《春秋》三傳中，《公羊傳》於西漢景帝時即立為學官，為三傳之冠。緣由為何？一般說法是《公羊傳》主張大一統、君尊臣卑、尊王攘夷等思想，符合了西漢國體制維繫的需要。本文試圖証明《公羊傳》所建構的經權觀也有類似的作用。《公羊傳》所以建構經權觀有其歷史因素。此歷史因素即高帝、文帝之間諸呂封王事件中王陵、陳平、周勃等人的事蹟。他們三人在整個事件中行徑大不相同，甚至相反相對。但他們三人的事蹟都關係西漢國祚及統治正當性的延續，都需予以合理的評價。經權觀正是西漢史家正面評價他們三人事蹟的理論基礎。《公羊傳》的經權觀當是呼應此段歷史經驗及需要而建構者。本文並試圖說明東漢章帝時賈逵評《公羊傳》「多任權變」的歷史緣由，由此突顯兩漢士人對權道觀看法的不同 ,以及《左傳》不能早立學官的理由。

Why did the kung-yang commentary of the Spring and Autumn Annals become the most dominant book in the Emperor Wu reign of the Western Han Dynasty? The general theory is that the kung-yang tradition proposed a system of political ethics that perfectly met the ideological need of the emprire. This paper examines a particular case to prove the above theory. The Empress Lu, as a regent of the empire after the death of the Emperor Hui, nominated four members of her own family as kings, in defiance of the oath said to have been sworn before Emperor Kao and his followers. At that time, Chancellor Wang Ling opposed her decision determinedly, while Chancellor Ch'en P'ing and General Chou P'o approved it complyingly. The latter two seemed to have betrayed their loyalty to the Emperor Kao. But it was them who put down the rebellion of the Lu kings and restored the imperial family of Liu after the death of the Empress Lu. How can we judge the deeds of these three follows of Emperor Kao separately and approvably? The Kung-yang commentary proposed a theory of ching(經) and chuan(權) to meet that purpose. Wang Ling who followed the principle of ching, while Ch'en and Chou followed the principle of chuan. They all are great officials of the Western Han Dynasty. In this way the authority of the reign of the Emperor Wen was justified. Therefore, the Kung-yang Commentary on the Spring and Autumn Annals provided an ideology for the consolidation of the Han empire.