Abstract The paper addresses a problem for the unification of quantum physics with the new Aristotelianism: the identification of the members of the category of substance (ousia). I outline briefly the role that substance plays in Aristotelian metaphysics, leading to the postulating of the Tiling Constraint. I then turn to the question of which entities in quantum physics can qualify as Aristotelian substances. I offer an answer: the theory of thermal substances, and I construct a fivefold case for thermal substances, based on the irreversibility of time, the definition of thermodynamic concepts, spontaneous symmetry breaking, phase transitions, and chemical form.
Abstract The paper addresses a problem for the unification of quantum physics with the new Aristotelianism: the identification of the members of the category of substance (ousia). I outline briefly the role that substance plays in Aristotelian metaphysics, leading to the postulating of the Tiling Constraint. I then turn to the question of which entities in quantum physics can qualify as Aristotelian substances. I offer an answer: the theory of thermal substances, and I construct a fivefold case for thermal substances, based on the irreversibility of time, the definition of thermodynamic concepts, spontaneous symmetry breaking, phase transitions, and chemical form.
"In this chapter, I argue that Aristotle's doctrine of hylomorphism, which con- ceived the natural world as consisting of substances which are metaphysically composed of matter and form, is ripe for rehabilitation in the light of quantum physics. I begin by discussing Aristotle's conception of matter and form, as it was understood by Aquinas, and how Aristotle's doctrine of hylomorphism was `physicalised' and eventually abandoned with the rise of microphysicalism. I argue that the phenomenon of quantum entanglement, and the emergence of irreducibly macroscopic phenomena in nite temperature quantum systems, have given us good reasons to doubt the truth of microphysicalism. In support of my argument, I show how to construct a hylomorphic interpretation of the de Broglie-Bohm theory that posits a single Cosmic Substance. I then show how to construct a hylomorphic interpretation of an alternative `contextual' wave function collapse theory (recently proposed by the physicists Barbara Drossel and George Ellis) which posits a plurality of Thermal Substances. Both of these neo-Aristotelian ontologies reject the microphysicalist dogma that nature consists fundamentally of some set of microscopic constituents."
This thesis contributes to the development of a ‘neo-Aristotelian’ ontology of powers that accommodates quantum phenomena. It offers a number of philosophical objections to ‘Super-Humean’ metaphysics, and constructs a sequence of models that aim to improve upon it, using the metaphysical toolbox constructed in Part I. In Part II, I explore how quantum entanglement challenges the ‘classical’ conception of the world as consisting of particles (or fields) with intrinsic physical properties (Chapter 3). I consider the metaphysical model offered by Super-Humeanism, which accommodates entanglement by combining a ‘primitive ontology approach’ to quantum mechanics with ontic structural realism (Chapter 4). According to Super-Humeans, the world is made of matter points constituted by distance relations. I raise three objections to its structuralist conception of matter. I then propose an alternative semi-Humean model, ‘Bohmian power structuralism’, which overcomes these objections through an ontology of ‘power-atoms’ with multi-track causal powers (Chapter 5). But its Humean conception of laws can be challenged. A second model, ‘power monism’, enriches the primitive ontology to include a ‘cosmic power’ that transforms the power-atoms into a cosmic whole, and supports an Aristotelian-essentialist conception of laws (Chapter 6). This model overcomes the difficulties with power structuralism, but is susceptible to Hawthorne’s ‘extrinsicality’ argument, excluding consciousness from the physical world. In Part III, I consider the emergence of thermochemical properties within macroscopic (or mesoscopic) quantum systems. Metaphysical models that incorporate only finite degrees of freedom, like Super-Humeanism, cannot accommodate properties like temperature and chemical entropy, which are represented in physics in the ‘thermodynamic limit’ (Chapter 7). I offer an additional argument against adopting a reductionist approach based on Putnam’s ‘permutation argument’ (Chapter 8). Finally, I outline a third model, ‘power pluralism’, in which the world consists of: a substrate of ‘power-gunk’, and ‘substantial powers’ that elicit substances from the power-gunk (Chapter 9). In this model, quantum-entangled microscopic particles are potential parts of macroscopic (or mesoscopic) substances, which have intrinsic thermochemical properties.
