In _Modal Logic for Open Minds,_ Johan van Benthem provides an up-to-date introduction to the field of modal logic, outlining its major ideas and exploring the numerous ways in which various academic fields have adopted it. Van Benthem begins with the basic theories of modal logic, semantics, bisimulation, and axiomatics, and also covers more advanced topics, such as expressive power and computational complexity. The book then moves to a wide range of applications, including new developments in information flow, intelligent agency, (...) and games. Taken together, the chapters show modal logic at the crossroads of philosophy, mathematics, linguistics, computer science, and economics. Most of the chapters are followed by exercises, making this volume ideal for undergraduate and graduate students in philosophy, computer science, symbolic systems, cognitive science, and linguistics. (shrink)

The book offers a proposal on how to define truth in all its complexity, without reductionism, showing at the same time which questions a theory of truth has to answer and which questions, although related to truth, do not belong within the scope of such a theory. Just like any other theory, a theory of truth has its structure and limits. The semantic core of the position is that truth-ascriptions are pro-forms, i.e. natural language propositional variables. The book also offers (...) an explanation of the syntactic behaviour of truth-terms, and the pragmatic roles of truth-acts. The theory of truth we present is a technical proposal, relatively uncontaminated by radical philosophical discussion. It makes indeed philosophical points, but it is intended to be a conceptual analysis, as neutral as possible, of the aspects that may serve as a point of departure for more philosophically-laden destinations. Like the Fregean account of quantifiers, which is prior to and, to a large extent, independent of the metaphysical debate about existence and its forms, or the Kaplanian view on demonstratives, that is neutral regarding the debate about individuals and the possibilities we have to actually “reach” them in a referring act, we intend our proposal about truth to be a sophisticated and explicative setting that helps to situate other debates about truth accurately, far from the distorted and sometimes strongly ideological discussions that have turned the topic into a paradigm of philosophical impasse. (shrink)

The recovery of Aristotle’s logic during the twelfth century was a great stimulus to medieval thinkers. Among their own theories developed to explain Aristotle’s theories of valid and invalid reasoning was a theory of consequence, of what arguments were valid, and why. By the fourteenth century, two main lines of thought had developed, one at Oxford, the other at Paris. Both schools distinguished formal from material consequence, but in very different ways. In Buridan and his followers in Paris, formal consequence (...) was that preserved under uniform substitution. In Oxford, in contrast, formal consequence included analytic consequences such as ‘If it’s a man, then it’s an animal’. Aristotle’s notion of syllogistic consequence was subsumed under the treatment of formal consequence. Buridan developed a general theory embracing the assertoric syllogism, the modal syllogism and syllogisms with oblique terms. The result was a thoroughly systematic and extensive treatment of logical theory and logical consequence which repays investigation. (shrink)

Some philosophers, notably Professors Quine and Geach, have stressed the analogies they see between pronouns of the vernacular and the bound variables of quantification theory. Geach, indeed, once maintained that ‘for a philosophical theory of reference, then, it is all one whether we consider bound variables or pronouns of the vernacular'. This slightly overstates Geach's positition since he recognizes that some pronouns of ordinary language do function differently from bound variables; he calls such pronouns ‘pronouns of laziness'. Geach's characterisation of (...) pronouns of laziness has varied from time to time, but the general idea should be clear from a paradigm example: A man who sometimes beats his wife has more sense than one who always gives in to her.The pronouns ‘one’ and ‘her’ go proxy for a noun or a noun phrase in the sense that the pronoun is replaceable in paraphrase by simple repetition of its antecedent. (shrink)

Buridan's life, works, and influence -- Buridan's logic and the medieval logical tradition -- The primacy of mental language -- The various kinds of concepts and the idea of a mental language -- Natural language and the idea of a formal syntax in Buridan -- Existential import and the square of opposition -- Ontological commitment -- The properties of terms (proprietates terminorum) -- The semantics of propositions -- Logical validity in a token-based, semantically closed logic -- The possibility of scientific (...) knowledge -- Buridan's anti-skepticism -- Buridan's essentialist nominalism. (shrink)

Of course we all know now that mathematics has proved that logic doesn't really make sense, but Etchemendy (philosophy, Stanford Univ.) goes further and challenges the received view of the conceptual underpinnings of modern logic by arguing that Tarski's model-theoretic analysis of logical consequences is wrong. He may have found the soft underbelly of the dead horse. Annotation copyrighted by Book News, Inc., Portland, OR.

