Licit and Illicit Risks in Thomas Aquinas’s De emptione et venditione ad tempus

Probability, Prudence, Danger: Thomas Aquinas on the Building of the Lexicon of Risk

“…a function going from states of the world to a set of consequences, we see on the one hand that whereas the formalisation of this function and the calculation of probabilities remain absent from Aquinas's work, the situations that would be described today in terms of a random variable do exist. On the other hand, we note that Aquinas's use of the lexicon of probability, prudence and danger shows the existence of a risk for all economic activities (namely analysis, sales and loans), for all agents (namely the seller, and Monsalve 2006;Franks 2009;Rajapakse 2010;Koehn and Wilbratte 2012;Ege 2014;Monsalve 2014a and2014b;Lapidus 2016 and2022;Dellemotte 2017: Sturn 2017Hirschfeld 2018;Santori 2019Santori , 2020Santori and 2021Koehler 2020;Januard 2021Januard , 2022aJanuard , 2022bJanuard , 2022c The nouns alea (chance, luck) and fortuna (luck, fortune), and the verbs angustio (to trouble, worry) or inquieto (to worry) and their derived forms are absent. The appearance of certain terms could be misleading.…”

“…The lexicon of prudence appears in the De emptione et venditione ad tempus, a short early letter in which Aquinas was dealing with forward selling (O'Rahilly 1928;Dondaine 1979, pp. 381-390;Januard 2022a;Januard 2022c). Aquinas distinguished between expenses that the merchant may licitly include in the price and those that he may not.…”