This paper investigates the use of theories of mechanics to provide answers to questions in the metaphysics of spatial location and persistence. Investigating spatial location, I find that in classical physics bodies pertend the region of space at which they are exactly located, while a quantum system spans a region at which it is exactly located. Following this analysis, I present a ‘no-go’ result which shows that quantum mechanics restricts the available options for locational persistence theories in an interesting way: (...) it demonstrates that the spatiotemporal path of a persisting thing is discrete in time. This leads to unpalatable consequences for both perdurantists and endurantists. In particular, I argue that Butterfield's ‘anti-pointilliste’ perdurantism is ruled out, and show that endurantists relying on immanent causation run into trouble. I conclude by suggesting the revival of Whitehead's alternative mode of persistence called ‘reiteration.’. (shrink)

Broadly speaking, there are three views on whether Leibniz’s Principle of the Identity of Indiscernibles (PII) is violated in the case of similar particles. According to the earliest view, PII is always violated (call this the no discernibility view); according to the more recent weak discernibility view, PII is at least valid in a weak sense. No and weak discernibility have been referred to as orthodoxy. Steven French has argued that although PII is violated, similar particles can still be regarded (...) as individuals, or, alternatively, as non-individuals: French famously concluded therefore that metaphysics is underdetermined by physics. Call this thesis orthodox underdetermination. Most recently, some authors have turned against orthodoxy by arguing that PII is valid in more than a weak sense – call this the new discernibility view, also referred to as heterodoxy. Since heterodoxy is backed up by physical considerations, metaphysics now seems to be determined by physics: physics indicates that PII is valid. In this paper, I argue that with respect to entangled states, there are two ways to establish PII’s validity, which yield two different ontological interpretations of entanglement. Therefore, a form of underdetermination returns within the heterodox framework. I argue that heterodox underdetermination deserves some attention, because the two ontological interpretations might yield different explanations of the violation of Bell inequalities. (shrink)

The aim of this paper is to reconstruct and correct one argument in support of the symmetrization postulate in quantum mechanics. I identify the central premise of the argument as a thesis specifying a particular ontic property of quantum superpositions. The precise form of this thesis depends on some underlying assumptions of a metaphysical character. I compare the exchange degeneracy argument with alternative formal arguments for the symmetrization postulate, and I discuss the role and meaning of labels in the symmetric/antisymmetric (...) representations of the states of many particles. (shrink)

The paper addresses the referring problem in quantum mechanics, by spelling out the alternatives with complete or individual concepts, with directly referential labels, and with intuition. The connection between the way of referring and some metaphysical theses about objects will be explained. Then, the paper intends to make plausible that the Kantian way is the best way for the quantum domain, including quantum field theories.

Both bosons and fermions satisfy a strong version of Leibniz’s Principle of the Identity of Indiscernibles (PII), and so are ontologically on a par with respect to the PII. This holds for non-entangled, non-product states and for physically entangled states—as it has been established in previous work. In this paper, the Leibniz strategy is completed by including the (bosonic) symmetric product states. A new understanding of Pauli’s Exclusion Principle is provided, which distinguishes bosons from fermions in a peculiar ontological way. (...) Finally, the program as a whole is defended against substantial objections. (shrink)