Clarify the nature of objective probability

Ascertain what objective probability (chance) is by developing a coherent account that can ground probabilistic claims in contexts such as Everettian quantum mechanics and scientific practice more generally, and that reconciles determinism, measurement, and observed frequencies where appropriate.

Background

In Chapter 4, the treatment of probability in the Everettian (many-worlds) interpretation requires reconciling deterministic unitary dynamics with the Born rule and subjective uncertainty; decision-theoretic derivations are surveyed but do not settle foundational questions about the nature of chance.

Chapter 6 explicitly identifies the status of objective probability as one of three core unresolved issues raised across the book’s three multiverse proposals.

References

I especially emphasized three problems, prompted by the three multiverses in succession: What is a possibility? What is objective probability? And what is an explanation? These are difficult open problems in philosophy.

— The Multiverse: a Philosophical Introduction  (2505.23639 - Butterfield, 29 May 2025) in Chapter 6, opening paragraphs

However, as the reader will see, this question has not yet achieved a definitive, satisfactory answer.

— Hidden Variables in Quantum Mechanics: A Journey Into de Broglie-Bohm Pilot-Wave Theory  (2608.18829 - Oldofredi, 19 Aug 2026) in Section 3.1, “Born’s Rule and the Interpretation of Probability”

Much remains open about why decoherent record structures support distinct observer perspectives and about the metaphysics of objective chance.

— Does Probability Require a Single History?  (2608.22733 - Baxter, 24 Aug 2026) in Conclusion, Section 4