Mon but ici est de réconcilier deux conceptions relativement populaires dans leurs domaines respectifs : d’une part, la théorie des contreparties (TC) de David Lewis, en métaphysique modale, d’autre part, la thèse de la rigidité mise en avant par Saul Kripke en sémantique. De prime abord, le concept de rigidité ne semble pas pouvoir s’appliquer dans TC : un terme rigide est censé désigner le même objet au travers des mondes possibles, tandis que TC formule les conditions de vérité des (...) énoncés modaux de re en termes non pas d’identité transmonde mais de similarité comparative. Je soutiens néanmoins qu’il peut y avoir de la rigidité au travers des ressemblances. Partant d’une suggestion de Lewis, je montre qu’on peut définir un concept de rigidité, la rigidité lewisienne (rigiditéL), qui est adapté à TC. Malheureusement, la thèse de la rigiditéL ainsi reformulée bute sur un obstacle de taille : l’extrême prodigalité de la relation de ressemblance qui prévaut dans TC entraîne une prolifération des relations de contrepartie, ce qui a pour effet de trivialiser la thèse de la rigiditéL, en faisant de tous les termes singuliers, sans discrimination, noms propres aussi bien que descriptions définies, des désignateurs rigidesL. Suivant une piste d’Allan Gibbard et de Lewis, je propose alors de relativiser la rigiditéL à un aspect de similarité variable selon le contexte conversationnel. De là, je forge un concept plus contraignant, celui d’hyper-rigiditéL, à l’aune duquel le contrepartiste peut enfin capturer la différence entre noms propres et descriptions définies. (shrink)

On Anselmian theism, God is, amongst other things, a necessary being. On genuine modal realism, possible worlds are maximal mereological sums of spatiotemporally connected individuals. I argue in this paper that AT and GMR are either incompatible or their conjunction leads to—amongst other things—modal collapse. Specifically, I argue: regardless of whether God is concrete or abstract, His necessary existence either is inconsistent with AT-GMR or it leads to, amongst other things, modal collapse for AT-GMR. I conclude the paper by contending (...) that, if I am correct, the ATist will have an argument against the truth of GMR, and the GMRist will have an argument against the truth of AT. (shrink)

In his paper, “Identity Statements and Essentialism,” Loux seeks to demonstrate sortal essentialism based on Frege’s thesis that all statements of number concerning a collection require that the members fall under the same sortal concept. I shall attempt to argue that a detailed analysis of Loux’s argument reveals it as failing to imply the type of sortal dependency thesis necessary for the justification of sortal essentialism. However, if one construes the transworld identity relation as no different from our run of (...) the mill identity relation, then his argument can serve as the basis for a proof of a type of nontrivial essentialism, thereby showing that the possible worlds picture of modality is indeed committed to a robust essentialism. (shrink)

In 1988, Michael Nyman composed the score for Peter Greenaway’s film Drowning by Numbers (or did something that we would ordinarily think of as composing that score). We can think of Nyman’s compositional activity as a “generative performance” and of the sound structure that Nyman indicated (or of some other abstract object that is appropriately related to that sound structure) as the product generated by that performance (ix).1 According to one view, Nyman’s score for Drowning by the Numbers—the musical work—is (...) the product generated by Nyman’s compositional activity (namely, an abstract object) and, more generally, artworks are identified with the products generated by compositional or other creative activities. Let’s call this view The Product Theory. By contrast, according to another view, Nyman’s score for Drowning by Numbers is the generative performance itself (namely, Nyman’s compositional activity) and, more generally, artworks are identified with generative performances themselves. Following David Davies in Art as Performance, let’s call this view The Performance Theory (80). In that book, Davies argues for The Performance Theory and against The Product Theory. (shrink)

If musical works are abstract objects, which cannot enter into causal relations, then how can we refer to musical works or know anything about them? Worse, how can any of our musical experiences be experiences of musical works? It would be nice to be able to sidestep these questions altogether. One way to do that would be to take musical works to be concrete objects. In this paper, we defend a theory according to which musical works are concrete objects. In (...) particular, the theory that we defend takes musical works to be fusions of performances. We defend this view from a series of objections, the first two of which are raised by Julian Dodd in a recent paper and the last of which is suggested by some comments of his in an earlier paper. (shrink)

