牟宗三（1909-1995）是二十世紀下半葉最重要的中國哲學家之一。雖然牟先生本質上是新儒學思潮的大家，實亦深受佛學思想影響。本文論證牟宗三哲學的本體與現象的兩層存有論範式，亦即執的存有論（attached ontology）與無執的存有論（detached ontology）。牟宗三的二元或兩層存有論，是為了建立道德形上學結構，乃儒家思想之核心假設。當牟宗三執持兩層構造之存有論時，大抵皆立足於其形上學之觀點，即不論是現象還是本質都處理實體。本文從朝倉友海（Tomomi Asakura）的評論出發，剖析兩層存有論之概念，闡明牟宗三原本僅考慮了存有與其現象界及本體界實體上的異同，未曾發展出實體與其存在自身之真正的存有性區別。在他哲學思想發展的晚期，牟宗三注意到此一矛盾，才開始構思基本存有論。

Mou Zongsan (1909-1995) belongs to the most important Chinese philosophers of the second half of the 20th century. In essence he was one of the main proponents of the Modern Confucian intellectual movement, but was simultaneously also heavily influenced by Buddhist thought. The present article describes his paradigm of double ontology, which is divided into the noumenal and phenomenal, or the attached and detached ontology. He points out that this bipolar or twofold ontology is considered to constitute the structure of moral metaphysics, which is a core supposition of Confucian thought. When Mou insists on a twofold structure for ontology, he always holds to his metaphysical standpoint, which deals with entities no matter whether they are phenomenal or noumenal. Based on Tomomi Asakura’s critique, the author analyses Mou's concept of double ontology, shedding light upon the fact that Mou considered only the ontic difference between entities and their two regions, phenomena and noumena, without ever developing the genuine ontological difference between entities and their own being itself. Only in the latest phase of his philosophical development did he start considering this inconsistency, and proceeding towards a model of fundamental ontology.