Modal Ersatizism

I propose an account of possible worlds. According to the account, possible worlds are pluralities of sentences in an extremely large language. This account avoids a problem, relating to the total number of possible worlds, that other accounts face. And it has several additional benefits.

According to actualism about possible worlds everything that exists is actual. Possible worlds and individuals are actually existing abstract parts of the actual world. Aristotelian actualism is a view that there are only actual individuals but no possible ones, nor their individual abstract representatives. Because of that, our actualist account of modality should differ depending on whether it concerns actual individuals or possible ones. The main goal of the dissertation is to develop a metaphysical framework for Aristotelian actualism. Chapter 1 (...) explains basic issues associated with the possible world approach to modality. I overview modal realist and actualist views on possible worlds and explain why I support the actualist approach. Subsequently, I introduce a distinction between Platonic and Aristotelian actualism, and discuss some semantic issues associated with actualism as such. In Chapter 2 I argue that Aristotelian actualism, modeled on linguistic ersatzism, is preferable over its Platonic counterpart. Subsequently, I propose a metaphysical framework for Aristotelian ersatzism which is based on a claim that our modal concepts work differently for actual and possible individuals. In order to explain that claim I introduce three specific differences concerning modal features of actual and possible individuals: (a) Representational Difference, according to which actual and possible individuals are represented differently by possible worlds; (b) Metaphysical Difference, according to which actual and possible individuals are represented by possible worlds as having different metaphysical nature; (c) Modal Difference, which says while there are singular and contingent possibilities involving actual individuals, all possibilities about possible individuals are general and necessary. I propose to interpret those differences in terms of the doctrines of haecceitism, antihaecceitism and existentialism. There is however no consensus on how those views should be characterized. Chapters 3, 4, and 5 focus on providing a precise characterization of those doctrines. Chapter 3 focuses on the doctrines of modal haecceitism and antihaecceitism, which I view as opposite accounts of how possible worlds represent possibilities. According to modal haecceitism what possible worlds say about particular individuals does not supervene on what they say qualitatively. Modal antihaecceitism is a denial of such a claim. Chapter 4 concerns metaphysical haecceitism and antihaecceitism, which I take to be alternative accounts of the fundamental structure of reality. For the metaphysical haecceitist reality contains irreducible singular facts, while for the metaphysical antihaecceitist reality is purely qualitative and general. Chapter 5 focuses on an argument between existentialists and antiexistentialists. Existentialists claim that there are contingent singular propositions, while antiexistentialists deny that. I defend existentialism against antiexistentialist counterarguments, as well as criticize some of the antiexistentialist accounts of singular propositions modeled on the notion of individual essence. In Chapter 6, by appealing to the results of investigations conducted in Chapters 3, 4 and 5, I reconsider Representational, Metaphysical and Modal Differences. According to a view that I propose: (a) Representational Difference entails (extreme) modal haecceitism for actual individuals but (extreme) modal antihaecceitism for possible individuals; (b) Metaphysical Difference entails metaphysical haecceitism (individualism) for actual individuals, but metaphysical antihaecceitism (generalism) for possible individuals; finally (c) Modal Difference entails existentialism: while there are singular and contingent possibilities involving actual individuals, all possibilities about possible individuals are general and necessary. In Chapter 6, I also explain the implications of those views for the various issues, including transworld identity, essentialism, or the modal status of modal space. Lastly, Chapter 7 overviews some semantic and metaphysical applications of Aristotelian ersatzism. I explain how it manages to accommodate Kripkean semantics and how it is able to account for the possibilities of indiscernibles, alien individuals and iterated modalities. I also address some possible objections to my proposal, including an issue of implicit representation and the Humphrey objection. (shrink)

Please note that this article belongs to the Special Issue on the Legacy of David Lewis but was included in issue 195:5 by mistake. It should be regarded as part of this selection of articles.

