Callicles was an ancient Greek philosopher who lived in Athens in the 5th century BC. He was a friend of the sophist Gorgias, who taught rhetoric (public speaking) for money. Callicles appears as a character in Plato’s dialogue Gorgias discussing with Socrates the belief that the strong should rule over the weak (“might makes right”). This belief was used to support the tyrants who had come to power in Athens at the time, such as the Thirty Tyrants, whose oligarchic rule (rule by few) convinced Plato against going into politics. Callicles believed that some people are naturally superior and that they should use this to their advantage. Human laws (nomos), in contast, are a way for the weak to have more than they would otherwise.
Callicles denies that there is any divine basis for human laws. He sees human laws (nomos) as a perversion of the laws of nature (physis), by which the strong are supposed to rule over the weak. Because most people are weak, according to Callicles, they have come together to create laws and governments in order to have more than they would otherwise. They then declare justice to be obedience to their laws. He encourages those who are naturally superior to see through this sham, and instead pursue their own advantage (physis). For Callicles, this is true justice. Nietzsche, a student of Greek philosophy, will also put forth this position in the 19th century.
Callicles puts forth the position that everyone should do what is in their best interest (this is known as ethical egoism). He believes that this is accomplished when everyone tries to satisfy their own desires (this is known as hedonism). Those who are best able to satisfy their own desires are indeed better than everyone else, attaining both virtue (arete) and happiness. In response to Callicles, as well as the views of the other sophists, Plato will present his own understanding of justice in the Republic.