Guide to Thomas Kuhn’s The Structure of Scientific Revolutions

Malcolm R. Forster: March 19, 1998

Note: I have tried to let Kuhn speak for himself whenever possible. The make is easier to distinguish the quotes from the paraphrases, I have written the quotes in boldface. All references are to the 1970 edition of The Structure of Scientific Revolutions.

1. A Paradigm is ...? Kuhn baptizes his famous notion of a scientific "paradigm" as originating from the "great works" of science, like Copernicus’s De Revolutionibus or Newton’s Principia. These great works became paradigms because they were "sufficiently unprecedented to attract an enduring group of adherents away from competing modes of scientific activity," and "sufficiently open-ended to leave all sorts of problems for the redefined group of practitioners to resolve." (p.10) The activity spurred by such great books goes by the name of "normal science." "There are ... only three normal foci for factual scientific investigation." (p.25.)

1. Determination of significant fact: Attempts to increase the accuracy and scope with which facts like the specific gravities and compressibilities of material, electrical conductivities and contact potentials occupy a significant fraction of the literature of experimental and observational science. This kind of activity is largely independent of the reigning paradigm - the Newtonian measurement of specific gravities, for example, was unchanged by the advent of Einstein's theory of mechanics.

2. Matches of fact with theory: (p.26) "A second usual but smaller class of factual determinations is directed to those facts that, though often without much intrinsic interest, can be compared directly with predictions from the paradigm theory." In support of the claim that these cases are rarer, Kuhn mentions that (p.26) "No more than three such areas are even yet accessible to Einstein's general theory of relativity."

3. The articulation of theory, which is "... empirical work undertaken to articulate the paradigm theory ..." This is broken up into three sub-categories. (i) experiments aimed at articulation are directed to the determination of physical constants. (ii) experiments aimed at quantitative laws: E.g. Boyle's Law relating gas pressure to volume. (iii) experiments to choose among alternative ways of applying the paradigm to new areas of interest. (p.29)

     This is one of the many places in which Kuhn might do well to make a distinction between theory and models. Let us stipulate that models are the sets of equations derived from theory plus auxiliary assumptions such that estimates of all adjustable parameters may be obtained from extant data (Kuhn uses the term ‘model’ in a different sense). Thus, the set of Newton’s equations of motion is not a model because it is impossible to make a precise quantitative comparison with data without (approximate) solutions of those equations. When Kuhn talks about the articulation of theory as a part of normal science, he is really referring to the development of models.      While normal science is a highly determined kind of activity, Kuhn is quick to deny that he is slipping back to naive inductivism: (p.42) In a footnote, Kuhn acknowledges the work of M. Polanyi, Personal Knowledge, Chicago, 1958, in which scientists’ success is said to depend on tacit knowledge acquired throughpractice, which cannot be articulated explicitly. The point, expanded in the postscript, is that scientists gain tacit knowledge of a theory through working through textbook or laboratory examples (called exemplars).

2. Normal Science Does Not Aim at Novelty: Contrary to a popular picture of science, Kuhn insists that (p.52) "Normal science does not aim at novelties of fact or theory and, when successful, finds none." This striking view challenges the critical rationalism of someone like Popper, who sees the heart of scientific rationality in the constant critical scrutiny of accepted scientific belief. Kuhn is concerned to dispel the idea that the common occurrence of scientific discoveries disproves his thesis. For if normal science aims at discovery, and discoveries are novel, then normal science aims at novelty. Kuhn claims that discoveries are always accompanied by changes in the prevailing paradigm. If he is right, then the existence of scientific discovery does not show that normal science aims at novelty, but only that novelty signals the end of normal science. Kuhn therefore views such discoveries as ‘small’ revolutions.      In summary, Kuhn’s argument is something like this: 1. All novelties of fact (discoveries) or theory lead to the end of normal science.2. Normal science does not aim at its own demise.Therefore, normal science does not aim novelties of fact or theory and, when successful, finds none. 

3. Discoveries are Rare Because Expectations Obscure our Vision: The fact the normal science does not aim at novelty, as Kuhn has argued, cries out for explanation. Briefly, Kuhn’s response is that scientists are entrenched within a certain way of seeing things, and this clouds their vision (they tend to see what they expect to see). As an instance of what Kuhn thinks is a general psychological phenomenon, he cites a study by J. S. Bruner and Leo Postman, "On the Perception of Incongruity: A

Paradigm," Journal of Personality XVIII (1949) 206-23. In this psychological experiment, subjects are shown ordinary playing cards mixed up with some anomalous cards, like a black four of hearts. Roughly speaking, the results show that subjects initially see what they expect to see (either the four of spades, or the four of hearts).     In sum, Kuhn seeks to explain the difficulty of discovery as an instance of the general psychological fact that our expectations cloud our perception of the world. 

4. No Paradigm Change without Crisis: Nevertheless, a paradigm (though resisting change) is playing an essential role in allowing a scientist to recognize something as anomalous, as contrary to expectation, and this is an important precondition for discovery (p.65). However, the process of improving fit between fact and theory is a part of normal science, so an anomaly, a failing of expectations, presents just another puzzle to be resolved by the construction of improved models. That is the standard fare of normal science. The point is that an anomaly is not by itself sufficient for paradigm change (that is the falsificationist’s folly).     For example, Ptolemy’s system of astronomy certainly faced discrepancies, but it was only when those discrepancies built up to crisis point that the conditions were ripe for change (p.68): "Given a particular discrepancy, astronomers were invariably able to eliminate it by making some particular adjustment in Ptolemy’s system of compounded circles. But... astronomy’s complexity was increasing far more rapidly than its accuracy and that a discrepancy corrected in one place was likely to show up in another."  Notice that Kuhn mentions complexity as requisite condition for paradigm change in this example. It is a necessary part of what defines a crisis in normal science. For, a sufficient number of compounded circles would provide perfect fit with the data at any one time. That Ptolemaic model would provide no discrepancies with existing data. But the crisis is revealed by the way it changes over time, for as Kuhn puts it, the "astronomy’s complexity was increasing far more rapidly than its accuracy and that a discrepancy corrected in one place was likely to show up in another."     On the other hand, Kuhn presents the Copernican revolution as an example which the crisis in the reigning Ptolemaic paradigm was almost the only reason for the change  (pp.75-6): "Copernicus’ more elaborate proposal was neither simpler nor more accurate than Ptolemy’s system. Available observational tests, as we shall see more clearly below, provided no basis of a choice between them." 

5. In Normal Science the Theory is Not Questioned: The fact that anomalies are the driving force behind theory change does not mean that scientists are following a falsificationists’ methodology. "Though they may begin to loose faith and then to consider alternatives, they do not renounce the paradigm that has led them into crisis. They do not, that is, treat anomalies as counterinstances, though in the

vocabulary of philosophy of science that is what they are."  (p.77) Rather: "The decision to reject one paradigm is always simultaneously the decision to accept another, and the judgment leading to that decision involves the comparison of both paradigms with nature and with each other." (p.79): "To reject one paradigm without simultaneously substituting another is to reject science itself." For Kuhn, anomalies are only treated as counterinstances by supporters of the competing paradigm.      For example, "Copernicus saw as counterinstances what most of Ptolemy’s other successors had seen as puzzles in the match between observation and theory."  (p.79) As Copernicus complained (quoted from Kuhn (1957), p.138), 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," Copernicus continues, "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." Again, we may note that Copernicus is not complaining about discrepancies per se, but about the fact that discrepancies in Ptolemy’s system are only removed ad hoc adjustments to the model.      From within a paradigm, from the viewpoint of normal science, anomalies are not seen as testing the theory. Yet Kuhn concedes (p.80) that "Normal science does and must continually strive to bring theory and fact into closer agreement, and that activity can easily be seen as testing or as a search for confirmation or falsification." "But science students accept theories on the authority of teacher and text, not because of evidence." (p.80) Hence the standards of critical rationality ascribed by Popper are not present.      There is a need to clarify what Kuhn is saying here. While uncritically taking the background theory for granted, normal science does subject the models derived from the theory to severe critical scrutiny. None of Kuhn’s examples undermine that idea that models are falsified (although there are independent reasons for thinking that such a view is too simple). So normal science strives to bring theory and fact into closer agreement by calling its models into question without ever criticizing the background theory itself. Kuhn does make use of a distinction between "approaches to problems" (models?) and the paradigm later in the book. Thus, while scientists will (p.144) "try out and reject a number of alternative approaches, rejecting those that fail to yield the desired result, he is not testing the paradigm when he does so."      The same point that is now often used in criticism of Popper’s falsificationism: Theories are never tested in isolation. And when they are tested, as in the Leverrier-Adams discovery of Neptune, it is the auxiliary assumptions (the assumption that Uranus was the outermost planet) that was criticized, and not Newton’s laws of

motion. 

6. New Paradigms Place New Relations Amongst the Data: When normal puzzle solving fails to resolve anomalies, crisis looms, and the nature of scientific activity gradually changes. (p.91) "The proliferation of competing articulations, the willingness to try anything, the expression of explicit discontent, the recourse to philosophy and to debate over fundamentals, all these are symptoms of a transition from normal to extraordinary research." When the transition is complete, the profession will have changed its view of the field, its methods, and its goals. One perceptive historian, viewing a classic case of a science’s reorientation by paradigm change, recently described it as "picking up the other end of the stick," 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." [Herbert Butterfield, The Origins of Modern Science, 1300-1800 (London, 1949), pp.1-7] Others who have noted this aspect of scientific advance have emphasized its similarity to a change in visual gestalt: the marks on paper that were first seen as a bird are now seen as an antelope, or vice versa. (p.85)      Butterfield’s description of theory change is an important clarification of Kuhn’s poetic reference seeing a duck and then seeing a rabbit. For there is a danger that we might take Kuhn’s duck-rabbit analogy too seriously, and view theory change as literally involving a change in perception, and therefore a change in the data themselves, rather than just a change in the relations amongst the data.      Another noteworthy feature of the above quote is the idea that the goals of science change when the paradigm changes. Presumably, this is because the goal of science is problem-solving, and this changes as the problems change. Yet one might also define problem-solving in a paradigm independent way (e.g., as the goal of finding predictively accurate models), in which case the goal would not change. But Kuhn does not appear to subscribe to such a view of science. 

7. Science is Non-Cumulative Because Terms Change their Meanings: In the meantime, Kuhn mounts an attack on the common idea that scientific knowledge is accumulative. He begins with the often quoted idea that most often, "the new

paradigm, or a sufficient hint to permit later articulation, emerges all at once, sometimes in the middle of the night, in the mind of a man deeply immersed in crisis." (p.90) If paradigms change in such a sudden way, how can they simply built on prior knowledge? For Kuhn (p.92), this indicates that scientific revolutions are "non-cumulative developmental episodes in which an older paradigm is replaced in whole or in part by an incompatible new one." Moreoever, paradigm choice in science are "Like the choice between competing political institutions, that between competing paradigms proves to be a choice between incompatible modes of community life." And the choice is a choice in community alliance, for "As in political revolutions, so in paradigm choice-there is no standard higher than the assent of the relevant community."  (p.94) Kuhn, of course, is acutely aware of the controversial nature of his denying standards higher than the assent of the relevant community. Traditional philosophy of science is premised on the claim that the logical structure of scientific theories provides intrinsic reasons for theory change independently of the prevailing social conditions. Kuhn is quick to confirm the impression that he rejects this working assumption. (p.95)

8. Historical Examples Show that Science is Non-Cumulative: Kuhn’s hunch is that scientific change brings about a change in the entities that are taken to be primitive and unexplained. For example, Aristotelians said that a stone fell because of its ‘nature’ drove it toward the center of the universe. Afterwards the normal seventeenth-century tradition of scientific practice insisted that "the entire flux of sensory appearances, including color, taste, and even weight, was to be explained in terms of the size, shape, position, and motions the elementary corpuscles of base matter." (p.104) The attribution of other qualities to the elementary atoms was a resort to the occult and therefore out of bounds for science. Famously, Molière ridiculed the doctor who explained opium’s efficacy as a soporific by attributing to it a dormitive potency. (p.104) Kuhn sees this not as a criticism of postulating mystical entities per se but of postulating an entity not accepted as primitive at the time. In that vein, Kuhn remarks that "During the last half of the seventeenth century many scientists preferred to say that the round shape of the opium particles enabled them to sooth the nerves about which they moved." 

9. Incommensurability: The lesson that Kuhn draws from these examples is that: "... the reception of a new paradigm often necessitates a redefinition of the corresponding science. Some old problems may be relegated to another science or declared entirely "unscientific." [e.g. alchemy] Others that were previously non-existent or trivial may, with a new paradigm, become the very archetypes of significant scientific achievement. [e.g., tidology, the study of the tides] The normal-scientific tradition that emerges from a scientific revolution is not only incompatible but often actually incommensurable with that which has gone

before." (p.103)     As far as the main conclusion is concerned, Kuhn’s argument is convincing. There is no doubt that the world view that emerges from a scientific revolution may be incommensurable in the weak sense described above - that new terms are not straightforwardly translatable, and the new paradigm leads to at least some incompatible predictions. However, there is a concomitant claim that should not go unchallenged. Are there really no objective standards on the acceptance of primitive entities, as Kuhn insinuates? Surely, it is reasonable to demand that postulated entities can at least be measured. Isn’t it conceivable that Molière’s disdain for the term ‘dormitive potency’ arose from the fact that the label adds nothing but a new way of saying "soporific"?

