Unaccusativity and the diachrony of null and cognate objects in Greek

In the present paper, we show that in contrast to the diachronic instability that unergatives and transitives present with regard to null and cognate objects, alternating unaccusative verbs constantly appear to meet more restrictions in null and cognate object constructions than the other verbal classes. The restrictions of the null objects with alternating unaccusatives hold irrespective of the structure and the voice morphology of the alternating unaccusatives: alternating unaccusative verbs can be found in causative constructions with null objects only of the most freely used type of null objects (generic null objects); the other verbal classes can appear with deictic null objects in Modern and Ancient Greek or even with referential null objects in Ancient Greek. Cognate objects in Ancient Greek show both argumental and adverbial characteristics: unergatives in Ancient Greek can take cognate objects of argumental or adverbial character, but unaccusatives only take adverbial cognate accusatives. The common complex (causative) template of alternating unaccusatives (in both causative and anticausative uses) can be observed as the cause of the obligatory presence of the patient argument in causative uses of alternating unaccusatives, while the dependence of atelic/telic interpretation in Ancient Greek (especially in Homeric Greek) on an aktionsart/situation type aspect can explain the differences found between the Ancient and the Modern Greek cognate constructions.