理氣之辨是中國哲學天道觀中的一個重要討論，王夫之 (船山) 通過理氣之辨來論誰真實存在具有自在自為的特性。氣本身具有隱顯合一 (通乎可見與不可見) 的特性，它意味著主體知能的界限，也是天命概念得以立身的基礎。因此，王船山把存在論範疇架構在氣的基礎上，把存在的真實性最終歸結為氣的真實性，這樣，存在的非人為構造性，也即其自在性就獲得了擔保。王船山區分了動詞性的理 (治理) 與名詞性的理 (條理)，認為後者只有奠基於前者才有意義，這樣，理就被規定為氣化過程中顯現出來的條理、秩序，是氣化運行有效性的標識。如果說氣的功能是始物、生物，它負責的是創造；那麼，理的實際作用是終物、成物，它負責的是利導、成就。因此，把存在論範疇奠定在氣的基礎上，能夠保證存在的創生性，存在的創生性是存在的自為性的積極表現。

The differentiation between li 理 (principle) and qi 氣 (ether) is an important thesis by which Wang Fuzhi 王夫之 (i.e. Wang Chuanshan 王船山) argued that reality is the unity of being-in-itself and being-for-itself. According to Wang Fuzhi, qi, whose essence is the interaction between xian 顯 (the visible) and yin 隱 (the invisible), is invisible and beyond our knowledge and ability and makes reality in itself, meanwhile, it is the root of the Heavenly Way. That means the reality is independant of human beings and exists by itself, and we cannot construct it by speculation. Therefore, Wang Fuzhi based all his ontological categories on the concept qi and reduced the authenticity of being­and-existence to that of qi. Wang Fuzhi distinguished the verbal “li,” which means to make something orderly, from the nounal “li,” which means the order, and based the latter on the former. “Li” became the order which inheres in the process of the movement of qi. The function of qi is creating, while the function of li is fulfilling. Thus, when li becomes the foundation of ontological categories, it can guarantee the creativeness of the existence, which is the active manifestation of the being-for-itself of the existence.