In slogan form, holism is the obscure thesis that the whole is more than the sum of its parts. Physics has been taken to exhibit holism of various kinds, associated with different ways of trying to make this thesis clear. On a more metaphysical approach, holism is the view that the existence or features of some physical whole are not determined by the existence and features of its constituent parts. This chapter discusses methodological holism in physics and considers whether the physical theories imply such metaphysical holism. While some form of ontological holism has occasionally been considered, the variety of metaphysical holism most clearly at issue in quantum mechanics is property holism. One may try to avoid the conclusion that experimental violations of Bell inequalities manifest a failure of Local Action by invoking ontological holism for events.
In slogan form, holism is the obscure thesis that the whole is more than the sum of its parts. Physics has been taken to exhibit holism of various kinds, associated with different ways of trying to make this thesis clear. On a more metaphysical approach, holism is the view that the existence or features of some physical whole are not determined by the existence and features of its constituent parts. This chapter discusses methodological holism in physics and considers whether the physical theories imply such metaphysical holism. While some form of ontological holism has occasionally been considered, the variety of metaphysical holism most clearly at issue in quantum mechanics is property holism. One may try to avoid the conclusion that experimental violations of Bell inequalities manifest a failure of Local Action by invoking ontological holism for events.
Abstract Quantum mechanics is often said to entail holism—that wholes are more than just the sum of their parts—and hence violate Humean supervenience. Certainly an entangled state cannot readily be interpreted in terms of the properties of the individual particles involved. But there is no clear general argument from quantum mechanics to holism. Still, each of the three major interpretations of quantum mechanics—Bohm, GRW, and many worlds—embodies some form of holism. One might try to rescue Humean supervenience by moving to high-dimensional representation of physical systems, or by constructing a theory with backward-in-time causation, but it is unclear if such strategies will succeed. If holism is accepted, some argue further that there are no individuals at the fundamental physical level: Either relations are fundamental, or the whole universe is fundamental. The arguments for these positions are assessed and found to be wanting.
Quantum mechanics is often credited for having clearly shown that the whole is something over and above the sum of its parts. We want to assess whether this is really the case, and if so, in what sense. We argue that there is indeed a sense in which this is true. Our argument is that even a weak realistic interpretation of quantum mechanics renders a particular metaphysical principle about property instantiation, that we label Property Compositional Determinateness, untenable. Yet there is another metaphysical principle about composition that is usually maintained to imply that composition of parts exhausts the whole they are part of, namely Mereological Extensionalism. In this case, contrary to widespread agreement, we argue that quantum mechanics does not provide any reason, either direct or indirect, to abandon such principle.
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.
A composite quantum system has properties that are incompatible with every property of its parts. The existence of such global properties incompatible with all local properties constitutes what I call "mereological holism"--the distinctive holism of Quantum Theory. Mereological holism has the dramatic conceptual consequence of making untenable the usual understanding of the "quantum system" as being a "physical object", since composed objects have properties compatible with those of its parts. The notion of "property" can be extended in a unique way to the whole class of operational probabilistic theories (shortly OPTs), of which the most relevant cases are Quantum Theory and Classical Theory. Whereas Classical Theory is not mereologically holistic, we can now search for other OPTs that are so. Within the OPT framework the role of the "system" is that of an input-output connection between two objective events. In non holistic theories, such as Classical Theory, the system can still be regarded as an "object". On the contrary, in holistic theories interpreting "system" as "object" constitutes an hypostatization of a theoretical notion.
The pros and cons of various forms of atomism and holism that are applicable both in physical science and today’s philosophy of nature are evaluated. To this end, Lewis’ thesis of Humean supervenience is presented as an important case study of an atomistic doctrine in philosophical thought. It is shown that Lewis’ ontological doctrine of Humean supervenience incorporates at its foundation the so-called separability principle of classical physics. In view of the systematic violation of the latter within quantum mechanics, it is argued that contemporary physical science posits non-supervenient relations over and above the spatiotemporal ones. Depending on the mode of assignment of states to physical systems — unit state vectors versus statistical density operators — we distinguish between strongly and weakly non-supervenient relations. It is demonstrated that in either case the relations of quantum entanglement constitute prototypical examples of irreducible physical relations that do not supervene upon a spatiotemporal arrangement of Humean qualities, weakening, thereby, the thesis of Humean supervenience. It is examined, in this respect, the status of Lewis’ recombination principle, whereas his conception of lawhood is critically investigated. It is concluded that the assumption of ontological reductionism, as expressed in Lewis’ Humean doctrine, cannot be regarded as a reliable code of the nature of the physical world and its contents. It is proposed instead that due to the undeniable existence of non-supervenient relations a metaphysic of relations of a moderate kind ought to be acknowledged as an indispensable part of our understanding of the natural world at a fundamental level.
It has been widely noted that Humean supervenience, according to which everything supervenes on intrinsic properties of point-sized things and the spatiotemporal relations between them, is at odds with the nonlocal character of quantum mechanics, according to which not everything supervenes on intrinsic properties of point-sized things and the spatiotemporal relations between them. In particular, a standard view is that the parts of a composite quantum system instantiate further relations which are not accounted for in Lewis's Humean mosaic. But that suggests a simple solution: Why couldn't Lewis simply add these new relations to the supervenience basis? The aim of this article is to use Humean supervenience as a foil to spell out a feature of entanglement of general metaphysical interest: The way in which the metaphysical lessons drawn for two-party systems ramify when systems of many parties are considered. The main conclusion is that the proposed simple fix in fact results in a supervenience thesis different in kind from Lewis's, by making the relations in the supervenience basis global in a certain sense. 1 Introduction 2 Basic Argument against Humean Supervenience 3 A Natural Line of Response 4 A Different Kind of Supervenience Thesis