Popper and Kuhn: The Core Claims

“Popper: 'The criterion of the scientific status of a theory is its falsifiability, or refutability, or testability. [...] Every genuine test of a theory is an attempt to falsify it or to refute it.' [...] A theory which is not refutable by any conceivable event is non-scientific. Irrefutability is not a virtue of a theory, as people often think, it is a vice. Kuhn: 'Normal science does not aim at novelties of fact or theory and, when successful, finds none. [...] If an anomaly is to evoke crisis, it must usually be more than just an anomaly. There are always difficulties somewhere in the paradigm-nature fit; most of them are set right sooner or later, often by processes that could not have been foreseen. The scientist who pauses to examine every anomaly he notes will seldom get significant work done.' — Popper, Conjectures and Refutations (1963); Kuhn, The Structure of Scientific Revolutions (1962); SEP 'Karl Popper'; SEP 'Thomas Kuhn'”