This book is intended to serve as an advanced text and reference work on modal logic, a subject of growing importance which has applications to philosophy and linguistics. Although it is based mainly on research which I carried out during the years 1969-1973, it also includes some related results obtained by other workers in the field (see the refer ences in Part 7). Parts 0, 1 and 2, can be used as the basis of a one year graduate course in modal logic. The material which they contain has been taught in such courses at Stanford since 1970. The remaining parts of the book contain more than enough material for a second course in modal logic. The exercises supplement the text and are usually difficult. I wish to thank Stanford University and Bar-Han University for making it possible for me to continue and finish this work, and A. Ungar for correcting the typescript. Bar-Ilan University, Israel Dov M. GABBA Y PART 0 AN INTRODUCTION TO GENERAL INTENSIONAL LOGICS CHAPTER 0 CONSEQUENCE RELATIONS Motivation We introduce the notions of a consequence relation (which is a generalization of the notion of a logical system) and of a semantics. We show that every consequence relation is complete for a canonical semantics. We define the notion of one semantics being Dian in another and study the basic properties of this notion. The concepts of this chapter are generalizations of the various notions of logical system and possible world semantics found in the literature.

conceptual, realist) theories of predication. Chapter IV.4 centers on an important class of expressions used for predication in connection with quantities: mass expressions. This chapter reviews the most well-known approaches to mass terms and the ontological proposals related to them. In addition to quantification and predication, matters of reference have constituted the other overriding theme for semantic theories in both philosophical logic and the semantics of natural languages. Chapter IV.5 of how the semantics of proper names and descrip presents an overview tions have been dealt with in recent theories of reference. Chapter IV.6 is concerned with the context-dependence of reference, in particular, with the semantics of indexical expressions. The topic of Chapter IV.7 is related to predication as it surveys some of the central problems of ascribing propositional attitudes to agents. Chap ter IV.8 deals with the analysis of the main temporal aspects of natural language utterances. Together these two chapters give a good indication of the intricate complexities that arise once modalities of one or the other sort enter on the semantic stage. in philosophical Chapter IV.9 deals with another well-known topic logic: presupposition, an issue on the borderline of semantics and prag matics. The volume closes with an extensive study of the Liar paradox and its many implications for the study of language (as for example, self reference, truth concepts and truth definitions).

A group of pre-eminent figures offer a conspectus of the interaction of game theory, logic and episemology in the formal models of knowledge, belief, deliberation and learning.

The Fourth Scandinavian Logic Symposium and the First Soviet-Finnish Logic Conference were held in JyvaskyIa, Finland, June 29-July 6, 1976. The Conferences were organized by a committee which consisted of the editors of the present volume. The Conferences were supported financially by the Ministry of Education of Finland, by the Academy of Finland, and by the Division of Logic, Methodology, and Philosophy of Science of the International Union of History of Science. The Philosophical Society of Finland and the Jyvaskyla Summer Festival gave valuable help in various practicalities. 35 papers by authors representing 10 countries were presented at the two meetings. Of those papers 24 appear here. THE EDITORS v TABLE OF CONTENTS PREFACE v PART 1/ PROOF THEORY GEORG KREISEL / Some Facts from the Theory of Proofs and Some Fictions from General Proof Theory 3 DAG PRAWITZ / Proofs and the Meaning and Completeness of the Logical Constants 25 v. A. SMIRNOV / Theory of Quantification and tff-calculi 41 LARS SVENONIUS/Two Kinds of Extensions of Primitive Recursive Arithmetic 49 DIRK VAN DALEN and R. STATMAN / Equality in the Presence of Apartness 95 PART II / INFINITARY LANGUAGES VEIKKO RANTALA / Game-Theoretical Semantics and Back-and- Forth 119 MAARET KAR TTUNEN / Infinitary Languages N oo~.

The present volume owes its existence to a proposal of Dr Esa Saarinen. Our aim was to celebrate the work of a living philosopher by presenting it both from his own point of view, through the medium of a philosophical autobiography, and from that of his closest philo sophical colleagues and adversaries. We felt that a philosophical career lived through vigorous controversy was best reflected not by adulation but in the spirit of that career - by open debate. Contributors were not constrained in their choice of topic, but their contributions fell naturally into groups linked with some of Peter Geach's principal areas of interest, and we have so grouped them in the book. There is an interweaving of biographical and philosophical themes, not only in Peter Geach's philosophical autobiography, but also in the introductions he has contributed to each section. Professor W. V. O. Quine's contribution, which consists of extracts from his correspondence with Peter Geach, has been set apart as it forms a natural bridge between Peter Geach's autobiography and the contri butions that follow. Their correspondence reproduced here throws new light on many familiar themes from the writings of both philosophers: among them, the objects of belief and other attitudes, issues in set theory, the nature of causality, and evolution in epistemology.

Bruno de Finetti (1906–1985) is the founder of the subjective interpretation of probability, together with the British philosopher Frank Plumpton Ramsey. His related notion of “exchangeability” revolutionized the statistical methodology. This book (based on a course held in 1979) explains in a language accessible also to non-mathematicians the fundamental tenets and implications of subjectivism, according to which the probability of any well specified fact F refers to the degree of belief actually held by someone, on the ground of her whole knowledge, on the truth of the assertion that F obtains.

An introduction to many-sorted logic as an extension of first-order logic.

Abductive Reasoning: Logical Investigations into Discovery and Explanation is a much awaited original contribution to the study of abductive reasoning, providing logical foundations and a rich sample of pertinent applications. Divided into three parts on the conceptual framework, the logical foundations, and the applications, this monograph takes the reader for a comprehensive and erudite tour through the taxonomy of abductive reasoning, via the logical workings of abductive inference ending with applications pertinent to scientific explanation, empirical progress, pragmatism and belief revision.

Modern mathematical logic would not exist without the analytical tools first developed by George Boole in The Mathematical Analysis of Logic and The Laws of Thought. The influence of the Boolean school on the development of logic, always recognised but long underestimated, has recently become a major research topic. This collection is the first anthology of works on Boole. It contains two works published in 1865, the year of Boole's death, but never reprinted, as well as several classic studies of recent decades and ten original contributions appearing here for the first time. From the programme of the English Algebraic School to Boole's use of operator methods, from the problem of interpretability to that of psychologism, a full range of issues is covered. The Boole Anthology is indispensable to Boole studies and will remain so for years to come.

Willard VanOrman Quine has probably been the most influential th American philosopher of the 20 century. His work spans over seven decades, and covers many domains in philosophy. He has made major contributions to the fields of logic and set theory, philosophy of logic and mathematics, philosophy of language, philosophy of science, epistemology and metaphysics. Quine's first work in philosophy was in the field of logic. His major contributions are the two set-theoretic systems NF (1936) and ML (1940). 1 These systems were alternatives to the type theory of Principia Mathematica or Zermelo's set theory, and are still being studied by 2 mathematicians. An indirect contribution to the field of logic is his strong resistance to moda110gic. Quine's objectIons to the notions of necessity and analyticity have influenced the development of moda110gic? Quine has had an enormous influence on philosophy of mathematics. When Quine entered philosophy there was a discussion on the foundations of mathematics between the schools of intuitionism, formalism, and conventionalism. Quine soon took issue with Carnap's conventionalism in "Truth by convention,,4 (1936). Quine has never joined one of the other schools, but has added new elements that are the basic ones of the 5 contemporary schools of nominalism, platonism, and structuralism. Quine has long been in the shadow of Benacerraf and Putnam in this field. At the moment there seems to be a renewed interest in Quine's work, and most philosophers explicitly refer to Quine's work.