简论逻辑条件及其自然语言表达

A Brief Discussion of Conditions and Their Natural Language Expression

必要条件、充分条件和充分必要条件是逻辑学中的重要概念,准确理解它们是正确应用逻辑知识的重要前提,也是教学中讲清楚其含义的基本要求。在引述了采用自然语言描述的这三个条件之后,讨论了应用中一些自然语言表达形式;为了消除歧义,基于现代逻辑中的命题概念和蕴涵联结词定义了这三个条件,并统一用命题符号p表示条件,以期避免用“前件”可能导致的误解;采用真值表方法分析了条件之间的关系,并简单讨论了拟定条件的基本原则。有限引入现代逻辑知识和丰富的应用示例表明,建立逻辑条件的定义有益于逻辑学教学和逻辑知识的应用。

Necessary conditions,sufficient conditions,and sufficient-essential conditions are important concepts in logic.An accurate understanding of them is an important prerequisite for the correct application of logical knowledge and a basic requirement for teaching their meaning clearly.After quoting the three conditions described in natural language,some forms of natural language expressions in applications are discussed.In order to eliminate ambiguity,the three conditions are defined based on the propositional concepts and implicational conjunctions in modern logic,and the propositional symbol p is used to represent the three conditions uniformly to avoid possible misunderstandings caused by the use of“antecedent”;The relationship between the three conditions is analyzed with the truth table method,and the basic principles for formulating the three conditions are briefly discussed.The limited introduction of modern logic knowledge and the rich application examples show that the definition of logical conditions established is beneficial to the teaching of logic and the application of logic knowledge.