If we are to distinguish mere non-being from that which is not, yet may be, from that which was not, yet could have been, or from that which will not be, yet could become, we are committed in some way to grant being to possibilities. The possible is not actual; yet it is not nothing. What then could it be? What ontological status could it possess? In Contingency, Time, and Possibility: An Essay on Aristotle and Duns Scotus, Pascal Massie opens these questions by combining two approaches: First, an original inquiry that analyses the notions of chance, fate, event, contradiction, and so forth, and suggests that the distinction between potency and act arises from a confrontation with the impossible. Second, a historical inquiry that focuses on Aristotle and Duns Scotus, two key figures contributing to a fundamental transformation in the history of Western ontology; namely, the transition from a metaphysics of nature (Aristotle) to a metaphysics of the will (Scotus). In doing so, this book departs from the prevailing interpretation of the history of modal logic according to which Scotus rejected the principle of plenitude attributed to Aristotle and replaced the ancient diachronic theory of possibilities with a synchronic one, thereby contributing to a "possible world's semantics." Rather, Massie argues that in its proper ontological import, the question of possibility concerns the limit between being and non-being and that this limit must be thought in terms of temporality. With Scotus, however, a radical shift occurs. Possibilities are understood in terms of will, creation, omnipotence, and transcending freedom. As such, they belong to the realm of what is supremely actual (i.e., superabundant activity). What used to be understood as a lesser degree of being (the quasi non-being of uninformed matter and mere possibilities) becomes the mark of omnipotence.

The concept of possible worlds is useful because it defines the four modalities – possibility, necessity, contingency, and impossibility – but a challenge lies in defining it. David Lewis’ polemical hypothesis (“genuine modal realism” as it is called) succeeds in it. Lewis’ modal realism stirred controversy because he maintains that a plurality of worlds exists. Some philosophers suggest that the Lewisian view is a violation to the law of parsimony, also known as Ockham’s Razor, i.e. not multiply entities beyond necessity. While avoiding a circular definition, Lewis constructs an inflated ontology. Is it worth it, and if we do not want to assume too many Lewisian worlds, what alternatives remain? Actualist modal realism and modal antirealism are the most relevant alternatives because modal abstentionism simply will not progress in this direction. This study evaluates the theories of possible worlds.

It seems reasonable to believe that there might have existed things other than those that in fact exist, or have existed. But how should we understand such claims? Standard semantic theories exploit the Leibnizian metaphor of a set of all possible worlds: a proposition might or must be true if it is true in some or all possible worlds. The actualist, who believes that nothing exists except what actually exists, prefers to talk of possible states of the world, or of ways that a world might be. But even the actualist still faces the problem of explaining what we are talking about when we talk about the domains of other possible worlds. In Mere Possibilities, Robert Stalnaker develops a framework for clarifying this problem, and explores a number of actualist strategies for solving it. Some philosophers have hypothesized a realm of individual essences that stand as proxies for all merely possible beings. Others have argued that we are committed to the necessary existence of everything that does or might exist. In contrast, Mere Possibilities shows how we can make sense of ordinary beliefs about what might and must exist without making counterintuitive metaphysical commitments. 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.

Throughout his philosophical career at Michigan, UCLA, Yale, and Oxford, Robert Merrihew Adams's wide-ranging contributions have deeply shaped the structure of debates in metaphysics, philosophy of religion, history of philosophy, and ethics. Metaphysics and the Good: Themes from the Philosophy of Robert Merrihew Adams provides, for the first time, a collection of original essays by leading philosophers dedicated to exploring many of the facets of Adams's thought, a philosophical outlook that combines Christian theism, neo-Platonism, moral realism, metaphysical idealism, and a commitment to both historical sensitivity and rigorous analytic engagement. Tied together by their aim of exploring, expanding, and experimenting with Adams's views, these eleven essays are coupled with an intellectual autobiography by Adams himself that was commissioned especially for this volume. As the introduction to the volume explains, the purpose of Metaphysics and the Good is to explore Adams's work in the very manner that he prescribes for understanding the ideas of others. By experimenting with Adams's conclusions, "pulling a string here to see what moves over there, so to speak", as Adams puts it, our authors throw into greater relief what makes Adams such an original and stimulating philosopher. In doing so, these essays contribute not only to the exploration of Adams's continuing interests, but they also advance original and important philosophical insights of their own.

Robert Stalnaker draws together in this volume the extent of his work in metaphysics. The central theme is the role of possible worlds in articulating our various metaphysical commitments. The essays presented reflect on the nature of metaphysics, with two of the essays featured being published for the first time.

Ever since Saul Kripke and others developed a semantic interpretation for modal logic, 'possible worlds' has been a much debated issue in contemporary metaphysics. To propose the idea of a possible world that differs in some way from our actual world - for example a world where the grass is red or where no people exist - can help us to analyse and understand a wide range of philosophical concepts, such as counterfactuals, properties, modality, and of course, the notions of possibility and necessity. This book examines the ways in which possible worlds have been used as a framework for considering problems in logic and argument analysis. The book begins with a non-technical introduction to the basic ideas of modal logic in terms of Kripke's possible worlds and then moves on to a discussion of 'possible for' and 'possible that'. The central chapters examine questions of meaning, epistemic possibility, temporal logic, metaphysics, and impossibility. Girle also investigates how the idea of a possible world can be put to use in different areas of philosophy, the problems it may raise, and the benefits that can be gained.

The philosophical study of what exists and what it means for something to exist is one of the core concerns of metaphysics. This introduction to ontology provides readers with a comprehensive account of the central ideas of the subject of being. This book is divided into two parts. The first part explores questions of pure philosophical ontology: what is meant by the concept of being, why there exists something rather than nothing, and why there is only one logically contingent actual world. Dale Jacquette shows how logic provides the only possible answers to these fundamental problems. The second part of the book examines issues of applied scientific ontology. Jacquette offers a critical survey of some of the most influential traditional ontologies, such as the distinction between appearance and reality, and the categories of substance and transcendence. The ontology of physical entities - space, time, matter and causation - is examined as well as the ontology of abstract entities such as sets, numbers, properties, relations and propositions. The special problems posed by the subjectivity of mind and of postulating a god are also explored in detail. The final chapter examines the ontology of culture, language and art.

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.