Quantum Mechanics 1

Cord Friebe (University of Seigen)
The paper provides a coherent, unified view to save Leibniz's Principle of the Identity of Indiscernibles (PII) in the quantum domain. The discerning defense of PII can be applied to non-entangled, (anti)symmetric states, and the summing defense is successful in the case of entangled, (anti)symmetric states. However, the hard problem is with symmetric product states: a more subtle summing defense is needed. A novel understanding of Pauli exclusion (and its denial) arises, so that fermions and bosons are on a par with respect to PII but nonetheless ontologically discerned in a way to be specified.

Sebastian Murgueitio Ramirez (University of Notre Dame)
Throughout this paper, I  argue that in Einstein's late texts there is not one but two "principles of separability."  I show that  both  principles are compatible with  entanglement and that both are necessary in order to run the incompleteness argument.  Furthermore, these principles shed new light on why 1) separability is crucial to physical thought and 2) why Einstein says that separability is required by the conventionality of physical systems.  My discussion  also allows us to better understand what it means to say that quantum mechanics is  a non-separable theory and why  the main definitions of the term "separability principle" found in the literature are inadequate.

Jeremy Steeger (University of Notre Dame)
Recent discussions of certain non-Kolmogorovian hidden variable theories for quantum theory have used Dutch books to argue that the probabilities in these theories cannot be given a reasonable subjective interpretation (Feintzeig 2014; Feintzeig and Fletcher 2017). Contrasting the theories in question with a popular framework for classical hidden variable theories (Spekkens 2005), I assess the assumptions that go into one plausible reconstruction of this no-go. I argue that the no-go is compelling, but only insofar as one is committed to certain response functions, or stipulations of probabilities conditional on certain facts about the world. Namely: the response functions must determine outcomes, and they must not depend on how a system is measured. I then sketch how the Dutch book argument used in the no-go may be applied to hidden variable theories with other sorts of response functions.

Peter Lewis (Dartmouth College)
Pragmatism about quantum mechanics provides an attractive approach to the question of what quantum mechanics says. However, the conclusions reached by pragmatists concerning the content of quantum mechanics cannot be squared with the way that physicists use quantum mechanics to describe physical systems. In particular, attention to actual use results in ascribing content to claims about physical systems over a much wider range of contexts than countenanced by recent pragmatists. The resulting account of the content of quantum mechanics is much closer to quantum logic, and threatens the pragmatist conclusion that quantum mechanics requires no supplementation.

Matthias Egg (University of Bern)
This paper critically assesses the proposal that scientific realists do not need to search for a solution of the measurement problem in quantum mechanics, but should instead dismiss the problem as ill-posed. James Ladyman and Don Ross have sought to support this proposal with arguments drawn from ontic structural realism and from a Bohr-inspired approach to quantum mechanics. I show that the first class of arguments is unsuccessful, because formulating the measurement problem does not depend on the metaphysical commitments which are undermined by ontic structural realism. The second class of arguments is problematic due to its refusal to provide an analysis of the term "measurement''. It turns out that the proposed dissolution of the measurement problem is in conflict not only with traditional forms of scientific realism but even with the rather minimal realism that Ladyman and Ross themselves defend.