Research On The Dyadic Deontic Logic System DDFS

J(o|¨)rg Hansen extends B.van Fraassen and J.F.Horty's deontic system to a new dyadic deontic system,which was called DDFS.This paper describes some property of DDFS,and prove all of the axioms and some of the theorem of DDFS using a different way.This paper also prove the soundness of it.The author describes a history of modern deontic logic resreach frist. In the second section,a overview of common monadic deontic logic systems,which are foundations upon which dyadic deontic logic system DDFS establishs,has been presented.The properties and problems ofmonadic deontic logic systems also be mentioned.Third chapter,the author introduced Van Wright's dyadic deontic logic system.Most dyadic deontic logic system based two of Van Wright's dyadic deontic logic system. The essential deontic operators of DDFS are"O~F" and "O~S",declared by Van Fraassen's Proposal and J.F.Horty.Using default theories of non-monotonic logic can give a description of thoese operatprs well.In the main chapter,it discusses all about DDFS.In the following part the author write about DDFS form three aspects:the formation of DDFS,the thesis and some important theorems of DDFS,the soundness of DDFS.Then giving the demonstration of soundness with a dissimilar manner.The next segments are chiefly about the further usage of DDFS and the issues unfathomed.DDFS.It can be discovered a great use for DDFS in many territories, either in logic or in ethics.