Protagoras

Protagoras (c. 490 BC – 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 is also believed to have created a major controversy during ancient times through his statement that "man is the measure of all things", meaning that there is no truth but that which individuals deem to be the truth.