Abstract

“A belief is knowledge only when proof against all doubt, even the most hyperbolic” – so premises Descartes. If unable to rule out the possibility that one is deceived by a demon (or is embodied in an envatted brain), therefore, one knows neither what one ostensibly sees, nor the truth of any conclusion one may infer from such “data,” or at least it cannot be any such inference that gives one knowledge of the truth of its conclusion.