Skepticism about the external world is self-undermining, because the falsity of skepticism is a necessary condition of the skeptical position's own essential commitments.

Kant-inspired transcendental arguments against skepticism about the external world were developed with vigor in the mid-twentieth century, notably by P. F. Strawson, most famously in his Kantian reflections in The Bounds of Sense (1966). These arguments are often reinterpretations of, or at least inspired by, Kant’s Transcendental Deduction and his Refutation of Idealism. Some are more ambitious than Kant’s would seem to be, insofar as they attempt to refute some variety of skepticism by showing