1. 1. The Principle of Universalizability-an informal explication This work is concerned with the so-called Principle of Universalizability. As we shall understand it, this principle represents a claim that moral properties of things (persons, actions, state of affairs, situations) are essentially independent of their purely 'individual' or-as one often says -'numerical' aspects. l Thus, if a thing, x, is better than another thing, y, then this fact is not dependent on x's being x nor on y's being y. If a certain person, a, has a duty to help another person, b, then this duty does not arise as a consequence of their being a and b, respectively. And if in a certain situation, W, it ought to be the case that certain goods are transferred from one person to another, then this moral obligation does not depend on the individual identities of the persons involved. The Universalizability Principle may also be expressed in terms of similarities. Instead of saying that the moral properties of x are essentially independent of the individual aspects of x, we may say that any object which is exactly similar to x, which is precisely like x in all non-individual, 'qualitative' respects, must exhibit exactly similar moral properties. Thus, if two persons are exactly similar to each other, (if they are placed in exactly similar circumstances, have exactly similar information, preferences, character, etc. ), then they will have exactly similar rights and duties.

The middle years of the nineteenth century saw two crucial develop ments in the history of modern logic: George Boole's algebraic treat ment of logic and Augustus De Morgan's formulation of the logic of relations. The former episode has been studied extensively; the latter, hardly at all. This is a pity, for the most central feature of modern logic may well be its ability to handle relational inferences. De Morgan was the first person to work out an extensive logic of relations, and the purpose of this book is to study this attempt in detail. Augustus De Morgan (1806-1871) was a British mathematician and logician who was Professor of Mathematics at the University of London (now, University College) from 1828 to 1866. A prolific but not highly original mathematician, De Morgan devoted much of his energies to the rather different field of logic. In his Formal Logic (1847) and a series of papers "On the Syllogism" (1846-1862), he attempted with great ingenuity to reformulate and extend the tradi tional syllogism and to systematize modes of reasoning that lie outside its boundaries. Chief among these is the logic of relations. De Mor gan's interest in relations culminated in his important memoir, "On the Syllogism: IV and on the Logic of Relations," read in 1860."

The concept of likeness to truth, like that of truth itself, is fundamental to a realist conception of inquiry. To demonstrate this we need only make two rather modest aim of an inquiry, as an inquiry, is realist assumptions: the truth doctrine (that the the truth of some matter) and the progress doctrine (that one false theory may realise this aim better than another). Together these yield the conclusion that a false theory may be more truthlike, or closer to the truth, than another. It is the aim of this book to give a rigorous philosophical analysis of the concept of likeness to truth, and to examine the consequences, some of them no doubt surprising to those who have been unduly impressed by the (admittedly important) true/false dichotomy. Truthlikeness is not only a requirement of a particular philosophical outlook, it is as deeply embedded in common sense as the concept of truth. Everyone seems to be capable of grading various propositions, in different (hypothetical) situations, according to their closeness to the truth in those situations. And (if my experience is anything to go by) there is remarkable unanimity on these pretheoretical judge ments. This is not proof that there is a single coherent concept underlying these judgements. The whole point of engaging in philosophical analysis is to make this claim plausible."

