TO IERU (lit: can say) is a formula which concerns epistemic judgement in Japanese. This formula indicates the validity of the speaker's expression or opinion in the text. How the information is validated reflects the text structure, therefore, by means of this formula, we can distinguish the information which the speaker has produced from that of the ″objective data″. This funciton is shared with ″TO IUKOTONI NARU (lit: become) ″, ″TO KANGAE RARERU (lit: be considered)″, ″NODA″ and ″WAKEDA″. We attempted to examine the differences between them.
