Brentano’s “Intentional In-Existence of the Object” as the Defining Mark of Mental Phenomena

In his Psychology from an Empirical Standpoint, Brentano lists several defining features of mental phenomena, including the most significant one: “the intentional (or mental) in-existence of an object”. Brentano’s notion of intentionality—a noun he never actually used—thus refers to the closely related concepts of “object” and “intentional in-existence.” These terms, in turn, have roots in Aristotle’s theory of perception and thought as they were interpreted by Medieval philosophy, and particularly by the Thomistic and neo-Thomistic traditions. When situated against this conceptual history, Brentano’s notion of intentionality emerges as a fundamental yet complex feature of mental phenomena, one which only seemingly is relational in nature and cannot be simply reduced to the concept of representation as it is commonly understood today. For Brentano, all mental features are grounded in intentionality, especially consciousness. This makes prevailing understandings of Brentano’s conception of inner consciousness as self-representational untenable.