ABSTRACT
In two of Plato’s dialogues, an important role is given to a prominent intellectual of a previous generation, a man who was already well-known when Socrates was relatively young, Protagoras of Abdera. There is little surviving evidence of Protagoras’ views that does not come to us via Plato’s writings, but the lines at the head of this chapter purport to be a direct quotation from something he wrote and are the epitome of his intellectual legacy. They are said to be found in a text that Protagoras wrote titled ‘On Truth’ and clearly involve the image of a ‘measure’ (metron, that by which anything is measured). It is clear from the discussion of this claim in the Theaetetus what Plato thinks they mean. Plato takes Protagoras to be claiming that each individual constitutes a standard or measure of what is true and what is false-including claims about what are correct attitudes and what is proper conduct.
