Karl Popper

Sir Karl Raimund Popper, an Austrian-British philosopher, academic, and social commentator, lived from 28 July 1902 to 17 September 1994. He is counted among the most significant philosophers of science of the 1900s. Popper rejected the classical inductivist approach to the scientific method, instead championing empirical falsification through his criterion of falsifiability. In his view, no theory in the empirical sciences can ever be proven true; it can only be falsified, meaning it must be open to scrutiny by decisive experiments.

Political philosophy

He also opposed the traditional justificationist view of knowledge, replacing it with what he called critical rationalism, which he described as the first non-justificational philosophy of criticism in the history of philosophy. Politically, Popper is remembered for his strong support of liberal democracy and the social criticism he believed were essential for a flourishing open society. He was a firm opponent of totalitarianism, communism, nationalism, fascism, historicism, and other ideas he considered reactionary and irrational, and he saw modern liberal democracies as the best example yet of an open society. Popper was born in Vienna, then part of Austria-Hungary, in 1902, into an upper-middle-class family.

Family and training

All four of his grandparents were assimilated Jews, but his family had converted to Lutheranism before his birth, and he was baptised as a Lutheran. His father, Simon Siegmund Carl Popper, was a lawyer from Bohemia with a doctorate in law from the University of Vienna. His mother, Jenny Schiff, was a skilled pianist of Silesian and Hungarian descent. Popper’s uncle was the philosopher Josef Popper-Lynkeus.

After moving to Vienna, the family rose quickly in society; his father became a partner in the law firm of the liberal mayor Raimund Grübl, taking over the business after Grübl’s death in 1898. Popper received his middle name from Grübl, though in his autobiography he mistakenly recalled that Grübl’s first name was Carl. His parents were close friends with Sigmund Freud’s sister Rosa Graf. His father, a bibliophile with a personal library of 12,000 to 14,000 volumes, had a deep interest in philosophy, classics, and social and political issues, and Popper inherited both the library and that disposition.

He later described his upbringing as decidedly bookish. At age 16, Popper left the Realgymnasium and began attending lectures at the University of Vienna as a guest student, studying mathematics, physics, philosophy, psychology, and the history of music. In 1919, he became drawn to Marxism, joining the Association of Socialist School Students and the Social Democratic Workers’ Party of Austria, which then fully embraced Marxism.

After a street battle in the Hörlgasse on 15 June 1919, where police shot eight of his unarmed party comrades, he rejected what he saw as Karl Marx’s historical materialism, abandoned Marxism, and remained a supporter of social liberalism for the rest of his life. He briefly worked in street construction but found the labour too heavy. While still a guest student, he began an apprenticeship as a cabinetmaker, completing it as a journeyman, as he dreamed of starting a daycare facility and thought furniture-making skills would be useful. He then volunteered at one of Alfred Adler’s children’s clinics.

In 1922, he passed his matura through a second-chance education program and became a regular university student. He qualified as a primary school teacher in 1924 and began working at an after-school care club for socially endangered children. In 1925, he enrolled at the newly founded Pädagogisches Institut, continuing his studies in philosophy and psychology. Around this time, he began courting Josefine Anna Henninger, who later became his wife.

In 1928, Popper earned a doctorate in psychology under Karl Bühler, with Moritz Schlick as the second chair of his thesis committee; his dissertation was titled On Questions of Method in the Psychology of Thinking. The following year, he obtained authorization to teach mathematics and physics in secondary school and started doing so. He married Josefine Anna Henninger in 1930. Fearing the rise of Nazism and the threat of the Anschluss, he spent his evenings and nights writing his first book, The Two Fundamental Problems of the Theory of Knowledge, hoping to publish something to secure an academic position in a safe country for people of Jewish descent.

He did not publish that two-volume work, but instead a condensed version with new material, The Logic of Scientific Discovery, in 1934. In it, he criticized psychologism, naturalism, inductivism, and logical positivism, and proposed his theory of potential falsifiability as the criterion to demarcate science from non-science. In 1935 and 1936, he took unpaid leave for a study visit to the United Kingdom. In 1937, he finally obtained a position that allowed him to emigrate to New Zealand, where he became a lecturer in philosophy.