The Structure of Scientific Revolutions by Thomas Kuhn (1962, 1970)
Problem: science is not cumulative as portrayed in textbooks and taught in schools. 1-3
I. The Establishment Scientific Community
There is no permanent fixed scientific truth. “If this book were being rewritten, it would therefore open with a discussion of the community structure of science.” 176 Science is social, done in a community.
“What are the essential characteristics of these communities? The scientist must, for example, be concerned to solve problems about the behavior of nature. In addition though his [sic] concern with nature may be global in its extent, the problems on which he works must be problems of detail. More important, the solutions that satisfy him may not be merely personal but must instead be accepted as solutions by many. The group that shares them may not, however, be drawn at random from the society as a whole, but is rather the well-defined community of the scientist’s professional compeers… Recognition of the existence of a uniquely competent professional group and acceptance of its role as the exclusive arbiter of professional achievement has further implications. The group’s members, as individuals and by virtue of their shared training and experience, must be seen as the sole possessors of the rules of the game or of some equivalent basis for unequivocal judgements.”168
Paradigm
A firm research consensus on which experiments are worth performing, plus what special equipment and measuring tools are needed.
Defines a science: No other criteria so clearly proclaims a field a science as a paradigm which is able to guide a whole group’s research. 22 It ends the need for constant reiteration of the fundamentals.
Theoretical and methodological beliefs which permit selection, evaluation and criticism of projects 17
Confidence to encourage scientists to undertake more precise esoteric and consuming sorts of work 18
Object for further articulation and specification under new or more stringent conditions 23
“Aristotle’s Physica, Ptolemy’s Almagest, Newton’s Principia and Opticks, Franklin’s Electricity, Lavoisier’s Chemistry, and Lyell’s Geology – these and many other works served for a time implicitly to define the legitimate problems and methods of a research field for succeeding generations of practitioners. They were able to do so because they shared two essential characteristics: Their achievement was sufficiently unprecedented to attract an enduring group of adherents away from competing modes of scientific activity. Simultaneously, it was sufficiently open-minded to leave all sorts of problems for the redefined group of practitioners to resolve.” 10
“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.” 206
Normal Science
“The success of a paradigm is at the start largely a promise of success discoverable in selected and still incomplete examples. Normal science consists in the actualization of that promise, an actualization achieved by extending the knowledge of those facts that the paradigm displays as particularly revealing, by increasing the extent of the match between those facts and the paradigm’s predictions, and by further articulation of the paradigm itself.
“Closely examined, whether historically or in the contemporary laboratory, that enterprise seems an attempt to force nature into the preformed and relatively inflexible box that the paradigm supplies. No part of the aim of normal science is to call forth new sorts of phenomena; indeed those that will not fit the box are often not seen at all. Nor do scientists normally aim to invent new theories, and they are often intolerant of those invented by others. Instead, normal scientific research is directed to the articulation of those phenomena and theories that paradigm already supplies.” 23-4
“Normal science does not aim at novelties of fact or theory and, when successful, finds none.” 52
Textbooks
“There are excellent reasons why revolutions have proved to be so nearly invisible. Both scientists and laymen take much of their image of creative scientific activity from an authoritative source that systematically disguises – partly for important functional reasons – the existence and significance of scientific revolutions. Only when the nature of that authority is recognized and analyzed can one hope to make historical example fully effective. Furthermore, the analysis now required will begin to indicate one of the aspects of scientific work that most clearly distinguishes it from every other creative pursuit except perhaps theology.
“As the source of authority, I have in mind principally textbooks of science together with both the popularizations and the philosophical works modeled on them. All three of these categories – until recently no other significant sources of information about science have been available except through the practice of research – have one thing in common: They address themselves to an already articulated body of problems, data and theory, most often to the particular set of paradigms to which the scientific community is committed at the same time they are written. Textbooks themselves aim to communicate the vocabulary and syntax of a contemporary scientific language. Popularizations attempt to describe these same applications in a language closer to that of everyday life. And philosophy of science analyzes the logical structure of the same completed body of scientific knowledge. All three record the stable outcome of past revolutions and thus display the bases of the current normal science tradition. To fulfill their function they need not provide authentic information about the way in which those bases were first recognized and then embraced by the profession.
