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.

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.

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 philosophy of modality investigates necessity and possibility, and related notions—are they objective features of mind-independent reality? If so, are they irreducible, or can modal facts be explained in other terms? This volume presents new work on modality by established leaders in the field and by up-and-coming philosophers. Between them, the papers address fundamental questions concerning realism and anti-realism about modality, the nature and basis of facts about what is possible and what is necessary, the nature of modal knowledge, modal logic and its relations to necessary existence and to counterfactual reasoning. The general introduction locates the individual contributions in the wider context of the contemporary discussion of the metaphysics and epistemology of modality.

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This book is a defense of modal realism; the thesis that our world is but one of a plurality of worlds, and that the individuals that inhabit our world are only a few out of all the inhabitants of all the worlds. Lewis argues that the philosophical utility of modal realism is a good reason for believing that it is true.

Timothy Williamson gives an original and provocative treatment of deep metaphysical questions about existence, contingency, and change, using the latest resources of quantified modal logic. Contrary to the widespread assumption that logic and metaphysics are disjoint, he argues that modal logic provides a structural core for metaphysics.

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.

Takashi Yagisawa argues for a new version of modal realism, the view that non-actual possible worlds and individuals are as real as the actual ones. He asserts that the notion of reality is primitive, existence is a relation between a thing and a domain, and ordinary objects are extended in spatial, temporal, and modal dimensions.