The idea of a method that contains firm, unchanging, and absolutely binding principles for conducting the business of science meets considerable difficulty when confronted with the results of historical research. We find, then, that there is not a single rule, however plausible, and however firmly grounded in epistemology, that is not violated at some time or another. It becomes evident that such violations are not accidental events … [D]evelopments, such as … the Copernican Revolution … occurred only because some thinkers either decided not to be bound by certain “obvious” methodological rules, or because they unwittingly broke them.

[I]f the notion of a theory-neutral observation language had been viable, and if theory changes were in fact cumulative, and if all scientists subscribed to the same methodological standards, and if there were mechanical algorithms for theory evaluation … then the positivists might well have been able to show wherein scientific rationality and objectivity consist. But that was not to come to pass … These days, social constructionists, epistemological anarchists, biblical inerrantists, political conservatives, and cultural relativists all find in the surviving traces of positivism grist for their mills; for what they find there appears to sustain their conviction that science has no particular claim on us, either as a source of beliefs or as a model of progressive, objective knowledge.