Philosopher of science who argued for the demarcation between true science and pseudoscience by means of a criterion he called falsifiability.
Born and educated in Vienna, Popper was trained in mathematics, physics, and philosophy during the same era that produced logical positivism. He was not, however, a member of the famed Vienna circle and in fact disagreed with it on many key issues. Anti-Semitism and the rise of Nazism restricted his career in Europe, but after the publication of his acclaimed first book. The Logic of Scientific Discovery (1935), he was able to get an academic position at Canterbury University in New Zealand. Later, he moved to England, and from 1949 until his retirement, he was a professor of logic and scientific method at the London School of Economics. His published work includes some of the most celebrated works of 20th-century philosophy, among them The Open Society and Its Enemies (1945) and The Poverty of Historicism (1957), as well as numerous essays.