1001Philosophers

Plato vs Protagoras

Plato presents Protagoras as the chief representative of the sophists, the professional teachers of rhetoric and virtue against whom Socrates and Plato defined philosophy. The dispute over what Protagoras meant and what is wrong with it is a foundational episode in Western philosophy.

At a glance

PlatoProtagoras
Dates428 BC – 348 BC490 BC – 420 BC
NationalityGreekGreek
EraAncientAncient
Movements Platonism, Ancient Greek Philosophy Sophism, Ancient Greek Philosophy
Profile Plato → Protagoras →

Where they agree

Both held that philosophy is concerned with how human beings ought to live and that virtue can be taught. Both took the political dimension of education seriously, and both rejected the appeal to divine revelation in favor of rational reflection on the nature of value.

Where they disagree

Protagoras' famous dictum — man is the measure of all things — was read by Plato as committing him to a thoroughgoing relativism: what is true is what seems true to each person, and there is no further fact about the matter. Plato responded by insisting that the very distinction between truth and seeming requires something fixed against which appearances are measured: namely, the Forms. The dispute is the origin of the Western argument over relativism, and Plato's refutation in the Theaetetus remains its canonical version.

Representative quotes

Plato

  • “The beginning is the most important part of the work.”

    The beginning in every task is the chief thing.

  • “Philosophy begins in wonder.”

    155d, The Dialogues of Plato , Volume 3, 1871, p. 377

  • “I shall assume that your silence gives consent .”

    435b

Protagoras

  • “Man is the measure of all things: of those that are, that they are; of those that are not, that they are not.”

    Πάντων χρημάτων μέτρον ἄνθρωπον εἶναι, τῶν μὲν ὄντων, ὡς ἔστι, τῶν δὲ μὴ ὄντων, ὡς οὐκ ἔστιν.

  • “Virtue can be taught.”

    Quoted in Plato, Protagoras , sec. 361a–b. Translated by C. C. W. Taylor, Plato: 'Protagoras' (Oxford, 1976) p. 56

  • “Πάντων χρημάτων μέτρον ἄνθρωπον εἶναι, τῶν μὲν ὄντων, ὡς ἔστι, τῶν δὲ μὴ ὄντων, ὡς οὐκ ἔστιν.”

    Man is the measure of all things : of things which are, that they are, and of things which are not, that they are not. | Quoted in Plato , Theaetetus , sec. 152a. Translated by John Stuart Mill , "Plato", in the Edinburgh Review (April 1866)

Continue reading