I am suggesting, of course, that the criteria of choice with which I began function not as rules, which determine choice, but as values, which influence it. Two men deeply committed to the same values may nevertheless, in particular situations, make different choices as, in fact, they do. But that difference in outcome ought not to suggest that the values scientists share are less than critically important either to their decisions or to the development of the enterprise in which they participate. Values like accuracy, consistency, and scope may prove ambiguous in application, both individually and collectively; they may, that is, be an insufficient basis for a shared algorithm of choice. But they do specify a great deal: what each scientist must consider in reaching a decision, what he may and may not consider relevant, and what he can legitimately be required to report as the basis for the choice he has made. Change the list, for example by adding social utility as a criterion, and some particular choices will be different, more like those one expects from an engineer. Subtract accuracy of fit to nature from the list, and the enterprise that results may not resemble science at all, but perhaps philosophy instead. Different creative disciplines are characterized, among other things, by different sets of shared values. If philosophy and engineering lie too close to the sciences, think of literature or the plastic arts. Milton's failure to set Paradise Lost in a Copernican universe does not indicate that he agreed with Ptolemy but that he had things other than science to do.
(Thomas S. Kuhn, "Objectivity, Value Judgment, and Theory Choice," chap. 13 in The Essential Tension: Selected Studies in Scientific Tradition and Change [Chicago and London: The University of Chicago Press, 1977], 320-39, at 331 [italics in original])
Note from KBJ: Kuhn's five criteria for theory choice (accuracy, consistency, scope, simplicity, and fruitfulness) are analogous to W. D. Ross's seven prima facie duties (fidelity, reparation, gratitude, justice, beneficence, self-improvement, and non-maleficence). Neither choosing a scientific theory nor deciding what one ought to do in the moral realm is a mechanical process. Both require judgment. This means that two people committed to the same criteria or prima facie duties can arrive at different results.
Keith Burgess-Jackson, J.D., Ph.D. 