David Lewis’s arguments against magical ersatzism are notoriously puzzling. Untangling different strands in those arguments is useful for bringing out what he thought was wrong with not just one style of theory about possible worlds, but with much of the contemporary metaphysics of abstract objects. After setting out what I take Lewis’s arguments to be and how best to resist them, I consider the application of those arguments to general theories of properties and relations. The constraints Lewis motivates turn out (...) to yield an argument for concretism about possible individuals that is quite different from the better-known Lewisian arguments for that position. The discussion also touches on the puzzling question of whether things are the way they are because of the properties they have, or are the properties and relations the way they are because of the things that have them. (shrink)

Dualism about possible worlds says that merely possible worlds aren’t concrete objects, but the actual world is concrete. This view seems to be the natural one for ersatzers about merely possible worlds to take; yet one is hard-pressed to find any defenders of it in contemporary modal metaphysics. The main reason is that Dualism struggles with the issue of how merely possible worlds could have been actual. I explain that there are two different Dualist strategies that can be taken to (...) address the problem. Furthermore, one or other of these strategies should be plausible to anyone who accepts both Existentialism—which tells us that the existence of singular propositions depends on what they directly refer to—and Serious Actualism—which tells us that things must exist in order to instantiate properties. Though it has long been ignored, Dualism is a live option. (shrink)

David Lewis objected to theories that posit necessary connections between distinct entities and to theories that involve a magical grasping of their primitives. In On the Plurality of Worlds, Lewis objected to nondescript ersatzism on these grounds. The literature contains several reconstructions of Lewis’ critique of nondescript ersatzism but none of these interpretations adequately address his main argument because they fail to see that Lewis’ critique is based on broader methodological considerations. I argue that a closer look at his methodology (...) reveals the broader objection he presented against nondescript ersatzism. This objection, I further argue, remains a challenge for the ersatzer who posits structure-less entities as possible worlds. (shrink)

This dissertation is about flexibility as a dimension of reality, an objective—independent of mind and language—phenomenon typically referred to as ‘metaphysical modality’. It develops a novel modal account of why reality could be different: that is, why claims like “Possibly, there are talking donkeys,” or “Humphrey could have won the election” are true or false. I contend that primitive dispositional properties called ‘powers’ explain such claims, and do so better than possible-world accounts of modality. The problem with possible-world accounts is (...) that they fail to capture what we mean by modal terms like ‘possibly’, ‘can’, or ‘necessarily’. The phenomenon they capture with possible worlds cannot adequately explain, for instance, that Humphrey regrets not winning the election because: he could have made a difference. Humphrey is told that he could have won the election because some entity represents him as such. But what does some entity’s representing Humphrey have to do with whether Humphrey could have won the election? Simply calling that entity a ‘possible world’ is no help. Powers do better in this regard, preserving a common-sense notion of modality where, because of what a power can do it acts as a cross-roads in history, marking places where reality could have unfolded differently. As such, powers are more clearly modally significant than possible worlds. The conclusion shows how to use powers to underwrite possible-world semantics without possible worlds. (shrink)

The distinction between quantitative and qualitative parsimony is supposed to allow David Lewis to dismiss one of the charges against his modal realism: that is, the charge of bloated ontology. The aim of this paper is to undermine Lewis's response to this objection. In order to do this, a distinction between multipliable and nonmultipliable objects is introduced. Based on this it is argued that the acceptance of Lewis's response requires one to believe in modal realism in the first place—that is, (...) one has to believe in the view that the existence of nonactual spatiotemporal worlds does not affect the quality of the ontological commitment. Although the paper focuses on the problem of the metaphysics of possible worlds, this should be regarded merely as a case study. Accordingly, the results of this analysis should find applications in other metaphysical debates as well. (shrink)

