"A paradigm is a powerful theoretical and methodological framework which defines the working lives of thousands of intelligent and disciplined minds. And paradigms do not attract the loyalty of such minds unless they 'work'. One of the first things a graduate student learns is that if there is a discrepancy between the paradigm and what he or she has discovered, then the automatic assumption is that the paradigm is right and the student wrong. Just as a good workman never blames his tools, so the diligent student never blames his paradigm"