Analysis risk and commercial risk: the first treatment of usury in Thomas Aquinas’s Commentary on the Sentences

Abstract

Whereas literature on Thomas Aquinas’s doctrine of usury has tended to focus on the Summa Theologiae, this paper highlights the contribution of his early work the Commentary on the Sentences. In this work, Aquinas distances himself from the Roman law mutuum and the assumption of a borrower’s state of necessity, and he introduces preliminary monetary elements. He thereby paves the way for a future understanding of surplus in intertemporal exchange. The monetary loan is presented as a commercial exchange involving not only commercial risk but also the risk of analytical errors in understanding the nature of the operation.