Popper Karl Raimund (1902–94), Austrian-born British philosopher best known for contributions to philosophy of science and to social and political philosophy. Educated at the University of Vienna (Ph.D., 1928), he taught philosophy in New Zealand for a decade before becoming a reader and then professor in logic and scientific method at the London School of Economics (1946–69). He was knighted in 1965, elected a fellow of the Royal Society in 1976, and appointed Companion of Honour in 1982 (see his autobiography, Unended Quest, 1976).
In opposition to logical positivism’s verifiability criterion of cognitive significance, Popper proposes that science be characterized by its method: the criterion of demarcation of empirical science from pseudo-science and metaphysics is falsifiability (Logik der Forschung, 1934, translated as The Logic of Scientific Discovery, 1959). According to falsificationism, science grows, and may even approach the truth, not by amassing supporting evidence, but through an unending cycle of problems, tentative solutions – unjustifiable conjectures – and error elimination; i.e., the vigorous testing of deductive consequences and the refutation of conjectures that fail (Conjectures and Refutations, 1963). Since conjectures are not inferences and refutations are not inductive, there is no inductive inference or inductive logic. More generally, criticism is installed as the hallmark of rationality, and the traditional justificationist insistence on proof, conclusive or inconclusive, on confirmation, and on positive argument, is repudiated. Popper brings to the central problems of Kant’s philosophy an uncompromising realism and objectivism, the tools of modern logic, and a Darwinian perspective on knowledge, thereby solving Hume’s problem of induction without lapsing into irrationalism (Objective Knowledge, 1972). He made contributions of permanent importance also to the axiomatization of probability theory (The Logic of Scientific Discovery, 1959); to its interpretation, especially the propensity interpretation (Postscript to The Logic of Scientific Discovery, 3 vols. 1982–83); and to many other problems (The Self and Its Brain, with John C. Eccles, 1977). Popper’s social philosophy, like his epistemology, is anti-authoritarian. Since it is a historicist error to suppose that we can predict the future of mankind (The Poverty of Historicism, 1957), the prime task of social institutions in an open society – one that encourages criticism and allows rulers to be replaced without violence – must be not large-scale utopian planning but the minimization, through piecemeal reform, of avoidable suffering. This way alone permits proper assessment of success or failure, and thus of learning from experience (The Open Society and Its Enemies, 1945). See also CONFIRMATION, DARWINISM, HIS- TORICISM , LOGICAL POSITIVISM , PHILOSOPHY OF SCIENCE , PROBABILITY , PROBLEM OF IN – DUCTION , RATIONALIT. D.W.M.