Giles of Rome on Sense Perception

Giles of Rome maintains that the senses are passive powers and more specifically receptive powers, that is, powers to receive something from sensible objects. The items that the senses receive from sensible objects are (sensible) intentional species of the corresponding sensible forms. This paper deals with Giles’s account of the cognitive role of intentional species in sense perception. The central question is how the intentional species of red received in the eyes is related to the act of seeing a red apple. Is such a species the act itself of seeing a red apple or rather something distinct from the act and causally related to it? And in the latter case, what kind of causality is involved? We shall see that Giles changed his mind on this subject, so that we have an early view and a mature view. His early view (found in his commentary on De anima) is that the intentional species is distinct from the corresponding sensory act and a cause of it, more precisely a formal cause. His mature view (found in De cognitione angelorum) is that (i) in the case of the external senses the intentional species is the same as the sensory act itself, whereas (ii) in the case of the internal senses two kinds of intentional species are involved, that is, that which is the same as the sensory act and another one that acts as a proxy for the sensible object.