Thomas Kuhn, answered from the texts and cited to the page.
The word I most wanted to keep, and the one I lost earliest to careless usage, is exemplar. Let me say what I actually meant by it. When I introduced disciplinary matrix as the replacement for the loose sociological sense of paradigm, I listed its components: shared symbolic generalizations, shared models (heuristic and metaphysical), shared values, and one further element that I wanted to emphasize above the rest.1
That element is the exemplar — the concrete problem-solution, the worked example students encounter in laboratory, on examination, at the end of a textbook chapter.2 It is, autobiographically, what led me to the word paradigm in the first place; having lost control of that word, exemplar is the replacement.3 Now, the standard view of such problems treats them as mere application — the student already knows the theory and is simply practicing its use.4
I think that description is correct after enough problems have been done, but never at the start. Doing problems is how one learns the language of a theory and acquires the knowledge of nature embedded in that language. Take Newton's second law, f = ma. That expression is a law-sketch, not a law proper; it must be rewritten in a different symbolic form for each physical situation before any deduction can proceed.5
For free fall it takes one form, for the pendulum another, for coupled oscillators yet another. What carries the student across these cases is not a set of explicit rules for making the transition — physicists share remarkably few such rules — but rather the trained perception of similarity acquired by exposure to the series of exemplary cases themselves.6
This is why the question "similar with respect to what?" is precisely the question that must not be asked.7 If one could supply correspondence rules specifying the criteria of resemblance, then doing problems would reduce to applying those rules, and the exemplar would be philosophically idle. But the similarity the exemplar teaches is not rule-governed in that way; it is closer to what happens when a child finds the animal shapes hidden in a drawing of shrubbery — once seen, they do not retreat into the background, and no explicit criterion was consulted in the finding.8
The philosophical consequence is this: acquiring an arsenal of exemplars is as integral to a scientist's formation as learning symbolic generalizations, and without it the student would never gain access to what the community actually knows about force, field, element, compound, nucleus, cell.9 The symbolic generalizations can be stated in propositions; the similarity-perception the exemplar instills cannot be fully captured that way, which is precisely why the exemplar is the more fundamental sense of paradigm — the sense I called, in "Second Thoughts on Paradigms," the second and more fundamental one.10
Among them would be: shared symbolic generalizations, like 'f = ma', or 'elements combine in constant proportion by weight'; shared models, whether metaphysical, like atomism, or heuristic, like the hydrodynamic model of the electric circuit; shared values, like the emphasis on accuracy of prediction, discussed above; and other elements of the sort.The Road Since Structure, p. 175
By it I mean, initially, the concrete problem-solutions that students encounter from the start of their scientific education, whether in laboratories, on examinations, or at the ends of chapters in science texts.The Structure of Scientific Revolutions, pp. 150–151
If I could, I would call these problem solutions paradigms, for they are what led me to the choice of the term in the first place. Having lost control of the word, however, I shall henceforth describe them as exemplars.The Road Since Structure, p. 175
Ordinarily problem solutions of this sort are viewed as mere applications of theory that has already been learned. The student does them for practice, to gain facility in the use of what he already knows.The Road Since Structure, pp. 176–177
That symbolic expression is, however, a law-sketch rather than a law. It must be rewritten in a different symbolic form for each physical problem before logical and mathematical deduction are applied to it.The Road Since Structure, pp. 176–177
physicists share few rules, explicit or implicit, by which they make the transition from law-sketch to the specific symbolic forms demanded by individual problems. Instead, exposure to a series of exemplary problem solutions teaches them to see different physical situations as like each other.The Road Since Structure, pp. 176–177
To the man who speaks of similarity or of analogy, we therefore at once pose the question: similar with respect to what? In this case, however, that is just the question that must not be asked, for an answer would at once provide us with correspondence rules.The Essential Tension, pp. 326–327
Much more nearly it resembles the child's puzzle in which one is asked to find the animal shapes or faces hidden in the drawing of shrubbery or clouds. The child seeks forms that are like those of the animals or faces he knows.The Essential Tension, pp. 326–327
Acquiring an arsenal of exemplars, just as much as learning symbolic generalizations, is integral to the process by which a student gains access to the cognitive achievements of his disciplinary group. Without exemplars he would never learn much of what the group knows about such fundamental concepts as force and field, element and compound, or nucleus and cell.The Essential Tension, pp. 326–327
Many of you will already have guessed that the term 'exemplar' provides a new name for the second, and more fundamental, sense of 'paradigm' in the book.The Essential Tension, pp. 317–319