“Man is the measure of all things”—Pragmatism in Plato
I was recently reading William James’ Pragmatism and his Varieties of Religious Experience as well as Bertrand Russell’s History of Western Philosophy in close succession, and I found two interesting passages in the History that connect Pragmatism to the Theaetetus by Plato.
In the Theaetetus, Plato discusses the teachings of Protagoras, who is primarily noted for his doctrine that “Man is the measure of all things.” Plato takes this to mean that each human being evaluates individually what she or he perceives, and that, when people differ, there is no objective truth to decide who is right and who is wrong.
As one of several possible solutions, Plato suggests that one opinion might not be truer than another, but it can be better. “For example,” explains Russell, “when a man has jaundice everything looks yellow. There is no sense in saying that things are really not yellow, but the colour they look to a man in health; we can say, however, that, since health is better than sickness, the opinion of the man in health is better.”
It is for this reason that one of the three founders of Pragmatism, F.C.S. Schiller, liked to call himself a disciple of Protagoras.
However, this does not mean that Plato was a Pragmatist. Even though, in his dialogue, he has Socrates suggest this interpretation of Protagoras, Socrates himself is not satisfied by it. “He urges, for example, that when a doctor foretells the course of my illness, he actually knows more of my future than I do. And when men differ as to what it is wise for the State to decree, the issue shows that some men had a greater knowledge as to the future than others had. Thus we cannot escape the conclusion that a wise man is a better measure of things than a fool.”