Objective but Non-Fundamental

Objective but Non-Fundamental: Einstein’s Statistical Interpretation, PBR, and Bohmian Mechanics

Lugano Philosophy Colloquia. Valia Allori

Quantum mechanics is empirically extraordinarily successful, yet the status of the wavefunction remains contested. This paper argues that the standard ψ-ontic/ψ-epistemic distinction obscures a possibility central to Einstein’s statistical interpretation: the wavefunction may be objective and physically significant without being either complete or fundamental. Analogous to a thermodynamic macrostate, ψ characterizes higher-level statistical regularities arising from a deeper microphysical reality. This perspective also qualifies the significance of the Pusey–Barrett–Rudolph (PBR) theorem, which constrains ψ-epistemic models that treat quantum mechanics as a fundamental theory of individual systems, but does not straightforwardly exclude an Einsteinian statistical interpretation. Bell and Kochen–Specker nevertheless rule out Einstein’s hoped-for local, non-contextual completion. I argue that the de Broglie–Bohm pilot-wave theory preserves the core of Einstein’s reductionist program by supplementing ψ with a spatiotemporal particle ontology and rendering quantum probabilities epistemic, while accepting contextuality and fundamental nonlocality. The resulting picture moves the debate beyond the simple opposition between ontic and epistemic interpretations toward questions of fundamentality, completeness, probability, and reduction.