 According to Kuhn in Structure, a loosely characterized group of activities, often consisting of competing schools, becomes a mature science when a few concrete problem solutions provide models for what good research is (or can be) in that domain. These exemplary problems-cum-solutions become the basis of a “paradigm” that defines what it is to do “normal science.” As its name suggests, normal science is the default state of a mature science and of the community of researchers who constitute it. The paradigm informs investigators what their domain of the world is like and practically guarantees that all legitimate problems can be solved in its terms. Normal science is convergent rather than divergent: it actively discourages revolutionary initiatives and essentially novel (unexpected) discoveries, for these threaten the paradigm. However, normal research is so detailed and focused that it is bound to turn up anomalous experimental and theoretical results, some of which will long resist the best attempts to resolve them. Given the historical contingencies involved in the formation of guiding paradigms as well as the fallibility of all investigators, it would be incredibly improbable for everything to end up working perfectly. According to Kuhn, anomalies are therefore to be expected. Historically, all paradigms and theory complexes face anomalies at all times. If and when persistent efforts by the best researchers fail to resolve the anomalies, the community begins to lose confidence in the paradigm and a crisis period ensues in which serious alternatives can now be entertained. If one of these alternatives shows sufficient promise to attract a dominant group of leading researchers away from the old paradigm, a paradigm shift or paradigm change occurs—and that is a Kuhnian revolution. The radicals accomplish this by replacing the former set of routine problems and problem-solving techniques (exemplars) by a new set of exemplars, making the old practices seem defective, or at least old fashioned.