Four levels of the Twofold Truth in the East Asian Yogācāra School

Truth is one of the central subjects not only in philosophy but also in religions. In this paper, I would like to examine the theory of twofold truth, one of the representative theories in the Mahāyāna Buddhism, especially focusing on the interpretation of Zenju 善珠 (732-797), an eminent scholar monk of the Japanese Yogācāra (Hossō) school in the Nara period. Based on Ji 基 (632-682) and Woncheuk 圓測 (613-696), Zenju explains four levels of the twofold truth which classifies the twofold truth (the conventional truth and the ultimate truth) under four levels respectively. He states that both verbal conventions and realities are the foundation of the truths (satya), and those eightfold truth forms a mutually linked system. The theory of four levels of the twofold truth also plays an important role in hetuvidyā or Buddhist logic. Zenju states that the restriction of the proof of vijñaptimātratā, zhengu 眞故 or “in the ultimate truth,” corresponds to the first three of four levels of the ultimate truth: the conventional ultimate truth, the ultimate truth based on real principles, and the ultimate truth based on realization. In verbal communication or debate with logical expressions, Zenju allows plural truths corresponding to opponents, including those of religions or thoughts other than Buddhism.