Realism with Quantum Faces: The Leggett–Garg Inequalities as a Case Study for Feyerabend's Views

Abstract

ABSTRACT In this paper I attempt to broaden Feyerabend scholarship by asking whether and how Feyerabend's philosophy of science, in particular his commitments to realism and pluralism about scientific theories as well as anarchism about scientific methods, is borne out in multidisciplinary research concerning the Leggett–Garg inequalities. These inequalities were derived explicitly to be a temporal analogue to Bell's inequalities: the viability of macroscopic realism is tested against the predictions of quantum mechanics by performing a series measurements on a macroscopic variable of one system at different time intervals, then evaluating correlations among resultant values. In the nearly forty years since Leggett and Garg's paper, questions continue to be raised whether common tests of these inequalities reveal genuine violations or merely experimental disturbances. There is also much debate about what genuine violations in fact signify, if (as most agree) they are not straight-forwardly analogous to Bell tests. Taking this fascinating and as yet largely unsettled episode from physics as a case study, I derive three Feyerabendian lessons that demonstrate the relevance of his views even today.