Individual, Self-Mastery, and the Common Good: Person as a Rational Subsistent in Aquinas

The notion of person has a long history both terminologically and conceptually. Even if it has its roots in Greek thought, it was primarily forged in Late Antiquity between Eastern and Western traditions and between Philosophy and Theology. An important milestone in this process was the Boethius’s formula individua substantia rationalis naturae, but its development in large part took place in Middle Ages, mainly with Thomas Aquinas. Both Boethius and Aquinas intended to unite Eastern and Western contributions, and perhaps this was the key to the success of their proposals. Aquinas considers the person as an individual with a peculiar dominion of its own acts on account of its rationality. Following Neoplatonic inspiration, he describes rationality as a mode of being able to perform an activity that gives the subject a special unity by returning into itself (reditio completa in seipsum). In this paper I propose that, for Aquinas, the “returning” of personal being (reditio) is not only reached through knowledge, but also through love. In this way, the being of a person is not only conserved, but it is increased in its intrinsic perfection.