Abstract
This paper examines the semantic function of actual potentials in modern Japanese by contrasting them with unmarked verbs, and focusing on volitionality and the relation between events and subjects. The conclusions are as follows. (1) It is revealed that it is possible to use actual potentials to describe events which occurred casually, so that the events described by actual potentials do not always occur with subjects' volitionality or expectation. (2) It is defined that actual potentials are sentences with the plus semantic distinction that means "Events are favorable and rare to subjects", and unmarked verbs are sentences with the neutral semantic distinction that means "Events occurred in the past". Therefore, although both actual potentials and unmarked verbs describe events which occurred only one time, they have relative expressions of events as plus events and neutral events from a semantic point of view. (3) As the achievement of events described by actual potentials is always uncertain, actual potentials not only describe events from the perspective of the subjects but also describe the results of events. Therefore, it is possible to use actual potentials to express the meaning of "unaccomplished events", which can not be applied to unmarked verbs. That is to say, unmarked verbs only work for describing the meanings of "accomplished events" and "unrealized events" because the function of unmarked verbs is just to describe whether events occurred once in the past or not.
