In On Law and Economy in Society, Weber presents trial by ordeal as being the archetype of formal irrationality. Drawing on illustrations of ordeal from the ancient Near East to the present day, this article critiques Weber and argues that a more nuanced understanding of the operation of ordeal reveals flaws and inconsistencies in Weber’s understanding of the ordeal, and consequently his classification of the phenomenon as being formally irrational. Ordeal is also a phenomenon of duality; the first aspect of human and magico-religious judges works with power dramas and sleight of hand to conceal the bias of a law-finding judge in a multiplex society. The second duality of nature bridges what participants in the ordeal believe is happening and its operation in practice. This means that ordeal cannot readily be categorised as being formally irrational as Weber claims and instead bridges both formal irrationality and substantive irrationality.