What is the defining characteristic of the mind according to Brentano?

According to Franz Brentano, the defining characteristic of the mind is intentionality. Intentionality refers to the quality of mental states that are directed towards or about something; that is, our thoughts and feelings always have an object or referent. Brentano famously stated that "every mental phenomenon is characterized by the fact that it refers to a something, an object." This means that when we think, feel, desire, or imagine, we are always engaged in a mental act that is aimed at an external or internal object, which is a fundamental aspect of how we understand and conceptualize our mental experiences.

This concept was highly influential, laying groundwork for later existential and phenomenological philosophies, especially in the work of philosophers such as Edmund Husserl, who expanded on Brentano's ideas. In contrast, other options like consciousness, behavioral response, and subconscious motivations describe aspects of psychology but do not capture the essence of what Brentano identified as distinctive about mental processes. Intentionality uniquely underscores the directedness of mental phenomena, making it a crucial aspect of Brentano's philosophy of mind.