I. Towards Philosophy Jan Srzednicki 3 LOGICAL CONCERNS OF PHILOSOPHICAL ANALYSIS Jerzy Perzanowski ONTOLOGIES AND ONTOLOGICS 23 Elizabeth Anscombe TRUTH, SENSE AND ASSERTION, OR: WHAT PLATO SHOULD HAVE TOLD THE SOPHISTS 43 Peter Geach IDENTITY OVER TIME 47 Joseph M. Font, Ventura Verdu 53 TWO LEVELS OF MODALITY: AN ALGEBRAIC APPROACH Boguslaw Wolniewicz 63 ELZENBERG'S LOGIC OF VALUES Jerzy Szymura WHEN MAY G. E. MOORE'S DEFINITION OF AN INTERNAL RELATION BE USED RATIONALLY? 71 II. Historical Perspective J6zef M. Bochenski HISTORY OF LOGIC AND THE CRITERIA OF RATIONALITY 85 Jan Waszkiewicz, Agnieszka Wojciechowska ON THE ORIGIN OF REDUCTIO AD ABSURDUM 87 vi CONTENTS Ewa ~arnecka-Bialy PREMONITION OF MATHEMATICAL LOGIC IN ARISTOTLE'S PRIOR ANALYTICS 97 Leopold Regner "IMPOSSIBlLIA" OF SIGER OF BRABANT 107 Tomasz Weber DEFENDING THESES IN MATHEMATICS AT A 19TH CENTURY UNIVERSITY 113 Gerhardt PlBchl BASIC NORM AND METALANGUAGE. HISTORICAL BACKGROUND OF KELSEN'S IDEAS 125 m. Logic and Natural Language Marek Tokarz EARLY SYSTEMS OF FORMAL PRAGMATICS 151 Barbara Stanosz DEDUCTION AND THE CONCEPT OF ASSERTION 159 Helmut Metzler METHODOLOGICAL INTERDEPENDENCIES BETWEEN CONCEPTUALIZATION AND OPERATIONALIZATION IN EMPIRICAL SOCIAL SCIENCES 167 Jaroslaw Fall GAME-THEORETICAL SEMANTICS APPLIED TO DEFINITE DESCRIPTIONS AND ANAPHORA 177 Karl-Heinz Krampitz ON LOGICAL ANALYSIS OF ORDINARY SENTENCES 191 Anna Madarasz GAME THEORETICAL SEMANTICS WITH VALUE-GAPS AND DISCOURSE ANALYSIS 199 Andrzej Lachwa THE SEMANTIC AND FORMAL CONNECTIONS BETWEEN TEXT COMPONENTS 221 Index of Names 227 L. . ::1. . ~t G. Elizabeth ANSCOMBE - University of Cambridge, England J6zef M.

This book grew out of an international symposium, organized in September 1986 by the Austrian Cultural Institute in Warsaw in cooperation with the Polish Philosophical Society. The topic was: The Vienna Circle and the Lvov-Warsaw School. Since the two phil- osophical trends existed in roughly the same time and were close- ly related, it was one of the purposes of the symposium to investigate both similarities and thp differences. Some thirty people took part in the symposium, nearly twenty contributions were presented and extensively discussed. The sym- posium owed much to the excellent organization and warm hospital- ity shown by Dr Georg Jankovic, the Director of the Austrian In- stitute. As the person in charge of the scientific programme of the symposium, I take pleasure to acknowledge this debt. It so happened that a month later another symposium of a similar character was held. It took place in the University of Manchester, on the occasion of the centenary of the births of Stanislaw Lesniewski, Tadeusz Kotarbiflski and Wladyslaw Tatarkie- wicz. Some papers read at the Manchester symposium form a part of the present volume. It was not possible, for technical reasons (the time factor was one of them), to include in this book all the material from the two symposia. Certain contributions have appeared elsewhere (for instance, K. Szaniawski's 'Ajdukiewicz on Non-Deductive Inference' was published in Danish Yearbook of Philosophy, Vol. 23). On the other hand, certain papers have been written special- ly for this volume.

This anthology of original essays has been nearly .two and one-half years in the making, and reflects the generous effort of many persons. To begin with, we thank the contributors to the volume, who not only cooperated with regards to their own works, but who also provided valuable advice concerning the over-all volume. One of the contributors was outstanding in his assistance and warrants special mention: we thank Professor Michel Meyer, for his encouragement, counsel, and dedication to see this project to comple tion. We would also like to thank Professor Jaakko Hintikka for his encouragement and Mrs. Kuipers of Reidel for her patience and under standing along the way. A project such as this could never have been completed without the unique assistance of members of the Department of Communication, Ohio State University: Ms. Kimberly Pasi and Mr. Charles Mawhirtcr. Also, special thanks are due to our graduate research assistant Ms. Susan Jasko, for her proofreading and bibliographic work. The pressures of developing a Festschrift are considerable and could not have been met without the cooperation and enthusiasm of Mrs. Perelman, especially in allowing us to publish Professor Perelman's address to Ohio State University as our introduction."

