Objectivist epistemology maintains that all knowledge is ultimately based on perception. "Percepts, not sensations, are the given, the self-evident." Rand considered the validity of the senses to be axiomatic and said that purported arguments to the contrary all commit the fallacy of the "stolen concept" by presupposing the validity of concepts that, in turn, presuppose the validity of the senses. She said that perception, being determined physiologically, is incapable of error. For example, optical illusions are errors in the conceptual identification of what is seen, not errors of sight itself. The validity of sense perception, therefore, is not susceptible to proof (because it is presupposed by all proof as proof is only a matter of adducing sensory evidence) nor should its validity be denied (since the conceptual tools one would have to use to do this are derived from sensory data). Perceptual error, therefore, is not possible. Rand consequently rejected epistemological skepticism, as she said that the skeptics' claim to knowledge "distorted" by the form or the means of perception is impossible.
Objectivist epistemology maintains that all knowledge is ultimately based on perception "Percepts not sensations are the given the self-evident" Rand considered the validity of the senses to be axiomatic and said that purported arguments to the contrary all commit the fallacy of the "stolen concept" by presupposing the validity of concepts that in turn presuppose the validity of the senses She said that perception being determined physiologically is incapable of error For example optical illusions are errors in the conceptual identification of what is seen not errors of sight itself The validity of sense perception therefore is not susceptible to proof (because it is presupposed by all proof as proof is only a matter of adducing sensory evidence) nor should its validity be denied (since the conceptual tools one would have to use to do this are derived from sensory data) Perceptual error therefore is not possible Rand consequently rejected epistemological skepticism as she said that the skeptics' claim to knowledge "distorted" by the form or the means of perception is impossible