本論文以先天善性與後天習性的關係為主軸，來討論王船山人性論的問題。由於船山以「氣」為本體，但並不否定「理」為氣化之主宰的意義，因此，論文首先分析船山論人性乃「理氣一體」的涵義，以及性與心既一又異的關係，說明性善而心可能（然而不必然）有不善。其次，說明人性必是「氣質中之性」，而因人人氣質各異，形成人性不一致又「相近」的情形。其三，論人性是先天的道德性與後天的習性渾合一體，故人既日受善性於天，亦可能因習於不善而日成不善之性。最後，對船山以習性一成乃「不可移」的觀點與性善、性日生日成之說之間的可能矛盾，嘗試加以會通。

This thesis discusses Wang Chuan-shan's theory of human nature, and focuses on the connection between inherent goodness and acquired habits. Wang Chuan-shan considered "disposition" as the noumenon, but he did not deny that "moral philosophy" determines the resultant disposition. Therefore, this study will first examine Wang Chuan-shan's concept of human nature: that "moral philosophy exists within disposition." Due to the fact that nature and "heart" are two sides of one coin, human nature is originally good but the heart can be (albeit not necessarily) bad. Second, human nature is a combination of "natural disposition and character", both of which vary from person to person. Consequently, while human nature varies among individuals, in many aspects, it is universally similar. Third, human nature is a combination of natural moral creativity and acquired habits. Even though people have an inherent natural goodness, they may acquire bad habits and develop a bad nature. Finally, contradictory arguments arose concerning Wang's theory that once established, habits were impervious to change; the philosophy that men were created 'good'; and the view that the nature of human beings could be changed. The thesis will also try to resolve these contradictions.