從鄭玄《三禮注》論「推致」之法

「推致」是漢人說禮的方法之一，用以彌補《禮》篇的闕散，以滿足漢王朝據經以制禮的需求。漢初的后倉已在應用，經師在家法興起後更利用它來穩固禮說權威。然而，「推致」的操作細節，記錄此事的《漢書》〈藝文志〉不見示例，僅「推《士禮》而致於天子」，而后倉等人的推致，見存者也相當有限，容易使人誤以為此法只是由卑而尊，或僅在階級禮數上做推擬。所幸，東漢鄭玄的《三禮注》留存豐富的「推致」資料，揭明操作的過程，足供後人一窺其奧。鄭玄推致的面向，涉及不同階級的禮制、相近的禮類、親疏關係之儀節，亦推演禮儀流程的變化、職官的職守；他甚至利用「推致」來辨正禮書訛誤、界定禮文屬性，與會通三《禮》成一體系，較后倉更為擴大。再者，「推致」可分為「約」法與「推次」兩類，後者尤為普遍，是以「禮數差次」做為推次的關鍵；舉凡有次第秩序的原則，皆屬差次的範疇，如階級尊卑、親疏關係、儀程變化、用物品質、陰陽五行，皆在其中。檢示鄭玄的操作，雖有差池，但零星偶現，瑕不掩瑜，故此法仍能影響後世學者治禮研經，歷久不墜。 “Tuizhi” 推致 is one of the most commonly used methods by Han dynasty scholars to explain the ritual system. Coping with a lack of ritual writings, the method was employed out of the need for dynastic rituals and to deduce which rituals should exist but remain unwritten. Today, only Sanli zhu 三禮注 written by Zheng Xuan 鄭玄 (127-200) of the Eastern Han still retains the details regarding the workings of “tuizhi,” and is therefore the area of research focus for this article. Despite inheriting his methodology from Western Han ritualists, Zheng Xuan did not limit the basis of his inference to the rites of the seventeen chapters within Yili 儀禮. Instead, based on integration, he adopted more referable principles and clues as well as expanding certain inferable aspects. Specifically, this article covers five main points of discussion. To begin, the author clarifies that “tuizhi” is actually divided into two categories: yuefa 約法 and tuici 推次, which serve to speculate on the rites of different classes. Next, the question of which rules are applied by tuici is proposed and analyzed. Thirdly, why did Zheng Xuan not refer to the ancient books of rites 古禮書, but instead simply relied on “tuizhi”? Furthermore, this paper discusses if, and how, Zheng Xuan applied “tuizhi” in other works. Lastly, both the shortcomings of Zheng Xuan's utilization of “tuizhi” as well as the impact of this method on later ritual studies will be reviewed.