A textbook on modal logic, intended for readers already acquainted with the elements of formal logic, containing nearly 500 exercises. Brian F. Chellas provides a systematic introduction to the principal ideas and results in contemporary treatments of modality, including theorems on completeness and decidability. Illustrative chapters focus on deontic logic and conditionality. Modality is a rapidly expanding branch of logic, and familiarity with the subject is now regarded as a necessary part of every philosopher's technical equipment. Chellas here offers an (...) up-to-date and reliable guide essential for the student. (shrink)

This major work challenges some widely held positions in epistemology - those of Peirce and Popper on the one hand and those of Quine and Kuhn on the other.

Ross, Alf Loar, Brian, Editor.Directives and Norms. New York: Humanities Press, [1967]. ix, 188 pp. Reprint available April 2009 by The Lawbook Exchange, Ltd. ISBN-13: 978-1-58477-961-2. ISBN-10: 1-58477-961-6. Cloth with dust jacket. $65.00 * Reprint of the first American edition. One of the most interesting jurists of the post-World War II era, Ross [1899-1979] was a legal and moral philosopher, scholar of international law and the leading representative of Scandinavian Legal Realism. This book and On Law and Justice (1958) are (...) his principal works. In Directives and Norms Ross asks whether imperatives (or, to use his term, 'directives') are subject to logic in the same way as indicatives. He shows the difference between indicative and directive discourse and explains the concepts 'directive' and 'norm' as they function in the social sciences, especially in the study of law. A contemporary essay in the Modern Law Review (32:544), though critical of this work, was still impressed by its "clear and convincing account" of these processes. (shrink)

Investigates the resolution of contradictions and ambiguous derogations in a code, by means of the imposition of partial orderings. Although formulated as a study in the logic of norms, it provided the initial ideas for work on the logic of theory (or belief) change, developed by the authors in a series of papers by the authors and Peter Gardenfors beginning in 1985.

The aim of the book is to introduce the reader to some new areas oflogic which have yet to find their way into the bulk of modern logic books written from the more orthodox direction of the mainstream of develop ments. Such a work seems to me much needed, both because of the in trinsic value and increasing prominence of the nonstandard sector of logic, and because this particular sector is of the greatest interest from the standpoint of philosophical implications (...) and applications. This book unites a series of studies in philosophical logic, drawing for the most part on material which I have contributed to the journal liter ature of the subject over the past ten years. Despite the fact that some of these essays have been published in various journals at different times, they possess a high degree of thematic and methodological unity. All of these studies deal with material of substantial current interest in philo sophical logic and embody a fusion of the modern techniques of logical and linguistic-philosophical analysis for the exploration of areas of logic that are of substantial philosophical relevance. (shrink)

It has been maintained that we are quite able to express (1*)–(4*) without the introduction of a dyadic deontic operator, provided only that we supply our standard deontic logic with a stronger conditional than material implication. The lesson learned from Chisholm's paradox has been the eminently convincing, indeed obvious, one: that what we ought to do is not determined by what is the case in some perfect world, but by what is the case in the best world we can ‘get (...) to’ from this world. What we ought to do depends upon how we are circumstanced. (shrink)

Lewis, D. Semantic analyses for dyadic deontic logic.--Salomaa, A. Some remarks concerning many-valued propositional logics.--Chellas, B. F. Conditional obligation.--Jeffrey, R.C. Remarks on interpersonal utility theory.--Hintikka, J. On the proper treatment of quantifiers in Montague semantics.--Mayoh, B.H. Extracting information from logical proofs.--Åqvist, L. A new approach to the logical theory of actions and causality.--Pörn, I. Some basic concepts of action.--Bouvère, K. de. Some remarks concerning logical and ontological theories.--Hacking, I. Combined evidence.--Äberg, C. Solution to a problem raised by Stig Kanger and (...) a set theoretical statement equivalent to the axiom of choice.--Lindström, P. On characterizing elementary logic.-- Scott, D. Rules and derived rules.--Hansson, B. A program for pragmatics.--Hermerén, G. Models.--Fenstad, J.E. Remarks on logic and probability.--Stenlund, S. Analytic and synthetic arithmetical statements. (shrink)

The conditional probability of h given e is commonly claimed to be equal to the probability that h would have if e were learned. Here I contend that this general claim about conditional probabilities is false. I present a counter-example that involves probabilities of probabilities, a second that involves probabilities of possible future actions, and a third that involves probabilities of indicative conditionals. In addition, I briefly defend these counter-examples against charges that the probabilities they involve are illegitimate.