“Gorgias, who was the perfect example of a 20th century skeptic transplanted into ancient Greece […] maintained three basic propositions: one, nothing exists; two, if anything existed, you couldn’t know it; three, if you could know it, you couldn’t communicate it. Now that is what you call skepticism.”
— Leonard Peikoff, “History of Philosophy” course, ARI, Lesson 7.
(I don’t like modern art. But if we look hard, there might be something to learn from it. The steel sculpture “Protagoras”, by Charles Ginnever, could well be considered the concretization of a philosophic idea. The sculpture changes shape as viewers move around it, the play of light and shadow on its triangular forms giving life to the massive structure. “The senses deceive” I’d say is the message. But, now, try to imagine someone jumping from this malformed idea (because it’s not the senses that are wrong, but the concepts we generate from them) to the conclusion that nothing exists. Perhaps some of the federal judges working at the Burger building, in St. Paul, Minnesota, where “Protagoras” is installed, would like it to vanish. But to assert it never existed would be a bit farfetched. Nevertheless, that’s exactly what sophists like Protagoras and Gorgias did.)
The sophists have been branded throughout history as greedy and imoral teachers, but that’s polemics for a history course, or one on Plato and his obsession with them. Leonard Peikoff focuses instead on the ideas they put forth — even if their main idea is the negation of all ideas.
“No type of sense perception can register everything. ‘A is A’ — and any perceptual apparatus is limited. By virtue of being able directly to discriminate one aspect of reality, a consciousness cannot discriminate some other aspect that would require a different kind of sense organs. Whatever facts the senses do register, however, are facts. And these facts are what lead a mind eventually to the rest of its knowledge.”
— Leonard Peikoff, “O.P.A.R.”, pages 43-44.
(A pencil or a stick appears bent in water. The ancient assumed, therefore, that the senses are invalid. The problem is when the modern keep repeating the same thing.)
Epistemology is the science that tells a fallible, conceptual consciousness how to gain knowledge of an independent reality. This implies a volitional process operating on valid data. Therefore, before studying epistemology per se, Objectivism must establish two facts: that the senses are valid, and that man is free to think or not.