Philosophy of Science and Mind

Karl Popper reoriented twentieth-century philosophy of science by proposing falsifiability, rather than verifiability, as the criterion that distinguishes genuine science from pseudoscience and metaphysics, addressing what he called the demarcation problem. In The Logic of Scientific Discovery (first published in German in 1934, translated into English in 1959), Popper argued that no finite number of confirming observations can conclusively verify a universal scientific law, since a single counterexample could always appear in the future, whereas a single genuine counterexample can conclusively falsify it; a theory is therefore scientific only if it makes risky predictions that could, in principle, be shown false by observation. On this criterion, Popper judged theories such as Marxist historical materialism and Freudian psychoanalysis to be pseudoscientific, since their proponents could always reinterpret any apparent counterevidence to fit the theory, making them unfalsifiable in practice. Popper's broader account of scientific method, developed further in Conjectures and Refutations (1963), described science as an ongoing process of bold conjecture followed by rigorous attempts at refutation, rather than a steady accumulation of verified certainties, a picture that stood in sharp contrast to the verificationism of the Vienna Circle.