In this chapter, I argue that Aristotle’s doctrine of hylomorphism, which conceived the natural world as consisting of substances which are metaphysically composed of matter and form, is ripe for rehabilitation in the light of quantum physics. I begin by discussing Aristotle’s conception of matter and form, as it was understood by Aquinas, and how Aristotle’s doctrine of hylomorphism was ‘physicalised’ and eventually abandoned with the rise of microphysicalism. I argue that the phenomenon of quantum entanglement, and the emergence of irreducibly macroscopic phenomena in finite temperature quantum systems, have given us good reasons to doubt the truth of microphysicalism. In support of my argument, I show how to construct a hylomorphic interpretation of the de Broglie-Bohm theory that posits a single Cosmic Substance. I then show how to construct a hylomorphic interpretation of an alternative ‘contextual’ wave function collapse theory (recently proposed by the physicists Barbara Drossel and George Ellis) which posits a plurality of thermal substances. Both of these neo-Aristotelian ontologies reject the microphysicalist dogma that nature consists solely of some set of microscopic constituents.
Abstract The neo-Aristotelian programme in natural philosophy comprises a family of theoretical frameworks that offer alternatives to quantum fundamentalism , i.e., to the metaphysical thesis that all the fundamental entities and all natural properties are represented explicitly in some model of quantum theory (whether or not supplemented by microphysical hidden variables or microphysically driven collapse mechanisms). I develop a taxonomy of possible Aristotelian interpretations of QM by considering seven choice points for quantum hylomorphism. I consider George Ellis and Barbara Drossel’s Contextual Wave Function Collapse theory, Alexander Pruss’s Traveling Forms model (Pruss 2018, 2023), and William Simpson’s Contextual Bohmian Mechanics, and locate them on this taxonomy. Finally, I take a stand (tentatively) on each of the seven choice points and suggest directions for further research.
The core of my doctoral thesis consists in the establishment and evaluation of different ontological interpretations of quantum field theory. I thus seek for an ontological picture of the most fundamental level of the physical world, under the assumption that quantum field theory provides a true description. I defend the view that algebraic quantum field theory is the most important formulation when ontological questions are concerned. Some of my more extensive studies deal with different substance ontologies as well as with process-ontological approaches. Eventually, I propose a dispositional trope ontology, according to which particularized properties and not substances are the most basic entities, in terms of which all other entities are to be analysed.
Abstract Metaphysicians should pay attention to quantum mechanics, but not because it provides definitive answers to many metaphysical questions. The theory itself is remarkably silent on the nature of the physical world, and the various interpretations of the theory on offer present conflicting ontological pictures. Rather, quantum mechanics is essential to the metaphysician because it reshapes standard metaphysical debates and opens up unforeseen new metaphysical possibilities. Even if quantum mechanics provides few clear answers, there are good reasons to think that any adequate understanding of the quantum world will result in a radical reshaping of our classical worldview in some way or other. Whatever the world is like at the atomic scale, it is almost certainly not the swarm of particles pushed around by forces that is often presupposed. This book guides readers through the theory of quantum mechanics and its implications for metaphysics in a clear and accessible way. The theory and its various interpretations are presented with a minimum of technicality. The consequences of these interpretations for metaphysical debates concerning realism, indeterminacy, causation, determinism, holism, and individuality (among other topics) are explored in detail, stressing the novel form that the debates take given the empirical facts in the quantum domain. While quantum mechanics may not deliver unconditional pronouncements on these issues, the range of possibilities consistent with our knowledge of the empirical world is relatively small—and each possibility is metaphysically revisionary in some way.