Radical skepticism
Radical skepticism or radical scepticism is the philosophical position that knowledge is most likely impossible. Radical skeptics hold that doubt exists as to the veracity of every belief and that certainty is therefore never justified. To determine the extent to which it is possible to respond to radical skeptical challenges is the task of epistemology or "the theory of knowledge".
Several Ancient Greek philosophers, including Plato, Cratylus, Carneades, Arcesilaus, Aenesidemus, Pyrrho, and Sextus Empiricus have been viewed as having expounded theories of radical skepticism.
In modern philosophy, two representatives of radical skepticism are Michel de Montaigne and David Hume.
As radical skepticism can be used as an objection for most or all beliefs, many philosophers have attempted to refute it. For example, Bertrand Russell wrote “Skepticism, while logically impeccable, is psychologically impossible, and there is an element of frivolous insincerity in any philosophy which pretends to accept it.”
