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I had trouble understanding this and had brought it up before but I thought I'd start a new thread on it, in case anyone has any further insights. In the original Leifer summary discussing the implications of PBR theorem on the various QM interpretations, Leifer argued that realists should become ψ-ontologists. He writes:

Can the quantum state be interpreted statistically? | Matt LeiferMatt Leifer

But this is what is confusing me. Harrigan and Spekken, whose definitions of ψ-ontic and ψ-epistemic are used in the PBR theorem briefly discuss the ontic nature of the different Bohmian interpretations and write:

403 Forbidden

Supporting this non-ontic reading for the nature of the minimalist Bohmian interpretation, Belousek writes:

Non-separability, Non-supervenience, and Quantum Ontology | Darrin Snyder Belousek - Academia.edu

Assuming that the PBR theorem is accurate, does this imply that the Durr et al. minimalist Bohmian interpretation is ruled out?

In quantum theory, we have a different notion of state-the wavefunction-and the question is: should we think of it as anontic state(more like a phase space point), anepistemic state(more like a probability distribution), or something else entirely? Here are three possible answers to this question:

1. Wavefunctions are epistemic and there is some underlying ontic state.Quantum mechanics is the statistical theory of these ontic states in analogy with Liouville mechanics.

2. Wavefunctions are epistemic, but there is no deeper underlying reality.

3. Wavefunctions are ontic(there may also be additional ontic degrees of freedom, which is an important distinction but not relevant to the present discussion).

The theorem in the paper attempts to rule outoption 1, which would meanthat scientific realists should become psi-ontologists.I am pretty sure that no theorem on Earth could rule out option 2, so that is always a refuge for psi-epistemicists, at least if their psi-epistemic conviction is stronger than their realist one.Pretty much all of the well-developed interpretations that take a realist stance fall under option 3, so they are in the psi-ontic camp.This includes the Everett/many-worlds interpretation,, and spontaneous collapse models. Advocates of these approaches are likely to rejoice at the PBR result, as it apparently rules out their only realist competition, and they are unlikely to regard anti-realist approaches as viable.de Broglie-Bohm theory

**Can the quantum state be interpreted statistically?**Can the quantum state be interpreted statistically? | Matt LeiferMatt Leifer

But this is what is confusing me. Harrigan and Spekken, whose definitions of ψ-ontic and ψ-epistemic are used in the PBR theorem briefly discuss the ontic nature of the different Bohmian interpretations and write:

Inspired by this pattern, Valentini has wondered whether the pilot-wave (and hence ontic) nature of the wave function in the deBroglie-Bohm approach might be unavoidable.A distinction is made between the quantum state of the universe and the conditional quantum state of a subsystem, defined in Ref. [79]. The latter is argued to be epistemic while the former is deemed to be nomic, that is, law-like, following the lines of Ref. [80] (in which case it is presumably a category mistake to try to characterize the universal wave function as ontic or epistemic). We shall not provide a detailed analysis of this claim here, but highlight it as an interesting possibility that is deserving of further scrutiny.On the other hand, it has been suggested by Wiseman that there exists an unconventional reading of the deBroglie-Bohm approach which is not ψ-ontic.

**Einstein, incompleteness, and the epistemic view of quantum states**403 Forbidden

Supporting this non-ontic reading for the nature of the minimalist Bohmian interpretation, Belousek writes:

The ﬁrst interpretive proposal I’ll call ‘minimalist’ (e.g., Durr et al. 1996). In this view, the only properties a Bohmian particle really possesses(in addition to its state-independent classical properties, mass and charge) are its actual position and velocity; all quantum properties or ‘observables’ represented by Hermitian operators, such as ‘spin,’ are regarded as merely ﬁctions or as constructions that only catalogue possible position measurement outcomes and are thus eliminated from the theory’s ontology (because they add neither empirical content nor explanatory power to the theory).On such an interpretation, there is simply no room for non-supervenience to arise in the ﬁrst place, even when the quantum state is non-separable.On this view one might further interpret the quantum state itself as having only an ‘instrumental’ signiﬁcance for statistical predictions, as merely representing a convenient summary of the possible motions of a system, and thus as being an abstract mathematical entity in conﬁguration space having no concrete existence in physical space (as do Durr et al .).

**Non‐separability, non‐supervenience, and quantum ontology**Non-separability, Non-supervenience, and Quantum Ontology | Darrin Snyder Belousek - Academia.edu

Assuming that the PBR theorem is accurate, does this imply that the Durr et al. minimalist Bohmian interpretation is ruled out?

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