Usulis (, ) are the majority Twelver Shi'a Muslim group. They differ from their now much smaller rival Akhbari group in favoring the use of ijtihad (i.e., reasoning) in the creation of new rules of fiqh; in assessing hadith to exclude traditions they believe unreliable; and in considering it obligatory to obey a mujtahid when seeking to determine Islamically correct behavior. Since the crushing of the Akhbaris in the late 18th century, it has been the dominant school of Twelver Shi'a and now forms an overwhelming majority within the Twelver Shia denomination. The name Usuli derives from the term Uṣūl al-fiqh (principles of jurisprudence). In Usuli thought, there are four valid sources of law: the Quran, hadith, ijma' and 'aql. Ijma' refers to a unanimous consensus. Aql, in Shia jurisprudence, is applied to four practical principles which are applied when other religious proofs are not applicable: bara'at (immunity), ihtiyat (recommended precautions), takhyir (selection), and istishab (the presumption of continuity in the previous state). The term Usuli is also sometimes used to refer more generally to students of usul especially among early Muslims, without regard to Shia Islam. Students/scholars of the principles of fiqh are distinguished from scholars of fiqh itself, whose scholars are known as faqīh (plural fuqahā'''). Background The Usuli believe that the Hadith collections contained traditions of varying degrees of reliability, and that critical analysis was necessary to assess their authority. In contrast, the Akhbari believe that the sole sources of law are the Qur'an and the Hadith, in particular the Four Books accepted by the Shia: everything in these sources is in principle reliable, and outside them, there was no authority competent to enact or deduce further legal rules. In addition to assessing the reliability of the Hadith, Usuli believes the task of the legal scholar is to establish intellectual principles of general application (Usul al-fiqh), from which particular rules may be derived by way of deduction. Accordingly, Usuli legal scholarship has the tools in principle for resolving new situations that are not already addressed in Quran or Hadith (see Ijtihad). Taqlid An important tenet of Usuli doctrine is Taqlid or "imitation", i.e. the acceptance of a religious ruling in matters of worship and personal affairs from someone regarded as a higher religious authority (e.g. an 'ālim) without necessarily asking for the technical proof. These higher religious authorities can be known as a "source of imitation" (Arabic