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.
The sophists were the first avowed skeptics in history, skepticism being the philosophical stance that no objective or certain knowledge is possible. They supported their case with many arguments, some weak like those from dreams or hallucinations, others stronger. The strongest of all and most influential up to our times is little more than a natural outcome of all presocratic philosophy since after Thales: If we can not trust our senses, then we don’t have access to true reality.
The central idea is that what we perceive depends on the object being perceived (obviously), but it also depends on the nature and condition of the sensory apparatus doing the perceiving. While it is true that our perceptions are indeed affected by our sensory organs (a colorblind won’t see red no matter what), the sophists will stray away from that true premise and falsely conclude that nothing can be known. Because perceptions vary from person to person, no one can perceive reality as it is; we only perceive the appearances of reality. We are locked inside our own minds, perceiving our perceptions.
It’s difficult to stress enough how influential that idea has been up to now — and how damaging for the history of thought — but I trust that by the end of this long series of posts on the history of philosophy it will be clearer. This is one of the most pervasive and perverse ideas ever put forth.
A logical consequence of the invalidity of the senses is that reason too is invalid. The sophists correctly assumed that reason depends upon the evidence of the senses, but if this evidence varies for each of us, reason can’t do much. “Garbage in, garbage out”. Moreover, they said, no one can even agree on what is rational, so how could we want reason to reach any truth?
Protagoras is known as the “chief of the sophists”. His famous statement, “Man is the measure of all things”, as interpreted today — “Each man is the measure of all things” — is the motto of subjectivism and relativism. He is the unrecognized idol of the present generation, who lives by the creed that there is not the truth, but truth for you and truth for me. Each with one’s own.
The sophists, of course, were neither theists nor atheists. That would demand that they took a stance, which, in turn, would mean they could know something. So, they were agnostics. Their ethics, therefore, could not come from God. Nor could it come from reality, since the senses are invalid. Their solution was a logical one: there is no objective ethics, only social convention. If you feel that a given path is good or right, go for it. All desires are ethically equal, because there’s nothing to go by, except arbitrary desires and passions. “Live by your desires”. “Express your passions” and you will achieve morality. But, if you don’t feel confident enough to do that, just follow the mores of society — the majority always knows better. Or, even, follow your gods if you believe so — religion is better than anarchy. In any case, skepticism equates all the way to the primacy of consciousness, which, in turn, equates to subjectivism and the denial of reality.