10. Development of Science’s Problems and Standards is Also Non-Cumulative: Kuhn has been arguing against a straw man thus far, in that very few philosophers thought that theory change was cumulative in any naive sense. But far more did, and still do, hold dearly to the view that the standards by which scientific theories are judged (goodness-of-fit, simplicity, unification, and so on) are constant across theory change. Kuhn, on the other hand, develops a line of argument that is more or less an inference to the best explanation - if we suppose that problems and standards change across paradigm shifts, then we may explain why there is so often a breakdown in communication. In the first place, there will be disagreements about the what counts as a solution to a problem because the problems are different, or at least redescribed. (pp.109-10) Furthermore, they are unlikely to agree on what the important problems are. (p.110) However, Kuhn has no argument to show that models from different paradigms cannot be compared on grounds of fit, simplicity, or unification, at least in principle.

11. Paradigms Transform Scientists’ View of the World: Psychological experiments show that expectations cloud and obscure perception (§3), and a paradigm produces expectations, and so a paradigm may skew observation:      The man who first saw the exterior of the box from above later sees its interior from below. Transformations like these, though usually more gradual and almost always irreversible are common concomitants of scientific training. Looking at a contour map, the student sees lines on paper, the cartographer a picture of a terrain. Looking at a bubble-chamber photograph, the student sees confused and broken lines, the physicist a record of familiar subnuclear events. (p.111)      In one psychological experiment, volunteers fitted with inverting lenses report that everything appears up side down at first, but they grow accustomed to the inversion. They learn to accurately predict where their hand should move in order to intercept an object, say, and report the experience of seeing everything the right side up. (And

when the lenses are first removed, everything appears to be up side down again!) According to Kuhn, (p.112) "literally as well as metaphorically, the man accustomed to inverting lenses has undergone a revolutionary transformation of vision." Yet Kuhn is quick to acknowledge that these known psychological facts about vision do not tell the affect, if any, of scientific training on vision.  (p.113) And prima facie, it is somewhat implausible to naively extend the idea to, say, the convert to a new paradigm. For example, "Looking at the moon, the convert to Copernicanism does not say, ‘I used to see a planet, but now I see a satellite.’ That locution would imply a sense in which the Ptolemaic system had once been correct. Instead, a convert to the new astronomy says, ‘I once saw the moon to be (or saw the moon as) a planet, but I was mistaken’."  (p.115) At the same time, there are clear analogies to the psychological phenomenon of "seeing what one expects to see" as in the case of seeing a black three of hearts as a three of spades. For instance:     "Sir William Herschel’s discovery of Uranus provides a first example and one that closely parallels the anomalous card experiment. On a least seventeen different occasions between 1690 and 1781, a number of astronomers, including several of Europe’s most eminent observers, had seen a star in positions that we now suppose must have been occupied at the time by Uranus... Herschel, when he first observed the same object twelve years later, did so with a much improved telescope of own manufacture. As a result, he was able to notice an apparent disk-size that was at least unusual for stars. Something was awry, and he therefore postponed identification pending further scrutiny. That scrutiny disclosed Uranus’ motion among the stars, and Herschel therefore announced that he had seen a new comet! Only several months later, after fruitless attempts to fit the observed motion to a cometary orbit, did Lexell suggest that the orbit was probably planetary." (p.115)        The question is whether there is evidence for the more radical conclusion that new paradigms can change the way we see the world, as opposed to changing the way we interpret what we see. Or maybe we should say that new paradigms actually change the world in which scientists work?!

124. Paradigms Change the World in which Scientists Work: Kuhn is testing the waters, wondering how far he should go. Should he really irritate the philosophers by claiming that paradigms change the world itself?      Using traditional instruments, some as simple as a piece of thread, late sixteenth-century astronomers repeatedly discovered that comets wandered at will through the space previously reserved for the immutable planets and stars. The very ease and rapidly with which astronomers saw new things when looking at old objects with old instruments may make us wish to say that, after Copernicus, astronomers lived in a different world. In any case, their research responded as though that were the case.

(pp.116-7)      Cautiously, Kuhn pushes the thesis a little further: "At the very least, as a result of discovering oxygen, Lavoisier saw nature differently. And in the absence of some recourse to that hypothetical fixed nature that he "saw differently," the principle of economy will urge us to say that after discovering oxygen Lavoisier worked in a different world."(p.118)      So far Kuhn has provided no detailed argumentation to support his analysis. Those details are really quite interesting in their own right, irrespective of whether they actually succeed in supporting the stronger conclusion. By way of elaboration, Kuhn contrasts the Aristotelian and Galilean view of a simple pendulum:      "To the Aristotelians, who believed that a heavy body is moved by its own nature from a higher position to a state of natural rest at a lower one, the swinging body was simply falling with difficulty. Constrained by the chain, it could achieve rest at its low point only after tortuous motion and a considerable time. Galileo, on the other hand, looking at the swinging body, saw a pendulum, a body that almost succeeded in repeating the same motion over and over again ad infinitum. And having seen that much, Galileo observed other properties of the pendulum as well and constructed many of the most significant and original parts of this new dynamics around them. From the properties of the pendulum, for example, Galileo derived his only full and sound arguments for the independence of weight and rate of fall, as well as for the relationship between vertical height and terminal velocity of motions down inclined planes. [Galileo Galilei, Dialogues concerning Two New Sciences, trans. H. Crew and A. de Salvio (Evanston, Ill., 1946), pp.80-81, 162-66.] All of these natural phenomena he saw differently from the way they had been seen before."  (pp.118-9)      But the conclusion drawn from this example is that "until that scholastic paradigm was invented, there were no pendulums, but only swinging stones, for the scientists to see. Pendulums were brought into existence by something very like a paradigm-induced gestalt switch." (p.120) This is a radical conclusion.

13. A Confusion between Seeing and Seeing As? At first glance, Kuhn’s extreme position appears to arise from a simple confusion between ‘seeing’ and ‘seeing as’. Isn’t the situation simply this: Both Aristotle and Galileo saw the thing that we now describe as a pendulum, even though Aristotle did not describe it in those terms. This is the same sense in which we say that someone totally ignorant of matters astronomical actually succeeds in seeing the planet Venus when they point to the evening star. On the other hand, Aristotle did not see pendulums as pendulums, in the same sense that our astronomical ignoramus does not see the evening star as the planet Venus. On this alternate view, our ignoramus sees the same thing as the expert astronomer - the difference is that the expert interprets what she sees as the planet Venus. But if this is the only alternative, then Kuhn thinks that we should continue to

say the post-paradigm scientist literally lives in a transformed world:      "What occurs during a scientific revolution is not fully reducible to a reinterpretation of individual and stable data. In the first place, the data are not unequivocally stable. A pendulum is not a falling stone, nor is oxygen dephlogisticated air. Consequently, the data that scientists collect from these diverse objects are, as we shall shortly see, themselves different. More important, the process by which either the individual or the community makes the transition from constrained fall to the pendulum or from dephlogisticated air to oxygen is not one that resembles interpretation. How could it do so in the absence of fixed data for the scientist to interpret? Rather than being an interpreter, the scientist who embraces a new paradigm is like the man wearing inverting lenses." (pp.121-22) 

14. Radical Incommensurability: When Kuhn asserts in the last passage that "the data are not unequivocally stable," he is stepping beyond the weak version of his incommensurability thesis. For if the data are incommensurable (because "A pendulum is not a falling stone, nor is oxygen dephlogisticated air"), then it would be false to claim that the two paradigms make incompatible predictions-the one is making predictions about a falling stone, and the other about a pendulum.The strong incommensurability thesis says everything the weak thesis says plus the claim that the empirical data for a given theory cannot be translated in a way that are neutral between competing theories. Of course, it is not hard to resist this stronger thesis (and so we should): The Aristotelian and Galilean predictions are about the same thing (an stone swinging on a rigid rod), even though they are described and even seen as differing in some respects (as a falling stone in the first instance, or as a pendulum in the second). There is no reason to deny that the predictions of the two paradigms are commensurable. Kuhn’s only argument to the contrary conclusion appears to revert back to his "gestalt shift" picture of paradigm change:     "Scientists then often speak of the "scales falling from the eyes" or 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. On other occasions the relevant illumination comes in sleep. Nor ordinary sense of the term ‘interpretation’ fits these flashes of intuition through which a new paradigm is born. Though such intuitions depend upon the experience, both anomalous and congruent, gained with the old paradigm, they are not logically or piecemeal linked to particular items of that experience as an interpretation would be. Instead, they gather up large portions of that experience and transform them to the rather different bundle of experience that will thereafter be linked piecemeal to the new paradigm but not to the old." (pp.122-23)       The last sentence in the quotation is another reference to Butterfield’s description of theory change (§7, above). There is a sense in which this description strengthens

the case against interpretation, since to exploit new relations is not to reinterpret old relations. However, it offers no support for a stronger incommensurability thesis. For the relations amongst data can change without the data themselves changing.

15. Need We Be So Concerned about Immediate Experience? Suppose we grant that "the immediate content of Galileo’s experience with falling stones was not what Aristotle’s had been." (p.125) But is experience at this personal level crucial to a deeper understanding of scientific change? In response to this objection, Kuhn emphatically denies that operations and measurements are paradigm independent, "the measurements to be performed on a pendulum are not the ones relevant to a case of constrained fall." (p.126) While Kuhn is undoubtedly right on this point, it is not enough to dismiss the objection. As philosophers of science, maybe we should discuss the concrete operations and measurements that the scientist performs in her laboratory even though they are paradigm dependent? Their paradigm dependence does not exclude them from being predicted by a competing paradigm. For example, it is perfectly sensible to ask whether Kepler’s laws predict the 3-D positions of Mars as inferred from the Copernican model better than the Copernican model best fitted to past data. There is nothing absurd about this, as Kuhn believes.

16. There Is No Such Thing as a Neutral Observation Language: Kuhn then goes on to argue against a second proposal to bypass consideration of "immediate experience": "[The analysis] might, for example, be conducted in terms of some neutral observation-language, perhaps one designed to conform to the retinal imprints that mediate what the scientists see."  (p.125) Kuhn’s reaction to the neutral observation language proposal is that retinal impressions do not map one-to-one onto perceptual experiences: (pp.126-27) "The duck-rabbit shows that two men with the same retinal impressions can see different things; the inverting lenses show that two men with different retinal impressions can see the same thing." However, it is not immediately clear how this fact undermines the proposal. Maybe Kuhn thinks that the absence of such a mapping means that a description of retinal impressions could not be unambiguously understood by all sides. But I think this is false. A theory-neutral observation language is not needed to compare the fit of models from different paradigms. The merit of the model is measured by how well it allows past data to predict future data, and the success of models from different paradigms can be compared against a common data set even when the data in question is theory-laden.

17. Philosophers have Disguised the Confirmation Situation: In considering traditional philosophical accounts of scientific confirmation, Kuhn first complains that philosophers have misrepresented confirmation as a relation between theory and evidence. Kuhn disagrees on two counts: First the question should be one about

scientific communities rather than theories: (p.144) "What causes the group to abandon one tradition of normal research in favor of another?" Second, (p.145) "testing occurs as part of the competition between two rival paradigms for the allegiance of the scientific community." Thus, confirmation or verification is not a relation between a theory and evidence, but a process of selection from amongst rival candidates: (p.146) "Verification is like natural selection: it picks out the most viable among the actual alternatives in a particular historical situation." Kuhn’s point about the comparative nature of confirmation is a good one.     Other philosophers of science, like Popper, have denied the existence of any verification procedures at all. Theories are never justified (because of problems with induction), but they may be disproven. Popper’s philosophy is that of falsificationism: Theories should be severely criticized in an attempt to falsify them. Survivors of such critical scrutiny are rationally acceptable, and are said to be corroborated.      "... the role thus attributed to falsification is much like the one this essay assigns to anomalous experiences, i.e. to experiences that, by evoking crisis, prepare the way for a new theory. Nevertheless, anomalous experiences may not be identified with falsifying ones. Indeed, I doubt that the latter exist. As has repeatedly been emphasized before, no theory ever solves all the puzzles with which it is confronted at an given time; nor are the solution already achieved often perfect. On the contrary, it is just the incompleteness and imperfection of the existing data-theory fit that, at any time, define many of the puzzles that characterize normal science. If any and every failure to fit were ground for theory rejection, all theories ought to be rejected at all times. On the other hand, if only severe failure to fit justifies theory rejection, then the Popperians will require some criterion of "improbability" or of "degree of falsification." In developing one they will almost certainly encounter the same network of difficulties that has haunted the advocates of the various probabilistic verification theories." (pp.146-47) 

18. Incommensurability is a Cause of Communication Breakdowns: Almost by way of review, Kuhn recalls that (p.148) "We have already seen several reasons why the proponents of competing paradigms must fail to make complete contact with each other’s viewpoints." The three reasons for communication breakdown are all "fundamental aspects of incommensurability." First, not all past successes are recognized as relevant problems in the new paradigm. For example, Cartesian vortex theory had a ready explanation of why all the planets revolve around the sun in the same direction. The problem was seen as extraneous to mechanics by the Newtonians who considered it as a question about the origin of the solar system. This is an example of what some refer to asKuhn loss (I heard the example and the term from Alan Musgrave): 

     "In the first place, the proponents of competing paradigms will often disagree about the list of problems that any candidate for paradigm must resolve. ... Lavoisier’s chemical theory inhibited chemists from asking why the metals were so much alike, a question that phlogistic chemistry had both asked and answered. The transition to Lavoisier’s paradigm had, like the transition to Newton’s meant a loss not only of a permissible question but of an achieved solution." (p.148)      The second fundamental aspect of incommensurability might be called meaning variance, and is often simply equated with incommensurability:      "Communication across the revolutionary divide is inevitably partial. Consider, for another example, the men who called Copernicus mad because he proclaimed that the earth moved. They were not either just wrong or quite wrong. Part of what they meant by ‘earth’ was fixed position. Their earth, at least, could not be moved." (p.149)      The third and most fundamental aspect of the incommensurability of competing paradigms might be referred to as world changes:      "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 some areas they see different things, and they see them in different relations "one to the other." (p.150)      I will not repeat what has already been said about the merit of these theses. 

