Protagoras (Greek: Πρωταγόρας; c. 490 – c. 420 BC) was a pre-Socratic Greek philosopher and is numbered as one of the sophists by Plato. In his dialogue, Protagoras, Plato credits him with having invented the role of the professional sophist.

He also is believed to have created a major controversy during ancient times through his statement that, "Man is the measure of all things", interpreted by Plato to mean that there is no absolute truth, but that which individuals deem to be the truth. Although there is reason to question the extent of the interpretation of his arguments that has followed, that concept of individual relativity was revolutionary for the time, and contrasted with other philosophical doctrines that claimed the universe was based on something objective, outside of human influence or perceptions.

Protagoras was a Greek philosopher, thinker and teacher. He is considered as the most famous of Greek Sophists. In fact, he is attributed for inventing the role of a professional Sophist. He is the one who introduced the contemporary dialogue on morality and politics to Athens and taught on subjects like, how human beings ought to manage their personal affairs and manage their household in the most efficient way, how to run the social affairs and most importantly, how to contribute to the society in general through one’s words and actions. In his role as a Sophist, which he continued for over 40 years, he continually raised the questions whether or not virtue is something that can be taught. He also professed relativism, which meant that truth is an individual based concept as what is true for one person can be false for another, depending on their varied perceptions. He was also a propagator of agnosticism and got into trouble with the Athenians as he claimed his skeptic thoughts over the existence of God in his book ‘On the Gods’.

Childhood & Early Life

Protagoras was born in Abdera, Thrace, in Ancient Greece. It is said that he was a porter and earned his living through shifting objects for others. He was once seen by philosopher Democritus while he was carrying some load.

Democritus was amazed at the defined technicality with which Protagoras had tied the load together. His faultless geometric precision bound Democritus to recognize him as a mathematics genius. He took him under his wings and introduced him to philosophy.

Life & Philosophy

Protagoras became a teacher and used to teach and profess the ideals related to politics and virtue. He was occupied with the matter of whether virtue can be taught or not throughout this philosophical career.

He was not like the other educators of his times, (who were involved with definite teaching in public speaking and oratory); rather he was more interested in teaching his students to reason the various phenomena one faces in human life.

Protagoras taught how human beings ought to manage their personal affairs and household in the most efficient way, how to run the social affairs and most importantly, how to contribute to the society in general through one’s words and actions.

Protagoras was interested in the matter of ‘orthoepeia’, which means that he believed in the most accurate use of words and grammar. It is also said that he invented taxonomy of speech acts like assertion, question, answer, command, etc.

He wrote ‘The Technique of Eristics’ - the book suggests that he was a teacher of public speaking and debate. It is also said that he was the first philosopher to take part in the oratory contests in the Olympic Games.

His famous work ‘Truth’, establishes him as a philosopher of relativism. He said in the book-- "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."

His philosophy of relativism meant that truth is relative and depends on the individual who perceives it as every individual has a different perception and criteria of identifying with the situation. His theories tend to contradict the objective truth.

Plato credits relativism to Protagoras and used his teachings as testing material for his own dedication to objective and transcendent realities and values. He attributes him to phenomenalism, where truth differs for each individual.

Protagoras was a promoter of skepticism. In ‘On the Gods’, a work now lost, he wrote that he was skeptic about existence of god. This caused anger among Athenians and he was exiled; all the copies of his work were destroyed.

Some of Protagoras’ works that was preserved through the centuries are: ‘Antilogiae’, ‘Truth’, ‘On the Gods’, ‘Art of Eristics’, ‘Imperative’, ‘On Ambition’, ‘On Incorrect Human Actions’, ‘on Virtues’, ‘On the Original State of Things and Trial over a Fee’, etc.

Major Works

The most prominent work from Protagoras, the work that Socrates extensively used in his later studies and philosophies, is his philosophy of relativism, in which he revealed that truth is relative and depends on how each individual perceives it.

Personal Life & Legacy

Protagoras is said to have died at the age of 70 and it is assumed that his death occurred circa 420.


Protagoras practiced as a Sophist for 40 years.

He was famous in Athens and was a friend of Pericles.

More on Personal Life & Legacy [2]

Protagoras was accused of impiety when he was seventy years old in c. 415 BCE; a charge in ancient Greece which carried a penalty of death. This was the same charge, which amounted to denying the traditional gods of Greece and promoting atheism, later leveled against Socrates in 399 BCE and which led to his execution. Many people were routinely charged with impiety and were able to pay a fine or otherwise escape prosecution but Protagoras chose, instead, to leave Athens before he could be brought to trial. He drowned at sea while trying to reach the Greek colony at Sicily.

Although his relativism was repeatedly, and brilliantly, refuted by Plato and those who followed him, Protagoras' thought continues to resonate and intrigue people in the present day. In spite of all the rational, objective, critiques of Protagoras' central claim, the concept of everything as relative to individual interpretation is impossible to completely refute. Protagoras lay the foundation in the west for questioning the most fundamental ideas about reality and perception in suggesting that the world one person sees may be radically different from the world their neighbor is experiencing.



[1] "The Famous People"

[2] "Ancient History Encyclopedia" by Joshua J. Mark

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