The standard version of the psychological criterion or theory of personal identity takes it that psychological connectedness is not necessary for personal identity, or for what matters in survival. That is, a future person can be you, and/or have what matters in survival for you, even though there is no psychological connectedness between you and that future person. David Lewis, however, holds that psychological connectedness is necessary to both identity and what matters (which he takes to coincide). This entails, Lewis (...) acknowledges, that if a human body were to live longer than connectedness lasts, then that body would ‘embody’ or ‘constitute’ a different person later on than it did to begin with. Moreover, Lewis accepts, a body may embody more than one person at any one time. Lewis claims that this can be reconciled to some degree with common sense if we count by person stages rather than by persons. I show, though, that Lewis' view cannot be salvaged in this way, and, moreover, that it leads to further absurdities. I conclude that as an account of identity and of what matters in survival, it is highly implausible, and most unsatisfactory. (shrink)

Perhaps if the future existed, concretely and individually, as something that could be discerned by a better brain, the past would not be so seductive: its demands would he balanced by those of the future. Persons might then straddle the middle stretch of the seesaw when considering this or that object. It might be fun. But the future has no such reality (as the pictured past and the perceived present possess); the future is but a figure of speech, a specter (...) of thought. (shrink)

It is sometimes said that no living philosopher is a genuine modal realist. This is no doubt an exaggeration. But at least this much is true: while we all partake of possible world talk when philosophizing, most of us regard this talk as incurring no commitment to a plurality of concrete worlds.

According to the Truthmaker Principle: every truth has a truthmaker. Attempts to come to grips with the Truthmaker Principle played a prominent role in Lewis’s metaphysical writings over the last fifteen years of his career. Although Lewis agreed that the truth of propositions must somehow be ontologically grounded, the Truthmaker Principle was too strong: it conflicted with two of Lewis’s most fundamental metaphysical assumptions, the uniqueness of composition and the Humean denial of necessary connections. Lewis endorsed instead a weaker principle: (...) Truth Supervenes on Being. But towards the end of his career, he changed course, noting that his critique of the Truthmaker Principle rested on essentialist assumptions that he, as a counterpart theorist, does not accept. Once freed from those assumptions, a counterpart theorist can accept the Truthmaker Principle after all without buying into unmereological composition and mysterious necessary connections. (shrink)

David Lewis's book 'On the Plurality of Worlds' mounts an extended defense of the thesis of modal realism, that the world we inhabit the entire cosmos of which we are a part is but one of a vast plurality of worlds, or cosmoi, all causally and spatiotemporally isolated from one another. The purpose of this article is to provide an accessible summary of the main positions and arguments in Lewis's book.

In this paper I argue, that if it is metaphysically possible for it to have been the case that nothing existed, then it follows that the right modal logic cannot extend D, ruling out popular modal logics S4 and S5. I provisionally defend the claim that it is possible for nothing to have existed. I then consider the various ways of resisting the conclusion that the right modal logic is weaker than D.

This paper argues for a possible-worlds interpretation of the arguments marshalled by Socrates against Protagoras in Plato’s Theaetetus. Specifically, it reads Protagoras’ position as implying a limited form of modal realism, and evaluates both the self-refutation sequence at 170a–71d and the Future Argument at 177c–9c on the basis of this reading. It emerges that Socrates’ project is only partly successful: while the three main arguments of the self-refutation sequence force Protagoras into ever more awkward and metaphysically top-heavy positions, and the (...) Future Argument is psychologically compelling, these arguments do not force a collapse of the relativist position. Protagoras can still defend himself, though the cost is high. (shrink)

The paper shows – contra what has been argued by Trenton Merricks – that counterpart theory, when conjoined with composition as identity, does not entail mereological essentialism. What Merrick’s argument overlooks is that contingent identity is but one of the effects of grounding identity across possible worlds on similarity.

The paper shows – contra what has been argued by Trenton Merricks – that counterpart theory, when conjoined with composition as identity, does not entail mereological essentialism. What Merricks's argument overlooks is that contingent identity is but one of the effects of grounding identity across possible worlds on similarity.