19. How Communication is Restored by Conversion to the New Paradigm: What I want to highlight here is the further thesis that (p.150) "before they can hope to communicate fully, one group or the other must experience the conversion that we have been calling a paradigm shift." For example, (p.151) "Max Planck ... 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.’" Or, (p.152) "Conversions will occur a few at a time until, after the last hold-outs have died, the whole profession will again be practicing under a single, but now different, paradigm." Partly by way of explication, and partly by way of argument, Kuhn tells us how conversion is induced and how resisted. There are three things that commonly sway scientists towards conversion.      The first is the claim to have solved crisis-provoking problems: "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. ... Copernicus thus claimed that he had solved the long-vexing problem of the length of the calendar year, Newton that he had reconciled terrestrial and celestial mechanics, Lavoisier that he had solved the problems of gas-identity and

of weight relations, and Einstein that he had make electrodynamics compatible with a revised science of motion." (pp.153-54)      The second road to conversion follows a claim to novel predictions: "... particularly persuasive arguments can be developed if the new paradigm permits the prediction of phenomena that had been entirely unsuspected while the old one prevailed. Copernicus’ theory, for example, suggested that planets should be like the earth, that Venus should show phases, and that the universe must be vastly larger than had previously been supposed. As a result, when sixty years after his death the telescope suddenly displaced mountains on the moon, the phases of Venus, and an immense number of previously unsuspected stars, those observations brought the new theory a great many converts, particularly among non-astronomers. In the case of the wave theory, one main source of professional conversions was even more dramatic. French resistance collapsed suddenly and relatively completely when Fresnel was able to demonstrate the existence of a white spot at the center of the shadow of a circular disk. That was an effect that not even he had anticipated but that Poisson, initially one of his opponents, had shown to be a necessary if absurd consequence of Fresnel’s theory." (pp.154-55)     The third and final category of claim that may cause conversion is the claim to simplicity:"Fortunately, there is also another sort of consideration that can lead scientists to reject an old paradigm in favor of a new. These are the arguments, rarely made entirely explicit, that appeal to the individual’s sense of the appropriate or the aesthetic-the new theory is said to ‘neater,’ ‘more suitable,’ or ‘simpler’ than the old. Probably such arguments are less effective in the sciences than in mathematics. ... Nevertheless, the importance of aesthetic considerations can sometimes be decisive. ... To see the reason for the importance of these more subjective and aesthetic considerations, remember what a paradigm debate is about. When a new candidate for paradigm is first proposed, it has seldom solved more than a few of the problems that confront it, and most of those solutions are still far from perfect. Until Kepler, the Copernican theory scarcely improved upon the predictions of planetary position made by Ptolemy. ... In short, if a new candidate for paradigm had to be judged from the start by hard-headed people who examined only relative problem-solving ability, the sciences would experience very few major revolutions." (pp.155-57)        These three considerations are parallel those put forward by William Whewell circa 1840, and predate that time. Whewell referred to the three tests of hypotheses as being (1) the prediction of phenomena of the same kind as those which the hypothesis was invented to explain, (2) the prediction of facts of a different and novel kind (the consilience of inductions), and (3) the tendency to simplicity and unity. 

20. The Evaluation of Paradigms is Future Oriented: Kuhn correctly points out that new paradigms, when proposed, are not veterans in the problem-solving business, and cannot compete on the basis of current problem-solving accomplishments. Rather, they are selected on the promise of future success. Such promises are hard to assess, which is why it is so rare for new paradigms to take hold unless the old one is in crisis (see §5). (pp.157-58)  The further claim that such decisions can only be made on faith is the substance behind charges that Kuhn sees science as an irrational or arational enterprise on a par with religious conversion. However, Kuhn adds that there must be a basis for this faith, though it need not be a rational basis:      "... crisis alone is not enough. There must also be a basis, though it need be neither rational nor ultimately correct, for faith in the particular candidate chosen. 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.... When first introduced, neither Copernicus’ astronomical theory nor De Broglie’s theory of matter had many other significant grounds of appeal. ... This is not to suggest that new paradigms triumph ultimately through some mystical aesthetic. On the contrary, very few men desert a tradition for these reasons alone. Often those who do turn out to have been misled. But 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." (p.158)

POSTSCRIPT

21. Paradigm as Disciplinary Matrix: In his original essay, Kuhn slowly introduces ‘paradigm’ to displace the more common philosophical usage of ‘theory’. In response to charges of vagueness and even equivocation in his use of the word ‘paradigm’, Kuhn now wishes to substitute the term, ‘disciplinary matrix’: "As currently used in philosophy of science ... ‘theory’ connotes a structure far more limited in nature and scope than the one required here. Until the term can be freed from its current implications, it will avoid confusion to adopt another. For present purposes I suggest ‘disciplinary matrix’: ‘disciplinary’ because it refers to the common possession of the practitioners of a particular discipline; ‘matrix’ because it is composed of ordered elements of various sorts, each requiring further specification." (p.182)       He then proceeds to define four components of a disciplinary matrix: symbolic generalizations, metaphysical presumptions, values, and exemplars.     Symbolic generalizations. (p. 182) "One important sort of component I shall label ‘symbolic generalizations’" like f = m a, or I = V/R, or "elements combine in constant proportion by weight," or "action equals reaction." This corresponds most

closely with what have been traditionally referred to as ‘theories’ or ‘laws’.      Metaphysical presumptions. (p.184) "Rewriting the book now I would describe such commitments as beliefs in particular models, and I would expand the category models to include also the relatively heuristic variety: the electric circuit may be regarded as a steady-state hydrodynamic system; the molecules of a gas behave like tiny elastic billiard balls in random motion."     Values: "Probably the most deeply held values concern predictions: they should be accurate; quantitative predictions are preferable to qualitative ones; whatever the margin of permissible error, it should be consistently satisfied in a given field; and so on. There are also, however, values to be used in judging whole theories: they must, first and foremost, permit puzzle-formulation and solution; where possible they should be simple, self-consistent, and plausible, compatible, that is, with other theories currently deployed. ... Other sorts of values exist as well-for example, should (or need not) be socially useful-but the preceding should indicate what I have in mind." (pp.184-85)       Exemplars: "Turn now to a fourth sort of element in the disciplinary matrix... For it the term ‘paradigm’ would be entirely appropriate, both philological and autobiographically; this is the component of a group’s shared commitments which first led me to the choice of that word. Because the term has assumed a like of its own, however, I shall here substitute ‘exemplar.’ By it I mean, initially, the concrete problem-solutions that student encounter from the start of their scientific education, whether in laboratories, in examinations, or at the ends of chapters in science texts. ... All physicists, for example, begin by learning the same exemplars: problems such as the inclined plane, the conical pendulum, and Keplerian orbits; instruments such as the vernier, the calorimeter, and the Wheatstone bridge." (pp.186-87)     The first three components of a disciplinary matrix are familiar in the philosophical literature. Kuhn’s fourth idea of an exemplar is the most interesting element, especially in light of denial of the traditional presumption that theories and laws determine the empirical content of science. Kuhn’s claim is startling at first: (p.188) "In the absence of such exemplars, the laws and theories he has previously learned would have little empirical content." How do exemplars determine empirical content? As an example:      "Galileo found that a ball rolling down an incline acquires just enough velocity to return it to the same vertical height on a second incline of any slope, and learned to see that experimental situation as like the pendulum with a point-mass for a bob. Huygens then solved the problem of the center of oscillation of a physical pendulum by imagining that the extended body of the latter was composed of Galilean point-pendula, the bonds between which could be

instantaneously released at any point in the swing. ...Finally, Daniel Bernoulli discovered how to make the flow of water from an orifice resemble Huygens’ pendulum. ... The three problems in the example, all of them exemplars for eighteenth-century mechanicians, deploy only one law of nature. Known as the Principle of vis viva, it was usually stated as: ‘Actual descent equals potential ascent.’" (pp.190-91) 

22. Tacit Knowledge Gained by Training with Exemplars: Kuhn elaborates upon the importance of exemplars as contributing to "tacit knowledge acquired through practice, which cannot be articulated explicitly." (See §2, A Paradigm is...?) (p.191): "To borrow once more Michael Polanyi’s useful phrase, what results from this process is ‘tacit knowledge’ which is learned by doing science rather than by acquiring rules for doing it."      Kuhn denies the charges of subjectivity and irrationality that usually follow close on the heels of such psychological solutions (remember Hume), at least on two counts: (p.191) "First, if I am talking at all about intuitions, they are not individual." The sort of tacit knowledge, manifested in intuition, which Kuhn appeals to is common to all members of a community. There is no variation within a community. "Second they are not in principle unanalyzable." On the second count, Kuhn suggests that neuropsychology might provide such an analysis, in stark contrast with the rule-based analysis that philosophers have traditionally sought (p.192). Kuhn’s suggestion predates the current explosion of research into neural networks, parallel distributed computers, or connectionism.     A possible objection is that neural states must be subject to laws, and therefore we may properly conceive of it as something we achieve by applying rules and criteria. Kuhn responds, in effect, by drawing the distinction familiar to the philosopher of mind between a merely rule-governed process (which covers everything) and a rule-following procedure, which follows a program or set of rules. Neural processing is rule-governed, but not rule-following:      "... the fact that the system obeys the same laws ... provides no reason to suppose that our neural apparatus is programmed to operate the same way in interpretation as in perception or in either as in the beating of our hearts. What I have been opposing in this book is therefore the attempt, traditional since Descartes but not before, to analyze perception as an interpretive process, as an unconscious version of what we do after we have perceived.      What makes the integrity of perception worth emphasizing is, of course, that so much past experience is embodied in the neural apparatus that transforms stimuli to sensations." (p.195)      Without providing any answers, it is worth raising some questions. (1) Exactly how much past experience is embodied in the neural apparatus that transforms stimuli to sensations? (2) Assuming that scientific judgment (or intuition?) is a distinct

neuropsychological process that accompanies or follows perception, is judgment an automatic unconscious process molded by educational experience? Or is judgment a slow, interpretive, rule-following procedure of the classical kind? In what follows, I will assume that Kuhn wishes to conflate perception (sensation) and judgment, and say the same about both - they are automatic, unconscious, non rule-following, procedures highly adapted to past educational experiences. (p.196) Educational training results in a stock of neurally encoded information that is used to make scientific judgments of various kinds - judgments of the relevance of data to theory, judgments of confirmation, judgments of what models to try next, judgments of simplicity, judgments of family resemblance. This does not fit the traditional view of knowledge, but the fact that it is subject to change through the discovery of misfits with the environment makes it worthy of the term:      "But it is strange usage, for one other characteristic is missing. We have not direct access to what it is we know, no rules or generalizations with which to express this knowledge. Rules which could supply that access would refer to stimuli not sensations, and stimuli we can know only through elaborate theory. In its absence, the knowledge embedded in the stimulus-to-sensation route remains tacit." (p.196)  

23. Communication Breakdown Can Be Overcome by Inter-Group Translation: As we have seen (§12) how Kuhn vacillates between a weak and strong stance on incommensurability. In the Postscript (written 7 years later) Kuhn appears to back off from the strong incommensurability thesis, which implied a on-going and insurmountable failure of translation across paradigms: Now Kuhn suggests that:      "... what the participants in a communication breakdown can do is recognize each other as members of different language communities and then become translators. Taking the differences between their own intra and inter-group discourse as itself a subject for study, they can first attempt to discover the terms and locutions that, used unproblematically within each community, are nevertheless foci of trouble for inter-group discussions. (Locutions that present no such difficulties may be homophonically translated.) Having isolated such areas of difficulty in scientific communication, they can next resort to their shared everyday vocabularies in an effort further to elucidate their troubles. Each may, that is, try to discover what the other would see and say when presented with a stimulus to which his won verbal response would be different. If they sufficiently refrain from explaining anomalous behavior as the consequence of mere error or madness, they may in time become very good predictors of each other’s behavior. Each will have learned to translate the other’s theory and its consequences into his own language and simultaneously to describe in his language the world to which that theory applies. That is what the historian of science regularly does (or should) when dealing with out-of-date theories."

