Prodicus as emphasizing need for civility, and debate not argument.
Idea of persuasion, not truth, as the goal of argument. Radical version: there is no truth to aim at; persuasion is what's left.
- endorses the radical thesis about truth;
- also says (says Plato) that can teach virtue;
- (capacity for) virtue shared equally among men, unlike, e.g., flute-playing ability; grounds why we punish lack of virtue but not lack of musical ability;
- "man is the measure of all things: of the things that are, that they are; of the things that are not, that they are not": relativist thesis.
- (1) Platonic version: there are only truths for X, i.e. what X judges to be true is true for X; there are no stance-independent truths.
Response: Virtue is what is to the advantage of X. So Protagoras teaches X what is advantageous to X. Similar idea in Republic from Thrasymachus: virtue the advantage of those who are stronger. So, what should happen (what is virtuous) is that the stronger get more than the weaker.
Problem: What is this Sophistic "should", if there is no absolute "should"?
Response: Distinguish custom from nature. By custom there are laws of, e.g. justice. Customs can, but need not, reflect the natural order. Natural for strong to dominate; custom for weak to band together to resist. Morality is just [ossified?] custom; the Sophists are defending the rightness of what's natural. [Are they just moral naturalists, then?]
- (2) Protagorean version: more modestly, idea that if it can seem to you that you do better, that's all that matters, or that you should care about [not quite how to phrase the more modest conclusion].
- stresses moral neutrality of his teachings: the teaching can be used for good or bad, but neither is anything to do with Gorgias;
- no such thing are being or non-being, and if there were, we couldn't know about it--a satire of the Eleatics;
- but a deeper point: given that there's no independent truth, or none accessible to us, what we're left with is rhetoric, persuasion, relativism.