Popper

Popper most commonly refers to Karl Popper, a 20th-century philosopher born in Vienna in 1902 and who later settled in the United Kingdom. He is renowned for developing critical rationalism and for advocating falsifiability as the criterion by which scientific theories are judged. Popper argued that science advances through bold conjectures that are subjected to potential refutation rather than through assured verification.

His writings challenge Logical Positivism and historicism. In The Logic of Scientific Discovery (1934), he formalized the view that science proceeds via conjecture and refutation, not by proving theories true. In The Open Society and Its Enemies (1945), and its later volumes, he defended liberal democracy, the rule of law, and open critique as safeguards against tyranny.

Popper is also the name of a JavaScript library, Popper.js, used to position tooltips and popovers in web interfaces. It calculates the best placement of a floating element relative to a reference element and adapts to viewport constraints. The library, maintained in modern form as @popperjs/core, is widely used in contemporary front-end development.