(p.202)      Part of what had previously obscured Kuhn’s view of the matter was his conflation of ‘persuasion’ with ‘conversion.’ In his original essay, Kuhn assumed that the only way that someone could understand the opposing viewpoint was to be converted to the new paradigm. Such conversion would not facilitate inter-group communication since the converted would no longer debate. But now Kuhn concedes that someone may see the other point of view, and even be persuaded by it, without being converted to the new paradigm (p.204)  

24. Rationality: Is Kuhn’s Description of Science Also a Prescription? A remarkable feature of Kuhn’s essay is how little Kuhn says or implies, in detail, about what would happen if things in science were different. Mostly, such implications are contained in his discussion of how the scientific community is different from other communities (see §24 Yet Science Does Progress, and §25 Progress by Natural Selection). Kuhn even restates his position in purely descriptive terms:      "Though scientific development may resemble that in other fields more closely than has often been supposed, it is also strikingly different. ... Consider, for example, the reiterated emphasis, above, on the absence or, as I should now say, on the relative scarcity of competing schools in the developed sciences. ... Or think again about the special nature of scientific education, about puzzle-solving as a goal, and about the value system which the scientific group deploys in periods of crisis and decision." (p.209)        The implication is that if the scientific community weren’t like that, then it would not accumulate problem-solutions. Kuhn reports that (p.207) "Some critics claim that I am confusing description with prescription, violating the time-honored philosophical theorem: ‘Is’ cannot imply ‘ought.’" By some kind of inference to the best explanation, he thinks his theory is warranted because scientists "behave as the theory says they should." If we include the suppressed premise that scientists behave rationally (so they behave as they ought to behave), then it might be a good argument. But it seems just all too quick and easy! For one thing, there is no reason why the same argument can’t be used to argue, say, that religious fundamentalists ought to read the bible if their goal is to know the truth about evolution, since their methods have been developed and selected for their success, do in fact behave as the theory says they should.     I think that Kuhn would be better of if he denied that his claims are prescriptive, or normative, at all. For example, the implication above is not that scientistsought to aim at the accumulation of problem-solutions, only that if that is their goal, then certain structural features of their community will be causally influential in bringing about this end. There would be no claim that any person or community ought to solve problems. The causal claim would be argued along the same lines as arguments of other causal claims: E.g., switch A controls that light because the light goes on or off

when I flick switch A, but the light does not respond when I flick switch B. Likewise, problem-solutions are achieved by communities of type A, but such achievements are not replicated by community B. There is no inference of ‘ought’ from ‘is’; just a causal conclusion being inferred from relevant evidence.      The problem is that Kuhn’s causal inferences are unsupported. As in the light switch example, no clue is given of the causal mechanisms behind those problem-solving achievements. What are the quite special characteristics of the world that allow for such achievements? As Kuhn stated in the closing paragraph of his original essay, such questions like "what must the world be like in order for us to know it?" are left unanswered.

Reference: http://philosophy.wisc.edu/forster/220/kuhn.htm

The Structure of Scientific Revolutions

by Thomas S. Kuhn

A Synopsis from the original by Professor Frank PajaresFrom the Philosopher's Web Magazine

I Introduction

A scientific community cannot practice its trade without some set of received beliefs. These beliefs form the foundation of the "educational initiation that prepares and licenses the student for professional practice". The nature of the "rigorous and rigid" preparation helps ensure that the received beliefs are firmly fixed in the student's mind. Scientists take great pains to defend the assumption that scientists know what the world is like...To this end, "normal science" will often suppress novelties which undermine its foundations. Research is therefore not about discovering the unknown, but rather "a strenuous and devoted attempt to force nature into the conceptual boxes supplied by professional education".

A shift in professional commitments to shared assumptions takes place when an anomaly undermines the basic tenets of the current scientific practice These shifts are what Kuhn describes as scientific revolutions - "the tradition-shattering complements to the tradition-bound activity of normal science" New assumptions –"paradigms" - require the reconstruction of prior assumptions and the re-evaluation of prior facts. This is difficult and time consuming. It is also strongly resisted by the established community.

II The Route to Normal Science

So how are paradigms created and what do they contribute to scientific inquiry?

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". These achievements must be sufficiently unprecedented to attract an enduring group of adherents away from competing modes of scientific activity and sufficiently open-ended to leave all sorts of problems for the redefined group of practitioners (and their students) to resolve. These achievements can be called paradigms. Students study these paradigms in order to become members of the particular scientific community in which they will later practice.

Because the student largely learns from and is mentored by researchers "who learned the bases of their field from the same concrete models" there is seldom disagreement over fundamentals. Men whose research is based on shared paradigms are committed to the same rules and standards for scientific practice. A shared commitment to a paradigm ensures that its practitioners engage in the paradigmatic observations that its own paradigm can do most to explain. Paradigms help scientific communities to bound their discipline in that they help the scientist to create avenues of inquiry, formulate questions, select methods with which to examine questions, define areas of relevance. and establish or create meaning. A paradigm is essential to scientific inquiry - "no natural history can be interpreted in the absence of at least some implicit body of intertwined theoretical and methodological belief that permits selection, evaluation, and criticism".

How are paradigms created, and how do scientific revolutions take place? Inquiry begins with a random collection of "mere facts" (although, often, a body of beliefs is already implicit in the collection). During these early stages of inquiry, different researchers confronting the same phenomena describe and interpret them in different ways. In time, these descriptions and interpretations entirely disappear. A pre-paradigmatic school appears. Such a school often emphasises a special part of the collection of facts. Often, these schools vie for pre-eminence.

From the competition of these pre-paradigmatic schools, one paradigm emerges - "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", thus making research possible. As a paradigm grows in strength and in the number of advocates, the other pre-paradigmatic schools or the previous paradigm fade.

A paradigm transforms a group into a profession or, at least, a discipline. And from this follow the formation of specialised journals, foundation of professional bodies and a claim to a special place in academe. There is a promulgation of scholarly articles intended for and "addressed only to professional colleagues, [those] whose knowledge of a shared paradigm can be assumed and who prove to be the only ones able to read the papers addressed to them".

III - The Nature of Normal Science.

If a paradigm consists of basic and incontrovertible assumptions about the nature of the discipline, what questions are left to ask?

When they first appear, paradigms are limited in scope and in precision. But more successful does not mean completely successful with a single problem or notably successful with any large number. Initially, a paradigm offers the promise of success. Normal science consists in the actualisation of that promise. This is achieved by extending the knowledge of those facts that the paradigm displays as particularly revealing, increasing the extent of the match between those facts and the paradigm's predictions, and further articulation of the paradigm itself.

In other words, there is a good deal of mopping-up to be done. Mop-up operations are what engage most scientists throughout their careers. Mopping-up is what normal science is all about! This paradigm-based research is "an attempt to force nature into the pre-formed and relatively inflexible box that the paradigm supplies". No effort is made to call forth new sorts of phenomena, no effort to discover anomalies. When anomalies pop up, they are usually discarded or ignored. Anomalies are usually not even noticed and no effort is made to invent a new theory (and there’s no tolerance for those who try). Those restrictions, born from confidence in a paradigm, turn out to be essential to the development of science. By focusing attention on a small range of relatively esoteric problems, the paradigm forces scientists to investigate some part of nature in a detail and depth that would otherwise be unimaginable" and, when the paradigm ceases to function properly, scientists begin to behave differently and the nature of their research problems changes.

IV - Normal Science as Puzzle-solving.

Doing research is essentially like solving a puzzle. Puzzles have rules. Puzzles generally have predetermined solutions.

A striking feature of doing research is that the aim is to discover what is known in advance. This in spite of the fact that the range of anticipated results is small compared to the possible results. When the outcome of a research project does not fall into this anticipated result range, it is generally considered a failure.

So why do research? Results add to the scope and precision with which a paradigm can be applied. The way to obtain the results usually remains very much in doubt - this is the challenge of the puzzle. Solving the puzzle can be fun, and expert puzzle-solvers make a very nice living. To classify as a puzzle (as a genuine research question), a problem must be characterised by more than the assured solution, but at the same time solutions should be consistent with paradigmatic assumptions.

Despite the fact that novelty is not sought and that accepted belief is generally not challenged, the scientific enterprise can and does bring about unexpected results.

V - The Priority of Paradigms.

The paradigms of a mature scientific community can be determined with relative ease. The "rules" used by scientists who share a paradigm are not so easily determined. Some reasons for this are that scientists can disagree on the interpretation of a paradigm. The existence of a paradigm need not imply that any full set of rules exist. Also, scientists are often guided by tacit knowledge - knowledge acquired through practice and that cannot be articulated explicitly. Further, the attributes shared by a paradigm are not always readily apparent.

Paradigms can determine normal science without the intervention of discoverable rules or shared assumptions. In part, this is because it is very difficult to discover the rules that guide particular normal-science traditions. Scientists never learn concepts, laws, and theories in the abstract and by themselves. They generally learn these with and through their applications. New theory is taught in tandem with its application to a concrete range of phenomena.

Sub-specialties are differently educated and focus on different applications for their research findings. A paradigm can determine several traditions of normal science that overlap without being coextensive. Consequently, changes in a paradigm affect different sub-specialties differently. "A revolution produced within one of these traditions will not necessarily extend to the others as well".

When scientists disagree about whether the fundamental problems of their field have been solved, the search for rules gains a function that it does not ordinarily possess .

VI - Anomaly and the Emergence of Scientific Discoveries.

If normal science is so rigid and if scientific communities are so close-knit, how can a paradigm change take place? Paradigm changes can result from discovery brought about by encounters with anomaly.

Normal science does not aim at novelties of fact or theory and, when successful, finds none. Nonetheless, new and unsuspected phenomena are repeatedly uncovered by scientific research, and radical new theories have again and again been invented by scientists . Fundamental novelties of fact and theory bring about paradigm change. So how does paradigm change come about? There are two ways: through discovery - novelty of fact - or by invention – novelty of theory. Discovery begins with the awareness of anomaly - the recognition that nature has violated the paradigm-induced expectations that govern normal science. The area of the anomaly is then explored. The paradigm change is complete

when the paradigm has been adjusted so that the anomalous become the expected. The result is that the scientist is able "to see nature in a different way".. How paradigms change as a result of invention is discussed in greater detail in the following chapter.

Although normal science is a pursuit not directed to novelties and tending at first to suppress them, it is nonetheless very effective in causing them to arise. Why? An initial paradigm accounts quite successfully for most of the observations and experiments readily accessible to that science's practitioners. Research results in the construction of elaborate equipment, development of an esoteric and shared vocabulary, refinement of concepts that increasingly lessens their resemblance to their usual common-sense prototypes. This professionalisation leads to immense restriction of the scientist's vision, rigid science, resistance to paradigm change, and a detail of information and precision of the observation-theory match that can be achieved in no other way. New and refined methods and instruments result in greater precision and understanding of the paradigm. Only when researchers know with precision what to expect from an experiment can they recognise that something has gone wrong.

Consequently, anomaly appears only against the background provided by the paradigm . The more precise and far-reaching the paradigm, the more sensitive it is to detecting an anomaly and inducing change. By resisting change, a paradigm guarantees that anomalies that lead to paradigm change will penetrate existing knowledge to the core.

VII - Crisis and the Emergence of Scientific Theories.

As is the case with discovery, a change in an existing theory that results in the invention of a new theory is also brought about by the awareness of anomaly. The emergence of a new theory is generated by the persistent failure of the puzzles of normal science to be solved as they should. Failure of existing rules is the prelude to a search for new ones . These failures can be brought about by observed discrepancies between theory and fact or changes in social/cultural climates Such failures are generally long recognised, which is why crises are seldom surprising. Neither problems nor puzzles yield often to the first attack . Recall that paradigm and theory resist change and are extremely resilient. Philosophers of science have repeatedly demonstrated that more than one theoretical construction can always be placed upon a given collection of data . In early stages of a paradigm, such theoretical alternatives are easily invented. Once a paradigm is entrenched (and the tools of the paradigm prove useful to solve the problems the paradigm defines), theoretical alternatives are strongly resisted. As in manufacture so in science--retooling is an extravagance to be reserved for the occasion that demands it . Crises provide the opportunity to retool.

VIII - The Response to Crisis.

The awareness and acknowledgement that a crisis exists loosens theoretical stereotypes and provides the incremental data necessary for a fundamental paradigm shift. Normal science does and must continually strive to bring theory and fact into closer agreement. The recognition and acknowledgement of anomalies result in crises that are a necessary precondition for the emergence of novel theories and for paradigm change. Crisis is the essential tension implicit in scientific research. There is no such thing as research without counterinstances. These counterinstances create tension and crisis. Crisis is always implicit in research because 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 .

In responding to these crises, scientists generally do not renounce the paradigm that has led them into crisis. Rather, they usually devise numerous articulations and ad hoc modifications of their theory in order to eliminate any apparent conflict. Some, unable to tolerate the crisis, leave the profession. As a rule, persistent and recognised anomaly does not induce crisis . Failure to achieve the expected solution to a puzzle discredits only the scientist and not the theory To evoke a crisis, an anomaly must usually be more than just an anomaly. Scientists who paused and examined every anomaly would not get much accomplished. An anomaly must come to be seen as more than just another puzzle of normal science.

All crises begin with the blurring of a paradigm and the consequent loosening of the rules for normal research. As this process develops, the anomaly comes to be more generally recognised as such, more attention is devoted to it by more of the field's eminent authorities. The field begins to look quite different: scientists express explicit discontent, competing articulations of the paradigm proliferate and scholars view a resolution as the subject matter of their discipline. To this end, they first isolate the anomaly more precisely and give it structure. They push the rules of normal science harder than ever to see, in the area of difficulty, just where and how far they can be made to work.

