Abstract

The essays in philosophical logic collected in this volume are dedicated to Henry S. Leonard who was one of the first American philosophers to urge the application of modern logic to non-mathematical areas. Leonard also inspired the development of certain areas of contemporary philosophical logic discussed in some of the papers of this volume. This is especially clear in the case of free, or presupposition free, logics which Leonard's early work on a logic of existence inspired. In one essay of this volume Bas C. Van Frassen further develops his work on the semantics of free logic. In another, Milton Fisk relates free logic to modal logic, suggesting a new semantics of strength to deal with various problems in the area and in a third essay, Karel Lambert relates free logic to certain logical puzzles about quantum theory. Leonard was also one of the first to entertain the idea of and discuss a logic of questions and an erotetic logic or logic of interests. The volume contains essays on these topics by Nuel D. Belnap and David Harrah. Leonard's interest in modal logic is reflected in Fisk's article as well as in an article by Richmond Thomason on modal logic and metaphysics. His interest in epistemic logic is seen in an essay on the logic of belief by Jon Vickers and an essay by Hintikka applying the logic of belief and knowledge to problems about the ontological argument. In addition to these essays, there are five others of high quality on diverse topics: R. M. Martin on intentions, Wilfrid Sellars on the metaphysics of the person, R. M. Chisholm on agency, Frederick Fitch on combinatory logic and negative numbers, and H. E. Hendry and G. J. Massey on Sheffer functions. This is a worthy memorial to a quietly influential American philosopher.--R. H. K.