Von Neumann Was Not a Quantum Bayesian

TL;DR

This paper critically examines the claim that John von Neumann was the first quantum Bayesian, arguing that historically this assertion is unsupported and clarifying misconceptions about von Neumann's role in QBism.

Contribution

It provides a historical analysis showing that von Neumann was not a quantum Bayesian, challenging the common misconception and clarifying the origins of QBism.

Findings

Von Neumann was not a quantum Bayesian.

The claim that von Neumann inaugurated QBism is historically unsupported.

Clarifies the distinction between von Neumann's work and QBism.

Abstract

Wikipedia has claimed for over three years now that John von Neumann was the "first quantum Bayesian." In context, this reads as stating that von Neumann inaugurated QBism, the approach to quantum theory promoted by Fuchs, Mermin and Schack. This essay explores how such a claim is, historically speaking, unsupported.