Kripke complained that counterpart theory makes modal claims be about counterparts and not about us, and that it is a misguided model of modality since we do not care about counterparts in the same way we care about ourselves. The first part of the complaint, I argue, has been met by Hazen and Lewis, while the second can be countered by observing that most of our modal concerns are about role‐fillers and that counterparts are well‐suited to such concerns. The role‐filler (...) analysis of modal concerns, however, does not seem to capture certain attitudes ‐ especially that of regret. Regret, however, I will argue, is not intrinsically modal and thus is no challenge to my general analysis of modal concerns. (shrink)

Using quantitative methods, we investigate the role of logic in analytic philosophy from 1941 to 2010. In particular, a corpus of five journals publishing analytic philosophy is assessed and evaluated against three main criteria: the presence of logic, its role and level of technical sophistication. The analysis reveals that logic is not present at all in nearly three-quarters of the corpus, the instrumental role of logic prevails over the non-instrumental ones, and the level of technical sophistication increases in time, although (...) it remains relatively low. These results are used to challenge the view, widespread among analytic philosophers and labeled here “prevailing view”, that logic is a widely used and highly sophisticated method to analyze philosophical problems. (shrink)

Divine necessity is the thesis that God must exist. In this paper, I give a brief survey of what the thesis is more exactly, the main arguments for it, and the main arguments against it.

This is the first part of a larger project that aims to develop a cross-categorical semantic account of a broad range of _as if_ constructions in English. In this paper, we focus on descriptive uses of _as if_ with regular truth-conditional content. The core proposal is that _as if_-phrases contribute hypothetical (_if_-like) and comparative (_as_-like) properties of situations, which are instantiated by an event, state, or larger situation when it resembles in some relevant respect its counterparts in selected stereotypical worlds (...) described by the clause embedded under _as if_. We motivate and develop this situation-semantic analysis in detail for examples like _Pedro danced as if he was possessed by demons_ where the modifying _as if_-adjunct is used to inferentially convey the manner of a reported activity. We extend this analysis to _as if_-complements of perception verbs in reports like _The soup tastes as if it contains fish sauce_, offering an alternative to conceptually problematic approaches that assimilate such perceptual resemblance reports to propositional attitude ascriptions. We also examine the predicative function of _as if_ in examples like _The state of the house is as if a tornado passed through it_ where the _as if_-phrase denotes a hypothetical comparative property of the nominal subject. (shrink)

In his (2002) Gonzalo Rodriguez-Pereyra provides a powerful articulation of the claim that Resemblance Nominalism provides the best answer to the so-called Problem of Universals. Resemblance Nominalism has not been popular for some time, and one influential reason for this is the widespread belief that Resemblance Nominalism cannot dispense with all universals. The realist critics appeal to what is known as Russell’s Regress (cf. Russell 1997). If properties are to be explained in terms of one object’s resembling another, then this (...) seems to leave the relational property of resemblance itself unexplained. The critics’ objection is that this property itself must be explained by a dyadic universal of resemblance. (shrink)

It is commonplace to formalize propositions involving essential properties of objects in a language containing modal operators and quantifiers. Assuming David Lewis’s counterpart theory as a semantic framework for quantified modal logic, I will show that certain statements discussed in the metaphysics of modality de re, such as the sufficiency condition for essential properties, cannot be faithfully formalized. A natural modification of Lewis’s translation scheme seems to be an obvious solution but is not acceptable for various reasons. Consequently, the only (...) safe way to express some intuitions regarding essential properties is to use directly the language of counterpart theory without modal operators. (shrink)

I present and develop the view that omissions are de re possibilities of actual events. Omissions do not literally fail to occur; rather, they possibly occur. An omission is a tripartite metaphysical entity composed of an actual event, a possible event, and a contextually specified counterpart relation between them. This view resolves ontological, causal, and semantic puzzles about omissions, and also accounts for important data about moral responsibility for outcomes resulting from omissions.

In this article, I defend Lewisian modal realism against objections arising from the possibility of ‘Island Universes’ and other similar cases. The problem comes from Lewis’ claim that possible worlds are spatio-temporally isolated. I suggest a modification of Lewisian modal realism in order to avoid this family of objections. This modification may sound quite radical since it amounts to abandoning the very notion of a possible world, but as radical as it may sound it in fact remains well in the (...) spirit of Lewis’ original view. (shrink)

In this article, I am interested in four versions of what is often referred to as "the Humphrey objection". This objection was initially raised by Kripke against Lewis's modal counterpart theory, so this is where I will start the discussion. As we will see, there is a perfectly good answer to the objection. I will then examine other places where a similar objection can be raised: it can arise in the case of temporal counterpart theory (in fact, it can arise (...) in the case of all kinds of counterpart theories, independently on modal realism), and a very similar worry can also arise against modal realism itself or against an ersatzist theory of possible worlds itself. For similar reasons, in similar situations, a similar objection will arise. What is interesting is that it is not the case that a similar response can be given in all of these similar cases. So, in the end, we will see what dissimilarities there are and how and why they are relevant. In particular, we will see the differences there are between alethic modalities and temporal modalities. In the case of alethic modalities (metaphysical necessity and possibility), the objection can be answered by appealing to the notion of representation, while this does not work very well in the case of temporal modalities. (shrink)

