Tusi argues that qiyas is not a religious proof and that rational deduction should be preferred over qiyas. He emphasizes that qiyas expresses assumptions and causes contradictions, and therefore, it should not be accepted as evidence in religious rulings. Tusi asserts that qiyas cannot be a valid proof and that religious rulings should be based on clear textual evidence. In this context, he discusses the arguments of both those who accept qiyas and those who reject it, stating that qiyas, being based on assumptions and probabilities, can lead to erroneous conclusions. He also argues that some verses cited as evidence for the validity of qiyas cannot be considered as proof, and that there are strong evidences showing that the use of qiyas is impermissible. Tusi critiques the narrations and opinions relied upon by the proponents of qiyas and asserts that applying qiyas solely based on the apparent meaning of the nass is incorrect. Over time, the stance of the Jafari school on qiyas weakened, and through scholars such as Muhaqqiq al-Hilli and Ibn al-Mutahhar al-Hilli, it evolved into a concept of ijtihad parallel to that of other schools. The article also evaluates the reasons for rejecting qiyas, especially the attitudes of the Imamiya and other schools toward qiyas, and presents the critiques that Tusi raised on this matter. It discusses how qiyas was debated among the Companions and Mujtahids in the past, with examples provided.