文頭における｢でなければ｣の構文分析

A Constructional Analysis of Sentence-initial Denakereba

本稿では、主に条件的用法をもつ｢でなければ｣の非条件的用法について考察した。特に、文頭における｢でなければ｣の構文を分析し、因果関係の構造を取らない場合、どのような構文的特徴をもつのかについて検討した。大きく二つのパタンーに分けられ、｢でなければ｣の前件述語にモダリティー形式を伴う場合、また、｢AでなければB｣といった｢選択肢の提示｣を表す場合に｢でなければ｣は、独立した形として自立性をもつことが確認できた。｢選択肢の提示｣という機能が｢。でなければ｣の形をとることに限られて現れる現象とは言えないが、前件と後件を完全に分離することにより、｢。でなければ｣の自立性を高める一つの原因になると考えられる。これらは｢でなければ｣独自の用法と見られ、｢接続詞｣用法へその機能を拡大していると言える。同時に、この現象は、条件形式でありながら非条件的用法をもつ｢機能語化｣の一例としてみなすことができると考えられる。

The phrase “denakereba” which appears at the beginning of a sentence is structurally characterized by always being accompanied by “de” without an accompanying preceding word. It is mainly used as the first clause in idiomatic expressions such as “nakerebanaranai”(must do), “nakerebaikenai” (must not do), where the second clause “naranai” or “ikenai” is omitted, and functions as a predicate expressing obligation. However, when the preceding word is omitted and “de nakereba” primarily works at the beginning of a sentence, it is not necessarily an expression of obligation. In this paper, we mainly examined the non-conditional usage of “denakereba” that has a conditional usage. In particular, we analyzed the syntax of “denakereba” at the beginning of a sentence and examined what syntactic features it has when it does not take a causal relationship structure. It can be divided into two patterns: when the preceding predicate of “denakereba” takes a modality form and when “denakereba” expresses “presenting choices” such as “A or B.” In both cases, “denakereba” has an independent form and autonomy, which is considered as its unique usage and expands its function to that of a conjunction. This phenomenon can also be seen as an example of the “grammaticalization” of a conditional form to a non-conditional usage.