北宋司馬光之〈疑孟〉，實為有宋一代非孟學者對孟子思想疑難之代表。其說至南宋被大量討論，胡宏〈釋疑孟〉雖身處其中，但多被前人所忽視。本文細查兩造理路，發現二人對於孟子思想的贊同或駁議，皆是源於心性認識不同而有之效應。司馬光認為心乃需治理，透過外在禮法、聖人教育積累方能成善，明禮、尊君、重史皆是其實踐人性成善的向度，不可單一的自信其心；然而胡宏則承繼孟子思想系統，心性同源，盡心知性，禮以時大，認為人能撐起道德判斷之標準依據在於自身，故進退皆能合於中道。兩人皆有其時代考量與自身思想之依據。如司馬光身處北宋複雜的政治處境，其致力於君王主權的維護乃當時所需，以及對於王安石變法自專自大的疑慮，反應在政治態度上的保守復古，皆是其人如何認識心性的重要背景。而胡宏則身當南宋，經歷了變法的失敗與制度的重建與毀損，故對北宋滅亡的困局做出更深一層的省思，兩者雖皆是對於制度背後的根據與脈絡，給予不同的回應方法，但這樣的判斷究竟依何而定？何者當為判斷之本？此中深刻的追問，逼使南宋儒者逐漸正視了內在道德心性之根本，而後開展出宋明理學的主要的問題意識

〞Doubt Mong,〞 written by Sima Guang in the Northern Song Dynasty, was definitely the masterpiece of non-Mong scholars doubting Mencius thoughts in the Song Dynasty. It was widely discussed in the Southern Song Dynasty. Even though Hu Hong's 〞Explaining Doubt Mong〞 was in it, it was mostly ignored by predecessors. In scrutinizing rational thinking directions of Sima Guang and Hu Hong, the endorsing or the refutation for Mencius thoughts were both from the effects of different kinds of mind awareness. Sima Guang thought that mind needed to be controlled and goodness could be achieved only through the accumulation of external rites and sage education. As a result, believing in one's own mind was not suggested. Instead, courtesy, respecting monarch, and regarding history were necessary. Hu Hong inherited Mencius's thought system, regarding mind homologous, dedication and intellectuality, and contemporary courtesy, believing that people established the standard of moral judgment based on themselves and thus advance and retreat could comply with doctrine of the mean. They had their own era considerations and basis of their own ideas. Sima Guang lived in a complex political situation of the Northern Song Dynasty and committed himself to the maintenance of the sovereignty of the emperors due to the requirement of the era. His doubts for the arrogance of the Political Reform of Wang Anshi performed conservatism and retro on the political attitudes, which was an important background of how people understood the minds. Hu Hong lived in the Southern Song Dynasty, experiencing reform failure, reconstruction and damage of the system, and thus he made deeper reflection for the dilemma of the demise of the North Song Dynasty. He doubted what led to the basis and context behind the system. Herein the profound questioning forced Confucians in the Southern Song Dynasty gradually faced the fundamental of inner moral disposition and then the major problems of Neo-Confucianism were carried out