Japanese ka-indefinites and the semantic domain of unknown to the speaker

What are the functions of the indefinite noun in Japanese, a language that does not obligatorily mark indefinite noun phrases? Through comparison with English indefinite expressions, this paper clarifies the semantics of the Japanese ka-indefinite in the light the semantic division known vs. unknown to the speaker (Haspelmath, Martin, 1997. Indefinite Pronouns. Oxford University Press, Oxford), a division which has received little attention in semantic research so far. This paper argues that rather than indefiniteness, the ka-indefinite expresses the speaker`s lack of knowledge of the identity of the referent.