本文以先秦語法標記「然」及「雖然」、「然則」、「然而」等為例，論證語體條件納入先秦語法演變研究的意義。起點是從《左傳》和《荀子》中的對話語體確認「雖然」、「然則」用於口語活動的人際照應功能，其次參酌傳統學者對古代文獻「然」的分析與解釋，援引先秦傳世文獻語料，釐析「然」在對話語體與非對話語體的用法，梳理出指代、表態語氣、轉折事理三種功能的流變關係，闡明在語體參照下可望更細緻地重構先秦語法演變。

The present paper demonstrates that linguistic register was the motivation for grammatical change in pre-Qin Chinese writings via a set of composites of ran 然, including suiran 雖然, ranze 然則, ran’er 然而 and ranhou 然後. Register has rarely been taken into serious account in previous studies on pre-Qin grammatical changes, but evidence from the above-mentioned composites unveils that innovation regarding the concessive markers ran and suiran was triggered by a shift in register. Examples from Zuo zhuan 左傳 and Xunzi 荀子 show that suiran and ranze were used consistently to indicate the addresser’s agreeable, or pleasing, attitude towards the addressee in spoken conversations. Suiran was reinterpreted as a concessive marker with the pleasing attitude preserved in oral discourses. When it was employed in the writing of a pseudo-oral style, however, the attitude faded out for a lack of interpersonal communication, and the concessive marker consequently prevailed. The evidence proves how an attitude marker was split from a demonstrative marker, and further, into a concessive marker. Taking this as a point of departure, the present paper proceeds to review the drastically diverging opinions held by traditional scholars on the grammatical functions of ran, and then proposes an integrated hypothesis on innovation concerning the concessive ran. Through analyzing the problematic issue of ran in pre-Qin Chinese, this paper argues for the necessity of viewing linguistic register as a factor of grammatical change, and of equal importance, for the justification of register grammar.