質問: Is it by any chance the case that, historically, the い-adjective ending 〜かった is a contraction originating from 〜くあった, where あった is the past inflection of ある? To me, it sure *sounds* plausible, and would be quite elegant given how 〜く and 〜ある seem to stick together in the negative forms of い-adjectives. Is this where 〜かった originates, or is this merely a coincidence? **例えば** * 高い (?) → 高い * 高かった (?) → 高く**あった** * 高くない (?) → 高く**ない** * 高くなかった (?) → 高く**な**く**あった**
回答: That is indeed correct. The -く form is the 連用形 (infinitive) of the adjectives, and from the earliest times it had the possibility to attach the verb -ar as an auxiliary to ease the further conjugation in the verbal categories (such as negation, mood, aspect). But, with the great reshuffle of the verbal paradigm during Late Middle Japanese (Ashikaga shogunate), most of these forms went out of usage. Nevertheless, the past form, newly formed during that period, employed this intervening verb (Frellesvig, Bjarke. A history of the Japanese language. Cambridge University Press, 2010. - p. 340 seems to claim that the appearance of a systematic past for adjectives is already an Edo development), originally employed without contraction, as -ku atta. There was the alternate in -ku gozatta at the time. As already mentioned, the contraction happened later.