Heureusement/malheureusement are antonym adverbs which are apparently symetrical, but malheureusement doesn't fit in the construction adv.que p : " Heureusement qu'il est parti à l'heure, sinon il aurait loupé son train./* Malheureusement qu'il est parti trop tard, sinon il n'aurait pas loupé son train. " According to existing studies, this phenomenon is related to the distinction theme/rheme, but we will demonstrate that this explanation is not entirely satisfactory. Based on a diachronic perspective, this paper proposes a supplementary interpretation of the semantic value of heureusement/malheureusement. Using the corpus data Frantext, we will show that paradoxically heureusement and malheureusement have followed reversed diachronic changes : malheureusement seems to be employed as a conjunctive adverb since the 16th century, while heureusement is first employed as a manner adverb focusing on the verb. We will then show that the structure heureusement que p, which appears late in the 18th century, has a peculiar semantico-pragmatic value, and is more than the mere predicative variant of heureusement as a conjunctive adverb.
