Logic for Thinking - From Mathematical Logic to Grammatical Logic

摘要

We see outer world with language and also think in inner world with language. Thinking is something different from imagining or dreaming; it is viewed as 'a logical act' associated with language. In this talk, we first characterize 'thinking' on the semantic level from the perspectives of Systemic Functional Linguistics and then investigate logic for thinking imbedded in language on the grammatical level. Conventional logic with relations such as AND, OR and IF-THEN was born from language; in fact, these are grammatical relations between clauses (sentences). Next we explore primary and higher-order logic for thinking. As a result, there are a variety of grammatical relations found between clauses. In addition, we consider when infants begin to think, reviewing their language development studied by Halliday and point out that grammar is a driving force for thinking as higher-order consciousness developed together with language. In this sense, resources necessary for thinking are all prepared in language.