Paradigm

Given that no new evidence or argument could overthrow a paradigm, Kuhn needs to explain "What causes the group [of professional scientists] to abandon one tradition of normal research in favor of another" (1996, p. 144). After pointing out that it is possible for a revolution to take place over generations without requiring individual scientists to change from one paradigm to another, Kuhn sets out four reasons that scientists may have for deciding to change paradigms. Two of these reasons, aesthetic considerations (including simplicity, unity, and so forth) and personal or political beliefs, are clearly subjective. We can understand how Lavoisier could have reasons to revolutionize chemistry that Priestley did not share, if the reasons given are personal and subjective. We do not expect others to have the same personal or subjective views or tastes that we do. Kuhn also says that a scientist may change from one paradigm to another if the new paradigm solves problems that the old one could not. New paradigms are successfully introduced when there is a crisis, that is, when scientists feel that the old paradigm is not working. To revolutionary scientists, what had been anomalies are now seen as refutations of the old paradigm. Although this reason for changing paradigms sounds objective, Kuhn argues that there is no objective way to know how seriously anomalies should be taken. Some, like Lavoisier, will feel that there is a crisis and a need for revolutionary change, while others, like Priestley, can look at the same situation and feel no need for change. To add to the sense that these two positions are subjective, Kuhn famously describes the change from one paradigm to another as a Gestalt shift, in which a picture of an old woman suddenly looks like a young woman or a duck suddenly looks like a rabbit. When they are seen from the perspective of the new paradigm, what had been minor anomalous puzzles suddenly show that the old paradigm was terribly wrong. Finally, Kuhn points out that in a revolutionary period, scientists must decide which paradigm is more promising for future success. Such forward-looking predictions are bound to be based on partial information and require belief in the promise of the paradigm. Kuhn calls this a matter of faith and argues that it too is subjective, like all of the reasons that scientists may have to change paradigms.