According to the indispensability argument, the fact that we quantify over numbers, sets and functions in our best scientific theories gives us reason for believing that such objects exist. I examine a strategy to dispense with such quantification by simply replacing any given platonistic theory by the set of sentences in the nominalist vocabulary it logically entails. I argue that, as a strategy, this response fails: for there is no guarantee that the nominalist world that go beyond the set of (...) sentences in the nominalist language such theories entail. However, I argue that what such theories show is that mathematics can enable us to express possibilities about the concrete world that may not be expressible in nominalistically acceptable language. While I grant that this may make quantification over abstracta indispensable, I deny that such indispensability is a reason for accepting them into our ontology. I urge that the nominalist should be allowed to quantify over abstracta whilst denying their existence and I explain how this apparently contradictory practice (a practice I call 'weaseling') is in fact coherent, unproblematic and rational. Finally, I examine the view that platonistic theories are simpler or more attractive than their nominalistic reformulations, and thus that abstract ought to be accepted into our ontology for the same sorts of reasons as other theoretical objects. I argue that, at least in the case of numbers, functions and sets, such arguments misunderstand the kind of simplicity and attractiveness we seek. (shrink)

(1) The average Mum has 2.4 children. (2) The number of Argle’s fingers equals the number of Bargle’s toes. (3) There are two possible ways in which Joe could win this chess game. In the right contexts, and outside the philosophy room, all the above sentences may be completely uncontroversial. For instance, if we know that Joe could win either by exchanging queens and entering an endgame, or by initiating a kingside attack then, if ignorant of Quine’s work on ontology, (...) we would take (3) to be uncontroversially true. (shrink)

According to the Genuine Modal Realist, there is a plurality of possible worlds, each world nothing more than a maximally inter-related spatiotemporal sum. One advantage claimed for this position is that it offers us the resources to analyse, in a noncircular manner, the modal operators. In this paper, we argue that the prospects for such an analysis are poor. For the analysis of necessity as truth in all worlds to succeed it is not enough that no modal concepts be used (...) in the realist's account of a possible world (a fact we grant); rather, such an analysis will succeed only if the set of worlds that is postulated is complete. By appealing to plausible truths about the number of possible alien natural properties, we show that there are serious difficulties in guaranteeing that such a set exists without taking some modal concept as primitive. Accordingly, at least in its current form, Genuine Modal Realism must curtail its analytic ambitions. (shrink)

This introduction to modality places the emphasis on the metaphysics of modality rather than on the formal semetics of quantified modal logic. The text begins by introducing students to the "de re/de dicto" distinction, conventionalist and conceptualist theories of modality and some of the key problems in modality, particularly Quine's criticisms. It then moves on to explain how possible worlds provide a solution to many of the problems in modality and how possible worlds themselves have been used to analyse notions (...) outside modality such as properties and propositions. Possible worlds introduce problems of their own and the book argues that to make progress with these problems a theory of possible worlds is required. The pros and cons of various theories of possible worlds are then examined in turn, including those of Lewis, Kripke, Adams, Stalnaker and Plantinga. (shrink)

Model theoretic considerations purportedly show that a certain version of structural realism, one which articulates the nvtion of structure via Ramsey sentences, is in fact trivially true. In this paper we argue that the structural realist is by no means forced to Ramseyfy in the manner assumed in the formal proof. However, the structural realist's reprise is short-lived. For, as we show, there are related versions of the model theoretic argument which cannot be so easily blocked by the structural realist. (...) We examine various ways in which the structural realist may respond, and conclude that the best way of blocking the model theoretic argument involves formulating his Ramseyfied theories using intensional operators. Introduction The model theoretic arguments On Ramseyfying away predicates The model theoretic argument bites back Restricting the second order quantifiers 5.1 Naturalness 5.2 Intrinsic 5.3 Qualitative 5.4 Contingent and causal Intensional operators and relations between properties Conclusion. (shrink)

Commonsense ontology contains both continuants and occurrents, but are continuants necessary? I argue that they are neither occurrents nor easily replaceable by them. The worst problem for continuants is the question in virtue of what a given continuant exists at a given time. For such truthmakers we must have recourse to occurrents, those vital to the continuant at that time. Continuants are, like abstract objects, invariants under equivalences over occurrents. But they are not abstract, and their being invariants enables us (...) to infer both their lack of temporal parts and that non-invariant predications about them must be relativized to times. \\\ [Joseph Melia] In this paper I try to eliminate occurrents from our ontology. I argue against Simons' position that occurrents are needed to supply truthmakers for existential claims about continuants. Nevertheless, those who would eliminate occurrents still need some account of our willingness to assert sentences that logically entail their existence. Though it turns out to be impossible to paraphrase away our reference to occurrents, I show that the truthmakers for such sentences are facts that involve only continuants. This is enough to allow us to regard our ordinary talk about occurrents as fictional. Finally, I argue that a proper conception of the underlying temporal facts about continuants can both avoid the problematic tensed theory of time and the problem of temporary intrinsics. (shrink)

In this paper I claim that Earman and Norton 's hole argument against substantivalist interpretations of General Relativity assumes that the substantivalist must adopt a conception of determinism which I argue is unsatisfactory. Butterfield and others have responded to the hole argument by finding a conception of determinism open to the substantivalist that is not prone to the hole argument. But, unfortunately for the substantivalist, I argue this conception also turns out to be unsatisfactory. Accordingly, I search for a conception (...) of determinism that is both independently plausible and capable of blocking the hole argument. (shrink)

