ʾUṣūl al-fiqh (Arabic: أصول الفقه, lit. roots of fiqh) or Principles of Islamic jurisprudence are traditional methodological principles used in Islamic jurisprudence (fiqh) for deriving the rulings of Islamic law (sharia).Traditional theory of Islamic jurisprudence elaborates how the scriptures (Quran and hadith) should be interpreted from the standpoint of linguistics and rhetoric. It also comprises methods for establishing authenticity of hadith and for determining when the legal force of a scriptural passage is abrogated by a passage revealed at a later date. In addition to the Quran and hadith, the classical theory of Sunni jurisprudence recognizes secondary sources of law: juristic consensus (ijmaʿ) and analogical reasoning (qiyas). It therefore studies the application and limits of analogy, as well as the value and limits of consensus, along with other methodological principles, some of which are accepted by only certain legal schools (madhhabs). This interpretive apparatus is brought together under the rubric of ijtihad, which refers to a jurist's exertion in an attempt to arrive at a ruling on a particular question. The theory of Twelver Shia jurisprudence parallels that of Sunni schools with some differences, such as recognition of reason (ʿaql) as a source of law in place of qiyas and extension of the notions of hadith and sunnah to include traditions of the imams. Source: Wikipedia (en)