Heyting'88 Summer School and Conference on Mathematical Logic, held September 13 - 23, 1988 in Chaika, Bulgaria, was honourably dedicated to Arend Heyting's 90th anniversary. It was organized by Sofia University "Kliment Ohridski" on the occasion of its centenary and by the Bulgarian Academy of Sciences, with sponsorship of the Association for Symbolic Logic. The Meeting gathered some 115 participants from 19 countries. The present volume consists of invited and selected papers. Included are all the invited lectures submitted for publication and the 14 selected contributions, chosen out of 56 submissions by the Selection Committee. The selection was made on the basis of reports of PC members, an average of 4 per sLlbmission. All the papers are concentrated on the topics of the Meeting: Recursion Theory, Modal and Non-classical Logics, Intuitionism and Constructivism, Related Applications to Computer and Other Sciences, Life and Work of Arend Heyting. I am pleased to thank all persons and institutions that contributed to the success of the Meeting: sponsors, Programme Committee members and additional referees, the members of the Organizing Committee, our secretaries K. Lozanova and L. Nikolova, as well as K. Angelov, V. Bozhichkova, A. Ditchev, D. Dobrev, N. Dimitrov, R. Draganova, G. Gargov, N. Georgieva, M. Janchev, P. Marinov, S. Nikolova, S. Radev, I. Soskov, A. Soskova and v. Sotirov, who helped in the organization, Plenum Press and at last but not least all participants in the Meeting and contributors to this volume.

Fragestellung und Losungsansatz der folgenden Untersuchungen 2 HUSSERL UND COHN Die vorliegende Arbeit vergleicht die Position des neukantianischen Dialektikers Jonas Cohn mit derjenigen des Phanomenologen Edmund Hus- serl. Bevor auf die thematischen Zielsetzungen der einzelnen Kapitel einge- gangen wird, seien einige Bemerkungen vorausgeschickt, die zeigen sollen, inwiefern einem solchen Vergleich Bedeutung zukommt. Grundsatzlich ist ein Vergleich philosophischer Positionen nur dann durchfuhrbar, wenn in irgend einer Hinsicht eine Gemeinsamkeit vorliegt. Sinnvoll wird ein Vergleich nur dann sein, wenn sich die Relata nicht in je- der Beziehung entsprechen und wenn die Grunde fur bestehende Diver- genzen und Konvergenzen durchsichtig gemacht werden konnen. Dabei kann, je nach Problemlage, mehr ein philosophiehistorischer oder ein kri- tisch-systematischer Blickwinkel den Vergleich bestimmen. Die vorliegende Arbeit legt den Schwerpunkt auf den letzteren Aspekt. Dies liegt nicht nur daran, dass letztlich philosophische Forschungen, an der Sa- che orientiert, sich argumentierend stets um das bemuhen sollten, woruber Ubereinstimmung herrschen kann. Wenn dem nicht so ware, bliebe alle Philosophiegeschichte bloss eine Aneinanderreihung beliebig austauschbarer Positionen. Gerade weil es aber eine Vielfalt philosophischer Ausgangs- punkte und Methoden gibt, sind die Philosophen herausgefordert, zu mogli- chen Gemeinsamkeiten Stellung zu nehmen -und dies auf eine Weise, die fur den anderen nachvollziehbar ist. Daruber hinaus ist aber gerade im Falle Husserls und Cohns eine systematisch-kritische Betrachtungsart angemes- sen.