All crises close in one of three ways. (i) Normal science proves able to handle the crisis-provoking problem and all returns to "normal." (ii) The problem resists and is labelled, but it is perceived as resulting from the field's failure to possess the necessary tools with which to solve it, and so scientists set it aside for a future generation with more developed tools. (iii) A new candidate for paradigm emerges, and a battle over its acceptance ensues. Once it has achieved the status of paradigm, a paradigm is declared invalid only if an alternate candidate is available to take its place . Because there is no such thing as research in the absence of a paradigm, to reject one paradigm without simultaneously substituting another is to reject science itself. To declare a paradigm invalid will require more than the falsification of the paradigm by direct comparison with nature. The judgement leading to this decision involves the comparison of the existing paradigm with nature and with the alternate candidate. Transition from a paradigm in crisis to a new one from which a new tradition of normal science can emerge is not a cumulative process. It is a reconstruction of the field from new fundamentals. This reconstruction changes some of the field's foundational theoretical generalisations. It changes methods and applications. It alters the rules.

How do new paradigms finally emerge? Some emerge all at once, sometimes in the middle of the night, in the mind of a man deeply immersed in crisis. Those who achieve fundamental inventions of a new paradigm have generally been either very young or very new to the field whose paradigm they changed. Much of this process is inscrutable and may be permanently so.

IX - The Nature and Necessity of Scientific Revolutions.

Why should a paradigm change be called a revolution? What are the functions of scientific revolutions in the development of science?

A scientific revolution is a non-cumulative developmental episode in which an older paradigm is replaced in whole or in part by an incompatible new one . A scientific revolution that results in paradigm change is analogous to a political revolution. Political revolutions begin with a growing sense by members of the community that existing institutions have ceased adequately to meet the problems posed by an environment that they have in part created. The dissatisfaction with existing institutions is generally restricted to a segment of the political community. Political revolutions aim to change political institutions in ways that those institutions themselves prohibit. As crisis deepens, individuals commit themselves to some concrete proposal for the reconstruction of society in a new institutional framework. Competing camps and parties form. One camp seeks to defend the old institutional constellation. One (or more) camps seek to institute a new political order. As polarisation occurs, political recourse fails. Parties to a revolutionary conflict finally resort to the techniques of mass persuasion.

Like the choice between competing political institutions, that between competing paradigms proves to be a choice between fundamentally incompatible modes of community life. Paradigmatic differences cannot be reconciled. When paradigms enter into a debate about fundamental questions and paradigm choice, each group uses its own paradigm to argue in that paradigm's defence The result is a circularity and inability to share a universe of discourse. A successful new paradigm permits predictions that are different from those derived from its predecessor . That difference could not occur if the two were logically compatible. In the process of being assimilated, the second must displace the first.

Consequently, the assimilation of either a new sort of phenomenon or a new scientific theory must demand the rejection of an older paradigm . If this were not so, scientific development would be genuinely cumulative. Normal research is cumulative, but not scientific revolution. New paradigms arise with destructive changes in beliefs about nature.

Consequently, "the normal-scientific tradition that emerges from a scientific revolution is not only incompatible but often actually incommensurable with that which has gone before". In the circular argument that results from this conversation, each paradigm will satisfy more or less the criteria that it dictates for itself, and fall short of a few of those dictated by its opponent. Since no two paradigms leave all the same problems unsolved, paradigm debates always involve the question: Which problems is it more significant to have solved? In the final analysis, this involves a question of values that lie outside of normal science altogether. It is this recourse to external criteria that most obviously makes paradigm debates revolutionary..

X - Revolutions as Changes of World View.

During scientific revolutions, scientists see new and different things when looking with familiar instruments in places they have looked before. Familiar objects are seen in a different light and joined by unfamiliar ones as well. Scientists see new things when looking at old objects. In a sense, after a revolution, scientists are responding to a different world.

Why does a shift in view occur? Genius? Flashes of intuition? Sure. Because different scientists interpret their observations differently? No. Observations are themselves nearly always different. Observations are conducted within a paradigmatic framework, so the interpretative enterprise can only articulate a paradigm, not correct it. Because of factors embedded in the nature of human perception and retinal impression? No doubt, but our knowledge is simply not yet advanced enough on this matter. Changes in definitional conventions? No. Because the existing paradigm fails to fit? Always. Because of a change in the relation between the scientist's manipulations and the paradigm or between the manipulations and their concrete results? You bet. It is hard to make nature fit a paradigm.

XI - The Invisibility of Revolutions.

Because paradigm shifts are generally viewed not as revolutions but as additions to scientific knowledge, and because the history of the field is represented in the new textbooks that accompany a new paradigm, a scientific revolution seems invisible.

The image of creative scientific activity is largely created by a field's textbooks. Textbooks are the pedagogic vehicles for the perpetuation of normal science. These texts become the authoritative source of the history of science. Both the layman's and the practitioner's knowledge of science is based on textbooks. A field's texts must be rewritten in the aftermath of a scientific revolution. Once rewritten, they inevitably disguise not only the role but the existence and significance of the revolutions that produced them. The resulting textbooks truncate the scientist's sense of his discipline's history and supply a substitute for what they eliminate. More often than not, they contain very little history at all. In the rewrite, earlier scientists are represented as having worked on the same set of fixed problems and in accordance with the same set of fixed canons that the most recent revolution and method has made seem scientific. Why dignify what science's best and most persistent efforts have made it possible to discard?

The historical reconstruction of previous paradigms and theorists in scientific textbooks make the history of science look linear or cumulative, a tendency that even affects scientists looking back at their own research . These misconstructions render revolutions invisible. They also work to deny revolutions as a function. Science textbooks present the inaccurate view that science has reached its present state by a series of individual discoveries and inventions that, when gathered together, constitute the modern body of technical knowledge - the addition of bricks to a building. This piecemeal-discovered facts approach of a textbook presentation illustrates the pattern of historical mistakes that misleads both students and

laymen about the nature of the scientific enterprise. More than any other single aspect of science, the textbook has determined our image of the nature of science and of the role of discovery and invention in its advance.

XII - The Resolution of Revolutions.

How do the proponents of a competing paradigm convert the entire profession or the relevant subgroup to their way of seeing science and the world? What causes a group to abandon one tradition of normal research in favour of another?

Scientific revolutions come about when one paradigm displaces another after a period of paradigm-testing that occurs only after persistent failure to solve a noteworthy puzzle has given rise to crisis. This process is analogous to natural selection: one theory becomes the most viable among the actual alternatives in a particular historical situation.

What is the process by which a new candidate for paradigm replaces its predecessor? At the start, a new candidate for paradigm may have few supporters (and the motives of the supporters may be suspect). If the supporters are competent, they will improve the paradigm, explore its possibilities, and show what it would be like to belong to the community guided by it. For the paradigm destined to win, the number and strength of the persuasive arguments in its favour will increase. As more and more scientists are converted, exploration increases. The number of experiments, instruments, articles, and books based on the paradigm will multiply. More scientists, convinced of the new view's fruitfulness, will adopt the new mode of practising normal science, until only a few elderly hold-outs remain. And we cannot say that they are (or were) wrong. Perhaps the scientist who continues to resist after the whole profession has been converted has ipso facto ceased to be a scientist.

XIII - Progress Through Revolutions.

In the face of the arguments previously made, why does science progress, how does it progress, and what is the nature of its progress?

To a very great extent, the term science is reserved for fields that do progress in obvious ways. But does a field make progress because it is a science, or is it a science because it makes progress? Normal science progresses because the enterprise shares certain salient characteristics, Members of a mature scientific community work from a single paradigm or from a closely related set. Very rarely do different scientific communities investigate the same problems. The result of successful creative work is progress.

Even if we argue that a field does not make progress, that does not mean that an individual school or discipline within that field does not. The man who argues that philosophy has made no progress emphasises that there are still Aristotelians, not that Aristotelianism has failed to progress. It is only during periods of normal science that progress seems both obvious and assured. In part, this progress is in the eye of the beholder. The absence of competing paradigms that question each other's aims and standards makes the progress of a normal-scientific community far easier to see. The acceptance of a paradigm frees the community from the need to constantly re-examine its first principles and foundational assumptions. Members of the community can concentrate on the subtlest and most esoteric of the phenomena that concern it. Because scientists work only for an audience of colleagues, an audience that shares values and beliefs, a single set of standards can be taken for granted. Unlike in other disciplines, the scientist need not select problems because they urgently need solution and without regard for the tools available to solve them. The social scientists tend to defend their choice of a research problem chiefly in terms of the social importance of achieving a solution. Which group would one then expect to solve problems at a more rapid rate? .

We may 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 . The developmental process described by Kuhn

is a process of evolution from primitive beginnings. It is a process whose successive stages are characterised by an increasingly detailed and refined understanding of nature. This is not a process of evolution toward anything. Important questions arise. Must there be a goal set by nature in advance? Does it really help to imagine that there is some one full, objective, true account of nature? Is the proper measure of scientific achievement the extent to which it brings us closer to an ultimate goal? The analogy that relates the evolution of organisms to the evolution of scientific ideas "is nearly perfect" . The resolution of revolutions is the selection by conflict within the scientific community of the fittest way to practice future science. The net result of a sequence of such revolutionary selections, separated by period of normal research, is the wonderfully adapted set of instruments we call modern scientific knowledge. Successive stages in that developmental process are marked by an increase in articulation and specialisation. The process occurs without benefit of a set goal and without benefit of any permanent fixed scientific truth. What must the world be like in order than man may know it?

Reference: http://des.emory.edu/mfp/kuhnsyn.html

The Structure of Scientific Revolutionsby Thomas S. Kuhn

Outline and Study Guideprepared by Professor Frank Pajares

Emory University

Chapter I - Introduction: A Role for History.

Kuhn begins by formulating some assumptions that lay the foundation for subsequent discussion and by briefly outlining the key contentions of the book.

A. A scientific community cannot practice its trade without some set of received beliefs (p. 4).

1. These beliefs form the foundation of the "educational initiation that prepares and licenses the student for professional practice" (5).

2. The nature of the "rigorous and rigid" preparation helps ensure that the received beliefs exert a "deep hold" on the student's mind.

B. Normal science "is predicated on the assumption that the scientific community knows what the world is like" (5)—scientists take great pains to defend that assumption.

C. To this end, "normal science often suppresses fundamental novelties because they are necessarily subversive of its basic commitments" (5).

D. Research is "a strenuous and devoted attempt to force nature into the conceptual boxes supplied by professional education" (5).

E. A shift in professional commitments to shared assumptions takes place when an anomaly "subverts the existing tradition of scientific practice" (6). These shifts are what Kuhn describes as scientific revolutions—"the tradition-shattering complements to the tradition-bound activity of normal science" (6).

1. New assumptions (paradigms/theories) require the reconstruction of prior

assumptions and the reevaluation of prior facts. This is difficult and time consuming. It is also strongly resisted by the established community.

2. When a shift takes place, "a scientist's world is qualitatively transformed [and] quantitatively enriched by fundamental novelties of either fact or theory" (7).

Chapter II - The Route to Normal Science.

In this chapter, Kuhn describes how paradigms are created and what they contribute to scientific (disciplined) inquiry.

A. 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" (10).

1. These achievements must bea. sufficiently unprecedented to attract an enduring group of adherents away

from competing modes of scientific activity andb. sufficiently open-ended to leave all sorts of problems for the redefined

group of practitioners (and their students) to resolve, i. e., research.2. These achievements can be called paradigms (10).3. "The road to a firm research consensus is extraordinarily arduous" (15).

B. "The successive transition from one paradigm to another via revolution is the usual developmental pattern of mature science" (12).

C. Students study these paradigms in order to become members of the particular scientific community in which they will later practice.

1. Because the student largely learns from and is mentored by researchers "who learned the bases of their field from the same concrete models" (11), there is seldom disagreement over fundamentals.

2. Men whose research is based on shared paradigms are committed to the same rules and standards for scientific practice (11).

3. A shared commitment to a paradigm ensures that its practitioners engage in the paradigmatic observations that its own paradigm can do most to explain (13), i.e., investigate the kinds of research questions to which their own theories can most easily provide answers.

D. "It remains an open question what parts of social science have yet acquired such paradigms" (15). [psychology? education? teacher education? sociology?]

E. Paradigms help scientific communities to bound their discipline in that they help the scientist to

1. create avenues of inquiry.2. formulate questions.3. select methods with which to examine questions.4. define areas of relevance.5. [establish/create meaning?]

F. "In the absence of a paradigm or some candidate for paradigm, all the facts that could

possibly pertain to the development of a given science are likely to seem equally relevant" (15).

G. A paradigm is essential to scientific inquiry—"no natural history can be interpreted in the absence of at least some implicit body of intertwined theoretical and methodological belief that permits selection, evaluation, and criticism" (16-17).

H. How are paradigms created, and how do scientific revolutions take place?1. Inquiry begins with a random collection of "mere facts" (although, often, a body

of beliefs is already implicit in the collection).a. During these early stages of inquiry, different researchers confronting the

same phenomena describe and interpret them in different ways (17).b. In time, these descriptions and interpretations entirely disappear.

