Which philosophical question addresses the existence of abstract concepts?

The philosophical question that addresses the existence of abstract concepts is indeed the Problem of Universals. This issue revolves around the nature of properties, concepts, and kinds, exploring how abstract ideas are related to the physical world. Specifically, it examines whether universals, such as "redness" or "beauty," exist independently of the objects that instantiate them or whether they are merely names or mental constructs.

Advocates of universals argue that these abstract concepts have a real existence that transcends individual instances. For example, when considering the concept of "justice," the Problem of Universals prompts us to ask whether justice exists as a standalone essence or simply as a label for various instances of just actions.

In contrast, the other philosophical problems listed do not primarily focus on the existence of abstract concepts. The Problem of Dualism generally explores the relationship between the mind and body, the Problem of Materialism denies the existence of anything beyond the physical, and the Problem of Idealism posits that reality is mentally constructed or immaterial. Thus, while all these philosophical discussions have significant implications in various areas of thought, the Problem of Universals specifically centers on understanding abstract concepts and their existence.