Protagoras
(born on 490 B.C. / died on 420 B.C.)
Protagoras was a thinker from ancient Greece. Considered a sophist or a pre-
Socratic, he was the author of the expression “man is the measure of all things”,
which implies a relativism (all knowledge is relative to man). Thus, the same
man can support some thing and then its opposite. If there are no truths, there
are opinions, but only opinions (which is the exact opposite of what Plato stated
in his Allegory of the Cave: that by straying and breaking free from opinions, we
can get closer to truths, these metaphysical entities). He is also famous for his
agnosticism: “Concerning the gods, I have no means of knowing whether they
exist or not”, which had him exiled from the City of Athens and his work burned.