本文比較當代新儒家（以唐君毅、牟宗三為例）與英語哲學界（以黃百銳、信廣來為例）對孟子之「端」（「仁之端也」之「端」）及「擴充」（「擴而充之」）的詮釋。（1）孟子之「端」乃牽連著「擴充」而言；牟宗三以「一處惻隱，處處惻隱」釋「擴充」。至於「擴充」的具體操作程序，黃百銳則有仔細剖析，足可補充新儒家之說。（2）然而，兩陣營於根本處卻有一不能調和的分歧：新儒家將孟子的人性論理解為一種「人性兩層論」—心之官為一層，耳目口鼻之官為一層，而英語學者在詮釋孟子之「端」及「擴充」時則不預設此種人性論解釋。（3）本文將論證，由於「人性兩層論」的詮釋更符合孟子文本，而在新儒家兩代表之中，牟宗三又比唐君毅更能貫徹此詮釋立場，故其對「端」與「擴充」的詮釋於四家之中應最為妥善。

This paper aims at comparing the different interpretations of Mencius's ＂duan＂ (＂the heart of compassion is the duan of benevolence＂) and ＂extension＂. We will examine two Contemporary New Confucians, Tang Chun-I and Mou Zhongsan, and two English academic world scholars, David B. Wong and Kwong-loi Shun. Mou understands ＂extension＂ as ＂revealing one's heart of compassion from right here to everywhere＂. Yet he doesn't provide a detailed explanation of this process. Wong's theory is far more detailed in this aspect and can be seen as a supplement to Mou's theory. However, we cannot ignore the deep difference between the two. While Mou and Tang understand Mencius's theory of human nature involves a two-level human nature, Wong and Shun's interpretation does not presuppose this. We will argue, the ＂two-level theory＂ is a better interpretation of the text and Mou's interpretation is far more consistent than Tang. Hence, Mou's interpretation of ＂duan＂ and ＂extension＂ is probably the best among the four.