Abstract: The concept of "the differential mode of association" was crafted by Fei Xiaotong and became one of the classics in Chinese social theory. In recent years, the concept has been quite thoroughly examined by scholars with a focus on the inner structure of the model, leaving one question largely unanswered. That is how the differential mode of association extends from kinship to "all under the heaven" (tianxia, the universal world). This paper provides an in-depth analysis of Four Scholars by looking into two key concepts of "outsider" and "good man" in the play.During Ming and Qing, the burgeoning economy brought frequent population movements that led to a new category of so-called "outsiders" who were somewhat removed from the conventional social relations and ethical obligation. Upon this category, the concept of "good man" was introduced into the popular vocabulary to distinguish those "outsiders" who seemed to represent a new type of ethical order. Actions of the main characters in Four Scholars were examined to explore the potential as well as the process of transforming an "outsider" into a "good man"-an important process of "extension" in the differential mode of association. Here the "ethical spirit" is also reexamined through the relationship between kinfolks and outsiders.

Key words: the differential mode of association, extension, Four Scholars, outsider, good man