This paper probes the elements of theoretical necessity, starting with the word ruo (若) in Duan Yucai’s Shuo Wen Jie Zi Zhu (段玉裁《說文解字註》). From the prospective of theoretical methods of “Ruo (若) ,” the theoretical necessity of “Ruo (若) ,” the exegesis functions of “Ruo (若) ” and different intonations with different modal particles, the author conducted multi-level and multi-dimensional analysis on “Ruo (若) ” in Duan Yucai’s Shuo Wen Jie Zi Zhu (段玉裁《說文解 字註》) so as to explore the concepts of theoretical necessity from Duan Yucai.

本文從段玉裁《說文解字注》中的“若”字入手，探究理論必要性的要素。從 “若”的理論方法、“若” 的理論必要性、“若”的訓詁功能以及不同語氣詞的不同語氣等方 面進行了多層次、多角度的研究、筆者對段玉裁《說文解字注》中的“若”進行了多層 次、多角度的分析，以探討段玉裁的理論必要性概念。

Abstract
1. Introduction
2. Grammaticalization and Theoretical Necessity of Ruo (若)
3. The Theoretical Necessity of the Deductively Directional StructureRuo (若)…ze (則)… (If… then…)
4. The Theoretical Necessity of Ruo (若) in the Annotation of DuanYucai’s Shuo Wen Jie Zi Zhu: A Different Prospective
    4.1. Logical Methods Using Ruo (若)
    4.2. The Symbols of Theoretical Necessity in Usage of Rz(若)
    4.3. The Theoretical Necessity of Ruo (若) in Exegetical Functions
    4.4. The Theoretical Necessity of Ruo (若) in Different Parts of Speech
    4.5. The Theoretical Necessity of Ruo (若) in Collocation with Modal Particles
5. The Value and Influence of Duan Yucai’s Shuo Wen Jie Zi Zhu fromthe Perspective Ruo (若) Usage
6. Conclusion
References
中文摘要

• De-yi WANG(Tianjin University; Shenyang City University, China) | 王德毅