The idea to produce the current volume was conceived by Jiirgen Mittelstrass and Robert E. Butts in 1978. Idealist philosophers are wrong about one thing: the temporal gap separating idea and reality can be very long indeed - even ten or so years Problems of timing were joined by personal problems and by the pressure of other professional commitments. Fortunately, James Brown agreed to cooperate in the editing of the volume; the infusion of his usual energy, good judgement and good-natured promptness saved the volume and made its produc tion possible. Despite the delays, the messages of the papers included in the book have not gone stale. An extremely worthwhile exercise in international philosophical cooperation has come to fruition; the German constructivist philosophical position is here represented in papers in English that will make its contemporary importance available to a larger audience. The editors owe thanks to many persons. All involved in the project owe much to the interest and support of Nicholas Rescher, a friend of the undertaking from the time of its inception. My review of the translations was helped immensely by Andrea Purvis' careful copy editing of the typescript. Most of all, however, we owe gratitude and admiration for the tireless efforts on behalf of this enterprise to Jiirgen Mittelstrass."

In the fall of 1985 Carnegie Mellon University established a Department of Philosophy. The focus of the department is logic broadly conceived, philos- ophy of science, in particular of the social sciences, and linguistics. To mark the inauguration of the department, a daylong celebration was held on April 5, 1986. This celebration consisted of two keynote addresses by Patrick Sup- pes and Thomas Schwartz, seminars directed by members of the department, and a panel discussion on the computational model of mind moderated by Dana S. Scott. The various contributions, in modified and expanded form, are the core of this collection of essays, and they are, I believe, of more than parochial interest: they turn attention to substantive and reflective interdis- ciplinary work. The collection is divided into three parts. The first part gives perspec- tives (i) on general features of the interdisciplinary enterprise in philosophy (by Patrick Suppes, Thomas Schwartz, Herbert A. Simon, and Clark Gly- mour) , and (ii) on a particular topic that invites such interaction, namely computational models of the mind (with contributions by Gilbert Harman, John Haugeland, Jay McClelland, and Allen Newell). The second part con- tains (mostly informal) reports on concrete research done within that enter- prise; the research topics range from decision theory and the philosophy of economics through foundational problems in mathematics to issues in aes- thetics and computational linguistics. The third part is a postscriptum by Isaac Levi, analyzing directions of (computational) work from his perspective.

This collection of essays is on the relation between probabilities, especially conditional probabilities, and conditionals. It provides negative results which sharply limit the ways conditionals can be related to conditional probabilities. There are also positive ideas and results which will open up areas of research. The collection is intended to honour Ernest W. Adams, whose seminal work is largely responsible for creating this area of inquiry. As well as describing, evaluating, and applying Adams's work the contributions extend his ideas in directions he may or may not have anticipated, but that he certainly inspired. In addition to a wide range of philosophers of science, the volume should interest computer scientists and linguists.

Relevance logics came of age with the one and only International Conference on relevant logics in 1974. They did not however become accepted, or easy to promulgate. In March 1981 we received most of the typescript of IN MEMORIAM: ALAN ROSS ANDERSON Proceedings of the International Conference of Relevant Logic from the original editors, Kenneth W. Collier, Ann Gasper and Robert G. Wolf of Southern Illinois University. 1 They had, most unfortunately, failed to find a publisher - not, it appears, because of overall lack of merit of the essays, but because of the expense of producing the collection, lack of institutional subsidization, and doubts of publishers as to whether an expensive collection of essays on such an esoteric, not to say deviant, subject would sell. We thought that the collection of essays was still (even after more than six years in the publishing trade limbo) well worth publishing, that the subject would remain undeservedly esoteric in North America while work on it could not find publishers (it is not so esoteric in academic circles in Continental Europe, Latin America and the Antipodes) and, quite important, that we could get the collection published, and furthermore, by resorting to local means, published comparatively cheaply. It is indeed no ordinary collection. It contains work by pioneers of the main types of broadly relevant systems, and by several of the most innovative non-classical logicians of the present flourishing logical period. We have slowly re-edited and reorganised the collection and made it camera-ready.

