在《莊子》一書中，「性」字只見於外、雜二篇而不見於內篇。但學人對《莊子》人性論的探討，反而常以內篇為主。他們主張內篇無「性」字而含有人性論的主要理據是：莊子活在人性論辯異常激烈的戰國中後期，不可能沒有對人性問題作過反思。基於此一認定，學人遂想方設法發掘或重構內篇的人性論。本文的目的，即在批判學人詮釋莊子人性論時所採取的方法進路，並分析外雜篇的「性」概念及相關問題。同時，本文亦嘗試對「內篇不言性」或「莊子不建立人性論」的現象提出一融貫解釋。

Even though the term xing in the ”Zhuangzi” appears only in the Outer and Miscellaneous Chapters, scholars, especially those who are interested in Daoist philosophy, have always taken instead the Inner Chapter, in which the term xing had never been used, as the most representative of Zhuangzi's theory of human nature. This is what they have in mind that it is impossible for Zhuangzi, who was an active thinker in the middle and later stages of warring states when there was a fierce debate on human nature, not to reflect on such philosophical issue. Based upon this belief, scholars with various approaches have been exhausting themselves by reconstructing the theory of human nature that has always been said to be implied in the Inner Chapter. In this article, I aim to give a critique on several approaches or methodologies that have been adopted by contemporary writers who are famous for interpreting Zhuangzi's theory of human nature, and to analyze the term xing and some related concepts mentioned in both Outer and Miscellaneous Chapters. I also try to explain why there is no xing occurred in the Inner Chapter (or why Zhuangzi had no interest in establishing a theory of human nature) in a coherent way.