“Textbooks being pedagogic vehicles for the perpetuation of normal science, have to be rewritten in whole or in part whenever the language, problem-structure, or standards of normal science change. They 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 preceded them. Unless he [sic] has personally experienced a revolution in his own lifetime, the historical sense either of the working scientists or of the lay reader of textbook literature extends only to the outcome of the most recent revolutions in the field.” 136-7
II. The Evolution of Paradigms
Pre-Paradigm
“In the early stages of the development of any science, different men [sic] confronting the same range of phenomena, but not usually all the same particular phenomena, describe and interpret them in different ways. What is surprising, and perhaps also unique in its degree to the fields we call science, is that such initial divergences should ever largely disappear.
“For they do disappear to a very considerable extent and then apparently once and for all. Furthermore, their beliefs and preconceptions, emphasized only some special part of the too sizable and inchoate pool of information. … To be accepted as a paradigm, a theory must seem better than its competitors, but it need not, and in fact never does, explain all the facts with which it can be confronted.” 17-8
Science in Crisis
The established paradigm’s “complexity was increasing far more rapidly than its accuracy and a discrepancy corrected in one place was likely to show up in another.” 68
“… the scientist’s conviction that incompatible rules for doing science cannot coexist except during revolutions when the profession’s main task is to eliminate all sets but one.” 170
“Paradigms provide scientists not only with a map but also with some of the directions essential for map-making. In learning a paradigm the scientist acquires theory, methods, and standards together, usually in an inextricable mixture. Therefore, when paradigms change, there are usually significant shifts in the criteria determining the legitimacy both of problems and of proposed solutions.” 109
“Copernicus complained that in his day astronomers were ‘so inconsistent in these [astronomical] investigations … that they cannot even explain or observe the constant length of the seasonal year.’ ‘With them,’ he concluded, ‘it is as though an artist were to gather the hands, feet, head and other members for his images from diverse models, each part excellently drawn, but not related to a single body, and since they in no way match each other, the result would be monster rather than man.’
“Einstein, restricted by current usage to less florid language, wrote only, ‘it was as if the ground had been pulled out from under one, with no firm foundation to be seen anywhere, upon which one could have built.’ And Wolfgang Pauli, in the months before Heisenberg’s paper on matrix mechanics pointed the way to a new quantum theory, wrote to a friend, ‘At the moment physics is again terribly confused. In any case, it is too difficult for me, and I wish I had been a movie comedian or something of the sort and had never heard of physics.’ That testimony is particularly impressive if contrasted with Pauli’s words less than five months later. ‘Heisenberg’s type of mechanics has again given me hope and joy in life. To be sure it does not supply the solution to the riddle, but I believe it is again possible to march forward.’” 83-4
Transition and Discovery
“Consider first discoveries, or novelties of fact, and then inventions, or novelties of theory.