This is part I of a two-part essay introducing case-intensional first order logic, an easy-to-use, uniform, powerful, and useful combination of first-order logic with modal logic resulting from philosophical and technical modifications of Bressan’s General interpreted modal calculus. CIFOL starts with a set of cases; each expression has an extension in each case and an intension, which is the function from the cases to the respective case-relative extensions. Predication is intensional; identity is extensional. Definite descriptions are context-independent terms, and lambda-predicates (...) and -operators can be introduced without constraints. These logical resources allow one to define, within CIFOL, important properties of properties, viz., extensionality and absoluteness, Bressan’s chief innovation that allows tracing an individual across cases without recourse to any notion of “rigid designation” or “trans-world identity.” Thereby CIFOL abstains from incorporating any metaphysical principles into the quantificational machinery, unlike extant frameworks of quantified modal logic. We claim that this neutrality makes CIFOL a useful tool for discussing both metaphysical and scientific arguments involving modality and quantification, and we illustrate by discussing in diagrammatic detail a number of such arguments involving the extensional identification of individuals via absolute properties, essential properties, de re vs. de dicto, and the results of possible tests. (shrink)

This paper follows Part I of our essay on case-intensional first-order logic (CIFOL; Belnap and Müller (2013)). We introduce a framework of branching histories to take account of indeterminism. Our system BH-CIFOL adds structure to the cases, which in Part I formed just a set: a case in BH-CIFOL is a moment/history pair, specifying both an element of a partial ordering of moments and one of the total courses of events (extending all the way into the future) that that moment (...) is part of. This framework allows us to define the familiar Ockhamist temporal/modal connectives, most notably for past, future, and settledness. The novelty of our framework becomes visible in our discussion of substances in branching histories, i.e., in its first-order part. That discussion shows how the basic idea of tracing an individual thing from case to case via an absolute property is applicable in a branching histories framework. We stress the importance of keeping apart extensionality and moment-definiteness, and give a formal account of how the specification of natural sortals and natural qualities turns out to be a coordination task in BH-CIFOL. We also provide a detailed answer to Lewis’s well-known argument against branching histories, exposing the fallacy in that argument. (shrink)

This is part I of a two-part essay introducing case-intensional first order logic, an easy-to-use, uniform, powerful, and useful combination of first-order logic with modal logic resulting from philosophical and technical modifications of Bressan’s General interpreted modal calculus. CIFOL starts with a set of cases; each expression has an extension in each case and an intension, which is the function from the cases to the respective case-relative extensions. Predication is intensional; identity is extensional. Definite descriptions are context-independent terms, and lambda-predicates (...) and -operators can be introduced without constraints. These logical resources allow one to define, within CIFOL, important properties of properties, viz., extensionality and absoluteness, Bressan’s chief innovation that allows tracing an individual across cases without recourse to any notion of “rigid designation” or “trans-world identity.” Thereby CIFOL abstains from incorporating any metaphysical principles into the quantificational machinery, unlike extant frameworks of quantified modal logic. We claim that this neutrality makes CIFOL a useful tool for discussing both metaphysical and scientific arguments involving modality and quantification, and we illustrate by discussing in diagrammatic detail a number of such arguments involving the extensional identification of individuals via absolute properties, essential properties, de re vs. de dicto, and the results of possible tests. (shrink)

In discussion of the "Principle of Identity" in the Treatise Hume presents a puzzle about identity - not a puzzle for semantics, like Frege's, but a puzzle for a theory of representation. In this essay I am less concerned with issues of Hume interpretation and more concerned with the puzzle itself.

