Falsificationism

Falsificationism is a philosophical view of science associated with Karl Popper. It challenges the verificationist program of the logical positivists by arguing that no number of positive observations can verify a universal theory, but a single counterexample can falsify it. Consequently, falsifiability—whether a theory can be tested in ways that could show it to be false—serves as a criterion for distinguishing scientific from non-scientific theories.

According to falsificationism, scientific progress proceeds through bold conjectures and critical testing. The aim is to formulate theories that make risky predictions, so that observation may refute them. When empirical data contradict a theory, the proper response is often to abandon or revise the theory rather than to accumulate more confirming evidence. Science is seen as an ongoing process of conjecture and refutation rather than a search for ultimate justification.

Falsifiability is distinct from falsification. Falsification is the act of disproving a theory; falsifiability is a property of a theory indicating it could be disproved by observation or experiment. Tests do not prove theories true; they assess them, and problematic results can motivate modifications. However, the Duhem-Quine problem notes that experimental tests rely on background assumptions, so isolating falsifications can be challenging.

Falsificationism has generated various criticisms. Notably, Imre Lakatos introduced idea of research programmes with protective belts; Thomas Kuhn and Paul Feyerabend challenged its universality. Despite criticisms, falsificationism has been influential in shaping scientific methodology and remains central to debates on how science distinguishes hypotheses from non-science, and how theories advance through refutation and revision.

Alternatives include critical rationalism and methodological empiricism; Popper's legacy emphasizes rational scrutiny and openness to refutation.