學界對於朱子說「惡」，業已累積豐富的研究成果；本文嘗試推進現有理解，重新探索與定位朱子惡論中「惡」的根源與責任問題。全文主要論證有三：一、朱子惡論牽涉一個龐大而複雜的觀念叢，種種線索結穴於屬「氣」之「心」作為作「惡」的關鍵。二、雖然「人心」無意識自動運行的心理機制，本來具有促進心理健康的作用；但其盲目運作以致掩蓋「道心」，即會導致「自欺」的問題。通過當前道德心理學與意識哲學的研究成果，有助闡明「自欺」何以是「惡」的根源。三、朱子以「氣」言「心」，難免遭受未能說明道德責任的理論質疑。同樣建基科學證據，有助說明無意識心理何以仍然可被究責；甚至「自欺」可被理解為自主心理，以致需要直接為其導致之「惡」承擔道德責任。期望本文能從比較哲學、跨領域研究的視野啟發新見，從而進一步闡明朱子惡論的獨特貢獻。

This paper extends the considerable scholarship on the concept of evil in Zhu Xi’s philosophy to explore and revisit the origin of evil and the issue of moral responsibility therein. There are three main arguments: 1) Zhu Xi’s theory of evil consists of a bundle of concepts, in which all evidence points towards the materialistic heart/mind as the crucial element of doing evil. 2) Although the unconscious, automatic psychological mechanism of the human-heart/mind (ren xin) may facilitate one’s mental health, its blind operation renders it prone to overwhelm the Dao-heart/ mind (dao xin), ultimately leading to self-deception. Currently, major developments in contemporary moral psychology and the philosophy of consciousness provide accessible clarifications for the relationship between self-deception and evil. 3) Since Zhu Xi interprets heart-mind under the domain of material forces, his own explanation of moral responsibility has been severely challenged. The emergence of new scientific evidence helps us better understand the culpability of unconscious psychological functions. As a result, self-deception could also be comprehended as a volitional act in order for an individual to be morally responsible for its vices. Navigating through this comparative and interdisciplinary perspective is vital to the effort to further clarify and provide contemporary relevance to the unique contribution of Zhu Xi’s theory of evil.