of Abdera was one of several fifth century Greek thinkers (including also Gorgias, Hippias, and Prodicus) collectively known as Older Sophists, a group of traveling teachers of intellectuals who were experts in rhetoric (the science of oratory) and related subjects. Protagoras is known primarily for three claims 1) that man is the measure of all things (which is often interpreted as a sort of radical relativism) 2) that he could make the “worse (or weaker) argument appear the better (or stronger)” and 3) that one could not tell if gods existed or not. While some ancient sources claim that these positions led to his having been tried for impiety in Athens and his books burned, these stories may well have been later legends. Protagoras’ notion that judgments and knowledge are in some way relative to the person judging or knowing has been very influential, and is still widely discussed in contemporary philosophy. Protagoras’ influence on the history of philosophy has been significant. Historically, it was in response to Protagoras and his fellow sophists that Plato began the search for transcendent forms or knowledge that could somehow anchor moral judgment. Along with the Older Sophists and Socrates, Protagoras was part of a shift in philosophical focus from the earlier Presocratic tradition of natural philosophy to an interest in human philosophy. He emphasized how human subjectivity determines the way we understand, or even construct, our world, a position that is still an essential part of the modern philosophic tradition.
Internet Encyclopedia of Philosophy