Presumption as a form of reasoning
A study of Jacopo Menochio’sDe praesumptionibus (1587)

Based exclusively on primary sources, this study charts the reformulation of judicial proof in the late 16th c. following the introduction of the dualism of direct/indirect (or artificial/inartificial) proof in Jacopo Menochio’s treatise De praesumptionibus (1587). This study is a textual analysis of the theoretical section of this treatise and of the network of texts recalled by this work.

Although methodologically this is a strictly historical study, it shows the relevance of historical judicial proof (and broadly of the question of fact) to the formation of some basic legal categories (e.g. dualism fact/law, general category of contract, interpretation).

This study is meant to be a contribution to the growing field of historical epistemology.


Above pictured are the three figures of enthymeme in Pier Vettori’s Commentary on Aristotle’s Rhetoric (1547). Menochio used this text to create his theory of presumptions. Fig 1 and 2 illustrate respectively (1) presumption juris et de jure and (2) pres. juris and pres. hominis. Fig. 3 illustrates the induction.