Jonte R. Hance, John Rarity, James Ladyman (2021), Quantum Studies: Mathematics and Foundations 9(3):333–341 (2022; online 2022-04-27); arXiv preprint first — ARXIV-2101.06436
Key takeaways
- Harrigan and Spekkens’ formal ψ-ontic and ψ-epistemic are contradictories only by stipulation. On the informal meanings (represents reality / represents knowledge), a wavefunction can be both, so PBR-type no-go theorems rule out overlapping support in state space, not epistemic readings as such.
Seeded from the abstract and a skim, before the reading in NOTE-072. What follows is what the work says about itself.
In quantum foundations, “ontic” (about what exists) and “epistemic” (about knowledge) have been identified with Harrigan and Spekkens’ formal definitions within the ontological models framework, and those definitions are mutually exclusive. The authors argue that nothing in the informal notions prevents a wavefunction from representing reality and knowledge at once. They propose that the Pusey–Barrett–Rudolph theorem, and much else in the debate, be reconsidered in that light.
Standing in the record
Filed from the survey of 2026-09-25 of work the anthology set aside as out of scope (tier C): 410 seconds of active reading over 1 session in the papers-feed tracker. It was filed Deferred, unread. NOTE-072 is the close reading of 2026-09-25, and it placed the work: Active — a short, clear statement that ψ-epistemic in the Harrigan–Spekkens sense is narrower than “epistemic”, worth reading for §III–V as a terminological caution when citing PBR. Its positive criterion (Eq. 6) is weak, since it amounts to predictive incompleteness of ψ. Its Appendix A contains claims that the record’s own readings contradict.
When seeded, before the reading in NOTE-072, the entry gave a priority for a deeper reading: low — It is short (7 pp.) and the skim covers its whole argument. Owner time is moderate (t=410, n=1). It is best re-read only alongside PBR.
What the seeding asked a deeper reading to check (NOTE-072 is that reading):
- It is the direct conceptual reply to PBR (c20) and bears on how the cluster should label “ψ-epistemic” toy theories such as Spekkens’ (c16). It fixes the terminology before anything else is filed.
- Check whether the Eq. 6 criterion does real work or just relabels incompleteness (non-ψ-complete models) as “epistemic”. Check responses from Leifer or Spekkens, if any.
Access when seeded: Crossref metadata and abstract for the DOI (online 2022-04-27, issue Aug 2022, pp. 333–341). The Springer PDF URL returned an HTML bot-check page. I read the full text from arXiv 2101.06436v4 (27 Apr 2022, 7 pp., “Matches published version”; v1 was 16 Jan 2021): §I–V.