This essay offers an original interpretation and defense of the doctrine of flux, as it is presented in Plato’s Theaetetus. The methodology of the paper’s analysis is in the style of rational reconstruction, and it is highly analytic in scope, in the sense that I will focus on the text itself, and only on certain parts of it too, while ignoring the rest of Plato’s extensive corpus, and without worrying about whether, how, and to what extent the interpretation of the (...) view coheres well with the other elements of the secret doctrine view discussed in the dialogue, as well. In the first part of the essay, I’ll offer my interpretation of the doctrine. Then, in the second part of the essay, I’ll examine two potential criticisms of the doctrine, including Socrates’s infamous linguistic paradox, and show how my interpretation of Heraclitean flux metaphysics is able to circumvent both. (shrink)

In this paper, I argue that David Lewis’s possible world semantics for counterfactual discourse and for fictional discourse are apparently inconsistent and in need of revision. The problem emerges for Lewis’s account once one considers how to evaluate ambifictional counterfactuals. Since this is likely not a concept familiar to most, and since it does not appear that the problem has been previously recognized in the critical literature, I will begin by rehearsing Lewis’s possible worlds semantics for counterfactuals and fiction. Then (...) I will explicate the distinction between intrafictional, extrafictional, interfictional, and ambifictional propositions. Next, I will state what an ambifictional counterfactual proposition is, and explain why this kind of discourse confounds Lewis’s system. I will conclude, finally, with a brief discussion of how the Lewisian would be best advised to resolve the paradox. (shrink)

In this paper Modern Essentialism is used to solve a problem of individuation of spacetime points in General Relativity that has been raised by a New Leibnizian Argument against spacetime substantivalism, elaborated by Earman and Norton. An earlier essentialistic solution, proposed by Maudlin, is criticized as being against both the spirit of metrical essentialism and the fundamental principles of General Relativity. I argue for a modified essentialistic account of spacetime points that avoids those obstacles.

In this paper I argue that Gareth Evans’ famous proof of the impossibility of de re indeterminate identity fails on a counterpart-theoretic interpretation of the determinacy operators. I attempt to motivate a counterpart-theoretic reading of the determinacy operators and then show that, understood counterpart-theoretically, Evans’ argument is straightforwardly invalid.

It is a commonsense thesis that unactualized possibilities are not parts of actuality. To keep his modal realism in line with this thesis, David Lewis employed his indexical account of the term “actual.” I argue that the addition of counterpart theory to Lewis’s modal realism undermines his strategy for respecting the commonsense thesis. The case made here also reveals a problem for Lewis’s attempt to avoid haecceitism.

An increasing amount of contemporary philosophy of mathematics posits, and theorizes in terms of special kinds of mathematical modality. The goal of this paper is to bring recent work on higher-order metaphysics to bear on the investigation of these modalities. The main focus of the paper will be views that posit mathematical contingency or indeterminacy about statements that concern the ‘width’ of the set theoretic universe, such as Cantor’s continuum hypothesis. Within a higher-order framework I show that contingency about the (...) width of the set-theoretic universe refutes two orthodoxies concerning the structure of modal reality: the view that the broadest necessity has a logic of S5, and the ‘Leibniz biconditionals’ stating that what is possible, in the broadest sense of _possible_, is what is true in some possible world. Nonetheless, I suggest that the underlying picture of modal set-theory is coherent and has attractions. (shrink)

In this paper, after clarifying certain features of Gideon Rosen’s Modal Fictionalism, I raise two problems for that view and argue that these problems strongly suggest that advocates of a “Deflationist Strategy” ought not to endorse, or adopt Rosen-style Modal Fictionalism.

As regards the question of what matters in survival two views have been identified: on the one hand, we have the view that what matters is identity (the so-called ?commonsense view?) and, on the other hand, we have the view that what matters is the holding of certain psychological connections between various mental states over time (the relation R). Several attempts have tried to reconcile these two views involving the so-called ?multiple occupancy view? or ?cohabitation thesis?. Even if the latter (...) comes in several formulations, common elements are, positing the appropriateness of a description of the fission case according to which the post-fission persons existed prior to fission and also, that what determines that two persons who exist at a certain time are distinct can be facts about what is the case at other times. The paper discusses three of the most influential formulations of the multiple occupancy view, which intend to reconcile identity with what matters, and argues that for various reasons these at least do not work in this regard. (shrink)

