In Plato's Protagoras Socrates criticises acrasia (incontinence). This criticism is a part of the proof that courage is knowledge. In this paper I intend to clarify the construction of the criticism in view of the relation between this criticism and that proof.
What relates the criticism of acrasia to the proof of an identitiy of courage and knowledge is a hedonistic thesis, which is a premiss of both. Before driticising acrasia, Socrates introduces this hedonistic thesis :``in so far as things are pleasant, are they not to that extent good, leaving their other consequences out of account? '' Here Socrates insists on a strong hedonistic thesis, for once all other respects than pleasure or pain are disregarded, pleasure would be the only good.
On the other hand Socrates distinguishes two contradictory stand-points about knowledge ; one is that knowledge is something fine which can rule a man, and another is that often a man who possesses knowledge is ruled not by it but by something else -- in one case he is ruled by passion and in another by pleasure and etc. I call the latter standpoint `acrasia' view collectively, for this standpoint doesn't admit that knowledge rules a man who possesses it.
Then Socrates says that if the masses admit their hedonistic standpoint, it is ludicrous for them to say that a man often does bad things though he knows they are bad and could abstain from doing them, because he is overcome by pleasures. What is ludicrous about the point? This problem has been discussed in various ways. The majority of interpreters take `g'eloion' a logical absurdity. But we may not necessarily have to regard it that way, for there is a possibility to understand it literally, i.e. as a ludicrous expression. Masses' description of acrasia, however, reflects awareness of a man who talk about acrasia that there is a possibility of another (and better ) choice of action. In other words, it is a description which includes the direction of a better choice or knowledge rather than self-contradictory one. In this direction Socrates elaborates his idea of the technique of measurement. And it is the lack of this technique or a kind of knowledge that acrasia boils down to.
Thus Socrates accomplished both his criticism of acrasia and the persuasion of sophists holding the hedonistic thesis.