2. A preparadigmatic school (movement) appears.a. Such a school often emphasizes a special part of the collection of facts.b. Often, these schools vie for preeminence.

3. From the competition of preparadigmatic schools, one paradigm emerges—"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" (17-18), thus making research possible.

4. As a paradigm grows in strength and in the number of advocates, the preparadigmatic schools (or the previous paradigm) fade.

a. "When an individual or group first produces a synthesis able to attract most of the next generation's practitioners, the older schools gradually disappear" (18).

b. Those with "older views . . . are simply read out of the profession and their work is subsequently ignored. If they do not accommodate their work to the new paradigm, they are doomed to isolation or must attach themselves to some other group" (19), or move to a department of philosophy (or history).

5. A paradigm transforms a group into a profession or, at least, a discipline (19). And from this follow the

a. formation of specialized journals.b. foundation of professional societies (or specialized groups within

societies—SIGs).c. claim to a special place in academe (and academe's curriculum).d. fact that members of the group need no longer build their field anew—

first principles, justification of concepts, questions, and methods. Such endeavors are left to the theorist or to writer of textbooks.

e. promulgation of scholarly articles intended for and "addressed only to professional colleagues, [those] whose knowledge of a shared paradigm can be assumed and who prove to be the only ones able to read the papers addressed to them" (20)—preaching to the converted.

f. (discussion groups on the Internet and a listerserver?)I. A paradigm guides the whole group's research, and it is this criterion that most clearly

proclaims a field a science (22).

Chapter III - The Nature of Normal Science.

If a paradigm consists of basic and incontrovertible assumptions about the nature of the discipline, what questions are left to ask?

A. When they first appear, paradigms are limited in scope and in precision.B. "Paradigms gain their status because they are more successful than their competitors in

solving a few problems that the group of practitioners has come to recognize as acute" (23).

1. But more successful does not mean completely successful with a single problem or notably successful with any large number (23).

2. Initially, a paradigm offers the promise of success.3. Normal science consists in the actualization of that promise. This is achieved by

a. extending the knowledge of those facts that the paradigm displays as particularly revealing,

b. increasing the extent of the match between those facts and the paradigm's predictions,

c. and further articulation of the paradigm itself.4. In other words, there is a good deal of mopping-up to be done.

a. Mop-up operations are what engage most scientists throughout their careers.

b. Mopping-up is what normal science is all about!c. This paradigm-based research (25) is "an attempt to force nature into the

preformed and relatively inflexible box that the paradigm supplies" (24).i. no effort made to call forth new sorts of phenomena.

ii. no effort to discover anomalies.iii. when anomalies pop up, they are usually discarded or ignored.iv. anomalies usually not even noticed (tunnel vision/one track

mind).v. no effort to invent new theory (and no tolerance for those who

try).vi. "Normal-scientific research is directed to the articulation of those

phenomena and theories that the paradigm already supplies" (24).

vii. "Perhaps these are defects . . . "1. ". . . but those restrictions, born from confidence in a

paradigm, turn out to be essential to the development of science. By focusing attention on a small range of relatively esoteric problems, the paradigm forces scientists to investigate some part of nature in a detail and depth that would otherwise be unimaginable" (24).

2. . . . and, when the paradigm ceases to function properly, scientists begin to behave differently and the nature of their research problems changes.

d. Mopping-up can prove fascinating work (24). [You do it. We all do it. And we love to do it. In fact, we'd do it for free.]

C. The principal problems of normal science.1. Determination of significant fact.

a. A paradigm guides and informs the fact-gathering (experiments and observations described in journals) decisions of researchers?

b. Researchers focus on, and attempt to increase the accuracy and scope of, facts (constructs/concepts) that the paradigm has shown to be particularly revealing of the nature of things (25).

2. Matching of facts with theory.a. Researchers focus on facts that can be compared directly with predictions

from the paradigmatic theory (26)b. Great effort and ingenuity are required to bring theory and nature into

closer and closer agreement.c. A paradigm sets the problems to be solved (27).

3. Articulation of theory.a. Researchers undertake empirical work to articulate the paradigm

theory itself (27)—resolve residual ambiguities, refine, permit solution of problems to which the theory had previously only drawn attention. This articulation includes

i. determination of universal constants.ii. development of quantitative laws.

iii. selection of ways to apply the paradigm to a related area of interest.

b. This is, in part, a problem of application (but only in part).c. Paradigms must undergo reformulation so that their tenets closely

correspond to the natural object of their inquiry (clarification by reformulation).

d. "The problems of paradigm articulation are simultaneously theoretical and experimental" (33).

e. Such work should produce new information and a more precise paradigm.

f. This is the primary work of many sciences.D. To desert the paradigm is to cease practicing the science it defines (34).

Chapter IV - Normal Science as Puzzle-solving.

Doing research is essentially like solving a puzzle. Puzzles have rules. Puzzles generally have predetermined solutions.

A. A striking feature of doing research is that the aim is to discover what is known in advance.

1. This in spite of the fact that the range of anticipated results is small compared to the possible results.

2. When the outcome of a research project does not fall into this anticipated result range, it is generally considered a failure, i.e., when "significance" is not obtained.

a. Studies that fail to find the expected are usually not published.b. The proliferation of studies that find the expected helps ensure that the

paradigm/theory will flourish.3. Even a project that aims at paradigm articulation does not aim

at unexpected novelty.4. "One of the things a scientific community acquires with a paradigm is a criterion

for choosing problems that, while the paradigm is taken for granted, can be assumed to have solutions" (37).

a. The intrinsic value of a research question is not a criterion for selecting it.

b. The assurance that the question has an answer is the criterion (37).c. "The man who is striving to solve a problem defined by existing

knowledge and technique is not just looking around. He knows what he wants to achieve, and he designs his instruments and directs his thoughts accordingly" (96).

B. So why do research?1. Results add to the scope and precision with which a paradigm/theory can be

applied.2. The way to obtain the results usually remains very much in doubt—this is

the challenge of the puzzle.3. Solving the puzzle can be fun, and expert puzzle-solvers make a very nice living.

C. To classify as a puzzle (as a genuine research question), a problem must be characterized by more than the assured solution.

1. There exists a strong network of commitments—conceptual, theoretical, instrumental, and methodological.

2. There are "rules" that limita. the nature of acceptable solutions—there are "restrictions that bound the

admissible solutions to theoretical problems" (39).i. Solutions should be consistent with paradigmatic assumptions.

ii. There are quasi-metaphysical commitments to consider.iii. There may also be historical ties to consider.

b. the steps by which they are to be obtained (methodology).i. commitments to preferred types of instrumentations.

ii. the ways in which accepted instruments may legitimately be employed.

D. Despite the fact that novelty is not sought and that accepted belief is generally not

challenged, the scientific enterprise can and does bring about such unexpected results.

Chapter V - The Priority of Paradigms.

How can it be that "rules derive from paradigms, but paradigms can guide research even in the absence of rules" (42).

A. The paradigms of a mature scientific community can be determined with relative ease (43).

B. The "rules" used by scientists who share a paradigm are not easily determined. Some reasons for this are that

1. scientists can disagree on the interpretation of a paradigm.2. the existence of a paradigm need not imply that any full set of rules exist.3. scientists are often guided by tacit knowledge—knowledge acquired through

practice and that cannot be articulated explicitly (Polanyi, 1958).4. the attributes shared by a paradigm are not always readily apparent.5. "paradigms may be prior to, more binding, and more complete than any set of

rules for research that could be unequivocally abstracted from them" (46).C. Paradigms can determine normal science without the intervention of discoverable rules

or shared assumptions (46). In part, this is because1. it is very difficult to discover the rules that guide particular normal-science

traditions.2. scientists never learn concepts, laws, and theories in the abstract and by

themselves.a. They generally learn these with and through their applications.b. New theory is taught in tandem with its application to a concrete range of

phenomena.c. "The process of learning a theory depends on the study of applications"

(47).d. The problems that students encounter from freshman year through

doctoral program, as well as those they will tackle during their careers, are always closely modeled on previous achievements.

3. Scientists who share a paradigm generally accept without question the particular problem-solutions already achieved (47).

4. Although a single paradigm may serve many scientific groups, it is not the same paradigm for them all.

a. Subspecialties are differently educated and focus on different applications for their research findings.

b. A paradigm can determine several traditions of normal science that overlap without being coextensive.

c. Consequently, changes in a paradigm affect different subspecialties differently—"A revolution produced within one of these traditions will not necessarily extend to the others as well" (50).

D. When scientists disagree about whether the fundamental problems of their field have been solved, the search for rules gains a function that it does not ordinarily possess (48).

Chapter VI - Anomaly and the Emergence of Scientific Discoveries.

If normal science is so rigid and if scientific communities are so close-knit, how can a paradigm change take place? This chapter traces paradigm changes that result from discovery brought about by encounters with anomaly.

A. Normal science does not aim at novelties of fact or theory and, when successful, finds none.

B. Nonetheless, new and unsuspected phenomena are repeatedly uncovered by scientific research, and radical new theories have again and again been invented by scientists (52).

C. Fundamental novelties of fact and theory bring about paradigm change.D. So how does paradigm change come about?

1. Discovery—novelty of fact.a. Discovery begins with the awareness of anomaly.

i. The recognition that nature has violated the paradigm-induced expectations that govern normal science.

ii. A phenomenon for which a paradigm has not readied the investigator.

b. Perceiving an anomaly is essential for perceiving novelty (although the first does not always lead to the second, i.e., anomalies can be ignored, denied, or unacknowledged).

c. The area of the anomaly is then explored.d. The paradigm change is complete when the paradigm/theory has been

adjusted so that the anomalous become the expected.e. The result is that the scientist is able "to see nature in a different way"

(53).f. But careful: Discovery involves an extended process of conceptual

assimilation, but assimilating new information does not always lead to paradigm change.

2. Invention—novelty of theory.a. Not all theories are paradigm theories.b. Unanticipated outcomes derived from theoretical studies can lead to the

perception of an anomaly and the awareness of novelty.c. How paradigms change as a result of invention is discussed in greater

detail in the following chapter.E. The process of paradigm change is closely tied to the nature of perceptual (conceptual)

change in an individual—Novelty emerges only with difficulty, manifested by resistance,

against a background provided by expectation (64).F. Although normal science is a pursuit not directed to novelties and tending at first to

suppress them, it is nonetheless very effective in causing them to arise. Why?1. An initial paradigm accounts quite successfully for most of the observations and

experiments readily accessible to that science's practitioners.2. Research results in

a. the construction of elaborate equipment,b. development of an esoteric and shared vocabulary,c. refinement of concepts that increasingly lessens their resemblance to their

usual common-sense prototypes.3. This professionalization leads to

a. immense restriction of the scientist's vision, rigid science, and resistance to paradigm change.

b. a detail of information and precision of the observation-theory match that can be achieved in no other way.

i. New and refined methods and instruments result in greater precision and understanding of the paradigm/theory.

ii. Only when researchers know with precision what to expect from an experiment can they recognize that something has gone wrong.

4. Consequently, anomaly appears only against the background provided by the paradigm (65).

a. The more precise and far-reaching the paradigm, the more sensitive it is to detecting an anomaly and inducing change.

b. By resisting change, a paradigm guarantees that anomalies that lead to paradigm change will penetrate existing knowledge to the core.

Chapter VII - Crisis and the Emergence of Scientific Theories.

This chapter traces paradigm changes that result from the invention of new theories brought about by the failure of existing theory to solve the problems defined by that theory. This failure is acknowledged as a crisis by the scientific community.

A. As is the case with discovery, a change in an existing theory that results in the invention of a new theory is also brought about by the awareness of anomaly.

B. The emergence of a new theory is generated by the persistent failure of the puzzles of normal science to be solved as they should. Failure of existing rules is the prelude to a search for new ones (68). These failures can be brought about by

1. observed discrepancies between theory and fact—this is the "core of the crisis" (69).

2. changes in social/cultural climates (knowledge/beliefs are socially constructed?).a. There are strong historical precedents for this: Copernicus, Freud,

behaviorism? constructivism?

b. Science is often "ridden by dogma" (75)—what may be the effect on science (or art) by an atmosphere of political correctness?

3. scholarly criticism of existing theory.C. Such failures are generally long recognized, which is why crises are seldom surprising.

1. Neither problems nor puzzles yield often to the first attack (75).2. Recall that paradigm and theory resist change and are extremely resilient.

D. Philosophers of science have repeatedly demonstrated that more than one theoretical construction can always be placed upon a given collection of data (76).

1. In early stages of a paradigm, such theoretical alternatives are easily invented.2. Once a paradigm is entrenched (and the tools of the paradigm prove useful to

solve the problems the paradigm defines), theoretical alternatives are strongly resisted.

a. As in manufacture so in science—retooling is an extravagance to be reserved for the occasion that demands it (76).

b. Crises provide the opportunity to retool.

Chapter VIII - The Response to Crisis.

The awareness and acknowledgment that a crisis exists loosens theoretical stereotypes and provides the incremental data necessary for a fundamental paradigm shift. In this critical chapter, Kuhn discusses how scientists respond to the anomaly in fit between theory and nature so that a transition to crisis and to extraordinary science begins, and he foreshadows how the process of paradigm change takes place.

A. Normal science does and must continually strive to bring theory and fact into closer agreement.

B. The recognition and acknowledgment of anomalies result in crises that are a necessary precondition for the emergence of novel theories and for paradigm change.

