A Science in Crisis?

Every now and then the processes of normal science break down, and some rather dramatic changes occur in the way in which practitioners view some important aspects of their subject. Kuhn calls the periods in which changes of this sort occur, “scientific revolutions,” and attributes a number of general properties to them, of which the following are perhaps the most important: 1 A novel theory emerges within normal science only after a pronounced failure in the normal science’s problem-solving activity. 2 An important sign of the breakdown of normal science is the proliferation of theories and of methodological discussion. 3 The problems with respect to which breakdown occurs are all of a type that had long been recognized by practitioners. 4 The actual solution to a crisis has been at least partially anticipated earlier, but in the absence of crisis those anticipations had been ignored. 5 The general intellectual framework of a normal science, including the puzzles, stylized facts, and research techniques, as well as the fuzzier commitments associated with itsworld-view, has a powerful inertial effect on the scientist who has absorbed it. This is of course highly functional for normal science but greatly complicates revolutions. Older scientists usually do not absorb revolutions. 6 A new and competing scientific framework redefines a number of puzzles and may also generate new puzzles. A puzzle in the old framework may become a counterexample in the new. An anomaly in the old theory may simply be a fact in the new one. Hence adherents to old and new tend to talk past one another. 7 The new theory emerges over a limited period of time. The full emergence of a crisis and of a solution which begins to attract adherents may take a decade or two. It takes another and longer period of time to work out the implications of the new framework. 8 Scientists who succeed in making the transition from old to new often report their experience as being rather like a mystic conversion, though it need not come in a flash as with many religious conversions.