Ijtihad (Arabic: اجتهاد ijtihād, [ʔidʒ.tihaːd]; lit. physical or mental effort, expended in a particular activity) is an Islamic legal term referring to independent reasoning or the thorough exertion of a jurist's mental faculty in finding a solution to a legal question. It is contrasted with taqlid (imitation, conformity to legal precedent). According to classical Sunni theory, ijtihad requires expertise in the Arabic language, theology, revealed texts, and principles of jurisprudence (usul al-fiqh), and is not employed where authentic and authoritative texts (Qur'an and Hadith) are considered unambiguous with regard to the question, or where there is an existing scholarly consensus (ijma). Ijtihad is considered to be a religious duty for those qualified to perform it. An Islamic scholar who is qualified to perform ijtihad is called a mujtahid.
By the beginning of the 10th century, development of Sunni jurisprudence prompted leading Sunni jurists to state that the main legal questions had been addressed and the scope of ijtihad was gradually restricted. In the modern era, this gave rise to a perception among Western scholars and lay Muslim public that the so-called "gate of ijtihad" was closed at the start of the classical era. While recent scholarship has disproved this notion, the extent and mechanisms of legal change in the post-formative period remain a subject of debate.
Starting from the 18th century, some Muslim reformers began calling for abandonment of taqlid and emphasis on ijtihad, which they saw as a return to Islamic origins. Public debates in the Muslim world surrounding ijtihad continue to the present day. The advocacy of ijtihad has been particularly associated with Islamic modernists and purist Salafi thinkers. Among contemporary Muslims in the West there have emerged new visions of ijtihad which emphasize substantive moral values over traditional juridical methodology.
Shia jurists did not use the term ijtihad until the 12th century, but they employed a rational mode of legal reasoning from the early period, and its scope was not narrowed as in the Sunni tradition, with the exception of Zaydi jurisprudence.
Etymology and definition
The word derives from the three-letter Arabic verbal root of ج-ه-د J-H-D (jahada, 'struggle'): the "t" is inserted because the word is a derived stem VIII verb. In its literal meaning, the word refers to effort, physical or mental, expended in a particular activity. In its technical sense, ijtihad can be defined as a "process of legal reasoning and hermeneutics through which the jurist-mujtahid derives or rationalizes law on the basis of the Qur'an and the Sunna".
The juristic meaning of ijtihād has several definitions according to scholars of Islamic legal theory. Some define it as the jurist’s action and activity to reach a solution. Al-Ghazālī (d. 505/1111) defines it as the “total expenditure of effort made by a jurist for the purpose of obtaining the religious rulings.” Similarly the ijtihād is defined as “the effort made by the mujtahid in seeking knowledge of the aḥkām (rulings) of the sharī‘ah (Islamic canonical law) through interpretation.”
From this point of view that ijtihād essentially consists of an inference (istinbāṭ) that extents to a probability (ẓann)[clarification needed]. Thus it excludes the extraction of a ruling from a clear text as well as rulings made without recourse to independent legal reasoning. A knowledgeable person who gives a ruling on the sharī‘ah, but is not able to exercise their judgement in the inference of the rulings from the sources, is not called a mujtahid but rather a muqallid.
Islamic scholar Asghar Ali Engineer cites a hadith related by a sahabi (companion of the Islamic prophet Muhammad) by the name of Muadh ibn Jabal (also Ma’adh bin Jabal), as the basis for ijtihad. According to the hadith from Sunan Abu-Dawud, Book 24, Muadh was appointed by Muhammad to go to Yemen. Before leaving he was asked how he would judge when the occasion of deciding a case arose.
Ma’adh said, according to the Quran. The Prophet thereupon asked what he would do if he did not find the solution to the problem in the Quran, to which Ma’adh said he would govern according to the Sunnah. But when the Prophet asked if he could not find it in the Sunnah also, Ma’adh said "ana ajtahidu" (I will exert myself to find the solution). The Prophet thereupon patted his back and told him he was right.
