The thesis of formal identity in Thomas Aquinas
Similarity; Knowledge; Formal Identity; Representation; Direct Realism.
When Thomas Aquinas states that our knowledge of material things occurs through similarity or through a process of assimilation, an ambiguity arises that gives rise to various interpretations. Even in the 13th century, this issue had already been the subject of criticism, notably the position of Peter Olivi, who argues that the notion of similarity, as presented by Thomas, implies a representative mental entity, whose nature would hinder or even prevent direct cognitive access to the world. In the 20th century, this debate gained renewed vigor among commentators on Thomas Aquinas, taking shape in two main interpretive currents: on the one hand, the direct realists; on the other, the representationalists. Direct realists argue that human cognition directly accesses external things; therefore, when Thomas mentions that we apprehend a similarity of the external world, the concept of ‘similarity’ must be understood as formal identity. Representationalist defenders argue that the cognitive act involves three elements: the thing, the knower, and a mental representation. The present study is dedicated precisely to investigating the adequacy of this thesis of formal identity in the context of Thomistic metaphysics of knowledge.