The “dragon” that graces the cover of this volume has a story that goes with it. In the summer of 1980, I was on the teaching staff of the Summer Institute on Medieval Philosophy held at Cornell University under the direction of Norman Kretzmann and the auspices of the Council for Philosophical Studies and the National Endowment for the Humanities. While I was giving a series of lectures there (lectures that contribute to this volume, as it turns out), I went (...) to my office one morning, and there under the door some anonymous wag from the Institute had slid the pen and ink drawing you see in the picture. It represents “Supposition” as a dragon, making a rude face at the viewer. The tail of the dragon is divided — not entirely accurately, as it turns out — into the various branches and subbranches of supposition. If the details are not altogether correct, the spirit is certainly understandable. (shrink)

“The problem of universals” in general is a historically variable bundle of several closely related, yet in different conceptual frameworks rather differently articulated metaphysical, logical, and epistemological questions, ultimately all connected to the issue of how universal cognition of singular things is possible. How do we know, for example, that the Pythagorean theorem holds universally, for all possible right triangles? Indeed, how can we have any awareness of a potential infinity of all possible right triangles, given that we could only (...) see a finite number of actual ones? How can we universally indicate all possible right triangles with the phrase ‘right triangle’? Is there something common to them all signified by this phrase? If so, what is it, and how is it related to the particular right triangles? The medieval problem of universals is a logical, and historical, continuation of the ancient problem generated by Plato's (428-348 B.C.) theory answering such a bundle of questions, namely, his theory of Ideas or Forms. (shrink)

The focus of the paper is a sophism based on the proposition ‘This is Socrates’ found in a short treatise on obligational casus attributed to William Heytesbury. First, the background to the puzzle in Walter Burley’s traditional account of obligations (the responsio antiqua), and the objections and revisions made by Richard Kilvington and Roger Swyneshed, are presented. All six types of obligations described by Burley are outlined, including sit verum, the type used in the sophism. Kilvington and Swyneshed disliked the (...) dynamic nature of the responsio antiqua, and Kilvington proposed a revision to the rules for irrelevant propositions. This allowed him to use a form of reasoning, the “disputational meta-argument”, which is incompatible with Burley’s rules. Heytesbury explicitly rejected Kilvington’s revision and the associated meta-argument. Swyneshed also revised Burley’s account of obligations, formulating the so-called responsio nova, characterised by the apparently surprising thesis that a conjunction can be denied both of whose conjuncts are granted. On closer inspection, however, his account is found to be less radical than first appears. (shrink)

This volume is the first annotated translation in any language of the entire text of the Summulae de dialectica, by the Parisian master of arts John Buridan (1300-1358). One of the most influential works in the history of late medieval philosophy, the Summulae is Buridan's systematic exposition of his nominalist philosophy of logic. Buridan's doctrine spread rapidly and for some two hundred years was dominant at many European universities. His work is of increasing interest today not only to historians of (...) medieval philosophy but also to modern philosophers, several of whom find in Buridan's ideas important clues to problems of contemporary philosophy. Gyula Klima provides a substantial introduction to Buridan's life and work and discusses his place in the history of logic. Through extensive notes Klima assists philosopher and medievalist alike to read Buridan with understanding and insight. Those with a philosophical interest in the relations among the structures of language, thought, and reality will find much to ponder in the Summulae. (shrink)

