In this paper, I explore one line of argument for the Humean Theory of Reasons, the view that all normative reasons are based on desires. Then, I suggest a way to block that argument inspired by Aquinas’s discussions on choice, will, and indeterminacy of reason alone.

The essay deals with Aquinas’theory of person, focusing especially on the relevance of this qualification in Saint Thomas’ theory of the «spiritual substances», on his rejection of Platonism and on his peculiar use of the Neoplatonic hierarchy of the intellecitve substances. We especially stress that Aquinas’functionalist theory of person places the concept of «dignity» as the ultimate foundation of rationality, understanding the latter as a specific assignement and a specific responsibility in the order of Creation.