One Good: The Mathematics of Ethics

Probably during the years at the Academy, Aristotle wrote a work known as Peri tagathou, on the good, exposing Plato’s teachings on the principles. Various sources confirm that Plato gave public lectures on the theme of the good, most notably Aristoxenus of Tarentum, who would in turn become Aristotle’s student. In his treatise on harmony, Aristoxenus recalls that, while many would gather to listen to Plato, they would leave dismayed since, instead of hearing about the good in the quotidian sense of the term, they would be subjected to speeches on mathematics and geometry, culminating with the statement of the identity of the good and the one. It is apparently in the course of these teachings that Plato laid out the so-called “doctrine of principles or origins,” which in recent years has been at the center of much research, especially in the circles of Tübingen and Milano. The essay considers the doctrines on the good from their pre-Socratic formulations to Aristotle's sustained reflection, traversing the ethico-political, psychological, physical, and logical investigations.