Thrasymachus was an ancient Greek philosopher born in Chalcedon in 459 BC. He was a sophist, traveling to different cities in Greece such as Athens to teach for money. He is famously depicted in Plato’s Republic arguing with Socrates about the nature of justice. Thrasymachus says that justice is simply the advantage of the stronger, since those in power create laws (nomos) that benefit themselves. Thrasymachus says people should, therefore, pursue injustice i.e. what is to their own advantage. He also said that the Gods clearly do not care about humans since they don’t enforce justice. Thrasymachus’ position, although cynical, was based on his understanding of the realities of political life in Athens at the time.

In the Republic, Thrasymachus says that those in power create laws (nomos) that serve their best interests. Socrates says that isn’t always the case, since rulers will sometimes make laws that are not in their best interest. Thrasymachus responds by saying that a “true ruler” would never do this, which is seen as a precursor of Machiavelli’s statement in the Prince, written in the 16th century, that a true statesmen doesn’t restrain himself in any way when it comes to maintaining his position of power. Seeing a city’s laws as serving the interests of the rulers rather than the citizens, Thrasymachus says that “justice is the advantage of the stronger.” He therefore says that people should instead pursue their own interests i.e. injustice.

Thrasymachus sees laws as the means by which the strong maintain their rule over the weak (“might makes right”). When justice is defined as obedience to these laws, as is normally the case, then justice becomes simply the citizens doing what is in the best interest of the rulers instead of what is in their own best interest. Thrasymachus is critical of this form of legalism. Like other sophist such as Antiphon and Callicles, he believes that instead of following laws (nomos), people should follow physis (i.e. “natural law”) and in this way will truly pursue virtue (arete) and find happiness. The government is an obstacle to self-fulfillment.

Callicles, another sophist, chose to redefine justice as pursuing one’s own advantage (physis) instead of the advantage of others (nomos). Thrasymachus agrees with Callicles, but instead of redefining justice in this way, instead he simply says by pursuing physis we should embrace injustice as a virtuous way of life. In this way, Thrasymachus brings up all sorts of questions of importance for social, moral, and political philosophy such as why we should act just rather than unjust if being unjust is more advantageous, and whether people should care about others i.e. social responsibility. Do rulers have certain responsibilities to their subjects? Do the subjects have rights? Should the strong rule over the weak? The questions provoked by Thrasymachus will be addressed seriously by Plato in the remainder of the Republic.

Thrasymachus’ role in his debate with Socrates is also seen as showing the limits of the Socratic Method. Because Thrasymachus does not acknowledge that justice is a virtue, Socrates is unable to move forward in the discussion. Thrasymachus’ unconventional position has also been seen as a precursor to Nietzsche, who studied ancient Greek philosophy, and believed that moral values were social conventions created by different political communities to serve their own purposes. In this way, Thrasymachus’ bold position both reflects the thoughts of his time, what is known as the Sophistic Enlightenment, as well as has served as a launching point for ethical and political thought in the Western philosophical tradition.