Counterfactual Reasoning, Realism and Quantum Mechanics: Much Ado About Nothing?

TL;DR

This paper clarifies the role of counterfactual reasoning in quantum nonlocality proofs, arguing that its use does not imply nonlocality and addressing misconceptions about realism and locality in EPR and Bell theorem discussions.

Contribution

It provides a logical clarification of the relation between locality and counterfactual reasoning, challenging claims that link counterfactuals to nonlocality and realism in quantum mechanics.

Findings

Counterfactual reasoning does not threaten locality in Bell's theorem.

Incompleteness arguments by Einstein are critically analyzed.

Claims equating counterfactuals with realism are refuted.

Abstract

I purport to show why old and new claims on the role of counterfactual reasoning for the EPR argument and the Bell theorem are unjustified: once the logical relation between locality and counterfactual reasoning is clarified, the use of the latter does no harm and the nonlocality result can well follow from the EPR premises. To show why, I critically review (i) incompleteness arguments that Einstein developed before the EPR paper, and (ii) more recent claims that equate the use of counterfactual reasoning with the assumption of a strong form of realism.