A key term in Sophistic rhetoric and philosophy of law.
Paradox of the Court (also called the Protagoras and Euathlus paradox) refers to a famous logical puzzle first recorded by Diogenes Laërtius. It arises from an agreement between the Sophist Protagoras and his pupil Euathlus: the pupil would pay his teacher only after winning his first court case. Protagoras later sues Euathlus for the fee. The two advance opposing arguments:
- Protagoras: If the court rules for me, Euathlus must pay by the judgment; if it rules for him, he has won his first case and must pay by contract. Therefore he must pay.
- Euathlus: If the court rules for me, I owe nothing by the judgment; if it rules for Protagoras, I have lost my first case and the contract condition is not met. Therefore I owe nothing.
Strictly speaking, both reason from the same premises to contradictory conclusions. The paradox is a classic example of self-reference in legal reasoning: the content of the court’s decision determines whether a contractual condition is satisfied, and that condition in turn determines what the decision should be.
Ancient reactions varied. Some later commentators suggested that the judge ought to decide against Protagoras, and then, in a separate suit, rule for him because the first case would constitute Euathlus’s first victory. Others argued that the problem is meaningless because a contract cannot validly set a condition that depends on a future judgment in a case about the contract itself—a form of circularity.
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The paradox illuminates the difference between logical validity and legal realism. Institutional law does not recognise purely circular payoffs; judges take into account the purpose of the contract, not just its letter. Yet the puzzle remains a useful tool for introducing students to self-reference, formal systems, and the limits of rule-based decision-making.
Referenced Works & Texts
- Diogenes Laërtius, Lives of the Philosophers, IX.50–56.
- W.K.C. Guthrie, A History of Greek Philosophy, Vol. III, Cambridge University Press, 1969, pp. 178–181.