated, and thus of assimilable, results is always small compared with the range that imagination can conceive."

"Even the project whose goal is paradigm articulated does not aim at the unexpected novelty."

"Normal science does not aim at novelties of fact or theory and, when successful, finds none." (p52)

"In science . . . novelty emerges only with difficulty, manifested by resistance, against a background provided by expectation." (p64)

"Previous practice of normal science has given every reason to consider them solved or all but solved, which helps to explain why the sense of failure, when it came, could be so acute." (p75)

"Philosophers of science have repeatedly demonstrated that more than one theoretical construction can always be placed upon a given collection of data." (p76)

". . .. the invention of alternatives is just what scientists seldom undertake . . ."

"As in manufacture so in science – retooling is an extravagance to be reserved for the occasion that deserves it."

". . . these anomalies will no longer seem to be simply facts. From within a new theory of scientific knowledge, they may instead seem very much like tautologies, statements of situations that could not conceivably have been otherwise." (P78)

". . . no paradigm that provides a basis for scientific research ever completely resolves all its problems." (p79)

". . . every problem that normal science sees as a puzzle can be seen, from another viewpoint, as a counterinstance and thus as a source of crisis."

(On new paradigms) "Rather it is a reconstruction of the field from new fundamentals, a reconstruction that enhances some of the field's most elementary theoretical generalisations as well as many of its paradigm methods and applications." (p85 )

". . . handling the same bundles of data as before, but placing them in a new system of relations with one another by giving them a different framework."

"Often a new paradigm emerges, at least in embryo, before a crisis has developed far or been explicitly recognised." (p86)

". . . the scientist in crisis will constantly try to generate speculative theories that, if unsuccessful, can be surrendered with relative ease." (p87)

"It is, I think, particularly in periods of acknowledged crisis that scientists have turned to philosophical analysis as a device for unlocking the riddles of their field. Scientists have not generally needed or wanted to be philosophers." (p88)

"Nor is it an accident that (in both these periods) the so-called thought experiment should have played so critical a role in the progress of research." " . . . the analytical thought experiment . . . is perfectly calculated to expose the old paradigm to existing knowledge in ways that isolate the root of crisis with a clarity unattainable in the laboratory."

"Almost always the men (sic!) who achieve these fundamental inventions of a new paradigm have been either very young or new to the field whose paradigm they change." ( that is, on its margins) p(90)

". . . the new theory might be simply a higher level theory than those known before, one that linked together a whole group of lower level theories without substantially changing any." (p95)

Often the importance of the resulting discovery would itself be proportional to the extent and stubbornness of the anomaly that foreshadowed it." (p96–97)

Newtonian theory seems to be derivable from Einsteinian of which it is therefore a special case." (p99)

"Without commitment to a paradigm there could be no normal science. Furthermore, that commitment must extend to areas and to degrees of precision for which there is no full precedent. If it did not, the paradigm could provide no puzzles that had not already been solved." (p100)

"The normal scientific tradition that emerges from a scientific revolution is not only incompatible with but often actually incommensurable with that which has gone before." (p103)

". . . when paradigms change, the world itself changes with them. Led by a new paradigm, scientists adopt new instruments and look in new places. Even more important, during revolutions scientists see new and different things when looking with familiar instruments in places they have looked before. It is rather as if the professorial community had been suddenly transported to another planet were familiar objects are seen in a different light and are joined by unfamiliar ones as well." (p111)

". . . paradigm changes do cause scientists to see the world of their research-engagement differently."