A ‘state of affairs’ is understood here as any kind of concrete entity that can play the role of truthmaker. Different ontologies propose different structures of entities to work as ‘states of affairs’ in this sense. Defenders of universals will propose for the role non- mereological structures of universals, objects and times. Defenders of tropes will propose tropes, either with or without universals and objects. Resemblance nominalists will propose primitive ontological facts of resemblance between objects in time. In any of (...) these cases, times are an essential component of a state of affairs. Any ontology of states of affairs, then, should clarify what times are in order to clarify what states of affairs are. An examination of the dominant reductivist conceptions of times shows that these connections have not yet been thought through carefully. In any of the dominant reductivist conceptions, times are entities that either include or describe everything that happens simultaneously at a given instant. Even in some cases they include the description of everything that happens at any time. If one introduce times taken as they are in any of these reductivist conceptions, it will be essential to a state of affairs everything that happens simultaneously with it, or even everything that happens at any time. Under some assumptions the internal relation of every state of affairs with every other state of affairs expands to the internal relation of everything with everything. This is an unhappy theoretical situation that calls for a more careful consideration of some central tenets in our ontology of time. (shrink)

The main aim in the forthcoming discussion is to contrast theistic modal realism and theistic actualist realism. Actualist realism is the dominant view among theists and presents the most serious challenge to theistic modal realism. I discuss various prominent forms of theistic actualist realism. I offer reasons for rejecting the view of metaphysical reality that actualist realism affords. I discuss theistic modal realism and show that the traditional conception of God is perfectly consistent with the metaphysics of genuine modal realism. (...) Indeed theistic modal realism is more suited to traditional theism than is any version of actualist realism. (shrink)

In Sections 1–7, I provide a detailed description of some of the advantages of theistic modal realism. The aim is to show specifically how theistic modal realism solves many of the intractable problems of philosophical theology. A detailed description of all of the advantages would require a much longer treatment. The aim is to give a good sense of the theoretical benefits that theistic modal realism affords traditional theists. I offer some concluding remarks in Section 8.

This essay shows that truth cannot be divorced from human experience and an individual’s world view, his or her weltanschauung. There exist different weltanschauungen that favour alternative truths. Thus, loosely speaking, truth is determined by context. It may be socially acceptable to prefer one among the alternative truths as truly true, but this goal necessarily involves taking an ideological perspective on what is perceived and accepted as the sole truth. In other words, it is prejudiced. The truth value assigned to (...) the proposition God exists starkly illustrates this claim, but in the course of this essay I demonstrate that alternative truths are widespread and that conflicting truths can co-exist within a community even when they create dissension. A hegemonic group will assert a preference for one truth over its alternatives, but that does not eliminate the existence of alternative truths. Alternative weltanschauungen need to be managed somehow, and the recognition that alternative truths exist is one step in their management. (shrink)

We argue that the future-like-ours argument against abortion rests on an important assumption. Namely, in the first trimester of an aborted pregnancy, there exists something that would have gone on to enjoy conscious mental states, had the abortion not occurred. To accommodate this assumption, we argue, a proponent of the future-like-ours argument must presuppose that there is ontic vagueness. We anticipate the objection that our argument achieves “too much” because it also applies mutatis mutandis to conscious humans. We respond by (...) showing that an explanation can be given for why it is wrong to kill conscious humans that is independent of the underlying metaphysics. Our response brings into focus a reason why—at least in the context of an ethical argument like the future-like-ours argument—appeal to a highly controversial metaphysics is ad hoc. Such metaphysics is not necessary to explain the wrongness of killing conscious humans, only nonconscious fetuses. (shrink)

Classical first-order logic can be extended in two different ways to serve as a foundation for mathematics: introduce higher orders, type theory, or introduce sets. As it happens, both approaches have natural analogs for quantified modal logics, both approaches date from the 1960’s, one is not very well-known, and the other is well-known as something else. I will present the basic semantic ideas of both higher order intensional logic, and intensional set theory. Before doing so, I’ll quickly sketch some necessary (...) background material from quantified modal logic. Except for standard material concerning propositional modal logics, the paper is essentially self-contained. (shrink)

This book presents an in-depth interpretation of three important parts of Leibniz's metaphysics: the metaphysical part of Leibniz's philosophy of logic, his essentially theological treatment of the central issues of ontology, and his theory of substance.

The aim of this chapter is to explore to some extent the relationship between identity and necessity in logic and metaphysics. First, I provide a historically-based summary of proofs of the necessity of identity, highlighting the importance of the role that self-identity plays. Second, I introduce two examples of metaphysical topics where the necessity of identity has played a pivotal role: the necessary a posteriori, and the coincidence of material objects. I argue that important aspects of these debates rest on (...) how we represent identity. Third, I consider some recent work on generalized identity. This opens up new prospects for explaining why identity is necessary. (shrink)