During the early period, ijtihad referred to the exercise of one's discretionary opinion (ra'y) on the basis of the knowledge of the precedent (‘ilm). Jurists used ra'y to help reach legal rulings, in cases where the Qur'an and Sunna did not provide clear direction for certain decisions. It was the duty of the educated jurists to come to a ruling that would be in the best interest of the Muslim community and promote the public good.
As religious law continued to develop over time, ra'y became insufficient in making sure that fair legal rulings were being derived in keeping with both the Qur'an and Sunna. However, during this time, the meaning and process of ijtihad became more clearly constructed. Ijtihad was “limited to a systematic method of interpreting the law on the basis of authoritative texts, the Quran and Sunna,” and the rulings could be “extended to a new problem as long as the precedent and the new situation shared the same clause.”
As the practice of ijtihad transformed over time, it became religious duty of a mujtahid to conduct legal rulings for the Muslim society. Mujtahid is defined as a Muslim scholar that has met certain requirements including a strong knowledge of the Qur'an, Sunna, and Arabic, as well as a deep understanding of legal theory and the precedent; all of which allows them to be considered fully qualified to practice ijtihad.
Around the beginning of the 10th century, most Sunni jurists argued that all major matters of religious law had been settled, allowing for taqlid (تقليد), "the established legal precedents and traditions," to take priority over ijtihād (اجتهاد).[need quotation to verify] This move away from the practice of ijtihād was made by the Hanafī and Malikī law schools, and the majority of Shafīʿis, but not by Hanbalīs or a number of prominent Shafīʿi jurists who believed that "true consensus" (ijmāʿ اجماع), apart from that of Muhammad's Companions, did not exist" and that "the constant continuous existence of mujtahids (مجتهد) was a theological requirement." After the 11th century, Sunni legal theory developed systems for ranking jurists according to their qualifications for ijtihad. One such ranking placed the founders of maddhabs, who were credited with being "absolute mujtahids" (mujtahid muṭlaq) capable of methodological innovation, at the top, and jurists capable only of taqlīd at the bottom, with mujtahids and those who combined ijtihād and taqlīd given the middle ranks.[Note 1] In the 11th century, jurists required a mufti (jurisconsult) to be a mujtahid; by the middle of the 13th century, however, most scholars considered a muqallid (practitioner of taqlīd) to be qualified for the role. During that era some jurists began to ponder whether practitioners of ijtihad continued to exist and the phrase "closing of the gate of ijtihād" (إغلاق باب الاجتهاد iġlāq bāb al-ijtihād) appeared after the 16th century.[Note 2]
The settling of Sunni law and increasing prominence of taqlid has at one point led most Western scholars to believe that the "gate of ijtihad" was in fact effectively closed around 900 C.E. In a 1964 monograph, which exercised considerable influence on later scholars, Joseph Schacht wrote that "a consensus gradually established itself to the effect that from that time onwards no one could be deemed to have the necessary qualifications for independent reasoning in religious law, and that all future activity would have to be confined to the explanation, application, and, at the most, interpretation of the doctrine as it had been laid down once and for all."[Note 3]
While more recent research has disproved the notion that the practice of ijtihad was abandoned in the 10th century — or even later — the extent of legal change during this period and its mechanisms remain a subject of scholarly debate.
During the turn of the 16th to 17th century, Sunni Muslim reformers began to criticize taqlid, and promoted greater use of ijtihad in legal matters. They claimed that instead of looking solely to previous generations for practices developed by religious scholars, there should be an established doctrine and rule of behavior through the interpretation of original foundational texts of Islam—the Qur'an and Sunna.[need quotation to verify]
Starting in the middle of the 19th century, Islamic modernists such as Sir Sayyid Ahmed Khan, Jamal al-din Al-Afghani, and Muhammad Abduh emerged seeking to revitalize Islam by re-establish and reform Islamic law and its interpretations to accommodate Islam with modern society. They emphasized the use of ijtihad, but in contrast to its original use, they sought to "apply contemporary intellectual methods" such as academic or scientific thought "to the task of reforming Islam". Al-Afghani proposed the new use of ijtihad that he believed would enable Muslims to think critically and apply their own individual interpretations of the innovations of modernity in the context of Islam.
