Conditionals in English and FOPL

该文主要论述了实质条件句和直述条件句的区别,并试图解决在逻辑分析此类句子时所面临的问题。用分析实质条件句的逻辑方法分析自然语言的直述条件句,其存在的问题主要表现在两个方面:1)实质条件句的推理模式明显不适合直述条件句(例如逆否推理和否定前件推理),2)将条件句的否定简单等同于前件与后件否定的合并,这往往不能成立。如果考虑到直述条件句的其它方面,或许能够较成功地解决目前存在的问题。首先,将“条件性”当作 if 的规约含义;其次,if 从句是从属于后件的根修饰语,然而不像多数副词性修饰成分,它们不传达新信息。条件句的不对称性,导致逆否推理在多数情况下难以成立或不可能成立。假前件不足以让条件性含义保留下来,因此否定前件推理似乎不能成立。

In the 1960＇s, both Montague （e.g. 1970, 222） and Grice （1975, 24） famously declared that natural languages were not so different from the formal languages of logic as people had thought. Montague sought to comprehend the grammars of both within a single theory, and Grice sought to explain away apparent divergences as due to the fact that the former, but not the latter, were used for conversation. But, if we confine our concept of logic to first order predicate logic （or FOPL） with identity （that is, omitting everything which is not required for the pursuit of mathematical truth）, then there are of course many other aspects, in addition to its use in conversation, which distinguish natural language from logic. Conventional implicature, information structure （including presupposition）, tense and time reference, and the expression of causation and inference are several of these, which combine as well with syntactic complexities which are unnecessary in first order predicate logic. In this paper I will argue that such distinguishing aspects should be more fully exploited to explain the differences between the material conditional of logic and the indicative conditional of one natural language （English）.