ABSTRACT In order to construct a satisfactory theory of cheng-yi 誠意, Zhu Xi 朱熹 develops an account of how self-deception is possible—a profound problem that has puzzled many philosophers. In Zhu’s opinion, zhi 知 can be divided into two categories: a priori knowing and empirical knowing. The further division of empirical knowing defines three sorts of self-deception: the self-deception caused by one’s ignorance, the self-deception caused by one’s superficial knowing, and the self-deception that may occur when one acquires genuine knowledge. (...) In this paper, I will construct a theoretical model of self-deception that follows Zhu’s criterial definition of self-deception in Daxue Zhangju 大學章句, thereby accounting for the possibility of these three sorts of self-deception. Better understanding of Zhu’s conception of self-deception could, moreover, open fruitful avenues for further work on his metaphysics and moral psychology. (shrink)