The Coalescence Approach to Inequivalent Representation: Pre-QM∞ Parallels

Abstract

Ruetsche [2011] argues that the occurrence of unitarily inequivalent representations in quantum theories withinfinitely many degrees of freedom poses a novel interpretational problem. According to Ruetsche, such theories compel us to reject the so-called ‘ideal of pristine interpretation’; she puts forward the ‘Coalescence Approach’ as an alternative. In this paper I offer a novel defence of the Coalescence Approach. The defence rests on the claim that the ideal of pristine interpretation already fails before one considers the peculiarities of QM∞: there are pre-QM∞ parallels to coalescence. Despite this departure from pristinism, the ‘modest’ view that emerges poses no threat to scientific realism.