Tusi had an important role in the formation and revival of Shia jurisprudence and law, as his life coincided with the burning of books and libraries. It is even said that he revived
hadith and Islamic jurisprudence. He defended the application of jurisprudence in respect to religious laws. One of his main accomplishments was that he was successful in propagation and making his methodology of argumentation and inference coherent: he had given to Shaykh Mufid a definite formulation of
ijtihad. His dominance was unrivaled for a long time and nearly all Islamic jurisprudence was affected by Tusi's opinions. Some of Tusi's works show that he was influenced by precedent jurists like
Sallar Deylami. Tusi's influence persisted until Ibn Idris al-Hilli, who criticized some of Tusi's views. He also produced biographies (
ilm-rijal), traditions, and compendia of knowledge (
Fihrist). He started developments that allowed Shia clerics to assume some of the roles previously permitted to only imams, such as collecting and distributing religious taxes, and organizing Friday prayers.
Usuli School In conflict between the
Akhbari and
Usuli schools, Tusi defended the Usuli and claimed that the rival Akhbari were literalists. and wrote in the introduction to one of his works: He compared the positions of the different legal schools of Islam and showed that there is little difference between them. Tusi, like his masters, refuted the legal analogy (
Qiyyas Fiqhi) in his manual of
Usul Fiqh.
Importance of reason His emphasis was on the rational dimension of religion, underlining that principles like the commandment to good and prohibition of evil are indispensable according to reason. Shaykh Tusi also used rational arguments to validate consensus (
ijma) as derived from the principle of
lutf. According to
lutf, God must provide believers with the conditions for religious obedience. ==Najaf Seminary==