Protagoras

Protagoras was a pre-Socratic Greek philosopher and a leading figure among the Sophists.

He lived during the fifth century BC and was highly influential in ancient Greece. Plato identifies him as the inventor of the professional Sophist role. Sophists were teachers who provided instruction in various subjects to students. Protagoras focused on teaching virtue and the skills needed for political life. He aimed to help people contribute effectively to their cities through both words and actions.

Legendary accounts describe a unique beginning to his education.

According to Aulus Gellius, Protagoras worked as a porter before becoming a philosopher. One day, the philosopher Democritus observed him carrying a load of wood. The wood was tied together with perfect geometric accuracy using a short cord. Democritus believed Protagoras was a mathematical prodigy because of this skill. He took Protagoras into his household to teach him philosophy. However, Protagoras did not share Democritus's enthusiasm for theoretical mathematics. He argued that perceptible lines in the natural world are not perfectly straight or curved. He believed the subject matter of geometry was often unknowable or distasteful.

Protagoras is most famous for the concept of relativism. He expressed this in his book titled *Truth*, which is also called *Refutations*. His most famous statement was: "Man is the measure of all things: of the things that are, that they are, of the things that are not, that they are not." This idea suggests that truth is relative to the individual. For example, if one person feels cold and another feels warm in the same breeze, both are correct. Their personal histories, experiences, and expectations determine their specific judgments. Plato interpreted this to mean there is no objective truth. However, Protagoras likely meant that individual perceptions define what is true for that person.

This philosophy of relativism had important social implications. Protagoras believed that respecting different opinions is necessary for a healthy community. He argued that democracy relies on open debate between people with different views. While he believed all views might be equally true to the person holding them, he did not say they were equal in importance. He taught that some perceptions could be harmful or lead to an ill mind. Therefore, he believed a Sophist should teach students how to discriminate between useful and harmful views. This process of learning to choose well is what he defined as teaching virtue.

Protagoras was a versatile teacher with a wide range of interests. He taught the proper management of households and public affairs. He also studied *orthoepeia*, which is the correct use of words. This included analyzing the literal meaning of words and an author's original intent. He even developed a taxonomy of speech acts, such as commands, questions, and assertions. His work extended to grammar, where he studied the classification of grammatical gender. He also wrote *Technique of Eristics*, a book about the practice of intellectual debate. Some critics, including Aristotle, claimed he taught people how to make weaker arguments appear stronger.

His views on religion were also quite distinctive and controversial. In his lost work *On the Gods*, he expressed a position of agnosticism. He wrote that he had no way of knowing if gods existed or what they were like. He cited the obscurity of the subject and the brevity of human life as reasons for this uncertainty. Some historical accounts, such as those by Diogenes Laërtius, claim this caused great anger in Athens. It is said the Athenians expelled him and burned his books in the marketplace. However, the historian John Burnet doubts this story. He notes that many of Protagoras's ideas survived to be discussed by later thinkers.

Estimating the exact dates of his life requires looking at surviving writings. Plato's dialogue *Protagoras* suggests he was old enough to be the father of other famous thinkers. This implies he was likely born no later than 490 BC. In the dialogue *Meno*, it is said he died at approximately age 70 after 40 years of practice. This would place his death around 420 BC, though this is not certain. Despite the loss of many of his original books, his influence on philosophy remains significant. He helped shape how people think about language, law, and the nature of truth.