Deontische Logik ohne Paradoxien, Semantik und Logik des Normativen

Deontic logicians try to fix the logically relevant aspects of the meanings of normative expressions and to reveal the logical relations between the corresponding sentences. From the very beginning, however, logicians and philosophers engaged in work on axiomatic Systems of deontic logic have faced so called problem of the „paradoxes of deontic logic“. What is covered by this label are deontic formulae which are provable in logic harmless-looking axiomatic systems, but which seem to be clearly false on certain natural interpretations providing them with that content. The problem of these paradoxes has been intensively discussed within the last decades. In the course of the debate, even quite fundamental assumptions of deontic logic have been newly questioned - for it seemed possible that involvement in paradoxes flows already from these very assumptions. In this work a new kind of formal semantics for a deontic language is developed. It embodies semantical considerations inspired by R. M. Hare's analyses of the meanings of normative expressions, a point of special importance being the representation within semantics of Hare's central concept of the universalizability of normative propositions. Those deontic formulae typically suspected of paradoxicality are shown by the author to be non-theorems of the logic thereby generated. Some of the customary formal semantics for deontic logic prove to be special cases of the semantics put forward, so that the author is in a position to explain the coming about of several typically paradoxical formulae: they become formal semantically valid just in case certain restrictions are introduced into the new semantic framework established. The book ends with the result that the assumptions hitherto taken as basic for deontic logic may be retained, at least as far as the paradoxes are concerned. For it has been shown that one can avoid the paradoxes without dropping those assumptions by use of a more intricate kind of formal semantics. The book will serve as an introduction to central questions of deontic logic, which, unsettled as they were, led to a rather sceptic attitude towards the prospects of this discipline. Nortmann offers a new semantics to overcome the problems.