Usury, and the Changing Shape of a Sin

Avarice is the vice whose treatment has changed most visibly with economic conditions. Medieval Christian moral theology, following Aristotle and a line of biblical texts, condemned usury, the taking of interest on a loan, as a species of avarice and as unnatural, since money was held to be barren; canon law prohibited it, and Jewish communities in Christian Europe were pushed into money-lending precisely because the prohibition applied to Christians, with consequences that fed centuries of antisemitism.

Islamic law maintains an analogous prohibition of riba, and modern Islamic finance is built around it. From the sixteenth century Christian theologians began to distinguish interest from usury and the prohibition eroded, though it was never formally repudiated in the way it is often assumed to have been. The history is a good corrective to the idea that the list of vices names fixed and self-evident wrongs; what counts as avarice has been argued over continuously.