Paradigm Shift

Paradigm shift is the central concept of Thomas Kuhn's The Structure of Scientific Revolutions (1962). Normal science, on Kuhn's account, proceeds within a paradigm — a shared set of theoretical commitments, exemplary problem-solutions, and methodological standards that organize a scientific community's work. Anomalies accumulate; eventually, when they exceed what the paradigm can accommodate, the community enters a period of crisis from which a new paradigm emerges.

Kuhn's most controversial claim is that successive paradigms are incommensurable: they ask different questions, count different things as data, and use central terms with different meanings. Scientific change is therefore not the cumulative approximation to truth that the older positivist tradition imagined but a series of discontinuous reconfigurations of conceptual practice. Critics from Popper to Lakatos charged that the account makes science irrational; defenders argued that Kuhn's analysis better fits the actual history of science than the older rational-reconstruction tradition.

Kuhn's distinction between normal and revolutionary science has been one of the most influential ideas in twentieth-century philosophy of science. Normal science is the patient, cumulative, problem-solving activity of a community working within an established paradigm. Revolutionary science is the discontinuous transition between paradigms, triggered by accumulated anomalies and the emergence of an alternative framework that handles them better. Kuhn's most controversial claim is that successive paradigms are incommensurable: they ask different questions, count different things as data, and use central terms with different meanings.

Kuhn's account has been extended and contested in many directions. Lakatos refined it by distinguishing progressive and degenerating research programmes. Feyerabend pushed Kuhn's relativism further. Larry Laudan defended a more rationalist account of theory choice. The contemporary literature on the social epistemology of science — Helen Longino, Miriam Solomon, Heather Douglas — has refined Kuhn's analysis of how scientific communities actually work. The popular use of paradigm shift has greatly outrun what Kuhn meant; the term often appears in business and self-help literature for any major change.