According to many actualist theories of modality, possible worlds should be identified with maximal and consistent sets of actually existing propositions called "world-stories". A set of propositions is said to be maximal if and only if for every (actually existing) proposition P , either P or its negation belongs to the set. In my talk, I will claim that this conception of maximality is problematic in case what has to be represented by a world-story is the possible non existence of (...) an actual individual. A representation of the possible non existence of an actual individual is either a representation that "encodes" the explicit information that the individual does not exist or a representation that does not contain any information about the individual in question. The former case corresponds to a world-story A that contains a proposition according to which a certain actually existing object, say O, does not exist, the latter case to a world-story B that simply does not contain any proposition about O. I will claim, however, that the first way is not good for the actualist (had A been the true world-story, something directly about a possible individual would have been true) while the second conflicts with the standard notion of maximality given above. In order to fix this problem, I will first propose to characterize the notion of "actual object that would have existed, had a certain set of propositions been true". I will then recursively define an alternative conception of maximality ("local maximality") that can be applied to world-stories aiming to represent, in an actualist acceptable way, the possible non-existence of an actual object. (shrink)

Truthmakers, truth conditions, and analyses are closely related, but distinct in rather important ways. A failure to properly appreciate their differences has led to some confusion regarding the role that possible worlds ought to play with respect to modality. Those philosophers who initially proposed the existence of possible worlds were understood as providing an analysis of modality. More recently, many have interpreted them as providing modal truthmakers. But, possible worlds are only suited to serve as truth conditions for modal truths. (...) My goals are as follows: First, to dispel this confusion by detailing the differences between these three concepts. Second, to apply the lesson learned to the famous Humphrey objection against possible worlds. While this objection, if successful, does undermine Lewisian modal realism, it only partially undermines ersatzism, and leaves available a route by which ersatzers may avoid the objection altogether. (shrink)

It is sometimes argued that there is an analogy between time and modality: What is true of time, mutatis mutandis, should be true of modality, and vice versa. However, I think that the importance of this analogy has not been truly appreciated in the literature. In this paper, I try to offer a plausible account of the relationship between time and modality based on what is known as presentist ersatzism. If the attempt succeeds, it will be shown that ersatzists about (...) time are better able to explain what possible worlds are. (shrink)

In Prior’s tense-logical analysis, we can avoid mentioning instants in our language by construing them as propositions of a special kind. Instead of qualifying instants by predicates, we may qualify propositions by modalities. Prior shows that by changing the informal interpretation of our modal-like language, we can similarly attempt to avoid ontological commitments to worlds and even to selves and other bona fide individuals. As he notes, the paraphrasing strategy works too generally to be of direct metaphysical use. I wish (...) to speak of several types of entities within one and the same language. This leads to the issue of cross-context identity: how to make sense of speaking of the same entity of one type relative to distinct entities of another type. My analysis employs the notion of world line. I discern a structure of mutually interrelated categories with three informal interpretations: tense, modal and egocentric. They correspond to different metaphysical views on the interrelations of time, logical alternatives and individuals. Prior’s dilemma regarding the possibility of modalizing, not only our talk concerning times and worlds, but even our discourse pertaining to the ‘real world of individuals’ does not vanish but reappears also in my setting. (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)

Actualist counterpart theory replaces David Lewis’s concrete possible worlds and individuals with ersatz worlds and individuals, but retains counterpart theory about de re modality. While intuitively attractive, this view has been rejected for two main reasons: the problem of indiscernibles and the Humphrey objection. I argue that in insisting that ersatz individuals play the same role as Lewisian individuals, actualists commit the particularist fallacy. The actualist should not require stand-ins for every Lewisian individual. Ersatz individuals should instead be construed as (...) representations of actually existing qualitative ways for individuals to be, or qualitative properties individuals can instantiate. This necessitates changes elsewhere. Non-instrumental uses of Kripke semantics and standard counterpart semantics also require stand-ins for particular non-actual individuals. I argue that the actualist should instead adopt a non-standard counterpart semantics that more clearly illuminates the role that actual properties and relations play in explaining de re possibilities and necessities. The result is an intuitive and forceful reply to both the problem of indiscernibles and the Humphrey objection. (shrink)