“Examining selected discoveries, we shall quickly find that they are not isolated events but extended episodes with a regularly recurrent structure. Discovery commences with the awareness of anomaly, i.e., with the recognition that nature has somehow violated the paradigm-induced expectations that govern normal science. It then continues with a more or less extended exploration of the area of anomaly. And it closes only when the paradigm theory has been adjusted so that the anomalous has become the expected. Assimilating a new sort of fact demands a more than additive adjustment of theory, and until that adjustment is completed – until the scientist has learned to see nature in a different way – the new fact is not a scientific fact at all.” 52-3
“Discovering a new sort of phenomenon is necessarily a complex event, one which involves recognizing both that something is and what it is … But if both observation and conceptualization, fact and assimilation to theory, are inseparably linked in discovery, then discovery is a process and must take time.” 55
Emergence of New
“The transition from a paradigm in crisis to a new one from which a new tradition of normal science can emerge is far from a cumulative process, one achieved by an articulation or extension of the old paradigm. Rather it is a reconstruction of the field from new fundamentals, a reconstruction that changes some of the field’s most elementary theoretical generalizations as well as many of its paradigm methods and applications. During the transition period there will be a large but never complete overlap between the problems that can be solved by the old and by the new paradigm. But there will be a decisive difference in the modes of solution. When the transition is complete, the profession will have changed its view of the field, its methods, and its goals. … a process that involves ‘handling the same bundle of data as before, but placing them in a new system of relations with one another by giving them a different framework.’ … a change in visual gestalt. That parallel can be misleading. Scientists do not see something as something else; instead, they simply see it.” 84-5
III. The Revolution from Alchemy to Chemistry: from Phlogiston (Air & Fire) to Oxygen
“The much-maligned phlogiston theory gave order to a large number of physical and chemical phenomena. It explained why bodies burned – they were rich in phlogiston – and why metals had so many more properties in common than did their ores. The metals were all compounded from different elementary earths combined with phlogiston, and the latter, common to all metals, produced common properties. In addition, the phlogiston theory accounted for a number of reactions in which acids were formed by the combustion of substances like carbon and sulfur. Also, it explained the decrease in volume when combustion occurs in a confined volume of air – the phlogiston released by combustion ‘spoils’ the elasticity of the air that absorbed it, just as fire ‘spoils’ the elasticity of a steel spring.” 99-100
“To see how closely factual and theoretical novelty are intertwined in scientific discovery examine a particularly famous example, the discovery of oxygen. At least three different men have a legitimate claim to it, and several other chemists must in the early 1770’s, have had enriched air in a laboratory vessel without knowing it. The progress of normal science, in this case of pneumatic chemistry, prepared the way to a breakthrough quite thoroughly. The earliest of the claimants to prepare a relatively pure sample of the gas was the Swedish apothecary, C.W.Scheele. We may, however ignore his work since it was not published until oxygen’s discovery had repeatedly been announced elsewhere and thus had no effect upon the historical pattern that most concerns us here. The second in time to establish a claim was the British scientist and divine, Joseph Priestly, who collected the gas released by heated red oxide of mercury as one item in a prolonged normal investigation of the ‘airs’ evolved by a large number of solid substances. In 1774 he identified the gas thus produced as nitrous oxide and in 1775, led by further tests, as common air with less than its usual quantity of phlogiston. The third claimant, Lavoisier, started the work that led him to oxygen after Priestly’s experiments of 1774 and possibly as the result of a hint from Priestly. Early in 1775 Lavoisier reported that the gas obtained by heating the red oxide of mercury was ‘air itself entire without alteration [except that]… it comes out more pure, more respirable.’ By 1777, probably with the assistance of a second hint from Priestly, Lavoisier had concluded that the gas was a distinct species, one of the two main constituents of the atmosphere, a conclusion that Priestly was never able to accept. 53-4
“The crisis preceded the emergence of Lavoisier’s oxygen theory of combustion. In the 1770s, many factors combined to generate a crisis in chemistry, and historians are not all together agreed about either their nature or their relative importance. But two of them are generally accepted as of first-rate significance: the rise of pneumatic chemistry and the question of weight relations. The history of the first begins in the 17th century with the development of the air pump and its deployment in chemical experimentation. During the following century, using that pump and a number of other pneumatic devices, chemists continued to believe that air was the only sort of gas. Until 1756, when Joseph Black showed that fixed air (CO2) was consistently distinguishable from normal air, two samples of gas were thought to be distinct only in their impurities.
