# Protagoras

Protagoras of Abdera (c. 490 – 420 BCE) was the first and most respected of the
sophists, the travelling teachers who, for a fee, taught young men how to
speak, argue and manage a household and a city. He visited Athens more than
once, was a friend of Pericles, and was asked by him to write the laws for the
new colony of Thurii. Plato gave his name to a dialogue and treated him, unlike
most sophists, with real respect.

## Man the measure

His famous sentence opened his book *Truth*:

> Of all things the measure is man: of the things that are, that they are; of
> the things that are not, that they are not.

The wind feels cold to one person and mild to another. Protagoras refused to
say that one of them is wrong. The wind *is* cold for the first and mild for
the second; there is no further fact, hidden behind both experiences, that
settles the matter. Applied to perception this is a modest claim. Applied to
justice and law, as he did apply it, it is not modest at all: what a city
decides is just, is just for that city, for as long as it decides so.

## Better and worse, not true and false

Protagoras saw the objection coming. If every opinion is true for its holder,
what is a teacher for? His answer was that opinions can be *better* or *worse*
even where none is truer. A doctor does not make a sick person's perceptions
false; he changes them into healthier ones. A good speaker does the same for a
city, replacing harmful customs with useful ones. This was the service he sold.

## On the gods

His other surviving sentence is the opening of a book *On the Gods*:

- He could not know whether they exist or not, nor what form they have.
- The obstacles were the obscurity of the subject and the shortness of life.

The Athenians are said to have burned his books for it and driven him from the
city; the story may be later invention. What is certain is that the two
sentences together, one on knowledge and one on the gods, mark the first time a
Greek thinker made a career of saying that certainty was not on offer.

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*Stoa Press · Philosophy Essays · Markdown edition*