Born and educated in Vienna, Popper shared with the logical positivists an interest in the foundations and the methodology of the natural sciences. After a period in New Zealand he moved to the London School of Economics where he became professor of logic and scientific method in 1949. Popper came to fame with his first book, Logik der Forschung (1935, trs. as The Logic of Scientific Discovery, 1959). In it he overturns the traditional attempts to found scientific method in the support that experience gives to suitably formed generalizations and theories. Stressing the difficulty the problem of induction puts in front of any such method, Popper substitutes an epistemology that starts with the bold, imaginative formation of hypotheses. These face the tribunal of experience, which has the power to falsify them, but not to confirm them (see falsifiability, falsification). A hypothesis that survives the ordeal of attempted refutation can be provisionally accepted as ‘corroborated’, but never assigned a probability.

The approach was extremely popular amongst working scientists, who recognized the value it puts upon imaginative theorizing and patient refutation, and who responded gladly to the liberating thought that it was not a sin but a mark of virtue to put forward a theory that is subsequently refuted. Philosophers have been more cautious, pointing out that something like induction seems to be involved when we rely upon well-corroborated theories. Nobody flies in an aeroplane purely because it is a bold, imaginative conjecture that it will stay in the air. However, many thinkers accept in essence his solution to the problem of demarcating proper science from its imitators, namely that the former results in genuinely falsifiable theories whereas the latter do not. Although falsification is more complex than Popper initially allowed, the idea encapsulates many people’s objections to such ideologies as psychoanalysis and Marxism.

Popper’s social and historical writings include the influential The Open Society and Its Enemies (1945) and The Poverty of Historicism (1957), attacking the view that there are fundamental laws of history that render its progress inevitable. In the first work Popper attacks this belief, which he associates with the illiberal totalitarianism that he finds in Plato, Hegel, and Marx, although it is unclear that his readings of these thinkers do justice to the stringent ethical conditions they place upon the rational political systems that they explore. Popper associates political virtue, like scientific virtue, with the possibility of free enquiry subject to constraints that minimize the chance of accepting bad systems.

http://www.bbc.co.uk/radio4/history/inourtime/inourtime_20070208.shtml An audio discussion of Popper by three philosophers

http://www.eeng.dcu.ie/~tkpw/index.html An internet forum on Popper’s work