Abstract In defending the fundamentality of the open systems view for quantum theory, Cuffaro and Hartmann (2024) articulate an account of frameworks in physics. They argue that the general quantum theory of open systems is a more fundamental framework than standard quantum theory. In this chapter, we articulate an account of frameworks using the examples of quantum field theory and statistical mechanics. We argue that what makes frameworks useful in physics is the combination of generality and abstractness of frameworks. In particular, their abstractness makes them poor targets for metaphysical analysis; the more concrete levels of theories or models are the appropriate target for ontological fundamentality claims.
Abstract In defending the fundamentality of the open systems view for quantum theory, Cuffaro and Hartmann (2024) articulate an account of frameworks in physics. They argue that the general quantum theory of open systems is a more fundamental framework than standard quantum theory. In this chapter, we articulate an account of frameworks using the examples of quantum field theory and statistical mechanics. We argue that what makes frameworks useful in physics is the combination of generality and abstractness of frameworks. In particular, their abstractness makes them poor targets for metaphysical analysis; the more concrete levels of theories or models are the appropriate target for ontological fundamentality claims.
Cuffaro and Hartmann have recently provided an extensive defense of the open systems view, according to which physical systems are best treated as fundamentally open, by arguing, in particular, that quantum systems should in general be taken to evolve non-unitarily over time. For all its merits, this defense faces one central limitation: little is known about the structure of non-unitary dynamics in the case of our best current theories. Yet there is cause for optimism: the standard effective field theory (EFT) framework, in which our best current theories are widely believed to be more reliably formulated, has been successfully generalized to an open EFT framework during the last decades. This paper defends the open systems view in the open EFT setting. We argue that the bottom-up open EFT framework, in which effective systems are treated as fundamentally open, is both more fundamental and more epistemically reliable than its top-down counterpart, in which effective systems are treated as derivatively open.
Cuffaro and Hartmann have recently provided an extensive defense of the open systems view, according to which physical systems are best treated as fundamentally open, by arguing, in particular, that quantum systems should in general be taken to evolve non-unitarily over time. For all its merits, this defense faces one central limitation: little is known about the structure of non-unitary dynamics in the case of our best current theories. Yet there is cause for optimism: the standard effective field theory (EFT) framework, in which our best current theories are widely believed to be more reliably formulated, has been successfully generalized to an open EFT framework during the last decades. This paper defends the open systems view in the open EFT setting. We argue that the bottom-up open EFT framework, in which effective systems are treated as fundamentally open, is both more fundamental and more epistemically reliable than its top-down counterpart, in which effective systems are treated as derivatively open.
Abstract There is a deeply entrenched view in philosophy and physics, the closed systems view, according to which isolated systems are conceived of as fundamental. On this view, when a system is evolving under the influence of its environment, this is always described in terms of a coupling between it and a separate system which taken together are isolated. In this chapter, we introduce the theoretical framework that we call standard quantum theory (ST), formulated in accordance with the closed systems view, and we consider approaches to interpreting the formalism of ST that take it to be complete in some sense. Broadly speaking, these can be grouped into two families. The first includes (neo-)Bohrian and related approaches, the second (neo-)Everettian. We argue, from the point of view of each, that although ST is formulated in accordance with the closed systems view, it is nevertheless ontologically committed to open systems in a way that other, for instance, classical, theoretical frameworks are not. We close with the suggestion that philosophical and foundational progress may be made through the adoption of an alternative theoretical framework, which might in principle involve a change in corresponding view, within which one can make sense of open systems dynamics in fundamental terms.
Abstract Open Systems: Physics, Metaphysics, and Methodology argues that many of the most illuminating questions in contemporary science are best approached by treating systems as inherently embedded in, and interacting with, their environments. While closed-system modelling has long dominated physics, recent advances—from non-equilibrium thermodynamics and open-system quantum dynamics to complex systems science and quantum causal modelling—show that environmental coupling is often not a dispensable complication but a defining feature. Bringing together leading scholars across physics and philosophy, this volume develops the “open systems view” and probes its limits. Part I sets out the view within quantum theory and clarifies its relations to alternative frameworks. Part II traces open/closed concepts across the history and practice of physics, from Newtonian celestial mechanics to blackbody radiation, gravity with boundaries, and biological emergence. Part III turns to the largest scales, examining cosmology, many worlds, and realism about the universal quantum state. Throughout, contributors connect formal tools—density matrices, Lindblad dynamics, interventionist causation—with methodological and metaphysical stakes, including autonomy, reduction, and fundamentality. The result is a unified guide to modelling, explanation, and ontology when closure is an idealisation rather than a premise.
Abstract Ontic structuralism or ontic structural realism in the philosophy of physics can be broadly considered as an interpretative strategy providing a set of conceptual and metaphysical tools—or, more ambitiously, an ontological framework—in order to account for central features of current fundamental physics. This article aims to review the main structuralist interpretative moves in the context of our two best fundamental physical theories of matter and spacetime, namely, quantum theory (quantum mechanics and quantum field theory) and general relativity. We highlight in particular the structuralist understanding of permutation invariance, entanglement and nonlocality in quantum theory, and of the dynamical features of spacetime, (gauge‐theoretic) diffeomorphism invariance and background independence in general relativity.
Abstract How should we interpret physical theories, and especially quantum theory, if we drop the assumption that we should treat it as an exact description of the whole universe? I expound and develop the claim that physics is about the study of autonomous, but not necessarily isolated, dynamical systems, and that when applied to quantum mechanics this entails that in general we should take quantum systems as having mixed states and non-unitary dynamics. I argue that nonetheless unitary dynamics continues to have a special place in physics, via the empirically-well-supported reductionist principles that non-unitarity is to be explained by restriction to a subsystem of a larger unitary system and that microscopic physics is governed by unitary and largely known dynamics. I contrast this position with the ‘Open Systems View’ advocated recently by Michael Cuffaro and Stephan Hartmann.