作为日本“怀德堂学派”的集大成者，中井履轩沿袭了以往怀德堂儒者重视《中庸》诚论的传统，尤其是在《中庸逢原》之中，中井履轩认为，《中庸》的作者子思不仅将诚作为“人道”，同时也将诚作为“天道”，这种从人伦社会到宇宙全体视域上的扩展是《中庸》诚论独创性的体现。不过，子思言天道之诚的目的不在于探讨“天道何以为诚”，而是为了引出“人道如何诚之”的问题，子思诚论的基本精神依旧在于人道。对此，中井履轩以“忠信”释诚，揭示了人道之诚的自足性，而不去追问诚的终极根据之所在。这一经学研究反映出来的问题意识与其说是朱子学，倒不如说更为接近伊藤仁斋之学。归根结底，中井履轩的学问与伊藤仁斋一样有着浓厚的“町人”学问的底色，诚作为与町人之“生业”紧密相关的重要德目，似乎无须从天道那里寻求其根据，亦难以引申为普遍性的理。
As the greatest Confucian studies researcher of Japan’s Kaitokudo School，Nakai Riken has followed the tradition that Kaitokudo’s Confucians attaching importance to the theory of Cheng in Zhong Yong. Especially in Zhong Yong Feng Yuan，Riken believes that Zisi，the author of Zhong Yong，not only regards Cheng as “Ren Dao”. This expansion of vision from human society to the entire universe is an important manifestation of the originality of Cheng theory in Zhong Yong. However，Zisi’s purpose of talking about Cheng of Tian Dao is not to discuss “how the way of Tian is Cheng”，but to raise the question of “how to be Cheng in the way of Ren”. In this regard，Riken uses “Zhong Xin” to interpret Cheng，revealing the self-sufficiency of Cheng of Ren Dao，and does not ask for the ultimate basis of Cheng. The problem consciousness reflected in this study of classics is closer to Ito Jinsai than to ZhuziXue. In the final analysis，Riken’s study has a strong foundation of “Chonin” study just like Jinsai. Cheng is an important virtue closely related to Chonin’scareer. It seems that there is no need to seek it from Tian Dao，and it is difficult to develop the meaning of universal principles.
