Deontic Logic Introductory And Systematic Readings

The present volume is a sequel to Deontic Logic: Introductory and Systematic Readings (D. Reidel Publishing Company, Dordrecht 1971): its purpose is to offer a view of some of the main directions of research in contemporary deontic logic. Most of the articles included in Introductory and Systematic Readings represent what may be called the standard modal approach to deontic logic, in which de on tic logic is treated as a branch of modal logic, and the normative concepts of obligation, permission and prohibition are regarded as analogous to the "alethic" modalities necessity, possibility and impossibility. As Simo Knuuttila shows in his contribution to the present volume, this approach goes back to late medieval philosophy. Several 14th century philosophers observed the analogies between deontic and alethic modalities and discussed the deontic interpretations of various laws of modal logic. In contemporary deontic logic the modal approach was revived by G. H. von Wright's classic paper 'Deontic Logic' (1951). Certain analogies between deontic and alethic modalities are obvious and uncontroversial, but the standard approach has often been criticized on the ground that it exaggerates the analogies and tends to ignore those features of normative concepts which distinguish them from other modalities.

Relevant to philosophy, law, management, and artificial intelligence, these papers explore the applicability of nonmonotonic or defeasible logic to normative reasoning. The resulting systems purport to solve well-known deontic paradoxes and to provide a better treatment than classical deontic logic does of prima facie obligation, conditional obligation, and priorities of normative principles.

The chapters in the present volume go beyond 'classical' extensional logic with respect to one important factor: they all include among the semantic constituents representations of so-called 'possible worlds'. The inclusion of such 'indices' has turned out to be the semantic mainstay in dealing with a number of issues having to do with intensional features of natural and artificial languages. It is, of course, an open question whether 'possible world' semantics is in the final analysis the proper solution to the many problems and puzzles intensional constructions raise for the logical analysis of the many varieties of discourse. At present, there seem to be about as many opponents as proponents with regard to the usefulness of having the semantics of intensional languages based on possible world constructs. Some attempts to come to grips with intensional phenomena which are not couched in the possible world framework are discussed in Volume IV of the Handbook. Chapter 1 is an extensive survey of the main systems of (propositional) modal logic including the most important meta-mathematical results and the techniques used in establishing these. It introduces the basic terminology and semantic machinery applied in one way or another in many of the subsequent chapters. Chapter 2 discusses the most significant developments in (propositional) tense logic which can of course be regarded as a special kind of modal logic, where the possible world indices are simply (ordered) moments of time.