Eristics

ERISTICS. – It is the art of disputation (ἐκέω “I contend”) with the aim of overcoming one’s opponent; it is commonly said that eristics is a degeneration of sophistry, but already Protagoras, on the assumption that no objective truth exists, taught how to make the worse argument prevail over the better: τὸν ἥττα λόγον χιέλτα ποιεῖν (some deny any connection between Protagoras’ doctrine and eristics, e.g.: A. Viale, Studi su Protagora, Gubbio 1942, p. 7 ff.).

Eristics was developed in practice in the Megarian school by Eubulides and Alexinus through a series of sophistical arguments, e.g. the liar (ὁ ψευδόμενος): if you are a liar and say that you are lying, at the same time you lie and tell the truth.