The authors provide an object-theoretic analysis of two paradoxes in the theory of possible worlds and propositions stemming from Russell and Kaplan. After laying out the paradoxes, the authors provide a brief overview of object theory and point out how syntactic restrictions that prevent object-theoretic versions of the classical paradoxes are justified philosophically. The authors then trace the origins of the Russell paradox to a problematic application of set theory in the definition of worlds. Next the authors show that an (...) object-theoretic analysis of the Kaplan paradox reveals that there is no genuine paradox at all, as the central premise of the paradox is simply a logical falsehood and hence can be rejected on the strongest possible grounds—not only in object theory but for the very framework of propositional modal logic in which Kaplan frames his argument. The authors close by fending off a possible objection that object theory avoids the Russell paradox only by refusing to incorporate set theory and, hence, that the object-theoretic solution is only a consequence of the theory’s weakness. (shrink)

Among the most remarkable developments in metaphysics since the 1950’s is the explosion of philosophical interest in possible worlds. This paper proposes an explanation of what possible worlds are, and argues that this proposal, the interpreted models conception, should be attractive to anyone who thinks that modal facts are primitive, and so not to be explained in terms of some non-modal notion of “possible world.” I articulate three constraints on any acceptable primitivist explanation of the nature of possible worlds, and (...) show that the interpreted models conception meets the three constraints. (shrink)

We need to understand the impossible. Francesco Berto and Mark Jago start by considering what the concepts of meaning, information, knowledge, belief, fiction, conditionality, and counterfactual supposition have in common. They are all concepts which divide the world up more finely than logic does. Logically equivalent sentences may carry different meanings and information and may differ in how they're believed. Fictions can be inconsistent yet meaningful. We can suppose impossible things without collapsing into total incoherence. Yet for the leading philosophical (...) theories of meaning, these phenomena are an unfathomable mystery. To understand these concepts, we need a metaphysical, logical, and conceptual grasp of situations that could not possibly exist: Impossible Worlds. This book discusses the metaphysics of impossible worlds and applies the concept to a range of central topics and open issues in logic, semantics, and philosophy. It considers problems in the logic of knowledge, the meaning of alternative logics, models of imagination and mental simulation, the theory of information, truth in fiction, the meaning of conditional statements, and reasoning about the impossible. In all these cases, impossible worlds have an essential role to play. (shrink)

Bob Hale presents a broadly Fregean approach to metaphysics, according to which ontology and modality are mutually dependent upon one another. He argues that facts about what kinds of things exist depend on facts about what is possible. Modal facts are fundamental, and have their basis in the essences of things--not in meanings or concepts.

Theories of content are at the centre of philosophical semantics. The most successful general theory of content takes contents to be sets of possible worlds. But such contents are very coarse-grained, for they cannot distinguish between logically equivalent contents. They draw intensional but not hyperintensional distinctions. This is often remedied by including impossible as well as possible worlds in the theory of content. Yet it is often claimed that impossible worlds are metaphysically obscure; and it is sometimes claimed that their (...) use results in a trivial theory of content. In this paper, I set out the need for impossible worlds in a theory of content; I briefly sketch a metaphysical account of their nature; I argue that worlds in general must be very fine-grained entities; and, finally, I argue that the resulting conception of impossible worlds is not a trivial one. (shrink)

Impossible worlds are representations of impossible things and impossible happenings. They earn their keep in a semantic or metaphysical theory if they do the right theoretical work for us. As it happens, a worlds-based account provides the best philosophical story about semantic content, knowledge and belief states, cognitive significance and cognitive information, and informative deductive reasoning. A worlds-based story may also provide the best semantics for counterfactuals. But to function well, all these accounts need use of impossible and as well (...) as possible worlds. So what are impossible worlds? Graham Priest claims that any of the usual stories about possible worlds can be told about impossible worlds, too. But far from it. I'll argue that impossible worlds cannot be genuine worlds, of the kind proposed by Lewis, McDaniel or Yagisawa. Nor can they be ersatz worlds on the model proposed by Melia or Sider. Constructing impossible worlds, it turns out, requires novel metaphysical resources. (shrink)

This article includes a basic overview of possible world semantics and a relatively comprehensive overview of three central philosophical conceptions of possible worlds: Concretism (represented chiefly by Lewis), Abstractionism (represented chiefly by Plantinga), and Combinatorialism (represented chiefly by Armstrong).

