Abstract

The article analyzes the occurrences and meaning of the expression ratio practica in the works of Albertus Magnus and Thomas Aquinas. A lexicographical survey shows that ratio practica appears in the philosophical vocabulary of Latin medieval philosophy starting from the second quarter of the thirteenth century. In particular, it occurs with some frequency in the early works of Albertus Magnus (before 1250), who uses ratio practica in connection with Augustine of Hippo’s theory of the double reason (ratio superior and ratio inferior). Albertus seems to abandon the use of ratio practica when he begins to engage with the exegesis of Aristotle. Notably, he uses it negligibly in the two commentaries on the complete version of the Nicomachean Ethics, of which, before 1250, he only knew the fi rst three books (Ethica nova and vetus). In contrast, Thomas Aquinas frequently uses the expression ratio practica, but only in contexts related to the psychological process preceding action, which Aristotle had primarily described in the Nicomachean Ethics. In short, thanks to Thomas, ratio practica is characterized as an Aristotelian notion, while Albertus’s merit lies in introducing it into the philosophical vocabulary.