1. Crisis is the essential tension implicit in scientific research (79).2. There is no such thing as research without counterinstances, i.e., anomaly.

a. These counterinstances create tension and crisis.b. Crisis is always implicit in research because 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 (79).

C. In responding to these crises, scientists generally do not renounce the paradigm that has led them into crisis.

1. They may lose faith and consider alternatives, but2. they generally do not treat anomalies as counterinstances of expected outcomes.3. They devise numerous articulations and ad hoc modifications of their theory in

order to eliminate any apparent conflict.4. Some, unable to tolerate the crisis (and thus unable to live in a world out of

joint), leave the profession.5. As a rule, persistent and recognized anomaly does not induce crisis (81).

6. Failure to achieve the expected solution to a puzzle discredits only the scientist and not the theory ("it is a poor carpenter who blames his tools").

7. Science is taught to ensure confirmation-theory.8. Science students accept theories on the authority of teacher and text—what

alternative do they have, or what competence?D. To evoke a crisis, an anomaly must usually be more than just an anomaly.

1. After all, there are always anomalies (counterinstances).2. Scientists who paused and examined every anomaly would not get much

accomplished.3. An anomaly can call into question fundamental generalizations of the paradigm.4. An anomaly without apparent fundamental import may also evoke crisis if the

applications that it inhibits have a particular practical importance.5. An anomaly must come to be seen as more than just another puzzle of normal

science.6. In the face of efforts outlined in C above, the anomaly must continue to resist.

E. All crises begin with the blurring of a paradigm and the consequent loosening of the rules for normal research. As this process develops,

1. the anomaly comes to be more generally recognized as such.2. more attention is devoted to it by more of the field's eminent authorities.3. the field begins to look quite different.4. scientists express explicit discontent.5. competing articulations of the paradigm proliferate.6. scholars view a resolution as the subject matter of their discipline. To this end,

theya. first isolate the anomaly more precisely and give it structure.b. push the rules of normal science harder than ever to see, in the area of

difficulty, just where and how far they can be made to work.c. seek for ways of magnifying the breakdown.d. generate speculative theories.

i. If successful, one theory may disclose the road to a new paradigm.

ii. If unsuccessful, the theories can be surrendered with relative ease.e. may turn to philosophical analysis and debate over fundamentals as a

device for unlocking the riddles of their field.7. crisis often proliferates new discoveries.

F. All crises close in one of three ways.1. Normal science proves able to handle the crisis-provoking problem and all

returns to "normal."2. The problem resists and is labeled, but it is perceived as resulting from the field's

failure to possess the necessary tools with which to solve it, and so scientists set it aside for a future generation with more developed tools.

3. A new candidate for paradigm emerges, and a battle over its acceptance ensues (84)—these are the paradigm wars.

a. Once it has achieved the status of paradigm, a paradigm is declared

invalid only if an alternate candidate is available to take its place (77).i. Because there is no such thing as research in the absence of a

paradigm, to reject one paradigm without simultaneously substituting another is to reject science itself.

ii. To declare a paradigm invalid will require more than the falsification of the paradigm by direct comparison with nature.

iii. The judgment leading to this decision involves the comparison of the existing paradigm with nature and with the alternate candidate.

b. Transition from a paradigm in crisis to a new one from which a new tradition of normal science can emerge is not a cumulative process. It is a reconstruction of the field from new fundamentals (85). This reconstruction

i. changes some of the field's foundational theoretical generalizations.

ii. changes methods and applications.iii. alters the rules.

c. How do new paradigms finally emerge?i. Some emerge all at once, sometimes in the middle of the night, in

the mind of a man deeply immersed in crisis.ii. Those who achieve fundamental inventions of a new paradigm

have generally been either very young or very new to the field whose paradigm they changed.

iii. Much of this process is inscrutable and may be permanently so.G. When a transition from former to alternate paradigm is complete, the profession changes

its view of the field, its methods, and its goals.1. This reorientation has been described as "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" or "picking up the other end of the stick" (85).

2. Some describe the reorientation as a gestalt shift.3. Kuhn argues that the gestalt metaphor is misleading: "Scientists do not see

something as something else; instead, they simply see it"(85).H. The emergence of a new paradigm/theory breaks with one tradition of scientific practice

that is perceived to have gone badly astray and introduces a new one conducted under different rules and within a different universe of discourse.

I. The transition to a new paradigm is scientific revolution—and this is the transition from normal to extraordinary research.

Chapter IX - The Nature and Necessity of Scientific Revolutions.

Why should a paradigm change be called a revolution? What are the functions of scientific revolutions in the development of science?

A. A scientific revolution is a noncumulative developmental episode in which an older paradigm is replaced in whole or in part by an incompatible new one (92).

B. A scientific revolution that results in paradigm change is analogous to a political revolution. [Note the striking similarity between the characteristics outlined below regarding the process of political revolution and those earlier outlined regarding the process of scientific revolution]

1. Political revolutions begin with a growing sense by members of the community that existing institutions have ceased adequately to meet the problems posed by an environment that they have in part created—anomaly and crisis.

2. The dissatisfaction with existing institutions is generally restricted to a segment of the political community.

3. Political revolutions aim to change political institutions in ways that those institutions themselves prohibit.

4. During a revolution's interim, society is not fully governed by institutions at all.5. In increasing numbers, individuals become increasingly estranged from political

life and behave more and more eccentrically within it.6. As crisis deepens, individuals commit themselves to some concrete proposal for

the reconstruction of society in a new institutional framework.7. Competing camps and parties form.

a. One camp seeks to defend the old institutional constellation.b. One (or more) camps seek to institute a new political order.

8. As polarization occurs, political recourse fails.9. Parties to a revolutionary conflict finally resort to the techniques of mass

persuasion.C. Like the choice between competing political institutions, that between competing

paradigms proves to be a choice between fundamentally incompatible modes of community life. Paradigmatic differences cannot be reconciled.

1. The evaluative procedures characteristic of normal science do not work, for these depend on a particular paradigm for their existence.

2. When paradigms enter into a debate about fundamental questions and paradigm choice, each group uses its own paradigm to argue in that paradigm's defense—the result is a circularity and inability to share a universe of discourse.

3. Fundamental paradigmatic assumptions are philosophically incompatible.4. Ultimately, scientific revolutions are affected by

a. the impact of nature and of logic.b. techniques of persuasive argumentation (a struggle between stories?).

5. A successful new paradigm/theory permits predictions that are different from those derived from its predecessor (98).

a. That difference could not occur if the two were logically compatible.b. In the process of being assimilated, the second must displace the first.

D. Consequently, the assimilation of either a new sort of phenomenon or a new scientific theory must demand the rejection of an older paradigm (95).

1. If this were not so, scientific development would be genuinely cumulative (the

view of science-as-cumulation or logical inclusiveness—see Chapter X).2. Recall that cumulative acquisition of unanticipated novelties proves to be an

almost nonexistent exception to the rule of scientific development—cumulative acquisition of novelty is not only rare in fact but improbable in principle (96).

3. Normal research is cumulative, but not scientific revolution.4. New paradigms arise with destructive changes in beliefs about nature (98).5. Kuhn observes that his view is not the prevalent view. The prevalent view

maintains that a new paradigm derives from, or is a cumulative addition to, the supplanted paradigm. [Note: This was the case in the late 1950s and early 1960s, when the book was published, but it is not the case today. As Kuhn points out, logical positivists were carrying the day then, but Structure proved revolutionary itself, and Kuhn's view is reasonably influential these days. Many would argue that Kuhn's view is now the prevalent view.] Objections to Kuhn's view include that

a. only the extravagant claims of the old paradigm are contested.b. purged of these merely human extravagances, many old paradigms have

never been and can never be challenged (e.g., Newtonian physics, behaviorism? psychoanalytic theory? logical positivism?).

c. a scientist can reasonably work within the framework of more than one paradigm (and so eclecticism and, to some extent, relativismrear their heads).

6. Kuhn refutes this logical positivist view, arguing thata. the logical positivist view makes any theory ever used by a significant

group of competent scientists immune to attack.b. to save paradigms/theories in this way, their range of application must be

restricted to those phenomena and to that precision of observation with which the experimental evidence in hand already deals.

c. the rejection of a paradigm requires the rejection of its fundamental assumptions and of its rules for doing science—they are incompatible with those of the new paradigm.

d. if the fundamental assumptions of old and new paradigm were not incompatible, novelty could always be explained within the framework of the old paradigm and crisis can always be avoided.

e. revolution is not cumulation; revolution is transformation.f. the price of significant scientific advance is a commitment that runs the

risk of being wrong.g. without commitment to a paradigm there can be no normal science.h. the need to change the meaning of established and familiar concepts is

central to the revolutionary impact of a new paradigm.i. the differences between successive paradigms are both necessary and

irreconcilable. Why?i. because successive paradigms tell us different things about the

population of the universe and about that population's behavior.ii. because paradigms are the source of the methods, problem-field,

and standards of solution accepted by any mature scientific

community at any given time.j. the reception of a new paradigm often necessitates a redefinition of the

corresponding science (103).i. Old problems are relegated to other sciences or declared

unscientific.ii. Problems previously nonexistent or trivial may, with a new

paradigm, become the very archetypes of significant scientific achievement.

7. Consequently, "the normal-scientific tradition that emerges from a scientific revolution is not only incompatible but often actually incommensurable with that which has gone before" (103).

E. The case for cumulative development of science's problems and standards is even harder to make than the case for the cumulative development of paradigms/theories.

1. Standards are neither raised nor do they decline; standards simply change as a result of the adoption of the new paradigm.

2. Paradigms act as maps that chart the direction of problems and methods through which problems may be solved.

3. Because nature is too complex and varied to be explored at random, the map is an essential guide to the process of normal science.

4. In learning a paradigm, the scientist acquires theory, methods, and standards together, usually in an inextricable mixture.

5. Therefore, when paradigms change, there are usually significant shifts in the criteria determining the legitimacy both of problems and of proposed solutions (109).

F. To the extent that two scientific schools disagree about what is a problem and what a solution, they will inevitably talk through each other when debating the relative merits of their respective paradigms (109).

1. In the circular argument that results from this conversation, each paradigm willa. satisfy more or less the criteria that it dictates for itself, andb. fall short of a few of those dictated by its opponent.

2. Since no two paradigms leave all the same problems unsolved, paradigm debates always involve the question: Which problems is it more significant to have solved?

3. In the final analysis, this involves a question of values that lie outside of normal science altogether—it is this recourse to external criteria that most obviously makes paradigm debates revolutionary (see B-8/9 above).

Chapter X - Revolutions as Changes of World View.

When paradigms change, the world itself changes with them. How do the beliefs and conceptions of scientists change as the result of a paradigm shift? Are theories simply man-made interpretations of given data?

A. During scientific revolutions, scientists see new and different things when looking with familiar instruments in places they have looked before.

1. Familiar objects are seen in a different light and joined by unfamiliar ones as well.

2. Scientists see the world of their research-engagement differently.

3. Scientists see new things when looking at old objects.

4. In a sense, after a revolution, scientists are responding to a different world.

B. This difference in view resembles a gestalt shift, a perceptual transformation—"what were ducks in the scientist's world before the revolution are rabbits afterward." But caution—there are important differences.

1. Something like a paradigm is a prerequisite to perception itself (recall G. H. Mead's concept of a predisposition, or the dictum it takes a meaning to catch a meaning).

2. What people see depends both on what they look at and on what their previous visual-conceptual experience has taught them to see.

3. Individuals know when a gestalt shift has taken place because they are aware of the shift—they can even manipulate it mentally.

4. In a gestalt switch, alternate perceptions are equally "true" (valid, reasonable, real).

5. Because there are external standards with respect to which switch of vision can be demonstrated, conclusions about alternate perceptual possibilities can be drawn.

a. But scientists have no such external standardsb. Scientists have no recourse to a higher authority that determines when a

switch in vision has taken place.6. As a consequence, in the sciences, if perceptual switches accompany paradigm

changes, scientists cannot attest to these changes directly.7. A gestalt switch: "I used to see a planet, but now I see a satellite." (This leaves

open the possibility that the earlier perception was once and may still be correct).8. A paradigm shift: " I used to see a planet, but I was wrong."9. It is true, however, that anomalies and crises "are terminated by a relatively

sudden and unstructured event like the gestalt switch" (122).C. Why does a shift in view occur?

1. Genius? Flashes of intuition? Sure.2. Paradigm-induced gestalt shifts? Perhaps, but see limitations above.3. Because different scientists interpret their observations differently? No.

a. Observations (data) are themselves nearly always different.b. Because observations are conducted (data collected) within a

paradigmatic framework, the interpretive enterprise can only articulate a paradigm, not correct it.

4. Because of factors embedded in the nature of human perception and retinal impression? No doubt, but our knowledge is simply not yet advanced enough on this matter.

5. Changes in definitional conventions? No.6. Because the existing paradigm fails to fit. Always.7. Because of a change in the relation between the scientist's manipulations and the

paradigm or between the manipulations and their concrete results? You bet.D. It is hard to make nature fit a paradigm.

Chapter XI - The Invisibility of Revolutions.

Because paradigm shifts are generally viewed not as revolutions but as additions to scientific knowledge, and because the history of the field is represented in the new textbooks that accompany a new paradigm, a scientific revolution seems invisible.

