The Many Worlds Interpretation, Holism, and the Born Rule

Everettianism is a realist many-worlds interpretation of quantum mechanics whose popularity has grown after Wallace (2012) resolved the objection that it cannot recover the Born rule.

Everettian ontologies are totally nonseparable (Wallace & Timpson, 2010), so they tend towards holism (Crull, 2013), which Schaffer (Schaffer, 2010; Ismael & Schaffer, 2020) characterizes as priority monism: the cosmos as a whole is fundamental, and grounds its parts.

I show that there are irreconcilable tensions between Everettianism and priority monism: the Everettian cosmos cannot have particles or ordinary macro-objects as parts, and if it did that would undercut Wallace’s decision theoretic recovery of the Born rule. In fact, Everettian holism is so strong that it undercuts many-worlds theory’s claim to be an interpretation of quantum mechanics distinct from superdeterminism.