Tadeusz Kotarbinski is one of towering figures in contemporary Polish philosophy. He was a great thinker, a great teacher, a great organizer of philosophical and scientific life (he was, among others, the rector of the Uni versi ty of t6dz, the president of the Polish Academy of Sciences, and the president of the International Institute of Philosophy), and, last but not least, a great moral authority. He died at the age of 96 on October 3, 1981. Kotarbinski was active in almost all branches of philosophy. He made many significant contributions to logic, semantics, ontology, epistemology, history of philosophy, and ethics. He created a new field, namely praxiology. Thus, using an ancient distinction, he contributed to theoretical as well as practical philoso hy. Kotarbinski regarded praxiology as his major philosophical "child." Doubtless, praxiology belongs to practical philosophy. This collection, howewer, is mainly devoted to Kotarbinski' s theoretical philosophy. Reism - Kotarbinski' s fundamental idea of ontology and semantics - is the central topic of most papers included here; even Pszczolowski' s essay on praxiology considers its ontological basis., Only two papers, namely that of Zarnecka-Bialy and that of Wolenski, are not linked with reism. However, both fall under the general label "Kotarbinski: logic, semantics and ontology." The collection partly consists of earlier published papers.

It has been shown how the common structure that defines a family of proofs can be expressed as a proof plan [5]. This common structure can be exploited in the search for particular proofs. A proof plan has two complementary components: a proof method and a proof tactic. By prescribing the structure of a proof at the level of primitive inferences, a tactic [11] provides the guarantee part of the proof. In contrast, a method provides a more declarative explanation of the proof by means of preconditions. Each method has associated effects. The execution of the effects simulates the application of the corresponding tactic. Theorem proving in the proof planning framework is a two-phase process: 1. Tactic construction is by a process of method composition: Given a goal, an applicable method is selected. The applicability of a method is determined by evaluating the method's preconditions. The method effects are then used to calculate subgoals. This process is applied recursively until no more subgoals remain. Because of the one-to-one correspondence between methods and tactics, the output from this process is a composite tactic tailored to the given goal. 2. Tactic execution generates a proof in the object-level logic. Note that no search is involved in the execution of the tactic. All the search is taken care of during the planning process. The real benefits of having separate planning and execution phases become appar ent when a proof attempt fails.

By North-American standards, philosophy is not new in Quebec: the first men tion of philosophy lectures given by a Jesuit in the College de Quebec (founded 1635) dates from 1665, and the oldest logic manuscript dates from 1679. In English-speaking universities such as McGill (founded 1829), philosophy began to be taught later, during the second half of the 19th century. The major influence on English-speaking philosophers was, at least initially, that of Scottish Empiricism. On the other hand, the strong influence of the Catholic Church on French-Canadian society meant that the staff of the facultes of the French-speaking universities consisted, until recently, almost entirely of Thomist philosophers. There was accordingly little or no work in modem Formal Logic and Philosophy of Science and precious few contacts between the philosophical communities. In the late forties, Hugues Leblanc was a young student wanting to learn Formal Logic. He could not find anyone in Quebec to teach him and he went to study at Harvard University under the supervision of W. V. Quine. His best friend Maurice L' Abbe had left, a year earlier, for Princeton to study with Alonzo Church. After receiving his Ph. D from Harvard in 1948, Leblanc started his profes sional career at Bryn Mawr College, where he stayed until 1967. He then went to Temple University, where he taught until his retirement in 1992, serving as Chair of the Department of Philosophy from 1973 until 1979.

The essays in this collection are written by students, colleagues, and friends of Nuel Belnap to honor him on his sixtieth birthday. Our original plan was to include pieces from fonner students only, but we have deviated from this ever so slightly for a variety of personal and practical reasons. Belnap's research accomplishments are numerous and well known: He has founded (together with Alan Ross Anderson) a whole branch of logic known as "relevance logic." He has made contributions of fundamental importance to the logic of questions. His work in modal logic, fonnal pragmatics, and the theory of truth has been highly influential. And the list goes on. Belnap's accomplishments as a teacher are also distinguished and well known but, by virtue of the essential privacy of the teaching relationship, not so well understood. We would like to reflect a little on what makes him such an outstanding teacher.