A. An increasing reliance on textbooks is an invariable concomitant of the emergence of a first paradigm in any field of science (136).

B. The image of creative scientific activity is largely created by a field's textbooks.1. Textbooks are the pedagogic vehicles for the perpetuation of normal science.2. These texts become the authoritative source of the history of science.3. Both the layman's and the practitioner's knowledge of science is based on

textbooks.C. A field's texts must be rewritten in the aftermath of a scientific revolution.

1. Once rewritten, they inevitably disguise no only the role but the existence and significance of the revolutions that produced them.

2. The resulting textbooks truncate the scientist's sense of his discipline's history and supply a substitute for what they eliminate.

a. More often than not, they contain very little history at all (Whitehead: "A science that hesitates to forget its founders is lost.")

b. In the rewrite, earlier scientists are represented as having worked on the same set of fixed problems and in accordance with the same set of fixed canons that the most recent revolution and method has made seem scientific.

c. Why dignify what science's best and most persistent efforts have made it possible to discard?

D. The historical reconstruction of previous paradigms and theorists in scientific textbooks make the history of science look linear or cumulative, a tendency that even affects scientists looking back at their own research (139).

1. These misconstructions render revolutions invisible.2. They also work to deny revolutions as a function.

E. Science textbooks present the inaccurate view that science has reached its present state by a series of individual discoveries and inventions that, when gathered together, constitute the modern body of technical knowledge—the addition of bricks to a

building.1. This piecemeal-discovered facts approach of a textbook presentation illustrates

the pattern of historical mistakes that misleads both students and laymen about the nature of the scientific enterprise.

2. More than any other single aspect of science, that pedagogic form [the textbook] has determined our image of the nature of science and of the role of discovery and invention in its advance.

Chapter XII - The Resolution of Revolutions.

How do the proponents of a competing paradigm convert the entire profession or the relevant subgroup to their way of seeing science and the world? What causes a group to abandon one tradition of normal research in favor of another? What is the process by which a new candidate for paradigm replaces its predecessor?

A. Scientific revolutions come about when one paradigm displaces another after a period of paradigm-testing that occurs

1. only after persistent failure to solve a noteworthy puzzle has given rise to crisis.2. as part of the competition between two rival paradigms for the allegiance of the

scientific community.B. The process of paradigm-testing parallels two popular philosophical theories about

the verification of scientific theories.1. Theory-testing through probabilistic verification.

a. Comparison of the ability of different theories to explain the evidence at hand.

b. This process is analogous to natural selection: one theory becomes the most viable among the actual alternatives in a particular historical situation.

2. Theory-testing through falsification (Karl Popper).a. A theory must be rejected when outcomes predicted by the theory are

negative.b. The role attributed to falsification is similar to the one that Kuhn assigns

to anomalous experiences.c. Kuhn doubts that falsifying experiences exist.

i. No theory ever solves all the puzzles with which it is confronted at a given time.

ii. It is the incompleteness and imperfection of the existing data-theory fit that define the puzzles that characterize normal science.

iii. If any and every failure to fit were ground for theory rejection, all theories ought to be rejected at all times.

iv. If only severe failure to fit justifies theory rejection, then theory-testing through falsification would require some criterion ofimprobability or of degree of falsification—thereby requiring

recourse to 1 above.C. It makes little sense to suggest that verification is establishing the agreement of fact with

theory.1. All historically significant theories have agreed with the facts, but only more or

less.2. It makes better sense to ask which of two competing theories fits the facts better.3. Recall that scientists in paradigmatic disputes tend to talk through each other.4. Competition between paradigms is not the sort of battle that can be resolved by

proofs.5. Since new paradigms are born from old ones, they incorporate much of the

vocabulary and apparatus that the traditional paradigm had previously employed, though these elements are employed in different ways.

6. Moreover, proponents of competing paradigms practice their trade in different worlds—the two groups see different things (i.e., the facts are differently viewed).

7. Like a gestalt switch, verification occurs all at once or not at all (150).D. Although a generation is sometimes required to effect a paradigm change, scientific

communities have again and again been converted to new paradigms.1. Max Planck: 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 grow up that is familiar with it.

2. But Kuhn argues that Planck's famous remark overstates the case.a. Neither proof nor error is at issue.b. The transfer of allegiance from paradigm to paradigm is a conversion

experience that cannot be forced.c. Proponents of a paradigm devote their lives and careers to the paradigm.d. Lifelong resistance is not a violation of scientific standards but an index

to the nature of scientific research itself.e. The source of the resistance is the assurance that

i. the older paradigm will ultimately solve all its problems.ii. nature can be shoved into the box the paradigm provides.

f. Actually, that same assurance is what makes normal science possible.g. Some scientists, particularly the older and more experienced ones, may

resist indefinitely, but most can be reached in one way or another.3. Conversions occur not despite the fact that scientists are human but because they

are.4. How are scientists converted? How is conversion induced and how resisted?

a. Individual scientists embrace a new paradigm for all sorts of reasons and usually for several at once.

i. idiosyncracy of autobiography and personality?ii. nationality or prior reputation of innovator and his teachers?

b. The focus of these questions should not be on the individual scientist but with the sort of community that always sooner or later re-forms as a single group (this will be dealt with in Chapter XIII).

c. The community recognizes that a new paradigm displays a quantitative precision strikingly better than its older competitor.

i. A claim that a paradigm solves the crisis-provoking problem is rarely sufficient by itself.

ii. Persuasive arguments can be developed if the new paradigm permits the prediction of phenomena that had been entirely unsuspected while the old paradigm prevailed.

d. Rather than a single group conversion, what occurs is an increasing shift in the distribution of professional allegiances (158).

e. But paradigm debates are not about relative problem-solving ability. Rather the issue is which paradigm should in the future guide research on problems many of which neither competitor can yet claim to resolve completely (157).

i. A decision between alternate ways of practicing science is called for.

ii. A decision is based on future promise rather than on past achievement.

iii. A scientist must have faith that the new paradigm will succeed with the many large problems that confront it.

1. There must be a basis for this faith in the candidate chosen.

2. Sometimes this faith is based on personal and inarticulate aesthetic considerations.

iv. This is not to suggest that new paradigms triumph ultimately through some mystical aesthetic.

f. The new paradigm appeals to the individual's sense of the appropriate or the aesthetic—the new paradigm is said to be neater, more suitable, simpler, or more elegant (155).

E. What is the process by which a new candidate for paradigm replaces its predecessor?1. At the start, a new candidate for paradigm may have few supporters (and the

motives of the supporters may be suspect).2. If the supporters are competent, they will

a. improve the paradigm,b. explore its possibilities,c. and show what it would be like to belong to the community guided by it.

3. For the paradigm destined to win, the number and strength of the persuasive arguments in its favor will increase.

4. As more and more scientists are converted, exploration increases.5. The number of experiments, instruments, articles, and books based on the

paradigm will multiply.6. More scientists, convinced of the new view's fruitfulness, will adopt the new

mode of practicing normal science (until only a few elderly hold-outs will remain).

a. And we cannot say that they are (were) wrong.

b. Perhaps the scientist who continues to resist after the whole profession has been converted has ipso facto ceased to be a scientist.

Chapter XIII - Progress Through Revolutions.

In the face of the arguments previously made, why does science progress, how does it progress, and what is the nature of its progress?

A. Perhaps progress is inherent in the definition of science.1. To a very great extent, the term science is reserved for fields that do progress in

obvious ways.2. This issue is of particular import to the social sciences.

a. Is a social science a science because it defines itself as a science in terms of possessing certain characteristics and aims to make progress?

b. Questions about whether a field or discipline is a science will cease to be a source of concern not when a definition is found, but when the groups that now doubt their own status achieve consensus about their past and present accomplishments (161).

i. Do economists worry less than educators about whether their field is a science because economists know what a science is? Or is it economics about which they agree?

ii. Why do not natural scientists or artists worry about the definition of the term?

3. We tend to see as a science any field in which progress is marked (162).B. Does a field make progress because it is a science, or is it a science because it makes

progress?C. Normal science progresses because the enterprise shares certain salient characteristics,

1. Members of a mature scientific community work from a single paradigm or from a closely related set.

2. Very rarely do different scientific communities investigate the same problems.D. The result of successful creative work is progress (162).

1. No creative school recognizes a category of work that is, on the one hand, a creative success, but is not, on the other, an addition to the collective achievement of the group.

2. Even if we argue that a field does not make progress, that does not mean that an individual school/discipline within that field does not.

3. The man who argues that philosophy has made no progress emphasizes that there are still Aristotelians, not that Aristotelianism has failed to progress.

E. It is only during periods of normal science that progress seems both obvious and assured.

1. In part, this progress is in the eye of the beholder.2. The absence of competing paradigms that question each other's aims and

standards makes the progress of a normal-scientific community far easier to see.

3. The acceptance of a paradigm frees the community from the need to constantly re-examine its first principles and foundational assumptions.

4. Members of the community can concentrate on the subtlest and most esoteric of the phenomena that concern it.

5. There are no other professional communities in which individual creative work is so exclusively addressed to and evaluated by other members of the profession.

a. Other professions are more concerned with lay approbation than are scientists.

b. Because scientists work only for an audience of colleagues, an audience that shares values and beliefs, a single set of standards can be taken for granted.

c. This insulation of the scientist from society permits the individual scientist to concentrate attention on problems that she has a good reason to believe she will be able to solve.

6. Unlike in other disciplines, the scientist need not select problems because they urgently need solution and without regard for the tools available to solve them [note the important contrast here between natural scientists and social scientists].

a. The social scientists tend to defend their choice of a research problem chiefly in terms of the social importance of achieving a solution.

b. Which group would one then expect to solve problems at a more rapid rate?

7. The effects of insulation are intensified by the nature of the scientific community's educational initiation.

a. The education of a social scientist consists in large part ofi. reading original sources.

ii. being made aware of the variety of problems that the members of his future group have, in the course of time, attempted to solve, and the paradigms that have resulted from these attempts.

iii. facing competing and incommensurable solutions to these problems.

iv. evaluating the solutions to the problems presented.v. selecting among competing existing paradigms.

b. In the education of a natural scientisti. textbooks (as described earlier) are used until graduate school.

ii. textbooks are systematically substituted for the creative scientific literature that made them possible.

iii. classics are seldom read, and they are viewed as antiquated oddities.

8. The educational initiation of scientists is immensely effective.9. The education of scientists prepares them for the generation through normal

science of significant crises (167).F. In its normal state, a scientific community is an immensely efficient instrument for

solving the problems or puzzles that its paradigms define—progress is the result of solving these problems.

G. Progress is also a salient feature of extraordinary science—of science during a revolution.

1. Revolutions close with total victory for one of the two opposing camps.2. When it repudiates a paradigm, a scientific community simultaneously renounces

most of the books and articles in which that paradigm had been embodied.3. The community acknowledges this as progress.4. In a sense, it may appear that the member of a mature scientific community is the

victim of a history rewritten by the powers that be(167).a. But recall that the power to select between paradigms resides in the

members of the community.b. The process of scientific revolution is in large part a democratic process.

H. And what are the characteristics of these scientific communities?1. The scientist must be concerned to solve problems about the behavior of nature.2. Although the concerns may be global, the problems must be problems of detail3. The solutions to problems that satisfy a scientist must satisfy the community.4. No appeals to heads of state or to the populace at large in matters scientific.5. Members of the community are recognized and are the exclusive arbiters of

professional achievement.a. Because of their shared training and experience, members of the

community are seen as the sole possessors of the rules of the game.b. To doubt that they share some basis for evaluation would be to admit the

existence of incompatible standards of scientific achievement.6. The community must see paradigm change as progress—as we have seen, this

perception is, in important respects, self-fulfilling (169).7. Discomfort with a paradigm takes place only when nature itself first undermines

professional security by making prior achievements seem problematic.8. The community embraces a new paradigm when

a. the new candidate is seen to resolve some outstanding and generally recognized problem that can be met in no other way.

b. the new paradigm promises to preserve a relatively large part of the concrete problem-solving ability that has accrued to science through its predecessors.

I. Though science surely grows in depth, it may not grow in breadth as well. When it does,1. this is manifest through the proliferation of specialties,2. not in the scope of any single specialty alone.

J. We may 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 (171).

1. The developmental process described by Kuhn is a process of evolution from primitive beginnings—a process whose successive stages are characterized by an increasingly detailed and refined understanding of nature.

2. This is not a process of evolution toward anything.3. Important questions arise.

a. Must there be a goal set by nature in advance?b. Does it really help to imagine that there is some one full, objective, true

account of nature?c. Is the proper measure of scientific achievement the extent to which it

brings us closer to an ultimate goal?4. The analogy that relates the evolution of organisms to the evolution of scientific

ideas "is nearly perfect" (172).a. The resolution of revolutions is the selection by conflict within the

scientific community of the fittest way to practice future science.b. The net result of a sequence of such revolutionary selections, separated

by period of normal research, is the wonderfully adapted set of instruments we call modern scientific knowledge.

c. Successive stages in that developmental process are marked by an increase in articulation and specialization.

d. The process occurs without benefit of a set goal and without benefit of any permanent fixed scientific truth.

5. What must the world be like in order that man may know it?

Synopsis of each chapter, not in outline form | Frederick Erickson on paradigms in social science Thomas Kuhn page

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