3. The Concept of a Paradigm
A mature science, according to Kuhn, experiences alternating phases of normal science and revolutions. In normal science the key theories, instruments, values and metaphysical assumptions that comprise the disciplinary matrix are kept fixed, permitting the cumulative generation of puzzle-solutions, whereas in a scientific revolution the disciplinary matrix undergoes revision, in order to permit the solution of the more serious anomalous puzzles that disturbed the preceding period of normal science.
A particularly important part of Kuhn's thesis in The Structure of Scientific Revolutions focuses upon one specific component of the disciplinary matrix. This is the consensus on exemplary instances of scientific research. These exemplars of good science are what Kuhn refers to when he uses the term ‘paradigm’ in a narrower sense. He cites Aristotle's analysis of motion, Ptolemy's computations of plantery positions, Lavoisier's application of the balance, and Maxwell's mathematization of the electromagnetic field as paradigms (1962/1970a, 23). Exemplary instances of science are typically to be found in books and papers, and so Kuhn often also describes great texts as paradigms—Ptolemy's Almagest, Lavoisier's Traité élémentaire de chimie, and Newton's Principia Mathematica and Opticks (1962/1970a, 12). Such texts contain not only the key theories and laws, but also—and this is what makes them paradigms—the applications of those theories in the solution of important problems, along with the new experimental or mathematical techniques (such as the chemical balance in Traité élémentaire de chimie and the calculus in Principia Mathematica) employed in those applications.
In the postscript to the second edition of The Structure of Scientific Revolutions Kuhn says of paradigms in this sense that they are “the most novel and least understood aspect of this book” (1962/1970a, 187). The claim that the consensus of a disciplinary matrix is primarily agreement on paradigms-as-exemplars is intended to explain the nature of normal science and the process of crisis, revolution, and renewal of normal science. It also explains the birth of a mature science. Kuhn describes an immature science, in what he sometimes calls its ‘pre-paradigm’ period, as lacking consensus. Competing schools of thought possess differing procedures, theories, even metaphysical presuppositions. Consequently there is little opportunity for collective progress. Even localized progress by a particular school is made difficult, since much intellectual energy is put into arguing over the fundamentals with other schools instead of developing a research tradition. However, progress is not impossible, and one school may make a breakthrough whereby the shared problems of the competing schools are solved in a particularly impressive fashion. This success draws away adherents from the other schools, and a widespread consensus is formed around the new puzzle-solutions.
This widespread consensus now permits agreement on fundamentals. For a problem-solution will embody particular theories, procedures and instrumentation, scientific language, metaphysics, and so forth. Consensus on the puzzle-solution will thus bring consensus on these other aspects of a disciplinary matrix also. The successful puzzle-solution, now a paradigm puzzle-solution, will not solve all problems. Indeed, it will probably raise new puzzles. For example, the theories it employs may involve a constant whose value is not known with precision; the paradigm puzzle-solution may employ approximations that could be improved; it may suggest other puzzles of the same kind; it may suggest new areas for investigation. Generating new puzzles is one thing that the paradigm puzzle-solution does; helping solve them is another. In the most favourable scenario, the new puzzles raised by the paradigm puzzle-solution can be addressed and answered using precisely the techniques that the paradigm puzzle-solution employs. And since the paradigm puzzle-solution is accepted as a great achievement, these very similar puzzle-solutions will be accepted as successful solutions also. This is why Kuhn uses the terms ‘exemplar’ and ‘paradigm’. For the novel puzzle-solution which crystallizes consensus is regarded and used as a model of exemplary science. In the research tradition it inaugurates, a paradigm-as-exemplar fulfils three functions: (i) it suggests new puzzles; (ii) it suggests approaches to solving those puzzles; (iii) it is the standard by which the quality of a proposed puzzle-solution can be measured (1962/1970a, 38–9). In each case it is similarity to the exemplar that is the scientists’ guide.
That normal science proceeds on the basis of perceived similarity to exemplars is an important and distinctive feature of Kuhn's new picture of scientific development. The standard view explained the cumulative addition of new knowledge in terms of the application of the scientific method. Allegedly, the scientific method encapsulates the rules of scientific rationality. It may be that those rules could not account for the creative side of science—the generation of new hypotheses. The latter was thus designated ‘the context of discovery’, leaving the rules of rationality to decide in the ‘context of justification’ whether a new hypothesis should, in the light of the evidence, be added to the stock of accepted theories.
Kuhn rejected the distinction between the context of discovery and the context of justification (1962/1970a, 8), and correspondingly rejected the standard account of each. As regards the context of discovery, the standard view held that the philosophy of science had nothing to say on the issue of the functioning of the creative imagination. But Kuhn's paradigms do provide a partial explanation, since training with exemplars enables scientists to see new puzzle-situations in terms of familiar puzzles and hence enables them to see potential solutions to their new puzzles.
More important for Kuhn was the way his account of the context of justification diverged from the standard picture. The functioning of exemplars is intended explicitly to contrast with the operation of rules. The key determinant in the acceptability of a proposed puzzle-solution is its similarity to the paradigmatic puzzle-solutions. Perception of similarity cannot be reduced to rules, and a fortiori cannot be reduced to rules of rationality. This rejection of rules of rationality was one of the factors that led Kuhn's critics to accuse him of irrationalism—regarding science as irrational. In this respect at least the accusation is wide of the mark. For to deny that some cognitive process is the outcome of applying rules of rationality is not to imply that it is an irrational process: the perception of similarity in appearance between two members of the same family also cannot be reduced to the application of rules of rationality. Kuhn's innovation in The Structure of Scientific Revolutions was to suggest that a key element in cognition in science operates in the same fashion.
