Particle indistinguishability has always been considered a purely quantum mechanical concept. In parallel, indistinguishable particles have been thought to be entities that are not properly speaking objects at all. I argue, to the contrary, that the concept can equally be applied to classical particles, and that in either case particles may (with certain exceptions) be counted as objects even though they are indistinguishable. The exceptions are elementary bosons (for example photons).

The metaphysical problem of individuation requires an answer to two different but intimately related questions: 1) How are we to characterize individuality ontologically? To what ontological category or logical type does individuality belong? 2) What sort of distinction is there between the individuality and nature of an individual, e.g., a real distinction, a modal distinction, a distinction of reason, or some other distinction My purpose in this article is to clarify a bare particular account of individuation and respond to objections (...) that have been raised against bare particulars as individuators. (shrink)

he relationship between metaphysics and science has recently become the focus of increased attention. Ladyman and Ross, in particular, have accused even naturalistically inclined metaphysicians of pursuing little more than the philosophy of A-level chemistry and have suggested that analytic metaphysics should simply be discontinued. In contrast, we shall argue, first of all, that even metaphysics that is disengaged from modern science may offer a set of resources that can be appropriated by philosophers of physics in order to set physics (...) within an interpretational framework. Secondly, however, we shall urge that insofar as metaphysics is intended to be more than just a toolbox it needs to accommodate the implications of physics if many of its core claims are to be sustained. We shall illustrate this last point with a discussion of the nature of laws and modality in the context of modern physics. (shrink)

A dialetheia is a sentence, A, such that both it and its negation, ¬A, are true (we shall talk of sentences throughout this entry; but one could run the definition in terms of propositions, statements, or whatever one takes as her favourite truth-bearer: this would make little difference in the context). Assuming the fairly uncontroversial view that falsity just is the truth of negation, it can equally be claimed that a dialetheia is a sentence which is both true and false.

One of the reasons provided for the shift away from an ontology for physical reality of material objects & properties towards one of physical structures & relations (Ontological Structural Realism: OntSR) is that the quantum-mechanical description of composite physical systems of similar elementary particles entails they are indiscernible. As material objects, they 'whither away', and when they wither away, structures emerge in their stead. We inquire into the question whether recent results establishing the weak discernibility of elementary particles pose a (...) threat for this quantum-mechanical reason for OntSR, because precisely their newly discovered discernibility prevents them from 'whithering away'. We argue there is a straightforward manner to consider the recent results as a reason in favour of OntSR rather than against it. (shrink)

The no-miracles argument for realism and the pessimistic meta-induction for anti-realism pull in opposite directions. Structural Realism---the position that the mathematical structure of mature science reflects reality---relieves this tension.

In this paper we deal with the problem of identity and individuality in quantum mechanics. We analyze three definitions of the concept of an individual and propose to check their merits in relation to the theory. In order to achieve our goals our approach also ties those definitions of individuality to two distinct kinds of naturalism in ontology: a strong version, according to which quantum mechanics must somehow authorize in a positive fashion the ontological concepts being dealt with, and a (...) weak naturalism, according to which quantum mechanics must be only compatible with those ontological concepts. We conclude that strong naturalism is incompatible with the three concepts of individuality in quantum mechanics, and we argue that weak naturalism is not completely motivated, so that the best position to be assumed, in the end, is that the entities are simply not individuals. That is, in its craving to be compatible with strong naturalism, individuality ends up evaporating and we are left with non-individuals. (shrink)

Radical ontic structural realism (ROSR) asserts an ontological commitment to ‘free-standing’ physical structures understood solely in terms of fundamental relations, without any recourse to relata that stand in these relations. Bain ([2013], pp.1621–35) has recently defended ROSR against the common charge of incoherence by arguing that a reformulation of fundamental physical theories in category-theoretic terms (rather than the usual set-theoretic ones) offers a coherent and precise articulation of the commitments accepted by ROSR. In this essay, we argue that category theory (...) does not offer a more hospitable environment to ROSR than set theory. We also show that the application of category-theoretic tools to topological quantum field theory and to algebraic generalizations of general relativity do not warrant the claim that these theories describe ‘object-free’ structures. We conclude that category theory offers little if any comfort to ROSR. 1 Introduction: Ridding Structures of Objects2 The Set-theoretic Peril for Radical Ontic Structural Realism3 Bain’s Categorial Strategy to Save Radical Ontic Structural Realism4 Throwing out the Relations with the Relata5 Categorial and Set-theoretical Structures6 Radical Suggestions from Topological Quantum Field Theory?7 Sheaves of Einstein Algebras as Radical Structures?8 Conclusions. (shrink)

Radical Ontic Structural Realism (ROSR) claims that structure exists independently of objects that may instantiate it. Critics of ROSR contend that this claim is conceptually incoherent, insofar as, (i) it entails there can be relations without relata, and (ii) there is a conceptual dependence between relations and relata. In this essay I suggest that (ii) is motivated by a set-theoretic formulation of structure, and that adopting a category-theoretic formulation may provide ROSR with more support. In particular, I consider how a (...) category-theoretic formulation of structure can be developed that denies (ii), and can be made to do work in the context of formulating theories in physics. Keywords: structural realism, category theory, general relativity.. (shrink)

A short review of some recent developments in the philosophy of physics is presented. I focus on themes which illustrate relations and points of common interest between philosophy of physics and three of its `neighboring' elds: Physics, metaphysics and general philosophy of science. The main examples discussed in these three `border areas' are decoherence and the interpretation of quantum mechanics; time in physics and metaphysics; and methodological issues surrounding the multiverse idea in modern cosmology.

The debate concerning the role of intuitions in philosophy has been characterized by a fundamental disagreement between two main camps. The first, the autonomists, hold that, due to the use in philosophical investigation of appeals to intuition, most of the central questions of philosophy can in principle be answered by philosophical investigation and argument without relying on the sciences. The second, the naturalists, deny the possibility of a priori knowledge and are skeptical of the role of intuition in providing evidence (...) in philosophical inquiry. In spite of the seemingly stark and deep disagreement between the autonomist and the naturalist, in this paper I will attempt to suggest that there is a way to mount a partial defense of intuition-based philosophical practice on naturalist grounds. As will be seen, doing so will require a number of concessions that will satisfy few autonomists while simultaneously disappointing those naturalists who might have thought that all notions of the a priori had been successfully laid to rest. However, I will argue that the account proposed here will preserve those features of traditional philosophical practice that matter most and better explain the history of successes and failures of that practice, thus answering the worries of the autonomist, and that the rejection of the No A Priori Thesis attendant with the account presented here is indeed demanded by the current theories of our best scientific understanding of the mind, thus pacifying the rabid naturalistic critic of any version of apriorism. (shrink)