Karl Popper
Karl Raimund Popper (1902–1994) was an Austrian-British philosopher whose work reshaped twentieth-century philosophy of science and political philosophy through his theory of falsifiability, critical rationalism, and defense of the open society. Born in Vienna in 1902, he studied philosophy, mathematics, and physics and received his doctorate from the University of Vienna in 1928. His first major philosophical work, published in German in 1934 and later translated as The Logic of Scientific Discovery, challenged the view that science advances primarily through inductive accumulation of observations. Popper argued instead that scientific theories should make testable predictions that could, in principle, be shown false; he therefore proposed falsifiability as a central criterion for distinguishing empirical science from non-scientific systems. After the rise of Nazism and the annexation of Austria, Popper emigrated to New Zealand, where he taught at Canterbury University College, before moving to Britain after the Second World War and joining the London School of Economics. In The Open Society and Its Enemies (1945), he criticized historicist theories of inevitable historical development and defended liberal democracy, institutional criticism, and the possibility of gradual social reform. His concept of critical rationalism held that knowledge progresses through conjecture, criticism, testing, and revision rather than through claims to final certainty.