What does Thrasymachus say in Plato's The Republic?

Thrasymachus outlines his ideas about justice and its influence. Rather than ground his theory in objective truths about justice or reasons for adhering to its boundaries, Thrasymachus states that justice is always in the interests of the strong and that it pays to contravene justice as opposed to uphold it. The main thrust of Thrasymachus’s argument stems from the fact that those in power decide what justice is and therefore choose to serve their own interest with it. Furthermore, he argues that justice is employed to restrain our natural desires, which are better fulfilled by individuals if they disregard normative conceptions of justice and do not adhere to them. Rather than justice being beneficial in itself, it is those who do not act justly and act in their own self-interest who actually acquire the best outcome.In addition, Thrasymachus argues that a truly skilled individual will never fail to carry out their role properly and thus they are not truly skilled if they do make a mistake. Following this, Thrasymachus claims that a ruler will never make a mistake when he is ruling and is therefore infallible. This shows that Thrasymachus feels the convention of justice to be unnecessary and unfounded on account of the fact that he presents it as being imposed upon the individual, who gains no real benefit.