Antiphon the Sophist

Antiphon was an Ancient Greek philosopher, who lived in the 5th century BC. He is also known as Antiphon of Athens or Antiphon the Sophist, in English. His identity is not known. At the end of the 5th century, there were many people named "Antiphon" in Athens: There was a person that was writer, orator, and politician,called Antiphon the Orator. People do not agree if this was the same person as the philosopher. There was also a poet writing tragedies, a fortune-teller, and a person helping people make sense of their dreams. All of them were called Antiphon. 
Three works are attributed to Antiphon the Sophist
Antiphon was also a mathematician: By inscribing polygons on a circle he was able to give an upper and lower limit for the value of Pi.This was later used when people tried to square the circle.