This is an advanced 2001 textbook on modal logic, a field which caught the attention of computer scientists in the late 1970s. Researchers in areas ranging from economics to computational linguistics have since realised its worth. The book is for novices and for more experienced readers, with two distinct tracks clearly signposted at the start of each chapter. The development is mathematical; prior acquaintance with first-order logic and its semantics is assumed, and familiarity with the basic mathematical notions of set theory is required. The authors focus on the use of modal languages as tools to analyze the properties of relational structures, including their algorithmic and algebraic aspects, and applications to issues in logic and computer science such as completeness, computability and complexity are considered. Three appendices supply basic background information and numerous exercises are provided. Ideal for anyone wanting to learn modern modal logic.

The Handbook of Modal Logic contains 20 articles, which collectively introduce contemporary modal logic, survey current research, and indicate the way in which the field is developing. The articles survey the field from a wide variety of perspectives: the underling theory is explored in depth, modern computational approaches are treated, and six major applications areas of modal logic (in Mathematics, Computer Science, Artificial Intelligence, Linguistics, Game Theory, and Philosophy) are surveyed. The book contains both well-written expository articles, suitable for beginners approaching the subject for the first time, and advanced articles, which will help those already familiar with the field to deepen their expertise. Please visit: http://people.uleth.ca/~woods/RedSeriesPromo_WP/PubSLPR.html - Compact modal logic reference - Computational approaches fully discussed - Contemporary applications of modal logic covered in depth

Propositional quantifiers are quantifiers binding proposition letters, understood as variables. This Element introduces propositional quantifiers and explains why they are especially interesting in the context of propositional modal logics. It surveys the main results on propositionally quantified modal logics which have been obtained in the literature, presents a number of open questions, and provides examples of applications of such logics to philosophical problems.

This is a thorough treatment of first-order modal logic. The book covers such issues as quantification, equality (including a treatment of Frege's morning star/evening star puzzle), the notion of existence, non-rigid constants and function symbols, predicate abstraction, the distinction between nonexistence and nondesignation, and definite descriptions, borrowing from both Fregean and Russellian paradigms.

The notions of necessity and possibility, as well as the notion of a possible world, are ubiquitous in philosophy. Nevertheless, these notions remain controversial. It also remains controversial whether metaphysics requires notions drawing distinctions which are finer than those which can be drawn in terms of necessity and possibility, such as the recently much-discussed notion of grounding. In order to make progress on these debates, this book develops a general framework for theorizing about such intensional notions using the tools of higher-order logic. The Foundations of Modality begins by motivating the use of higher-order logic, and introduces a particularly simple form of higher-order logic. Progress is made on well-trodden territory concerning modality and possible worlds by considering first the question how fine propositions are individuated. Peter Fritz uses both logical results and philosophical arguments to motivate a relatively coarse-grained individuation of propositions. Fritz shows that a number of putative metaphysical notions are ruled out by this theory of individuation. Furthermore, the theory allows the controversial notion of (metaphysical) necessity to be delineated as the broadest necessity, which applies just to the single tautologous proposition. This book also vindicates appeals to possible worlds: First, it shows that if anything plays the theoretical role of possible worlds, then certain propositions do so. Second, it argues that there are in fact the required propositions playing the role of possible worlds; this is shown using the notion of plural quantification over propositions in higher-order logic.

An introductory textbook on modal logic the logic of necessity and possibility.