Is quantum mechanics merely a theory for us?

TL;DR

The paper tackles how definite classical facts arise from quantum superpositions without appealing to an absolute, observer-independent basis. It develops an agent-centric perspectival account in which the system–environment decomposition and the observables that decohere are fixed by an embodied agent's physical constitution and epistemic constraints, with decoherence producing stable, public facts for that agent class. By integrating decoherence, causal perspectivalism, and embodied phenomenology, the work reframes measurements as agent-relative interactions and treats quantum mechanics as a structurally real, human-conditional description of world interactions rather than a universal, disembodied theory. This approach addresses no-go results for relational quantum mechanics by grounding basis selection in embodiment, offering a principled path to objectivity and classicality that emerges from embodied engagement with the world, while acknowledging that intersubjective consistency across divergent agents remains an avenue for further exploration.

Abstract

This paper develops an agent-centric account of measurement that treats the preferred-basis problem is fundamentally perspectival. On this view, the system--apparatus--environment decomposition and the observables that are apt to become classically robust are determined by the physical constitution and epistemic constraints of an embodied class of agents. Decoherence then stabilises those agent-specified observables, yielding facts that are stable for us without positing an absolute, observer-independent basis. On this picture, `measurements' are public not because they are metaphysically privileged, but because agents like us share the relevant sensorimotor and operational structure. I motivate this account through a discussion of two recent no-go results for relational quantum mechanics (RQM) (Brukner,2021;Pienaar,2021), and a subsequent response (DiBiagio and Rovelli, 2022): my aim is not to defend RQM per se, but to refine the relational insight with a principled account of basis selection rooted in embodiment. I provide a phenomenological gloss, drawing on body-schema considerations, to argue that quantum mechanics is best understood as an idiosyncratically human description of interactions with the physical world -- a structurally constrained, agent-indexed framework within which classicality emerges.