「理氣論」是朱子三大主要義理之一，朱子對「理氣論」有「宇宙生成論」及「本體論」兩說法；在「宇宙生成論」說法中又有「中性的宇宙生成論」及「道德的宇宙生成論」二說；而在「本體論」說法之「理」則同時指涉「中性事物之理」與「道德事物之理」等，故知朱子「理氣論」意涵歧雜多樣。本文除引朱子原典，另據近世學者如馮友蘭、勞思光、牟宗三、唐君毅等先生的詮釋，近世諸家認為「理氣論」同時講「宇宙生成論」與「本體論」兩範疇；然到底是談「中性事物之理」或「道德事物之理」，則馮、勞二氏站在前者立場，牟、唐二氏立基後者觀點；唯牟氏只將朱子「理」視為客觀超越而不活動的死理，唐氏則將之解為「心之理」而與陸王無異。

＂Li-Qi Theory＂ is the three major theories proposed by Zhu Xi, Zhu Xi's ＂Li-Qi Theory＂ includes two scopes: ＂cosmogony＂ and ＂ontology.＂ ＂Cosmogony＂ includes two concepts: ＂neutral cosmogony＂ and ＂moral cosmogony.＂ In ＂ontology,＂ ＂li＂ refers to both ＂li of neutralmatters＂ and ＂li ofmoralmatters.＂ Therefore, the meanings of Zhu Xi's ＂Li-Qi Theory＂ are complicated and diversified. In addition to citing the original texts of Zhu Xi, this study also based on the interpretations of scholars in modern age, such as You-lan Feng, Ssu-kuang Lau, Zhonsan Mo, and Jun-yi Tang. In modern age, various schools of thought suggest that ＂Li-Qi Theory＂ concurrently includes two scopes: ＂cosmogony＂ and ＂ontology.＂ However, was the focus of Li-Qi theory on ＂li of neutral matters＂ or ＂li of moral matters?＂ Feng and Lau suggested that the focus was on the former, while Mo and Tang suggested that the focus was on the latter. However,Mo only viewed Zhu Xi's ＂li＂ as objective, inactive, and dead li, while Tang viewed it as ＂li of mind＂ which is the same as the perspectives of Lu and Wang.