The Frauchiger-Renner argument: A new no-go result?

Abstract

In April 2016, Daniela Frauchiger and Renato Renner published anarticle online in which they introduce a Gedankenexperiment that led them to conclude that single-world interpretation of quantum theorycannot be self-consistent. In a new version of the paper, published in September 2018, the authors moderate their original claim by concluding that quantum theory cannot be extrapolated to complex systems, at least not in a straightforward manner. In this article our purpose is to offer acareful reconstruction of Frauchiger and Renner´s argument, which in general isn ot elucidated with sufficient detail in the many debates about its assumptions and scope. Such a reconstruction will allow us to clarify some points about the role of the agents´ knowledge and of the hypothesis of collapse in the structure of the argumentation. The final aim of the present paper is to show that the analysis of the F-R argument leads to a dilemma: either it is an original way to reproduce the proof of the contextuality of quantum mechanics, or it is illegitimate because appeals to inferences forbidden by the algebraic structure of quantum propositions.