The Republic

Thrasymachus is the only sophist of the group, making his impassioned argument with Socrates especially significant. His emotional response to Socrates's cool and calculated logic emphasizes the major distinctions between the sophists and philosophers: the former practice rhetoric seeking to persuade, the latter practice logic seeking truth. Indeed, the fact that Thrasymachus gets angry and storms out of Cephalus's house prevents him from learning about justice with the rest of the group, something a true lover of wisdom would never do.

Glaucon and Adeimantus are far more open-minded, even when they disagree with Socrates. After Thrasymachus storms out in Book 1, Glaucon and Adeimantus trade off as interlocutors (alongside Cephalus and Polemarchus) for the rest of The Republic. As opposed to the ever-argumentative Thrasymachus, Glaucon and Adeimantus simply know less than Socrates (although Socrates himself might disagree with that claim). They are foils for Socrates in that they always further the investigation into justice. Often they agree with Socrates, but even when they propose arguments or counterarguments Socrates appears to successfully rebut them. Ultimately, they highlight and help showcase Socrates's wisdom, which is important for maintaining Socrates's ethos, for adding weight to Socrates's arguments, and for maintaining the privileged position of philosophers within The Republic and the ideal state.