区分“必须”和“应当”的道义逻辑系统研究

A Logical Analysis of Must and Ought in Deontic Logic

“应当”“允许”“禁止”等道义概念在道义逻辑中受到了普遍的关注,学者对其给出了不同的概念理解和形式化表达。“传统定义方案”认为五种基本的真性模态对应着五个规范状态,“传统三重分类法”则将真性模态划分为“应当”“可选择的”“禁止”三个共同穷尽所有命题、且相互排斥的矩形单元。在此基础上构建关于道义模态词的四重分类法,有利于指明传统伦理理论和道义逻辑中普遍忽视的将“应当”作为“允许”的对偶算子这一错误假定,同时对于解决SDL语言在规范性概念表达能力上有所欠缺的问题具有借鉴和应用价值。

This paper mainly discusses whether the concepts of necessity and ought should be distinguished in deontic logic system.This paper first briefly introduces the concept and formal expression of must and ought by some scholars,then analyzes and constructs the quaternary classification of deontic modalities,and points out that must is the dual operator of permissible rather than ought in deontic logic.After that,the conception of must and ought as basic operators is compared with that of positive permission and ought as basic operators.