Symmetry, indiscernibility, and the generalist picture

This thesis consists of four independent but thematically interrelated papers, plus an addendum to one of these papers.
Chapter 1 defends the view that Leibniz subscribed to generalism, or the view that the world is fundamentally purely qualitative in character. In particular, I respond to Cover & O'Leary-Hawthorne’s (1999) claim that Leibniz’s use of symmetry considerations in the correspondence with Clarke reveals that he was not a generalist. In addition, I claim that what reveals Leibniz’s generalism is not—as many scholars seem to believe—his mere commitment to his theory of truth, theory of complete individual substances and Principle of the Identity of Indiscernibles (PII). Rather, I argue, it is the fact that Leibniz claimed to derive the PII from his theories of truth and complete individual substances which ultimately demonstrates his commitment to generalism.
Chapter 2 examines the putative relationship between two notions: symmetry and qualitativity. I argue that, on the standard metaphysical construal of the notion of qualitativity, a widely-held view about the relationship between these two notions is mistaken. However, I also argue that on a nonstandard construal of the notion of qualitativity due to Ismael & van Fraassen (2003), the alleged relationship between the two notions holds much more promise. I finish by expanding upon Ismael & van Fraassen's own account of the notion of qualitativity relevant to the notion of symmetry, and in doing so I attempt to elucidate the methodology of symmetry reasoning in physics more generally.
This chapter is followed by a brief addendum. Here, I discuss two recent independent proposals — due to Adam Caulton (forthcoming) and Shamik Dasgupta (forthcoming, a)—for understanding the methodology of symmetry reasoning that are prima facie very similar to the view that I defend at the end of Chapter 2. I argue that both proposals differ from my own, and each other, in subtle but nevertheless highly non-trivial respects.
Chapter 3 argues that the focus of much contemporary discussion concerning the proper role and philosophical significance of a modern-day version of the PII is misplaced. More specifically, I argue that metaphysicians' criticism of the notion of weak discernibility on the basis of its alleged inability to ground objects' numerical diversity is orthogonal to Saunders' (2003a) main concern in his original paper, which is to use the notion of weak discernibility as part of a broader program for interpreting physical theories. I subsequently assess this interpretative program, and suggest some reasons for thinking it implausible.
Chapter 4 discusses a variety of recent objections to generalism. The objections are related by the fact that all of them appeal, at some stage in the relevant line of argument, to the possibility of worlds containing qualitatively indisii cernible individuals. I argue that none of these objections ultimately succeed. Thus, I claim that a significant class of difficulties for the view is obviated.
Lightly-edited versions of some of these chapters have already been accepted for publication. At the time of writing, Chapter 1 is forthcoming in Studia Leibnitiana; Chapter 2 (without the addendum) has appeared in Tomasz Bigaj and Christian Wüthrich's edited collection Metaphysics in Contemporary Physics (Amsterdam/New York, NY: Rodopi, 2015); and Chapter 3 is forthcoming in Ergo. Chapter 4 and the addendum to Chapter 2 are currently unpublished.

Advisor: Pooley, O
Saunders, S