Sir Karl Raimund Popper (1902–1994) is well known for his insistence that it be necessary to be able to say what would make scientific claims false. He was born in Austria and grew up near Ludwig Wittgenstein (1889–1951) in Vienna, Austria, but not under wealthy circumstances. He had to leave Germany in the late 1930s, and after teaching in New Zealand he was a professor at the London School of Economics. Popper is as famous for his philosophy of science as for his political thought, which he developed in The Open Society and Its Enemies (1945, fifth revised edition, 1965).