This article for the Stanford Encyclopedia for Philosophy provides a state of the art survey and assessment of the contemporary debate about truth-makers, covering both the case for and against truth-makers. It explores 4 interrelated questions about truth-makers, (1) What is it to be a truth-maker? (2) Which range, or ranges, of truths are eligible to be made true (if any are)? (3) What kinds of entities are truth-makers? (4) What is the motivation for adopting a theory of truth-makers? And (...) adds that there's another question to often put aside by metaphysicians but has critical consequences for truth-makers: (5) What are the truth-bearers? (shrink)

Se resumen las ventajas y desventajas de la formalización en filosofía. Se concluye que la filosofía formalizada es una especialidad en peligro que necesita ser revitalizada, y que debe incrementar sus interacciones con la filosofía no formalizada. El estilo enigmático, que es común en la lógica filosófica, debe llevar a discusiones explícitas sobre la relación problemática entre modelos formales, conceptos filosóficos y temas que motiven su desarrollo.

About twenty-five years ago, Charles Parsons published a paper that began by asking why we still discuss the Liar Paradox. Today, the question seems all the more apt. In the ensuing years we have seen not only Parsons’ work (1974), but seminal work of Saul Kripke (1975), and a huge number of other important papers. Too many to list. Surely, one of them must have solved it! In a way, most of them have. Most papers on the Liar Paradox offer (...) some explanation of the behavior of paradoxical sentences, and most also offer some extension for the predicate ‘true’ that they think is adequate, at least in some restricted setting. But if this is a solution, then the problem we face is far from a lack of solutions; rather, we have an overabundance of conflicting ones. Kripke’s work alone provides us with uncountably many different extensions for the truth predicate. Even if it so happens that one of these is a conclusive solution, we do not seem to know which one, or why. We should also ask, given that we are faced with many technically elegant but contradictory views, if they are really all addressing the same problem. What we lack is not solutions, but a way to compare and evaluate the many ones we have. (shrink)

Typically, a logic consists of a formal or informal language together with a deductive system and/or a model-theoretic semantics. The language is, or corresponds to, a part of a natural language like English or Greek. The deductive system is to capture, codify, or simply record which inferences are correct for the given language, and the semantics is to capture, codify, or record the meanings, or truth-conditions, or possible truth conditions, for at least part of the language.

Terence Parsons presents a new study of the development and continuing value of medieval logic, which expanded Aristotle's basic principles of logic in important ways. Parsons argues that the resulting system is as rich as contemporary first-order symbolic logic.

This title is part of UC Press's Voices Revived program, which commemorates University of California Press’s mission to seek out and cultivate the brightest minds and give them voice, reach, and impact. Drawing on a backlist dating to 1893, Voices Revived makes high-quality, peer-reviewed scholarship accessible once again using print-on-demand technology. This title was originally published in 1973.

This is a brief, accessible introduction to the thought of the philosopher John Buridan (ca. 1295-1361). Little is known about Buridan's life, most of which was spent studying and then teaching at the University of Paris. Buridan's works are mostly by-products of his teaching. They consist mainly of commentaries on Aristotle, covering the whole extent of Aristotelian philosophy, ranging from logic to metaphysics, to natural science, to ethics and politics. Gyula Klima argues that many of Buridan's academic concerns are strikingly (...) similar to those of modern philosophy and his work sometimes quite directly addresses modern philosophical questions. (shrink)

This chapter gives a survey of the field of philosophy where the philosophical foundations of modern logic were discussed and where such themes of logic were discussed that were on the borderline between logic and other branches of the philosophical enterprise, such as metaphysics and epistemology. The contributions made by Gottlob Frege and Charles Peirce are included since their work in logic is closely related to and also strongly motivated by their philosophical views and interests. In addition, the chapter pays (...) attention to a few philosophers to whom logic amounted to traditional Aristotelian logic and to those who commented on the nature of logic from a philosophical perspective without making any significant contribution to the development of formal logic. (shrink)