“After Black’s work the investigation of gases proceeded rapidly, most notably in the hands of Cavendish, Priestly, and Scheele, who together developed a number of new techniques capabel of distinguishing one sample of gas from another. All these men, from Black through Scheele, believed in the phlogiston theory and often employed it in their design and interpretation of experiments. Scheele actually first produced oxygen by an elaborate chain of experiments designed to dephlogistate heat. Yet the net result of their experiments was a variety of gas samples and gas properties so elaborate that the phlogiston theory proved increasingly little able to cope with laboratory experience. Though none of these chemists suggested that the theory should be replaced, they were unable to apply it consistently. By the time Lavoisier began his experiments on airs in the early 1770s, there were almost as many versions of the phlogiston theory as there were pneumatic chemists. That proliferation of versions of a theory is a very usual symptom of crisis.
“The increasing vagueness and decreasing utility of the phlogiston theory for pneumatic chemistry were not, however, the only source of the crisis that confronted Lavoisier. He was also much concerned to explain the gain in weight that most bodies experience when burned or roasted, and that again is a problem with a long prehistory. At least a few Islamic chemists had known that some metals gain weight when roasted. In the 17th century several investigators had concluded from this same fact that a roasted metal takes up some ingredient from the atmosphere. But in the 17th century that conclusion seemed unnecessary to most chemists. If chemical reactions could alter the volume, color and texture of the ingredients, why should they not alter weight as well? Weight was not always taken to be the measure of quantity of matter. Besides, weight-gain on roasting remained an isolated phenomenon. Most natural bodies (i.e. wood) lose weight on roasting as the phlogiston theory was later to say they should.
“During the 18th century, however, these initially adequate responses to the problem of weight-gain became increasingly difficult to maintain. Partly because the balance was increasingly used as a standard chemical tool and partly because the development of pneumatic chemistry made it possible and desirable to retain the gaseous products of reactions, chemists discovered more and more cases in which weight-gain accompanied roasting. Simultaneously, the gradual assimilation of Newton’s gravitational theory led chemists to insist that gain in weight must mean gain in quantity of matter. Those conclusions did not result in rejection of the phlogiston theory, for that theory could be adjusted in many ways. Perhaps phlogiston had negative weight, or perhaps fire particles or something else entered the roasted body as phlogiston left it. There were other explanations besides. But if the problem of weight-gain did not lead to rejection, it did lead to an increasing number of special studies in which this problem bulked large. One of them, ‘On phlogiston considered as a substance with weight and [analyzed] in terms of the weight changes it produces in bodies with which it unites’, was read to the French Academy early in 1772, the year which closed with Lavoisier’s delivery of his famous sealed note to the Academy’s Secretary [that he was creating a new science, chemistry]. Before that note was written, a problem that had been at the edge of the chemist’s consciousness for many years had become an outstanding unsolved puzzle. Many different versions of the phlogiston theory were being elaborated to meet it. Like the problems of pneumatic chemistry, those of weight-gain were making it harder and harder to know what the phlogiston theory was. Though still believed and trusted as a working tool, a paradigm of 18th century chemistry was gradually losing its unique status. Increasingly, the research it guided resembled that conducted under the competing schools of the pre-paradigm period, another typical effect of crisis.” 69-72
“What Lavoisier announced in his papers from 1777 on was not so much the discovery of oxygen as the oxygen theory of combustion. That theory was the keystone for a reformulation of chemistry so vast that it is usually called the chemical revolution. Indeed, if the discovery of oxygen had not been an intimate part of the emergence of the new paradigm for chemistry, the question of priority from which we began would never have seemed so important. In this case as in others, the value placed upon a new phenomenon and thus upon its discoverer varies with our estimate of the extent to which the oxygen was not by itself the cause of the change in the chemical theory. Long before he played any part in the discovery of the new gas, Lavoisier was convinced both that something was wrong with the phlogiston theory and that burning bodies absorbed some part of the atmosphere. That much he had recorded in a sealed note deposited with the Secretary of the French Academy in 1772. What the work on oxygen did was to give much additional form and structure to Lavoisier’s earlier sense that something was amiss. It told him a thing he was already prepared to discover – the nature of the substance that combustion removes from the atmosphere. That advance awareness of difficulties must be a significant part of what enabled Lavoisier to see in experiments like Priestly’s a gas that Priestly had been unable to see there himself. Conversely, the fact that a major paradigm revision was needed to see what Lavoisier saw must be the principle reason why Priestly was, to the end of his life, unable to see it. 56 [You will understand this story much better if you read it a second time.]
