The Challenge of Thrasymachus: Knowledge and Advantage

Emmet Penney
2 min readSep 8, 2020


4. Knowledge and Advantage

Once Socrates has Thrasymachus’ consent he makes a crucial maneuver. Socrates asks him if he thinks rulers make mistakes when they lay down laws. No fool, Thrasymachus assents. But Socrates then relates that to his previous point. If rulers make mistakes, then sometimes they legislate to their disadvantage, which means that subjects in obedience to those laws (a just act in and of itself) actually harm the regime. Thus, justice can’t simply be the advantage of the stronger and that conception of justice can’t necessarily work in tandem with recognizing obedience as justice. First, it seemed that the advantage of the stronger worked well with obedience, as I laid out above. But now, they’ve been disaggregated because Socrates has braided together governance with knowledge. While Thrasymachus’ definition of justice applied to multiple political regimes, Socrates’ line of argument has narrower permissions for legitimate rule.

Of course, Thrasymachus’ definition didn’t necessarily exclude the possibility of folly. Rather, he was making an empirical observation of a trend rather than an iron law of rulership. Yet his feet sink in the quicksand of the Socratic dialectic. He concedes to Socrates the equation of knowledge as the determinate of political advantage. In other words, rulers don’t automatically rule in their own interest, because they have to know what is and is not in their interest in the first place. In hoping to clarify his position, and to distance himself from Cleitophon’s far more radical intervention that advantage is whatever the strong think it is, Thrasymachus contends that you don’t call a cobbler a cobbler because he’s bad at making shoes. Rather, you call him a cobbler because he makes shoes at all. And that goes for rulers, too.

Or, that would be the more persuasive case to make. Instead, Thrasymachus claims Socrates is a sycophant who purposely misconstrues his arguments to do him harm. That’s only half-way true. Thrasymachus hurts his own position by insisting that “the ruler, insofar as he is a ruler, does not make mistakes; and not making mistakes, he sets down what is best for himself. And this must be done by the man who is ruled,” (341a). He accepts Socrates’ sleight of hand, his subtle yoking together of knowledge and rule, the moment he insists on the “rightness” of a given ruler.

This moves them along to the next phase of their engagement.

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