Abstract

I argue that Thomas Aquinas’s Identity Formula—the statement that the “intellect in act is the intelligible in act”—does not, as is usually supposed, express his position on how the intellect accesses extramental realities (responding to the so-called “mind-world gap”). Instead, it should be understood as a claim about the metaphysics of intellection, according to which the perfection requisite for performing the act of understanding is what could be called “intellectual-intelligible being.” In reinterpreting Aquinas’s Identity Formula, I explore the notion of being “in act” as an intellect or intelligible (intelligibile actu, intellectus actu), his curious comments about an “order” or “genus” of intelligibles, and the relationship of understanding and being-understood.