Sixteenth-century presumption theory.
A study of Jacopo Menochio’s De praesumptionibus (1587)

Based entirely on primary sources, this study traces how judicial proof was reconceptualised in the late sixteenth century, following Jacopo Menochio’s introduction of the distinction between artificial and inartificial proofs in his De praesumptionibus (1587). It offers a close textual analysis of the treatise’s theoretical section and of the network of works it engages with.

Although methodologically a strictly historical inquiry, the study shows how early modern debates on judicial proof shaped foundational legal categories such as the fact/law distinction, the general concept of contract, and the theory of interpretation.

The work aims to contribute to the expanding field of historical epistemology.

The images above illustrate the three reasoning patterns identified by Petrus Victorius in his 1547 Commentary on Aristotle’s Rhetoric. Each produces a different kind of conclusion: one that is necessary (fig. 1), one that is probable by abduction (fig. 2), and one that is probable by induction (fig. 3).

Jacopo Menochio adopted this framework to construct a theory of proof that was later taken up by the Natural lawyers and ultimately absorbed into modern codifications. Several major legal doctrines formulated in the late sixteenth century—such as the distinction between direct and indirect proofs, the separation of law and fact, contract theory, and the idea of interpretation—rest on this rhetorical foundation.