In this chapter, the metaphysics of quantum possibilities, as a form of res potentia, is discussed. The transactional picture, together with quantum possibility, can be understood in terms of Kant’s contrast between phenomena and noumena, with quantum possibility constituting an element of the noumenal realm. This formulation sheds light on the connection between the two realms. It also provides a “middle way” between realism and antirealism and resolves puzzles surrounding the notion of causation. Concerns about structural realism are also addressed.