On the grammaticalization of Japanese verbal negative marker

Abstract In Japanese, the verbal negative marker nai appears in both negated verbs (as a sentential negator) and compound negative adjectives (as an affix). Negative nai used as a sentential negator is a syntactically independent word devoid of adjectival properties despite its adjectival inflection, whereas negative nai appearing in negative adjectives is a derivational affix. On the basis of idiomatic expressions, the present article argues that the lexical word nai ‘null, empty’ has developed into the affix nai while retaining its lexical properties via morphologization. On the other hand, the functional negator nai is argued to have emerged from the same lexical word nai via decategorialization, which induces a shift from a lexical to a functional category. The analysis taking the two uses of nai to trace back to the common source of the lexical negative adjective word nai provides a natural account for why nai has these two totally different uses.