Sophism of Euathlos

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The sophism of Euathlos, also known as Antistréphon (Greek antistrephôn = the one who turns back ), is a well-known paradox of ancient Greek philosophy .

Euathlos was trained by Protagoras of Abdera (approx. 485-415 BC), the famous rhetorician and outstanding teacher of sophistry . They agreed that Euathlos would not have to pay for his education until he won his first trial. But now Euathlos took on another profession, therefore did not lead any lawsuits, consequently could not win any and therefore did not want to pay for his training. Protagoras then threatened him with a lawsuit and argued as follows: "Euathlos has to pay in any case: Either according to our agreement, because he wins this trial, or because the court condemns him to it." Euathlos, a Sophist well trained by Protagoras, held it however: "I do not have to pay under any circumstances, because either I lose the process, then my training was bad and the agreement continues to apply, or the court will rule in my favor."

From the point of view of traditional logic, this sophism only represents an apparent paradox because it violates the so-called identity principle . In this context, Euathlos has not one, but two different functional identities: on the one hand, he is a lawyer on his own behalf, and on the other hand, he is a defendant. Whether he has to pay or not therefore depends on the subjective point of view. This example is therefore of wonderful elegance to the followers of the Sophists.


  • Richard Goulet: Euathlos. In: Richard Goulet (ed.): Dictionnaire des philosophes antiques . Volume 3, CNRS Éditions, Paris 2000, ISBN 2-271-05748-5 , pp. 244-245
  • Peter Suber: The Paradox of Self-Amendment , Peter Lang, 1990, ISBN 0-8204-1212-0 ( online )
  • Friedrich Kirchner: Antistrephone . In: Kirchner: Dictionary of basic philosophical terms . Meiner, Leipzig 1907 ( online )