Identify the appropriate type of perspectivism for classical Relational Quantum Mechanics

Determine which specific version of realism about perspectival facts—privileged-perspective realism, fragmentalism, or external relativism—should be adopted to provide a coherent metaphysical foundation for classical Relational Quantum Mechanics, clarifying how the interpretation’s "relative facts" are to be understood within that framework.

Background

The paper argues that classical Relational Quantum Mechanics (RQM) is best reconstructed with the Unrestricted Iteration Principle (UIP), which renders a straightforward relationalist reading untenable and instead points toward a perspectivist framework. However, the literature has not settled which variety of perspectivism is suitable, and Fine’s trilemma highlights competing options (privileged-perspective realism, fragmentalism, external relativism) with distinct costs.

The author explicitly lists the type of perspectivism appropriate for RQM as an open question that needs addressing to complete the conceptual development of perspectivist versions of RQM.