This work is divided into two parts. Part I contains sixteen critical es says by prominent philosophers and computer scientists. Their papers offer insightful, well-argued contemporary views of a broad range of topics that lie at the heart of philosophy in the second half of the twen tieth century: semantics and ontology, induction, the nature of prob ability, the foundations of science, scientific objectivity, the theory of naming, the logic of conditionals, simulation modeling, the relatiOn be tween minds and machines, and the nature of rules that guide be havior. In this volume honoring Arthur W. Burks, the philosophical breadth of his work is thus manifested in the diverse aspects of that work chosen for discussion and development by the contributors to his Festschrift. Part II consists of a book-length essay by Burks in which he lays out his philosophy of logical mechanism while responding to the papers in Part I. In doing so, he provides a unified and coherent context for the range of problems raised in Part I, and he highlights interesting relationships among the topics that might otherwise have gone un noticed. Part II is followed by a bibliography of Burks's published works."

Stanislaw Lesniewski (1886-1939) was one of the leading Polish logicians and founders of the Warsaw School of Logic whose membership included, beside himself, Jan Lukasiewicz, Tadeusz Kotarbinski, Alfred Tarski, and many others. In his lifetime LeSniewski published only a few hundred pages. He produced many important results in many areas of mathematics; these stood in various relations to each other, and to materials produced by others, and, in time, created more and more editorial problems. Very many were left unpublished at the time of his death. Then in 1944 in the fire of Warsaw the whole of this material was burned and lost -a considerable loss since a great deal of what is important could have been reconstructed from these notes. The present publication aims at presenting unique Lesniewski's materials from alternative sources comprising lecture notes taken during some of Lesniewski's lectures and seminars delivered at the University of Warsaw be tween the two world wars. The editors are aware of the limitations of student notes which cannot compensate for the loss of the original materials. However, they are unique in reflecting Lesniewski's ideas as he himself presented them. Already at the time of his death it was realized that these notes would provide a unique access to Lesniewski's own thought as well as a valuable record of some of the activities of the Warsaw School of Logic."

Formal ontology combines two ideas, one originating with Husserl, the other with Frege: that of ontology of the formal aspects of all objects, irrespective of their particular nature, and ontology pursued by employing the tools of modern formal disciplines, notably logic and semantics. These two traditions have converged in recent years and this is the first collection to encompass them as a whole in a single volume. It assembles essays from authors around the world already widely known for their work in formal ontology, and illustrates that through the application of formal methods the ancient discipline of ontology may be put on a firm methodological basis. The essays not only illuminate the nature of ontology and its relation to other areas, in language, logic and everyday life, but also demonstrate that common issues from the analytical and phenomenological traditions may be discussed without ideological barriers. Audience: advanced students of and specialists in philosophy, linguistics, cognitive science, computer science, database engineering.

such questions for centuries (unrestricted by the capabilities of any hard ware). The principles governing the interaction of several processes, for example, are abstract an similar to principles governing the cooperation of two large organisation. A detailed rule based effective but rigid bureaucracy is very much similar to a complex computer program handling and manipulating data. My guess is that the principles underlying one are very much the same as those underlying the other. I believe the day is not far away in the future when the computer scientist will wake up one morning with the realisation that he is actually a kind of formal philosopher! The projected number of volumes for this Handbook is about 18. The subject has evolved and its areas have become interrelated to such an extent that it no longer makes sense to dedicate volumes to topics. However, the volumes do follow some natural groupings of chapters. I would like to thank our authors are readers for their contributions and their commitment in making this Handbook a success. Thanks also to our publication administrator Mrs J. Spurr for her usual dedication and excellence and to Kluwer Academic Publishers for their continuing support for the Handbook.

