Foundations of Physics

Relational Quantum Mechanics and (Soft) Perspectivism

Niccolò Covoni, Vincenzo Fano, Marco Sanchioni

Published Dec 18, 2025• 4 citations

Abstract

Abstract This paper examines the role of perspectivism in Relational Quantum Mechanics, situating it within the broader landscape of quantum interpretations and the scientific realism debate. We argue that, while interpretations such as QBism embrace strong forms of perspectivism, Relational Quantum Mechanics adopts a “soft” perspectivism, limiting the observer’s role to selecting experimental contexts without compromising its realist framework. We also explore the historical roots of Relational Quantum Mechanics, showing that relational ideas in the works of Bohr and other pioneers similarly avoided strong perspectivist commitments. By analyzing both contemporary and historical perspectives, we argue that Relational Quantum Mechanics offers a minimalist yet robust relational interpretation, distinct from more subjectivist approaches.

DOI: 10.1007/s10701-025-00906-6

Related papers

QBism and relational interpretation of quantum mechanics from the point of view of a contextual quantum realism (CQR)

François-Igor Pris

A realist interpretation of quantum mechanics is proposed - Contextual Quantum Realism (CQR) - according to which there exists a categorical distinction between the ideal (theory, observation instrument) and the real (quantum physical systems, properties), and, consequently, quantum ontology is context-sensitive. CQR is compared with QBism and Relational Quantum Mechanics (RQM), both of which also claim to offer realist interpretations. However, both approaches conflate the ideal and the real, thereby introducing an anti-realist dimension. RQM is an objectivist (physicalist) interpretation that naturalizes epistemic concepts, whereas QBism is subjectivist (phenomenological). RQM and QBism share a common presupposition of (post-)Modern philosophy - namely, the reduction of reality to objectivity - which CQR explicitly rejects.

arXiv:2510.09237Oct 10, 20250 citations

The Observer as an Agent: Relational Quantum Mechanics, QBism, and the Problem of Subjectivity

Michael Shatnev

The role of the observer remains a central conceptual challenge in the foundationsof quantum mechanics. This work examines the observer as an agent whoseparticipation is structurally indispensable for the emergence of physical facts. RelationalQuantum Mechanics and QBism—two influential agent-centered interpretations—recast quantum states, measurement outcomes, and objectivity as relationalor personalist rather than observer-independent. By analyzing their conceptualcommitments, we clarify how these frameworks illuminate the problem of subjectivityand the limits of classical realism.The discussion extends beyond physics to the broader question of whether agencyand subjectivity can be eliminated from scientific and technological practices. Drawingon insights from Pauli, Stapp, and d’Espagnat, we argue that attempts tofully operationalize the observer obscure essential features of experience and understanding.Contemporary artificial intelligence systems exemplify this tension: theydemonstrate high functional performance while lacking subjectivity, intentionality,and responsibility.We suggest that the displacement of the subject—from quantum interpretationto algorithmic decision-making—reflects a deeper structural shift in modern knowledge.Treating the observer as an agent is not merely an interpretive option but aconceptual requirement for coherent accounts of measurement, understanding, andresponsible action in an age increasingly shaped by operational intelligence withoutsubjects.

Feb 6, 20260 citations

Phenomenology, Perspectivalism and (Quantum) Physics

Steven French

Abstract It has been claimed that Massimi’s recent perspectival approach to science sits in tension with a realist stance. I shall argue that this tension can be defused in the quantum context by recasting Massimi’s perspectivalism within a phenomenological framework. I shall begin by indicating how the different but complementary forms of the former are manifested in the distinction between certain so-called ‘-epistemic’ and ‘-ontic’ understandings of quantum mechanics, namely QBism and Relational Quantum Mechanics, respectively. A brief consideration of Dieks’ perspectivism will then lead to a consideration of the much-maligned and typically dismissed role of the observer in the measurement process. This opens the door to London and Bauer’s presentation of a form of ‘phenomenological quantum perspectivalism’ that brings together Massimi’s two forms and explicitly eschews the ‘naïve’ realism that creates the above tension. I shall conclude with some reflections on how intersubjectivity can still be established within this framework, focusing in particular on how Massimi’s idea of ‘interlacing’ scientific perspectives can be accommodated, using the example of a ‘new cosmopolitanism’ that gave rise to Bose-Einstein statistics.

Foundations of PhysicsMay 28, 20246 citations

Perspectival Quantum Realism

Dennis Dieks

Abstract The theories of pre-quantum physics are standardly seen as representing physical systems and their properties. Quantum mechanics in its standard form is a more problematic case: here, interpretational problems have led to doubts about the tenability of realist views. Thus, QBists and Quantum Pragmatists maintain that quantum mechanics should not be thought of as representing physical systems, but rather as an agent-centered tool for updating beliefs about such systems. It is part and parcel of such views that different agents may have different beliefs and may assign different quantum states. What results is a collection of agent-centered perspectives rather than a unique representation of the physical world. In this paper we argue that the problems identified by QBism and Quantum Pragmatism do not necessitate abandoning the ideal of representing the physical world. We can avail ourselves of the same puzzle-solving strategies as employed by QBists and pragmatists by adopting a perspectival quantum realism. According to this perspectivalism (close to the relational interpretation of quantum mechanics) objects may possess different, but equally objective properties with respect to different physically defined perspectives. We discuss two options for such a perspectivalism, a local and a nonlocal one, and apply them to Wigner’s friend and EPR scenarios. Finally, we connect quantum perspectivalism to the recently proposed philosophical position of fragmentalism.

arXiv:2211.05674Foundations of PhysicsAug 1, 202221 citations

Info-Computation and Observer-Dependence in Quantum

Gordana Dodig-Crnković

Quantum mechanics reveals that physical quantities and informational states are not absolute but relational, depending on the context of interaction between systems. While classical physics already contained relational elements—most clearly in Galilean relativity and Einstein’s relational spacetime—the quantum domain extends relationality to physical properties and facts themselves. In this paper, I develop an info-computational perspective on relational quantum mechanics (RQM), conceiving observers as informational agents embedded within physical processes. Quantum states are understood as constraints on possible interactions rather than intrinsic attributes of isolated systems. I review key relational, perspectival, and information-theoretic approaches—including QBism, perspectival quantum realism, reference-frame–dependent observables, categorical quantum mechanics, and graph-based formalisms—and argue that they converge on a view of physics grounded in relations and information flow. Relational objectivity emerges through inter-agent translation rules rather than observer independence, providing a unified framework for understanding quantum measurement, inter-observer agreement, and physical ontology.

Jan 14, 20260 citations

Many Worlds, Many Minds, and (Many) Relations

Steven French

Abstract Accounts of quantum theory that bring to the fore the relationship between the system and the observer, or measuring device, include Everett’s ‘Many Worlds’ interpretation and Rovelli’s ‘Relational Quantum Mechanics’, both of which are considered in Chapter 9. The former understands the state of a system as relative to that of the observer and in Everett’s original formulation, the definite outcomes obtained through measurement were manifested via the observer’s memory sequences. The subjectivist aspect of this interpretation is made even more explicit in the so-called ‘Many Minds’ variant. Relational Quantum Mechanics likewise adopts a relational or perspectival approach to the states of the system under observation. In this chapter both approaches are considered as offering a way of aligning quantum theory with the correlationist feature of phenomenology. Both are then compared with QBism and the pros and cons of all three are considered in terms of possible avenues for developing a phenomenological form of quantum theory.

Nov 23, 20230 citations