The rise of quantum information theory has lent new relevance to experimental tests for non-classicality, particularly in controversial cases such as adiabatic quantum computing superconducting circuits. The Leggett-Garg inequality is a “Bell inequality in time” designed to indicate whether a single quantum system behaves in a macrorealistic fashion. Unfortunately, a violation of the inequality can only show that the system is either (i) non-macrorealistic or (ii) macrorealistic but subjected to a measurement technique that happens to disturb the system. The “clumsiness” (...) loophole (ii) provides reliable refuge for the stubborn macrorealist, who can invoke it to brand recent experimental and theoretical work on the Leggett-Garg test inconclusive. Here, we present a revised Leggett-Garg protocol that permits one to conclude that a system is either (i) non-macrorealistic or (ii) macrorealistic but with the property that two seemingly non-invasive measurements can somehow collude and strongly disturb the system. By providing an explicit check of the invasiveness of the measurements, the protocol replaces the clumsiness loophole with a significantly smaller “collusion” loophole. (shrink)

John Preston has claimed that we must understand Paul Feyerabend's later, post-1970, philosophy in terms of a disappointed Popperianism: that Feyerabend became a sceptical, relativistic, literal anarchist because of his perception of the failure of Popper's philosophy. I argue that this claim cannot be supported and trace the development of Feyerabend's philosophy in terms of a commitment to the central Popperian themes of criticism and critical explanatory progress. This commitment led Feyerabend to reject Popper's specific methodology in favour of a (...) pluralistic methodology, but the commitment to the central values of criticism and critical explanatory progress remained . Moreover, methodological pluralism does not imply scepticism, relativism, or literal anarchism. Feyerabend was not a disappointed Popperian, but, in many respects, a die-hard pluralistic Popperian. (shrink)

In a recent paper, I have analysed and criticised Leggett and Garg’s argument to the effect that macroscopic realism contradicts quantum mechanics, by contrasting their assumptions to the example of Bell’s stochastic pilot-wave theories, and have applied Dzhafarov and Kujala’s analysis of contextuality in the presence of signalling to the case of the Leggett–Garg inequalities. In this chapter, I discuss more in general the motivations for macroscopic realism, taking a cue from Einstein’s criticism of the Bohm theory, then go on (...) to summarise my previous results, with a few additional comments on other recent work on Leggett and Garg. [To appear in: E. Dzhafarov, Contextuality from Quantum Physics to Psychology.]. (shrink)

In this paper we focus on two claims, put forward by Feyerabend in his later writings , which constitute the metaphysical core of his view of scientific inquiry. The first, that we call the pliability thesis, is the claim that the world can be described by indefinitely many conceptual systems, none of them enjoying a privileged status. The second, that we call the resistance thesis, is the claim that the pliability of the world is limited, i.e., not all the different (...) conceptual systems that can be used to describe the world will be equally successful: the world offers resistance to some attempts to describe it. We show that, in spite of the later Feyerabend’s notorious antirealist leanings, the pliability thesis is fully compatible with a robustly realist view of science, and we suggest that, surprisingly, Feyerabend’s insights concerning the limited pliability of the world turn out to be those of a potential ally of sophisticated versions of scientific realism. (shrink)

In this paper, we discuss various aspects of Heisenberg’s thought on hidden variables in the period 1927–1935. We also compare Heisenberg’s approach to others current at the time, specifically that embodied by von Neumann’s impossibility proof, but also views expressed mainly in correspondence by Pauli and by Schroedinger. We shall base ourselves mostly on published and unpublished materials that are known but little-studied, among others Heisenberg’s own draft response to the EPR paper. Our aim will be not only to clarify (...) Heisenberg’s thought on the hidden-variables question, but in part also to clarify how this question was understood more generally at the time. (shrink)