Karl Raimund Popper (July 28, 1902 - September 17, 1994), was an Austrian-born, British philosopher of science. He was also a social and political thinker of considerable stature, a staunch defender of liberal democracy[?] and the principles of social criticism upon which it is based, and an implacable opponent of authoritarianism. He is best known for his repudiation of the classical observationalist-inductivist account of science, his espousal of falsifiability as a criterion of demarcation between science and non-science, and his defence of the 'Open Society[?]'.
Born in Vienna in 1902 to middle-class parents of Jewish origins, Karl Popper was educated at the University of Vienna. He took a Ph.D. in philosophy in 1928, and taught in secondary school from 1930 to 1936. In 1937, concerns about the growth of Nazism led him to emigrate to New Zealand, where he became lecturer in philosophy at Canterbury University College[?], Christchurch. In 1946, he moved to England to become reader in logic and scientific method at the London School of Economics, where he was appointed professor in 1949. He was knighted[?] by Queen Elizabeth II in 1965, and was elected Fellow of the Royal Society[?] in 1976. He retired from academic life in 1969, though he remained intellectually active until his death in 1994. He was invested with the Insignia of a Companion of Honour in 1982.
Popper won many awards and honors in his field, including the Lippincott Award[?] of the American Political Science Association[?], the Sonning Prize, and fellowships in the Royal Society, British Academy[?], London School of Economics, Kings College London[?], and Darwin College Cambridge[?]. Austria awarded him the Grand Decoration of Honour in Gold.
Popper coined the term critical rationalism[?] to describe his philosophy. This designation is significant, and indicates his rejection of classical empiricism[?], and of the observationalist-inductivist account of science that had grown out of it. Popper argued strongly against the latter, holding that scientific theories are universal in nature, and can be tested only indirectly, by references to their implications. He also held that scientific theory, and human knowledge generally, is irreducibly conjectural[?] or hypothetical[?], and is generated by the creative imagination in order to solve problems that have arisen in specific historico-cultural settings. Logically, no number of positive outcomes at the level of experimental testing can confirm a scientific theory, but a single genuine counter-instance is logically decisive: it shows the theory, from which the implication is derived, to be false. Popper's account of the logical asymmetry between verification and falsification lies at the heart of his philosophy of science. It also inspired him to take falsifiability as his criterion of demarcation between what is and is not genuinely scientific: a theory should be accounted scientific if and only if it is falsifiable. This led him to attack the claims of both psychoanalysis and contemporary Marxism to scientific status, on the basis that the theories enshrined by them are not falsifiable. His scientific work was influenced by his study of Albert Einstein's theory of relativity.
In The Open Society and Its Enemies and The Poverty of Historicism, Popper developed a powerful critique of historicism and a defence of the 'Open Society', liberal democracy[?]. Historicism is the theory that history develops inexorably and necessarily according to knowable general laws towards a determinate end. Popper considered this view to be the principal theoretical presupposition underpinning most forms of authoritarianism and totalitarianism. He accordingly attacked it, arguing that it is founded upon mistaken assumptions regarding the nature of scientific law and prediction. Since the growth of human knowledge is a causal factor in the evolution of human history, and since "no society can predict, scientifically, its own future states of knowledge", it follows, he argued, that there can be no predictive science of human history. For Popper, metaphysical and historical indeterminism go hand in hand.
Some have claimed Popper as "one of the foremost critics of authoritarianism in the twentieth century, yet also arguably the premier philosopher of science during a century of unparalleled scientific discovery". However, in recent years his reputation has diminished among those in the hard sciences.
Some of his critics seek to vindicate the claims of historicism or holism to intellectual respectability, or psychoanalysis or Marxism to scientific status.
Many critics argue that in principle or in point of detail, his philosophy of science is mistaken. For example, the Quine-Duhem thesis argues that it is impossible to test a single hypothesis on its own, since each one comes as part of an environment of theories. Thus we can only say that the whole package of relevant theories has been collectively falsified, but cannot conclusively say which element of the package must be replaced. An example of this is given by the discovery of the planet Neptune: when the motion of Uranus was found not to match the predictions of Newton's laws, the theory "There are seven planets in the solar system" was rejected, and not Newton's laws themselves.
One of Popper's students and advocates is the investor George Soros, who says that his investment strategies are based on a Popperian skepticism about the reliability of any human belief. Soros is one of the most successful investors in history.
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An earlier version (http://www.nupedia.com/article/557/) of the above article was posted on 16 May 2001 on Nupedia; reviewed and approved by the Philosophy and Logic group; editor, Wesley Cooper ; lead reviewer, Wesley Cooper ; lead copyeditors, Cindy Seeley and Ruth Ifcher.