Protagoras of Abdera was one of the many 5th century Greek thinkers (including also Gorgias, Hippias, and Prodicus) better known as the oldest sophists in the world, they were a group of itinerant professors or intellectuals who considered themselves experts in rhetoric. (which was the science of oratory) and in matters related to it. It was and is mainly known for three claims: that man is the measure of all things (which is often interpreted as a kind of radical relativism ), that it could make the “worst (or weakest) argument appear better (More strong) “and that one could not know if the godsdid or did not actually exist. Although some ancient sources claim that these positions led to his being tried in Athens and his books burned, these stories may well have been later legends. Protagoras’s idea that judgments and knowledge are somehow relative to the person who judges or knows has been very influential and is still widely discussed in contemporary philosophy.

  • Occupation:  Sophist Philosopher
  • Why he’s famous: For being an expert in all things rhetoric

Who was Protagoras?

Protagoras was an important thinker in Greece during the 5th century. One of the most renowned sophists and one of the oldest as well. Itinerant and intellectual professor considered an expert in rhetoric , and in all matters related to it.

  • Biography of Protagoras
  • Thought of Protagoras
  • Contributions of Protagoras
  • Plays

Biography of Protagoras

According to information from ancient authors, Protagoras was a native of Abdera , although some thought that he was a native of Teos , a city located in Asia Minor. He was a faithful follower and disciple of Democritus and also related to some magicians of Persia when King Xerxes was expelled against Greece. He also worked as a loader and invented a cushion called tyle , which made the transport of loads lighter. He was part of the group of creators of rhetorical art and introduced the eristic reasoning. He charged hefty sums of money to teach and his educational trade earned him huge income even larger than the famous sculptors of the time. He led a wandering life teaching in different Greek cities. His relationship with Greece had two cycles, one in which he was closely related to the powerful of the city, and another, in which he was repudiated and condemned. Apparently he drowned during a trip he made to Sicily, when he was fleeing the accusations of impiety of which he was and the victim in the city of Athens (416 BC).

Thought of Protagoras

The main principle of Protagoras referred to the status of the human being when facing the world around him. For him, man was the measure of all things. It is usually designated with the expression Homo mensura which means “Man is the measure of all things”, and it was a phase widely used by him. For Protagoras, the sentence that was issued had different interpretations since it was difficult to determine the individual or collective meaning. He used three basic expressions:  the man, the measure and the things. The interpretation in the individual sense showed man as a concrete being. The interpretation in the collective sense had two different approaches, one that addressed the expression of each human social group and the other that considered it from a generic point of view. He strongly criticized all the superstitions and religious rites that existed in his time, but he always maintained an agnostic and skeptical position, not necessarily atheistic. Two famous dialogues by Plato , Theaetetus and Protagoras, refuted the doctrines of Protagoras.

Contributions of Protagoras

Its influence within the history of philosophy has been very significant for humanity. Historically, it was in response to Protagoras and his fellow sophists that Plato began the search for forms or more knowledge that were transcendent and could somehow anchor moral judgment . It was part of a shift in philosophical focus from the earlier pre-Socratic tradition of natural philosophy to an interest in human philosophy . He emphasized the way in which subjectivity Humanity determines the way in which we understand, or even construct, our world, a position that remains an essential part of the modern philosophical tradition.


Of his most important works that we can rescue are: Truth and On the gods , of which only some small fragments are preserved. The doctrine of Protagoras has been interpreted, since Plato (who dedicated a dialogue to it, entitled Protagoras), as a relativism that would be expressed in the famous maxim that “man is the measure of all things.” He affirmed that of objects we know not what they are, but what they appear to us to be, in other words, not the essence but the appearance, and at the same time he defended the conventional character of moral norms.

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