According to Brentano, what characterizes mental phenomena?

Brentano's characterization of mental phenomena is grounded in his emphasis on the intentionality of mental acts. Intentionality refers to the capacity of the mind to direct itself towards objects, ideas, or states of affairs, which imbues mental phenomena with meaning. This perspective posits that mental experiences, such as thoughts, desires, and emotions, inherently relate to something beyond themselves, thus reflecting a rich tapestry of significance.

In contrast, the other options do not align with Brentano's views. For instance, mental phenomena are not traditionally understood as measurable and objective, which pertains more to physical sciences rather than psychology's subjective nature. Additionally, while unpredictability can be a quality of some mental states, it is not a defining characteristic of mental phenomena according to Brentano. Lastly, sole reliance on physical evidence contradicts his argument that mental processes cannot be fully accounted for through physical means alone – highlighting that mental phenomena cannot be reduced to purely physical explanations.

Therefore, the correct answer emphasizes the inherent meaning found within mental experiences, consistent with Brentano's exploration of the intentionality and relational aspects of our mental life.