本文從三個方面梳理〈中庸〉誠論的思想史脈絡，藉此論證〈中庸〉誠論係儒家誠論的原創性文本，並推定〈中庸〉是先秦儒學前期的文本。其一，著眼於〈中庸〉的特殊文本形式，考察〈中庸〉誠論形成的文本內部脈絡，從而梳理出子思之儒如何透過引用孔子的「中庸」、「祭祀禮儀／文武之政」教言，發展出以「誠」為「道」的修身、政治論述。其二，著眼於〈中庸〉引述的文王之詩，考察周代政治演變的軌跡，從而梳理出子思之儒如何因應戰國早、中期「文武之政」失能的政治境況，而以「至誠」典範詮釋文王之德，藉此回應彼時的政治新局。其三，著眼於先秦儒學的發展脈絡，考察〈中庸〉、孟、荀誠論的論述旨趣，分別以教義論、心性論、體制論界定之，從而梳理出三者如何因應時代境況而發展出不同理論面向的誠論系譜。綜合三方面的梳理所得，本文推定〈中庸〉係先秦儒學前期的文本，而〈中庸〉誠論則是子思之儒為了回應戰國早、中期「文武之政」失能的政治境況而提出的一套政治論述，可以視為先秦儒家誠論的原創性文本。

With three aspects, this article analyzes and discusses the meaning of The Doctrine of the Mean’s sincerity discourse from the viewpoint of thought history. It expounds and proves that the sincerity discourse of The Doctrine of the Mean is an original text of Confucian sincerity discourse and deduces that The Doctrine of the Mean is a Confucian text of the earlier period of pre-Qin. First, based on the special form of The Doctrine of the Mean, it investigates the book’s internal organization formed with its sincerity discourse. The article discovers how the scholars of Zi-Si’s school developed a self-cultivational and political discourse that regarded “sincerity” as the “Dao” through quoting Confucius’s teaching words “the mean” and “the sacrificial etiquette / King Wen’s and King Wu’s governances.” Second, based on the part of King Wen’s poems quoted in The Doctrine of the Mean, it explores the trajectory of the Zhou dynasty’s political evolution. It clarifies how the scholars of Zi-Si’s school responded to the political situations of the early and middle stages of the Warring States when “King Wen’s and King Wu’s governances” lost their functions. They used the model of “extreme sincerity” to interpret King Wen’s virtues and respond to the new political situation at that time. Third, based on the development process of pre-Qin Confucianism, the article scrutinizes the central ideas of the sincerity discourses of The Doctrine of the Mean, Meng-Zi, and Xun-Zi and defines them respectively as the doctrine discourse, the mind discourse, and the institution discourse. It further finds out how the three discourses developed sincerity discourse pedigrees of different theoretical aspects according to the situations of their times. Integrating the results of the analysis on the three aspects, this article concludes that The Doctrine of the Mean is a Confucian text of the earlier period of pre-Qin. Its sincerity discourse is a set of political discourse that the scholars of Zi- Si’s school put forward. The discourse is a response to the political situations of the early and middle stages of the Warring States, when the “King Wen’s and King Wu’s governances” lost their functions. It can be viewed as an original text of pre-Qin Confucian sincerity discourse.