朱子以“真实无妄”训解《中庸》之“诚”的诠释方式为学界普遍接受，但伊藤仁斋提出应以“真实无伪”代替“真实无妄”，削弱“诚”的“合理性”而强调其“真实性”，以面对存在失常的天道。并且这种“合理性”的弱化随着仁斋“圣人之道诚而已矣”的论断，转移到了圣人身上。相良亨称之为“过”，而认为天道与圣人皆贵“改过”。天道亦作为对圣人之行的描述退居于后。仁斋此解展现的不仅是对“诚”之字义训解的转变，更是其从朱子学到古义学的转变。其对天道与圣人之“真实性”的关注、对天人关系的分离、对“诚”之意涵的提纯以及对朱子学易沦于佛老的批判，在解构朱子学形而上学的尝试中，为儒学经典诠释带来了新路径。
Zhu Zi’s interpretation of “Cheng” in the Zhongyong by using “zhen shi wu wang” is generally accepted by scholars，but Ito Jinsai proposes that “zhen shi wu wei” should be used instead of “zhen shi wu wang”. In this way，the “reasonableness” in “Cheng” is weakened and the “truthfulness” is emphasized，so as to face the true Tiandao，which may out of order. And this weakening of “reasonableness” is transferred to the saints with Jinsai’s assertion that “the Dao of the saints is only Cheng”. Sagara tooru refers to this as a ‘fault’，arguing that both Tiandao and the Dao of the saints are worthy of “correction”. Moreover，Tiandao takes a back seat to the description of the sage’s actions. What Jinsai’s new interpretation shows is not only a shift in the interpretation of the meaning of the word “Cheng”，but also a shift from Zhu Xi’s philosophy to kogigaku. Its practical concern for the authenticity of Tiandao and the sage，its rupture of the relationship between Tian and human，its purification of the meaning of Cheng，and its criticism of the ease with which Zhu Xi’s philosophy degenerated into Buddha and Lao，deconstructed Zhuzi’s metaphysics and brought about a new path of interpretation of the Confucian classics.
