There is a great muddle quite innocently generated by T. S. Kuhn's candor in trying to fathom what contributes to what he calls a "paradigm shift" or the incipient stages of supporting a potentially "new paradigm". Kuhn says straight out, in The Structure of Scientific Revolutions, that: first, the usual arguments in favor of a new paradigm (those he had himself explored up to the point of raising the question) "concern the competitors' ability [that is, the old and the new paradigms] to solve problems"; second, where new paradigms begin to gain ground, this criterion is often, puzzlingly, "neither individually nor collectively compelling"; hence, third, "other arguments, rarely made entirely explicit . . . appeal to the individual's sense of the appropriate or the aesthetic — the new theory [being] said to be "neater", "more aesthetic", "more suitable", or 'simpler" than the old". Kuhn speaks of "the importance of these more subjective and aesthetic considerations", but warns us against the suggestion "that new paradigms triumph ultimately through some mystical aesthetic".¹ Kuhn was able to offer a variety of cases in which the ability of the new paradigm "to solve problems' could not have been decisive: the dispute regarding Copernicus and Ptolemy, for instance, and that regarding Priestley and Lavoisier being the best known. (It was Popper's charge that Kuhnian "paradigm shifts' almost never occur and that ""normal" science is [not] normal".)²