Mutual Recognition in the Philosophy of Physics: QBism, Phenomenology, Hegel

Recent developments in QBism (Quantum Bayesianism) have shifted focus toward its underlying ontology, particularly regarding agency and intersubjectivity. The paper addresses how QBism resolves Wigner's friend paradox by examining the relationship between two standard formulations: treating quantum states as personal probability assignments versus treating all users of quantum theory as agents on an equal footing. The author investigates the philosophical structures required to support this agential framework and asks why agency in QBism possesses a mutually recognitive structure.

QBism treats quantum mechanics as a single-user normative tool for guiding personal degrees of belief rather than a description of an external physical reality. When applied to Wigner's friend paradox, this subjectivist approach avoids contradictions by recognizing that different agents hold independent personal probability assignments based on their respective experiences. However, simply noting that other agents exist is insufficient to resolve the paradox without a deeper framework. The author argues that consistent intersubjective use of quantum theory requires agents to mutually acknowledge one another as autonomous loci of action and experience. Denying a friend's consciousness in favor of a super-observer's perspective undermines the very foundation of the observing agent's own capacity to use the theory.

While QBism establishes a formal requirement for mutual recognition among agents, it initially lacks an explanatory account of why agency possesses this structure or why solipsism should be rejected. To bridge this gap, the paper turns to the phenomenological ontology of Maurice Merleau-Ponty, which grounds the conditions of experience in intersubjectivity. The author then traces these themes further back to G. W. F. Hegel's account of mutual recognition in the lord-bondsman dialectic. Hegel's logical structure of self-consciousness provides an even more robust foundation than phenomenology alone, supplying novel conceptual resources to rigorously articulate and justify QBist ontology.