Sir Karl Raimund Popper, CH FRS FBA was an Austro-British philosopher and professor at the London School of Economics. He is generally regarded as one of the greatest philosophers of science of the 20th century. He also wrote extensively on social and political philosophy. In 1992 he was awarded the Kyoto Prize in Arts and Philosophy for "symbolising the open spirit of the 20th century" and for his "enormous influence on the formation of the modern intellectual climate".
Popper is known for his attempt to repudiate the classical observationalist/inductivist form of scientific method in favour of empirical falsification. He is also known for his opposition to the classical justificationist account of knowledge which he replaced with critical rationalism, "the first non justificational philosophy of criticism in the history of philosophy". In political discourse, he is known for his vigorous defence of liberal democracy and the principles of social criticism that he came to believe made a flourishing "open society" possible.