ABSTRACT
In the penultimate chapter of a controversial book first published fifteen years ago, I considered the ways scientists are brought to abandon one time-honored theory or paradigm in favor of another. Such decision problems, I wrote, “cannot be resolved by proof.” To discuss their mechanism is, therefore, to talk “about techniques of persuasion, or about argument and counterargument in a situation in which there can be no proof.” Under these circumstances, I continued, “lifelong resistance [to a new theory]... is not a violation of scientific standards.... Though the historian can always find men—Priestley, for instance—who were unreasonable to resist for as long as they did, he will not find a point at which resistance becomes illogical or unscientific.” 1 Statements of that sort obviously raise the question of why, in the absence of binding criteria for scientific choice, both the number of solved scientific problems and the precision of individual problem solutions should increase so markedly with the passage of time. Confronting that issue, I sketched in my closing chapter a number of characteristics that scientists share by virtue of the training which licenses their membership in one or another community of specialists. In the absence of criteria able to dictate the choice of each individual, I argued, we do well to trust the collective judgment of scientists trained in this way. “What better criterion could there be,” I asked rhetorically, “than the decision of the scientific group?” 2
