面對唐宋社會轉折所帶來的佛教合法性危機，宋代佛教思想家對自身傳統有一反思性調整。在將《起信論》「真如隨緣」思維進一步納入到天臺性具體系後，宋代天臺以「理毒性惡」的形式對天臺傳統「性惡」論予以新的表達。由於對此命題的理解存有分歧，天臺內部的論辯極為激烈。山外派孤山智圓承認性惡法門，但堅持理毒乃理體隨緣而成，不是本具，故理毒非是性惡。山家派四明知禮則基於別理隨緣說，以為理毒乃是理體本具之毒害，故理毒即是性惡。理毒性惡之爭體現了天臺宗傳統性惡論範式在宋代的轉向，指向了天臺宗人對懺法實踐的不同理解。

Faced with the challenge of process of social secularization in song Dynasty, Buddhist thinkers tried to adjust the teachings of Buddhism to protect the legal status of Buddhism.By integrating the theory of Tathatã pratityasamutpada in Mahãyãna-šraddhotpãda-sãstra into Tiantai “nature inclusion” (xingju) thought, the theory of “inherent evil” was expressed by means of “The Poison of Principle is the Evil Inherent in the Buddha-Nature” by Tiantai monks in Song Dynasty.Zhili, the master of Shan-Jia party sticked to the new proposition which was contradicted by Zhiyuan, a famous monk of Shan-wai party. The intense debate not only reflected the turn of Paradigm of “Inherent Evil” theory of Tian-Tai in Song Dynasty, but also pointed out Tiantai monks’ different attitudes to Buddhist ritual.