This introduction to modality places the emphasis on the metaphysics of modality rather than on the formal semetics of quantified modal logic. The text begins by introducing students to the "de re/de dicto" distinction, conventionalist and conceptualist theories of modality and some of the key problems in modality, particularly Quine's criticisms. It then moves on to explain how possible worlds provide a solution to many of the problems in modality and how possible worlds themselves have been used to analyse notions (...) outside modality such as properties and propositions. Possible worlds introduce problems of their own and the book argues that to make progress with these problems a theory of possible worlds is required. The pros and cons of various theories of possible worlds are then examined in turn, including those of Lewis, Kripke, Adams, Stalnaker and Plantinga. (shrink)

In this reply, we defend our argument for the incompleteness of Genuine Modal Realism against Paseau's criticisms. Paseau claims that isomorphic set of worlds represent the same possibilities, but not only is this implausible, it is inimical to the target of our paper: Lewis's theory of possible worlds. We argue that neither Paseau's model-theoretic results nor his comparison to arithmetic carry over to GMR. We end by distinguishing two notions of incompleteness and urge that, for all that Paseau has said, (...) GMR remains incomplete in the relevant sense. (shrink)

[Peter Simons] Commonsense ontology contains both continuants and occurrents, but are continuants necessary? I argue that they are neither occurrents nor easily replaceable by them. The worst problem for continuants is the question in virtue of what a given continuant exists at a given time. For such truthmakers we must have recourse to occurrents, those vital to the continuant at that time. Continuants are, like abstract objects, invariants under equivalences over occurrents. But they are not abstract, and their being invariants (...) enables us to infer both their lack of temporal parts and that non-invariant predications about them must be relativized to times. \\\ [Joseph Melia] In this paper I try to eliminate occurrents from our ontology. I argue against Simons' position that occurrents are needed to supply truthmakers for existential claims about continuants. Nevertheless, those who would eliminate occurrents still need some account of our willingness to assert sentences that logically entail their existence. Though it turns out to be impossible to paraphrase away our reference to occurrents, I show that the truthmakers for such sentences are facts that involve only continuants. This is enough to allow us to regard our ordinary talk about occurrents as fictional. Finally, I argue that a proper conception of the underlying temporal facts about continuants can both avoid the problematic tensed theory of time and the problem of temporary intrinsics. (shrink)

1. The problemLewis identifies the monadic property being F with the set of all actual and possible Fs; the dyadic relation R is identified with the set of actual and possible pairs of things that are related by R; and so on . 1 Egan has argued that the fact that some properties have some of their properties contingently leads to trouble: " Let @ be the actual world, in which being green is [someone's] favourite property, and let w be (...) a world in which being green is [nobody's] favourite property. Since being green is somebody's favourite property in @, it must be a member of … being somebody's favourite property. Since being green is not anybody's favourite property in w, it must not be a member of being somebody's favourite property. Contradiction. " Egan suggests identifying properties with functions from worlds to extensions. However, as Lewis and others have complained, this has the drawback of turning monadic properties into relations . 2 In this article, we shall show that the Lewisian has the resources to block the above argument while simultaneously respecting the adicity of the relevant property and the contingency of the predication without changing his theory of properties. However, our analysis reveals a hidden ambiguity in the Lewisian conception of properties, and on either disambiguation the resulting account of properties seems inadequate.2. On ‘being someone's favourite property’The phrase ‘ being someone's favourite property’ is ambiguous. Given Lewis's ontology of possibilia, where the phrase picks out a monadic property it is not one that is possessed contingently; where it picks out a property that is possessed contingently it is not one that is monadic. But the argument works only if being someone's favourite property is both monadic and possessed contingently.Why should …. (shrink)

In his paper, Leuenberger discerns two salient conceptions of logical validity. Strikingly, neither of these conceptions involves modality. He goes on to use these conceptions as a framework to explore certain recent investigations in the logic of modality, where he ingeniously articulates and proves interesting theses about the logic of contingentism. While I think there’s much of interest in Leuenberger’s results, and that his conception of de facto validity gives a unified account of philosophers’ talk of the logic of time (...) and modality, in this note I suggest that perhaps he is too hasty to dismiss the modal conception of validity and that, moreover, his concept of de facto validity may be too inclusive. (shrink)

In this paper, I discuss Moore’s assessment of Lewis’s metaphysical theorizing. While I am sympathetic to Moore’s complaint that much contemporary metaphysics lacks the scope and reach of older metaphysical theories, I take issue with Moore’s diagnosis: neither lack of self-consciousness, nor Quinean naturalism, nor the post-Quinean restitution of necessity is to blame. Rather, the lack of impact of Lewis’s system should be attributed to the very high weight he attaches to conservatism: the preservation of commonsense and ordinary thought and (...) talk. Yet one can agree with Quine that there should be no first philosophy without, as Lewis does, putting philosophy last. Finally, I argue against Moore that, for the Quinean naturalist, there is no conflict between the metaphysician’s armchair methodology and the view that the truths so discovered are on a par with science. (shrink)

A discussion of Ted Sider's argument for perdurantism on the grounds of the possibility of timeless worlds.