A Study on the Asymmetric Phenomenon in the Negative Forms of Deontic Modal Auxiliaries

In Modern Chinese, the expressions bu yao(不要), bu xu(不須), and buyong(不用) all represent the negation of modal auxiliaries denoting necessity. However, while bu xu and bu yong indicate ‘exemption’, bu yao conveys ‘prohibition’. Previous studies suggest that the meaning of ‘prohibition’ in bu yao developed pragmatically from the meaning of ‘exemption’. However, considering that other forms such as bu bi(不必) also express ‘exemption’, this raises the question of why only bu yao developed the meaning of ‘prohibition’.<br/> This study, from a diachronic perspective, finds that in Classical Chinese, bu yao, bu xu, and bu yong all conveyed not only ‘exemption’ and ‘prohibition’ but also the meaning of ‘impossibility’. Bu yao had the highest frequency of occurrence in both ‘prohibition’ and ‘impossibility’ meanings, while bu xu and bu yong were more frequently used to indicate ‘exemption’. This suggests that the ‘prohibition’ meaning of bu yao developed from the ‘impossibility’ meaning. The absence of the ‘impossibility’ meaning in bu bi explains why it does not carry a meaning of ‘prohibition’.<br/> The phenomenon in which the negative form of a deontic modal auxiliary indicating necessity expresses ‘impossibility’ is a cross-linguistic phenomenon. This arises from the mismatch between the position of the negative element and its scope. This results from the fixation of the negative element’s position, which in turn arises from the weakening of its autonomy due to grammaticalization. The fixation of the negative element’s position leads to a fusion phenomenon. In Modern Chinese, representative forms that exhibit a mismatch between the position of the negative element and its scope include the negative forms of deontic modals such as bu yao(不要) and epistemic modals such as bu hui(不会). Both of these forms exhibit fusion in terms of both the formation of portmanteau forms and the elevation of their grammatical status.