Falsificationism — Karl Popper’s thesis that the mark of empirical science is falsifiability: a theory is scientific if it can, in principle, be refuted by experience. The term derives from Latin falsus (“wrong”) and facere (“to make”). The position was set out in The Logic of Scientific Discovery (Logik der Forschung, 1934, dated 1935 on the title page; English version 1959), especially in §§4–6, and popularized in Conjectures and Refutations (1963). Popper starts from the problem of induction, formulated by Hume (see deduction and induction): no number of confirming observations proves a universal law, yet a single contrary observation can logically refute it. This asymmetry grounds his criterion of demarcation between science and non-science. Theories such as Einstein’s, which risk testable predictions (like the deflection of light observed in 1919), contrast, in Popper’s view, with historical Marxism, psychoanalysis, and Adler’s psychology, which can accommodate any outcome. Scientific progress would be a cycle of bold conjectures and attempts at refutation; theories that survive severe tests are not proved but “corroborated” (ch. X). Central criticisms: the Duhem–Quine thesis, on which hypotheses are not tested in isolation, so refutation can always be redirected to auxiliary hypotheses (Duhem, 1906; Quine, 1951); Thomas Kuhn, in The Structure of Scientific Revolutions (1962), observes that scientists do not abandon paradigms at every anomaly; Imre Lakatos proposed a “sophisticated falsificationism” of research programmes (1970); Paul Feyerabend, in Against Method (1975), denies that any universal method exists. See empiricism, Thomas Kuhn, Imre Lakatos, Paul Feyerabend, and the article Philosophy of science: Popper, Kuhn, falsification, and paradigms.
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