Ho Hsiu Hwang.(1970). Deontic Logic and Imperative Logic.
何秀煌著。《規範邏輯導論》，三民書局，台北，1970。

To the memory of
Professor Henry S. Leonard

Preface

This monograph deals with the problem of whether current systems of deontic and imperative logic formalize satisfactorily our intuitive deontic and imperative notions, and the problem of whether those systems can be used to justify normative reasonings. Some semantical inadequacies of the current systems are noted and suggestions are made for their removal.
Chapter One contains reconstructions of certain well-known systems of deontic logic: von Wright's system vW, Fisher-Åqvist's system FÅ, a family of systems called OT*, OS4* and OS5*, and Anderson's systems OM, OM' and OM." The systems OT*, OS4* and OS5*are developed quite thoroughly: a number of important theorems are proved, the problem of irreducible deontic modalities is solved for each system and containment relations among the systems are studied. Certain familiar problems and difficulties of current deontic logic are examined, for instance, the paradoxes of "derived obligation", contrary-to-duty imperatives and Chisholm's dilemma, the Kantian Principle and the paradox of the Good Samaritan.
In Chapter Two certain amendments are made to the systems OT*,OS4*and OS5*. The deontic operator 'O' (obligation) is explained in terms of, and hence relativized to, a set of moral rules. Deontic variables are taken to range over propositions that we call circumstantialized act-propositions, or simply CM-act-propositions, in which the elements of agent, time and location of endeavoring are specified. An attempt is made to justify these amendments by metaethical observations. Hintikka-style semantics is furnished. Quantifiers are readily introducible into the amended systems, and it is argued that quantified deontic logic is necessary to express some moral codes or moral principles. Some suggestions about solving in the amended systems the paradoxes and difficulties listed above are advanced. Finally, the problem of introducing alethic modalities into deontic logic is raised. The Kantian Principle and the "law" that what is necessary is obligatory and what is impossible is forbidden are discussed.
In the last chapter the relation between the evaluative and directive uses of language in a moral context is examined. An attempt is made to show that a deontic logic and the corresponding imperative logic are isomorphic models of a related normative logic. An attempt is also made to explicate the notion of normative validity. A partial characterization of the truth conditions for deontic ( or imperative )sentences is proposed, and it is argued that the usual definition of (assertoric) validity is applicable to normative arguments. Finally, the problem of the possibility of imperative logic is raised. Jψrgensen's dilemma and related problems are examined. Two unorthodox imperative operators, which are imperative counterparts of 'You are permitted to do...' and ' It is indifferent that you do...' are introduced. Attention to these operators seems to contribute to a correct understanding of certain disputed argument forms.
Three appendices are included: a list of axioms and rules, a list of definitions, and a list of theorems. There is also a comprehensive bibliography that lists most of the important works in deontic and imperative logic through 1968.
The author wishes to express his deep gratitude to Professor Gerald J. Massey for his untiring and time-consuming careful reading of the material when it was submitted as the author's doctoral dissertation to Michigan State University in 1969. Professor Massey's detailed criticism and helpful suggestions have led to many improvements both in formulation and in argumentation.
Thanks are also due to Professor Herbert E. Hendry and Professor George C. Kerner with whom discussions always turned out to be fruitful and beneficial to the author.