"Scientists then often speak of the "scales falling from their eyes" or of the "lightning flash" that "inundates" a previously obscure puzzle, enabling its components to be seen in a new way that for the first time permits its solution." (p122)

". . . it is hard to make nature fit a paradigm." (p135)

"In short, (textbooks) have to be rewritten in the aftermath of each Scientific Revolution, and, once rewritten, they inevitably disguise not only the role but the very existence of the revolutions that produce them. " (p137)

"The result is a persistent tendency to make the history of science look linear or cumulative, a tendency that even affects scientists looking back at their own research." (p139)

"Any new interpretation of nature, whether a discovery or a theory, emerges first in the mind of one or a few individuals. It is they who first learn to see science and the world differently, and their ability to make the transition is facilitated by two circumstances that are not common to most other members of their profession. Invariably their attention has been intensely concentrated upon the crisis-provoking problems; usually, in addition, they are men so young or so new to the crisis–ridden field that practice has committed them less deeply than most of their contemporaries to the world view and rules determined by the old paradigm." (p144)

". . . paradigm testing occurs only after persistent failure to solve a noteworthy puzzle has given rise to crisis." (p145)

". . . testing occurs as part of the competition between two rival paradigms for the allegiance of the scientific community."

"Noting that no new theory can ever be exposed to all possible relevant tests, they ask not whether a theory has been verified but rather about its probability in the light of the evidence that actually exists."

"Though each may hope to convert the other to his way of seeing his science and its problems, neither may hope to prove his case. The competition between paradigms is not the sort of battle that can be resolved by proofs." (p148)

"In the first place, the components of competing paradigms will often disagree about the list of problems that any candidate for paradigm must resolve."

"Darwin, in . . . his Origin of Species, wrote: "Although I am fully convinced of the truth of the views given in this volume . . . I by no means expect to convince experienced naturalists whose minds are stocked with a multitude of facts all viewed, during a long course of years, from a point of view directly opposite to mine . . . [But] I look with confidence to the future, – to young and rising naturalists, who will be able to view both sides of the question with impartiality." (p151)

"And Max Planck, . . . in his Scientific Autobiography, sadly remarked that "a new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it.""

"Conversions will occur a few at time, until after the last hold-outs have died, the whole profession will again be practising under a single, but now a different, paradigm." (p152)

"Probably the single most prevalent claim advanced by the proponents of a new paradigm is that they can solve the problems that have led the old one to a crisis. When it can legitimately been made, this claim is often the most effective one possible." (p153)

"Crucial experiments" – those able to discriminate particularly sharply between the two paradigms – have been recognised and attested before the paradigm was even invented"

". . . the new theory is said to be "neater," "more suitable or "simpler" than the old." (p155)

"The early versions of most new paradigms are crude." (p156)

"Ordinarily, it is only much later, after the new paradigm has been developed, accepted and exploited that apparently decisive arguments . . . are developed."

". . . the opponents of the new paradigm can legitimately claim that even in the area of crisis it is little superior to its traditional rival."

"In addition, the defenders of traditional theory and procedure could almost always point to problems that its new rival has not solved but that for their view are no problems at all." (p157)

"A decision between alternate ways of practising science is called for, and in the circumstances that decision must be based less on past achievement than on future promise. The man who embraces a new paradigm at an early stage must often do so in defiance of the evidence provided by problem-solving." (p157–158)

"Something must make at least a few scientists feel that the new proposal is on the right track, and sometimes it is only personal and inarticulate aesthetic considerations that can do that." (p158)

". . . if a paradigm is ever to triumph it must gain some first supporters, men who will develop it to the point where hardheaded arguments can be produced and multiplied."

"At the start a new candidate for paradigm may have few supporters, and on occasions the supporters' motives may be suspect. Nevertheless, if they are competent, they will improve it, explore its possibilities, and show what it would be like to belong to the community guided by it." (p159)

". . . if the paradigm is one destined to win its fight, the number and strength of the persuasive arguments in its favour will increase."

"Gradually the number of experiments, instruments, articles, and books based upon the paradigm will multiply. Still more men, convinced of the new view's fruitfulness, will adopt the new mode of practising normal science, until at last only a few elderly hold-outs remain. And even they, we cannot say, are wrong."

". . . the man who continues to resist after his whole profession has been converted has ipso facto ceased to be a scientist."

"There are losses as well as gains in scientific revolutions, and scientists tend to be peculiarly blind to the former." (p167)