Zongfa(宗法) is an system aimed to unite many kindred groups in a way that the eldest centered. It examine an order of the kindred. Since the age of Chunqiu-Zhanguo(春秋戰國), Zongfa had ceased as a result of the replacement of Fengjian(封建).
Wan Si-tai found the distinction between primary line(Daizong:大宗) and minor lines(Xiaozong:小宗) in the difference of each status. He also argued that the distinction between Daizong and Xiaozong would come out since five generations passed. Wan Si-tai recognized the difficulty of the revival of Zongfa, but he presented Fengjian as a solution. And he emphasized the recovery of the mind of Guli(古禮) in Jingdian(經典).
Mao Chi-ling said that the reason of the shape of Zongfa was the discontinuation of Zhuhou(諸侯) and his brothers in kinsfolk. Because of the value of identification, the main line of descent was very important. Meanwhile, he explained Xing(姓), Shi(氏), and Zu(族). According to his theory, Xing separated into Shi, and Shi separated into Zu again. Eventually, Shi and Zu mean Daijong and Xiaozong.
To explain Zongfa, Wan Si-tai took notice of the union. He was unbound to the union of kindred in that time. And he took a serious view of Jingxue, so he emphasized the recovery of Guli and Jingdian and the importance of Fengjian at once.
Mao Chi-ling criticized Wan Si-tai's theories, for example, the interpretation of Biezi(別子), the level explanation of Daizong and Xiaozong, and the understanding of Zong(宗) with generation. His interpretation about words and phrases is clearer than Wan Si-tai's. And he concentrated on many examples in Jingdian. So Mao Chi-ling's theory of Zongfa has stronger color of Kaojuxue(考證學) than Wan Si-tai's.