Towards an essentialist account of modality
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There are certain things which are not only true, but which also must be true--such as the proposition that 2 + 2 = 4. On the other hand, there are some things which are not actually the case, but which possibly could have been the case--thus, though they unfortunately did not, it possible that the Bruins won the 2013 Stanley Cup. In this dissertation I consider the question of what such facts of necessity and possibility consist in. I try to determine what it is that accounts for why certain things must be true, and why certain things that are not true nevertheless might have been true. I consider and reject various accounts before defending an account of modality which appeals to facts concerning the essences or natures of things. Chapter 1 mainly serves as a general introduction to various issues in the metaphysics of modality and introduces various distinctions and concepts that are important to the field. I discuss the possible worlds analysis of necessity and possibility, focusing mainly upon versions that appeal to the view that possible worlds are to be identified with actually existing abstract entities of some sort (e.g. sets of propositions). I argue that while abstract possible worlds have some role to play in modal metaphysics, they are not fit to provide an account of what necessity and possibility consist in. Finally, I provide an overview of Chapters 2-5. In Chapter 2 I turn my attention to Lewisian modal realism. According to Lewisian modal realism, possible worlds are concrete entities, just like our own, and the facts of necessity and possibility can be reduced to non-modal facts concerning what is true at such worlds. After presenting the Lewisian view and elaborating upon its virtues I give an overview of various objections to the view. I then consider in depth the objection that the Lewisian analysis of modality must involve a circular appeal to primitive modal notions, arguing that the Lewisian can provide a satisfactory response to the circularity charge. Ultimately I reject Lewisian modal realism. I argue that its ontology of concrete possible worlds must satisfy certain modal restrictions and that the most plausible explanation of why they should do so must take certain primitive modal features of reality to be ontologically basic. In Chapter 3 I turn my attention to accounts of modality which eschew possible worlds in favor of grounding modality in the existence and natures of actually existing properties. First I consider "Aristotelian" property-based accounts according to which modality is grounded in the nature of dispositions or power properties. I argue that a problem arises for dispositional accounts of possibility to the extent that they must appeal to the natures of possible, but non-actual dispositions. Furthermore, I argue that truths of necessity are not amenable to a purely dispositional account. I argue that in order to deal with these problems the best option is for the dispositionalist to supplement their account by appealing to the sort of essentialism I defend in Chapter 5. I then turn my attention to "Platonist" property-based accounts according to which modality is governed by intrinsic relations holding between Platonic properties. I argue that the view must appeal to certain necessities concerning the natures of Platonic properties and that in doing so the view succumbs to a fatal regress. In Chapter 4 I turn my attention to a deflationist view of modality defended by Ted Sider. According to this view, the world is a fundamentally amodal place and the distinction between the necessary and the contingent is ultimately drawn by us. On this view, necessary truths are simply true propositions of certain kinds that we consider to be important, and our distinction between necessary and contingent propositions fails to carve nature at its joints. The plausibility of this view hinges upon Sider's contention that the world is fundamentally amodal. I argue that Sider's reasons for thinking this are unpersuasive, thus undercutting the motivation for the view. I also argue that we have reason to think, by Sider's own lights, that the modal notion of a disposition is fundamental, and that this gives us good reason to think that modal notions are objective, contra Sider. In Chapter 5 I defend an essentialist account of modality according to which necessary truths are determined by the natures or essences of things. In doing so I develop upon and clarify Kit Fine's idea that metaphysically necessary truths are those propositions true in virtue of the nature all things whatsoever, while rejecting the suggestion that this constitutes a reduction of metaphysical necessity to essence. I then develop the view that metaphysical necessity is grounded in facts about essences. Importantly, the account which I defend is a hybrid account: while I argue that certain truths of possibility are accounted for in terms of essence, I argue that a purely essentialist account of possibility is untenable, holding that truths of possibility are, to a large extent, grounded in dispositions.