[12] In political discourse, he is known for his vigorous defence of liberal democracy and the principles of social criticism that he believed made a flourishing open society possible.

He was a dogged opponent of totalitarianism, nationalism, fascism, romanticism, collectivism, and other kinds of (in Popper’s view) reactionary and irrational ideas, and identified modern liberal democracies as the best-to-date embodiment of an open society.

[9] Popper left school at the age of 16 and attended lectures in mathematics, physics, philosophy, psychology and the history of music as a guest student at the University of Vienna.

[9] After the street battle in the Hörlgasse on 15 June 1919, when police shot eight of his unarmed party comrades, he turned away from what he saw as the philosopher Karl Marx's historical materialism, abandoned the ideology, and remained a supporter of social liberalism throughout his life.

Fearing the rise of Nazism and the threat of the Anschluss, he started to use the evenings and the nights to write his first book Die beiden Grundprobleme der Erkenntnistheorie (The Two Fundamental Problems of the Theory of Knowledge).

After the Ludwig Boltzmann Gesellschaft failed to establish him as the director of a newly founded branch researching the philosophy of science, he went back again to the United Kingdom in 1986, settling in Kenley, Surrey.

Popper won many awards and honours in his field, including the Lippincott Award of the American Political Science Association, the Sonning Prize, the Otto Hahn Peace Medal of the United Nations Association of Germany in Berlin and fellowships in the Royal Society,[4] British Academy, London School of Economics, King's College London, Darwin College, Cambridge, Austrian Academy of Sciences and Charles University, Prague.

[33] In 1992, he was awarded the Kyoto Prize in Arts and Philosophy for "symbolising the open spirit of the 20th century"[34] and for his "enormous influence on the formation of the modern intellectual climate".

His most important works in the field of social science—The Poverty of Historicism (1944) and The Open Society and Its Enemies (1945)—were inspired by his reflection on the events of his time and represented, in a sense, a reaction to the prevalent totalitarian ideologies that then dominated Central European politics.

[42] He also held that scientific theory, and human knowledge generally, is irreducibly conjectural or hypothetical, and is generated by the creative imagination to solve problems that have arisen in specific historico-cultural settings.

Alan Chalmers gives "The brick fell upward when released" as an example of an imaginary observation that shows that Newton's law of gravitation is falsifiable.

Popper's student W.W. Bartley III tried to radicalise this idea and made the controversial claim that not only can criticism go beyond empirical knowledge but that everything can be rationally criticised.

An event that happened in 1919 had a profound effect on him: During a riot, caused by the Communists, the police shot several unarmed people, including some of Popper's friends, when they tried to free party comrades from prison.

The riot had, in fact, been part of a plan by which leaders of the Communist party with connections to Béla Kun tried to take power by a coup; Popper did not know about this at that time.

[56]: 732  In 1957, Popper would dedicate The Poverty of Historicism to "memory of the countless men, women and children of all creeds or nations or races who fell victims to the fascist and communist belief in Inexorable Laws of Historical Destiny.

"[54] In 1947, Popper co-founded the Mont Pelerin Society, with Friedrich Hayek, Milton Friedman, Ludwig von Mises and others, although he did not fully agree with the think tank's charter and ideology.

[71]These frequently quoted passages are only a small part of what Popper wrote on evolution, however, and may give the wrong impression that he mainly discussed questions of its falsifiability.

He said that evolution of the genotype must, as the creationists say, work in a goal-directed way[78] but disagreed with their view that it must necessarily be the hand of god that imposes these goals onto the stage of life.

Popper was a key figure encouraging patent lawyer Günter Wächtershäuser to publish his iron–sulfur world hypothesis on abiogenesis and his criticism of "soup" theory.

On the creation-evolution controversy, Popper initially wrote that he considered it a somewhat sensational clash between a brilliant scientific hypothesis concerning the history of the various species of animals and plants on earth, and an older metaphysical theory which, incidentally, happened to be part of an established religious beliefwith a footnote to the effect that he agree[s] with Professor C.E.

However, although Popper was a body-mind dualist, he did not think that the mind is a substance separate from the body: he thought that mental or psychological properties or aspects of people are distinct from physical ones.

[93] Popper objected to organised religion, saying "it tends to use the name of God in vain", noting the danger of fanaticism because of religious conflicts: "The whole thing goes back to myths which, though they may have a kernel of truth, are untrue.

In 1946, Popper founded the Department of Philosophy, Logic and Scientific Method at the London School of Economics (LSE) and there lectured and influenced both Imre Lakatos and Paul Feyerabend, two of the foremost philosophers of science in the next generation.

For his part, Hayek dedicated a collection of papers, Studies in Philosophy, Politics, and Economics, to Popper, and in 1982 said, "ever since his Logik der Forschung first came out in 1934, I have been a complete adherent to his general theory of methodology.

"[100] Popper also had long and mutually influential friendships with art historian Ernst Gombrich, biologist Peter Medawar, and neuroscientist John Carew Eccles.

[...] The value of individual freedom is likely to assume increasing importance in the immediate future.Most criticisms of Popper's philosophy are of the falsification, or error elimination, element in his account of problem solving.

The theories are passed on, not as dogmas, but rather with the challenge to discuss them and improve upon them.Another objection is that it is not always possible to demonstrate falsehood definitively, especially if one is using statistical criteria to evaluate a null hypothesis.

[115] The philosopher Adolf Grünbaum argues in The Foundations of Psychoanalysis (1984) that Popper's view that psychoanalytic theories, even in principle, cannot be falsified is incorrect.

[116] The philosopher Roger Scruton argues in Sexual Desire (1986) that Popper was mistaken to claim that Freudian theory implies no testable observation and therefore does not have genuine predictive power.

[118] The philosopher John Gray argues that Popper's account of scientific method would have prevented the theories of Charles Darwin and Albert Einstein from being accepted.