「量」的な言語表現を含むことが量的含意を解釈することに必要なのか？

抄録

The basis of language seems to reside in an inferential nature. It is known that 5-year-olds erroneously accept expressions such as “Some of the horses jumped over the fence” when they see (all) three of the horses actually jumping over the fence. One proposed reason for this is that young children do not yet fully understand that the scalar terms such as “some” imply “not all.” For example, suppose a kindergarten teacher said to her class, “booshi wo kabutteinai otomodachi ga imasu (Some of the friends do not wear a hat),” this expression may not mean that all of the friends are hatless, but only some of the friends are hatless. In such case, the Japanese expression itself may not include any scalar terms, nonetheless, the meaning “some” seems to be implied. In two experiments, we asked Japanese 3-, 5-year-olds, and adults to interpret similar expressions without using explicit indication of “some.” The results revealed that many adults readily grasped the implicit “some” meaning in such utterances. On the contrary, 5-year-olds failed to perceive the implication of “some” and instead interpreted the statement as “All friends are hatless,” utilizing an ad hoc implicature. Interestingly, the performance of 3-year-olds seemed to be based on a logical interpretation, i.e., “at least one.” The study implies that while the word “some” is not explicitly stated in Japanese, adult speakers inferred a scalar meaning. However, young children on the other hand, are still in the process of developing this ability. The findings are discussed in relation to scalar alternatives and shared intentionality. The study confirmed the basis of language inherently encompasses an inferential nature.