The relation between logic and knowledge provoked a heated debate since the 1960s. The epistemic approaches, found their formal argument in the mathematics of Brouwer and intuitionistic logic. And following Michael Dummett - started to call themselves: antirealists'. Others persisted with the formal background of the Frege-Tarski tradition, where Cantorian set theory is linked via model theory to classical logic. Jaakko Hintikka tried to join both traditions by means of what is now known as explicit epistemic logic'. Here the epistemic content is introduced into the object language as an operator which yield propositions from propositions rather than as metalogical constraint on the notion of inference. The Realism-Antirealism debate had thus three players: classical logicians, intuitionists and explicit epistemic logicians. The editors of the present volume think that in these days and age of Alternative Logics, where manifold developments in logic happen in a breathtaking pace, this debate should be revisited. Using the most recent logical and epistemological tools, this book provides a novel and refreshing view on the most important topics of the Realism vs. Antirealism debate. Its general scope is to show the most recent developments in philosophical logic to deal with problems inherited from this debate. It is meant for researcher and advanced students in philosophy, logic, formal methods. It's complete collection with a variety of approaches, it is written by leading authors in the fields, every chapter is self-contained.

Aristotle's modal syllogistic has been an object of study ever since the time of Theophrastus; but these studies (apart from an intense flowering in the Middle Ages) have been somewhat desultory. Remarkably, in the 1990s several new lines of research have appeared, with series of original publications by Fred Johnson, Richard Patterson and Ulrich Nortmann. Johnson presented for the first time a formal semantics adequate to a de re reading of the apodeictic syllogistic; this was based on a simple intuition linking the modal syllogistic to Aristotelian metaphysics. Nortmann developed an ingenious de dicto analysis. Patterson articulated the links (both theoretical and genetic) between the modal syllogistic and the metaphysics, using an analysis which strictly speaking is neither de re nor de dicto. My own studies in this field date from 1976, when my colleague Peter Roeper and I jointly wrote a paper "Aristotle's apodeictic syllogisms" for the XXIInd History of Logic Conference in Krakow. This paper contained the disjunctive reading of particular affirmative apodeictic propositions, which I still favour. Nonetheless, I did not consider that paper's results decisive or comprehensive enough to publish, and my 1981 book The Syllogism contained no treatment of the modal syllogism. The paper's ideas lay dormant till 1989, when I read Johnson's and Patterson's initial articles. I began publishing on the topic in 1991. Gradually my thoughts acquired a certain comprehensiveness and systematicity, till in 1993 I was able to take a semester's sabbatical to write up a draft of this book.

Prior's view on intensionality and truth is based on the principle that sentences never name, that what sentences say cannot be otherwise signified, that a sentence says what it says whatever the type of its occurrence, and that sentential quantification is neither eliminable, substitutional, nor referential. The text defends each of these principles.

It is with great pleasure that we are presenting to the community the second edition of this extraordinary handbook. It has been over 15 years since the publication of the first edition and there have been great changes in the landscape of philosophical logic since then. The first edition has proved invaluable to generations of students and researchers in formal philosophy and language, as well as to consumers of logic in many applied areas. The main logic article in the Encyclopaedia Britannica 1999 has described the first edition as 'the best starting point for exploring any of the topics in logic'. We are confident that the second edition will prove to be just as good. ! The first edition was the second handbook published for the logic commu nity. It followed the North Holland one volume Handbook of Mathematical Logic, published in 1977, edited by the late Jon Barwise, The four volume Handbook of Philosophical Logic, published 1983-1989 came at a fortunate temporal junction at the evolution of logic. This was the time when logic was gaining ground in computer science and artificial intelligence circles. These areas were under increasing commercial pressure to provide devices which help and/or replace the human in his daily activity. This pressure required the use of logic in the modelling of human activity and organisa tion on the one hand and to provide the theoretical basis for the computer program constructs on the other.