论Modus Ponens

On Modus Ponens

本文从澄清"modus ponens"的拉丁文涵义并揭示它在实际使用中的不同所指入手,沿着语义进路分别在经典逻辑与以超相容性逻辑LP为例的非经典逻辑中审查MP的有效性。基于对"逻辑"和"推理"(某种使用逻辑的心智行动)的区分,刻画"无MP的逻辑"之于自然语言以及实际推理何以可能。根据对前述脉络的整体把握,对"为什么采用超相容性逻辑作为我们的语言的逻辑"以及"一个超相容性的逻辑如何与‘拒斥不相容’的原则共存"这两个问题给出反思性说明。

This paper starts with the clarification of the ambiguity of＂modus ponens＂ （abbre- viated ＂MP＂）. Next we classify its various referents, that is, two different roles played in practical uses： as an argument form （affirming the antecedent） and as a derivation rule （detachment or implication elimination）. Along the semantic approach, we examine the validity of MP in the viewpoint of classical and non-classical logics （e.g., LP） respectively. In the light of the distinctions between ＂logic＂ and ＂reasoning＂, we demonstrate that why we always seem like comply with MP when do practical reasoning, provided our paraconsistent logic of ordinary language is detachment-free. Finally, we provide some reflections for critical issues involved in the abovementioned thread.