Laura Ruetsche

Van Fraassen's 1991 modal interpretation of Quantum Mechanics offers accounts of measurement and state preparation. I argue that both accounts overlook a class of interactions I call General Unitary Measurements, or GUMs. Ironically, GUMs are significant for van Fraassen's account of measurement because they challenge it, and significant for his account of preparation because they simplify it. Van Fraassen's oversight prompts a question about modal interpretations: developed to account for ideal measurement outcomes, can they consistently account as well for the whole horizon of laboratory practices by which we investigate QM?

According to a regnant criterion of physical equivalence for quantum theories, a quantum field theory (QFT) typically admits continuously many physically inequivalent realizations. This, the second of a two-part introduction to topics in the philosophy of QFT, continues the investigation of this alarming circumstance. It begins with a brief catalog of quantum field theoretic examples of this non-uniqueness, then presents the basics of the algebraic approach to quantum theories, which discloses a structure common even to ‘physically inequivalent’ realizations of a QFT. Finally, it introduces and evaluates a handful of strategies for interpreting quantum theories in the face of the non-uniqueness of their Hilbert space representations.

To most laypersons and scientists, science and progress appear to go hand in hand, yet philosophers and historians of science have long questioned the inevitability of this pairing. As we take leave of a century acclaimed for scientific advances and progress, Science at Century's End, the eighth volume of the Pittsburgh-Konstanz Series in the Philosophy and History of Science, takes the reader to the heart of this important matter. Subtitled Philosophical Questions on the Progress and Limits of Science, this timely volume contains twenty penetrating essays by prominent philosophers and historians who explore and debate the limits of scientific inquiry and their presumed consequences for science in the 21st century

Taking Arthur Fine’s The Shaky Game as my inspiration, and the recent 25th anniversary of the publication of that work as the occasion to exercise that inspiration, I sketch an alternative to the “Naturalism” prevalent among philosophers of physics. Naturalism is a methodology eventuating in a metaphysics. The methodology is to seek the deep framework assumptions that make the best sense of science; the metaphysics is furnished by those assumptions and supported by their own support of science. The alternative presented here, which I call “Locavoracity,” shares Naturalism’s commitment to making sense of science, but alters Naturalism’s methodology. The Locavore’s sense-making projects are piecemeal, rather than sweeping. The Locavore’s hypothesis is that the collection of local sense-making projects fails to issue a single overarching unifying framework deserving of the title “the metaphysics that makes the best sense of science.” I muster some examples supporting the Locavore hypothesis from the interpretation of quantum field theories.

Van Fraassen's 1991 modal interpretation of Quantum Mechanics offers accounts of measurement and state preparation. I argue that both accounts overlook a class of interactions I call General Unitary Measurements, or GUMs. Ironically, GUMs are significant for van Fraassen's account of measurement because they challenge it, and significant for his account of preparation because they simplify it. Van Fraassen's oversight prompts a question about modal interpretations: developed to account for ideal measurement outcomes, can they consistently account as well for the whole horizon of laboratory practices by which we investigate QM?

This is the first of a two-part introduction to some interpretive questions that arise in connection with quantum field theories (QFTs). Some of these questions are continuous with those familiar from the discussion of ordinary non-relativistic quantum mechanics (QM). For example, questions about locality can be rigorously posed and fruitfully pursued within the framework of QFT. A stark disanalogy between QFTs and ordinary QM – the former, but not the latter, typically admit infinitely many putatively physically inequivalent realizations – prompts relatively novel questions, questions about how to understand and adjudicate different strategies for equipping quantum theories with content. Part I sketches the fate of locality and related notions in QFT, then documents the non-uniqueness unprecedented in ordinary QM but rampant in QFT. Part II presents foundations issues raised by non-uniqueness.

An “intrinsically mixed” state is a mixed state of a system that is ‘orthogonal’ to every pure state of that system. Although the presence of such states in the quantum theories of infinite systems is well known to those who work with such theories, intrinsically mixed states are virtually unheralded in the philosophical literature. Rob Clifton was thoroughly familiar with intrinsically mixed states. I aim here to introduce them to a wider audience—and to encourage that audience to cultivate their acquaintance by suggesting that intrinsically mixed states undermine assumptions framing standard discussions of the quantum measurement problem

: Some feminist epistemologists make the radical claim that there are varieties of epistemically valid warrant that agents access only through having lived particular types of contingent history, varieties of epistemic warrant to which, moreover, the confirmation-theoretic accounts of warrant favored by some traditional epistemologists are inapplicable. I offer Aristotelian virtue as a model for warrant of this sort, and use loosely Aristotelian vocabulary to express, and begin to evaluate, a range of feminist epistemological positions