Inconsistent accounts: Song debates and writings on Wei Zheng’s change of allegiance

The Cheng-Ma Debate refers to the discussion between Cheng Yi 程頤 and Sima Guang 司馬光 around Wei Zheng 魏徵 changing allegiance. Tang Taizong 唐太宗 killing his brother, forcing his father aside to ascend the throne, and later becoming an enlightened ruler and Wei Zheng changing allegiance to his enemy and later becoming a sagely minister reveals an inconsistency between objective events and ethical principles. The interpretation and writing of this inconsistency was a new topic that the neo-Confucians posed to historians. This article closely compares narratives of Wei Zheng changing allegiance and Tang Taizong ascending the throne found in Comprehensive Mirror to Aid in Government (Zizhi tongjian 資治通鑒), Mirror of Tang (Tangjian 唐鑒), and Outline and Detials of the Comprehensive Mirror (Tongjian gangmu 通鑒綱目), and points out that Comprehensive Mirror makes quiet changes, Tangjian highlights ethical principles over history, and Outline and Detials returns to Comprehensive Mirror in its narrative and emphasizes both ethical principles and history. In the end, what wins out is a simple narrative that conforms more to a flattened philosophy loyalty to one’s ruler.