Everett and the Born Rule

TL;DR

This paper critically examines decision-theoretic derivations of the Born rule within the Everett interpretation, highlighting key assumptions that are incompatible with Everett's framework and challenging their validity.

Contribution

It provides a critical assessment showing that certain assumptions in decision-theoretic derivations of the Born rule are incompatible with the Everett interpretation.

Findings

Decision-theoretic assumptions are inconsistent with Everett.

Outcome likelihood linked to wavefunction coefficients conflicts with Everett.

Some derivations of the Born rule do not hold under Everett interpretation.

Abstract

During the last ten years or so, derivations of the Born rule based on decision theory have been proposed and developed, and it is claimed that these are valid in the context of the Everett interpretation. This claim is critically assessed and it is shown that one of its key assumptions, although natural in the context of the Copenhagen interpretation, is not consistent with that of Everett. It is further argued that any interpretation that relates outcome likelihood to the expansion coefficients connecting the wavefunction with the eigenfunctions of the measurement operator must be inconsistent with the Everett interpretation.