You and I can differ in what we say, or believe, even though the things we say, or believe, are logically equivalent. Discussing what is said, or believed, requires notions of content which are finer-grained than sets of (metaphysically or logically) possible worlds. In this paper, I develop the approach to fine-grained content in terms of a space of possible and impossible worlds. I give a method for constructing ersatz worlds based on theory of substantial facts. I show how this (...) theory overcomes an objection to actualist constructions of ersatz worlds and argue that it naturally gives rise to useful notions of fine-grained content. (shrink)

Bringsjord (1985) argues that the definition W of possible worlds as maximal possible sets of propositions is incoherent. Menzel (1986a) notes that Bringsjord’s argument depends on the Powerset axiom and that the axiom can be reasonably denied. Grim (1986) counters that W can be proved to be incoherent without Powerset. Grim was right. However, the argument he provided is deeply flawed. The purpose of this note is to detail the problems with Grim’s argument and to present a sound alternative argument (...) for his conclusion – basically the argument Russell gave to establish a well-known paradox in The Principles of Mathematics. (shrink)

This summarizes of some prominent views about the metaphysics of possible worlds.

The book also sheds new light on the nature of metaphysical theorizing by exploring the interaction of semantic and metaphysical issues, the connections between different metaphysical issues, and the nature of ontological commitment.

Suppose that reality consists of parallel universes of every variety imaginable. No path through space and time leads from one to another, and each universe is causally isolated from the rest. Some physicists believe a ‘multiverse’ hypothesis not terribly distant from this one simplifies quantum mechanics and provides an elegant explanation of why our universe has its particular laws. Suppose as science advances we come to accept the multiverse hypothesis, so construed.

Accounts of propositions as sets of possible worlds have been criticized for conflating distinct impossible propositions. In response to this problem, some have proposed to introduce impossible worlds to represent distinct impossibilities, endorsing the thesis that impossible worlds must be of the same kind; this has been called the parity thesis. I show that this thesis faces problems, and propose a hybrid account which rejects it: possible worlds are taken as concrete Lewisian worlds, and impossibilities are represented as set-theoretic constructions (...) out of them. This hybrid account (1) distinguishes many intuitively distinct impossible propositions; (2) identifies impossible propositions with extensional constructions; (3) avoids resorting to primitive modality, at least so far as Lewisian modal realism does. (shrink)

In this paper, I distinguish between two varieties of actualism—hardcore actualism and softcore actualism—and I critically discuss Ross Cameron’s recent arguments for preferring a softcore actualist account of the truthmakers for modal truths over hardcore actualist ones. In the process, I offer some arguments for preferring the hardcore actualist account of modal truthmakers over the softcore actualist one.

Robert Stalnaker is an actualist who holds that merely possible worlds are uninstantiated properties that might have been instantiated. Stalnaker also holds that there are no metaphysically impossible worlds: uninstantiated properties that couldn't have been instantiated. These views motivate Stalnaker's "two dimensional" account of the necessary a posteriori on which there is no single proposition that is both necessary and a posteriori. For a necessary proposition is true in all possible worlds. If there were necessary a posteriori propositions, that would (...) mean that there were propositions true in all possible worlds but which could only be known to be true by acquiring empirical evidence. Consider such a purported proposition P. The role of empirical evidence for establishing P's truth would have to be to rule out worlds in which P is false. If there were no such worlds to be ruled out, we would not require evidence for P. But by hypothesis, P is necessary and so true in all metaphysically possible worlds. And on Stalnaker's view, the metaphysically possible worlds are all the worlds there are. So there can be no proposition that is true in all possible worlds, but that we require evidence to know. In this way, the motivation for Stalnaker's two dimensional account of the necessary a posteriori rests on his denying that there are metaphysically impossible Worlds. I argue that given his view of what possible worlds are, Stalnaker has no principled reason for denying that there are metaphysically impossible worlds. If I am right, this undercuts Stalnaker's motivation for his two dimensional account of the necessary a posteriori. (shrink)

Magical ersatzism is the view that possible worlds are primitive abstract entities. In On the Plurality of Worlds, David Lewis presented what appeared to many to be a devastating argument against magical ersatzism. In this paper, I show that Lewis’ central argument does not succeed. Magical ersatzism remains a viable theory of possible worlds.