IV. Science as Social
Social Paradigm Shift
“A more refined solution of the problem of progress in the sciences must be sought.” 170
Social Science should be more practical. See Tools For Conviviality by Ivan Illich.
“It remains an open question what parts of social science have yet acquired such paradigms at all.” 15
Science as Revolution
“Why should a change in paradigm be called a revolution? In the face of the vast and essential differences between political and scientific development, what parallelism can justify the metaphor that finds revolutions in both?
“One aspect of the parallelism must already be apparent. Political revolutions are inaugurated by a growing sense that existing institutions have ceased adequately to meet the problems posed by an environment that they have in part created. In much the same way, 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 the paradigm itself had previously led the way. In both political and scientific development the sense of malfunction that can lead to crisis is prerequisite to revolution.
“Political revolutions aim to change political institutions in ways that those institutions themselves prohibit. Their success therefore necessitates the partial relinquishment of one set of institutions in favor of another, and in the interim, society is not fully governed by institutions at all. … In increasing numbers, individuals become increasingly estranged from political life and behave more and more eccentrically within it. Then, as the crisis deepens, many of these individuals commit themselves to some concrete proposal for the reconstruction of society in a new institutional framework. At that point the society is divided into competing camps or parties, one seeking to defend the old institutional constellation, the others seeking to institute some new one. And, once that polarization has occurred, political recourse fails. Because they differ about the institutional matrix within which political change is to be achieved and evaluated, because they acknowledge no supra-institutional framework for the adjudication of revolutionary difference, the parties to a revolutionary conflict must finally resort to the techniques of mass persuasion. Though revolutions have had a vital role in the evolution of political institutions, that role depends upon their being partially extrapolitical or extrainstitutional events.
“Like the choice between competing political institutions, that between competing paradigms proves to be a choice between incompatible modes of community life. Because it has that character, the choice is not and cannot be determined merely by the evaluative procedures characteristic of normal science, for these depend in part upon a particular paradigm, and that paradigm is at issue. When paradigms enter, as they must, into a debate about paradigm choice, their role is necessarily circular. Each group uses its own paradigm to argue in that paradigm’s defense.
“Whatever its force, the status of the circular argument is only that of persuasion. It cannot be made logically or even probabilistically compelling for those who refuse to step into the circle. The premises and values shared by the two parties to a debate over paradigms are not sufficiently extensive for that. As in political revolutions, so in paradigm choice – there is no standard higher than the assent of the relevant community. To discover how scientific revolutions are effected, we shall therefore have to examine not only the impact of nature and of logic, but also the techniques of persuasive argumentation effective within the quite special groups that constitute the community of scientists.” 92-4
Publications by Thomas Kuhn
Robert Boyle and Structural Chemistry in the 17th Century, 1952
The Copernican Revolution: Planetary Astronomy in the Development of Western Thought, 1957
Newton’s Optical Papers, 1958
The Caloric Theory of Adiabatic Compression, on the speed of sound, 1958
The Essential Tension: Tradition and Innovation in Scientific Research, 1959
The Historical Structure of Scientific Discovery, Science, p. 760-4, June 1, 1962
A Function for Thought Experiments, 1963
Comment on the Relations of Science and Art, 1969
Prepared by the Institute for Public Science & Art
uploaded to the wiki by Jon Li