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.

David Lewis' objection to a generic theory of modality which he calls ‘magical ersatzism’ is that its linchpin, a relation he calls ‘selection’, must be either an internal or an external relation, and that this is unintelligible either way. But the problem he points out with classifying selection as internal is really just an instance of the general problem of how we manage to grasp underdetermined predicates, is not peculiar to magical ersatzism, and is amenable to some familiar solutions. He (...) provides no compelling grounds for thinking that classifying selection as external is unintelligible, and his argument has a false presupposition. I conclude that magical ersatzism is still a viable option in the metaphysics of modality. (shrink)

Aim of this paper is to present and evaluate linguistic ersatzism, an actualist metaphysics of modality according to which possible worlds are maximal and consistent sets of sentences. In the first section, I make some general considerations about reductive theories of modality and the relation between modality and possible worlds, in the second I present a specific version of linguistic ersatzism and in the last section I present what I take to be the major problem for this kind of theories, (...) namely that of finding a suitable surrogate for the possibilist’s notion of a merely possible object. (shrink)

The study of metaphysical possibility involves two central questions: What are possible worlds? Is there an empty possible world? In looking at the first question we consider the different accounts of possible worlds—Lewisian realism, ersatzism, etc. In looking at the second question we consider the discussions of metaphysical nihilism, the modal ontological arguments, etc. In this paper I am drawing these two questions together in order to show how the position we hold on one of these issues affects the position (...) we should hold on the other. (shrink)

The study of metaphysical possibility involves two central questions: (i) What are possible worlds? (ii) Is there an empty possible world? In looking at the first question we consider the different accounts of possible worlds-Lewisian realism, ersatzism, etc. In looking at the second question we consider the discussions of metaphysical nihilism, the modal ontological arguments, etc. In this paper I am drawing these two questions together in order to show how the position we hold on one of these issues affects (...) the position we should hold on the other. (shrink)

Are there, in addition to the various actual objects that make up the world, various possible objects? Are there merely possible people, for example, or merely possible electrons, or even merely possible kinds? We certainly talk as if there were such things. Given a particular sperm and egg, I may wonder whether that particular child which would result from their union would have blue eyes. But if the sperm and egg are never in fact brought together, then there is no (...) actual object that my thought is about. Or again, in the semantics for modal logic we presuppose an ontology of possibilia twice over. For first, we countenance various possible worlds, in addition to the actual world; and second, each of these worlds is taken to be endowed with its own domain of objects. These will be the actual objects of the world in question, but they need not be actual simpliciter, i.e., actual objects of our world. What are we to make of such discourse? There are four options: (i) the discourse is taken to be unintelligible; (ii) it is taken to be intelligible but nonfactual, i.e. as not in the business of stating facts; (iii) it is taken to be factual but reducible to discourse involving no reference to possibilia; (iv) it is taken to be both factual and irreducible. These options range from a full-blooded form of actualism at one extreme to a full-blooded form of possibilism at the other. The two intermediate positions are possibilist in that they accept the intelligibility of possibilist discourse but actualist in that they attempt to dispense with its prima facie commitment to possibilia. All four positions have found advocates in the literature. Quine, in his less irenic moments, favours option (i); Forbes advocates option (ii), at least for certain parts of possibilist discourse; many philosophers, including Adams and myself, opt for (iii); while Lewis and Stalnaker have endorsed versions of (iv), that differ in how full-blooded they take the possible objects to be.. (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)

_Possible Worlds_ presents the first up-to-date and comprehensive examination of one of the most important topics in metaphysics. John Divers considers the prevalent philosophical positions, including realism, antirealism and the work of important writers on possible worlds such as David Lewis, evaluating them in detail.

This book discusses a range of important issues in current philosophical work on the nature of possible worlds. Areas investigated include the theories of the nature of possible worlds, general questions about metaphysical analysis and questions about the direction of dependence between what is necessary or possible and what could be.