One modernist argument for applying ijtihad to sharia law is that while "the principles and values underlying Sharia (i.e. usul al-fiqh)" are unalterable, human interpretation of sharia is not. Another, (made by Asghar Ali Engineer of India), is that the adaat (customs and traditions) of Arabs were used in the development of the sharia, and form an important part of it. They are very much not divine or immutable, and have no more legal justification to be part of the sharia than the adaat of Muslims living beyond the home of the original Muslim in the Arab Hejaz. The
ummah was no longer a homogenous group but comprised of various cultural communities with their own age-old customs and traditions. ... When Imam Al-Shafi‘i moved from Hejaz to Egypt, which was a confluence of Arab and Coptic cultures, he realised this and changed his position on several issues.
In Indonesia, following considerable debate among the ulema, Indonesian adaat "become part of Sharia as applicable in that country". This use of ijtihad to apply adaat applies to mu’amalat (socio-economic matters such as marriage, divorce, inheritance), rather than Ibadah fiqh (ritual salat, sawm, zakat, etc.). Asghar Ali Engineer argues that while the Arab adaat the Quran was revealed in was "highly patriarchal" and still informs what is understood as sharia, the "transcendental Quranic vision" is for "absolutely equal rights" between genders and should guide ijtihad of sharia.
Islamism and Salafism
Contemporary Salafis are major proponents of ijtihad. They criticize taqlid and believe ijtihad makes modern Islam more authentic and will guide Muslims back to the Golden Age of early Islam. Salafis assert that reliance on taqlid has led to Islam's decline.
The Muslim Brotherhood traces its founding philosophies to al-Afghani's ijtihad. The Muslim Brotherhood holds that the practice of ijtihad will strengthen the faith of believers by compelling them to better familiarize themselves with the Quran and come to their own conclusions about its teachings. But as a political group the Muslim Brotherhood faces a major paradox between ijtihad as a religious matter and as a political one. Ijtihad weakens political unity and promotes pluralism, (which is also why many oppressive regimes reject ijtihad's legitimacy).
Osama Bin Laden supported ijtihad. He criticized the Saudi regime for disallowing the "free believer" and imposing harsh restrictions on successful practice of Islam. Thus, Bin Laden believed his striving for the implementation of ijtihad was his "duty" (takleef).
Qualifications of a mujtahid
A mujtahid (Arabic: مجتهد, "diligent") is an individual who is qualified to exercise ijtihad in the evaluation of Islamic law. The female equivalent is a mujtahida. In general mujtahids must have an extensive knowledge of Arabic, the Qur'an, the Sunnah, and legal theory (Usul al-fiqh). Sunni Islam and Shi'i Islam, due to their divergent beliefs regarding the persistence of divine authority, have different views on ijtihad and the qualifications required to achieve mujtahid. In order to clarify how ijtihad differs in Sunni and Shi'i Islam it is necessary to explore the historical development of this position in both branches.
In the years immediately following Mohammed's death, Sunni Muslims practiced ijtihad because they saw it as an acceptable form of the continuation of sacred instruction. Sunni Muslims, therefore, began to practice ijtihad primarily through the use of personal opinion, or ra'y. As Muslims turned to the Quran and Sunnah to solve their legal issues, they began to recognize that these divine proponents did not deal adequately with certain topics of law. Therefore, Sunni Muslims began to find other ways and sources for ijtihad such as ra'y, which allowed for personal judgment of Islamic law. Sunni Muslims justified this practice of ra'y with a particular hadith, which cites Muhammad's approval of forming an individual sound legal opinion if the Qur'an and Sunnah contain no explicit text regarding that particular issue. Therefore, during the first two and a half centuries of Islam there were no restrictions placed on scholars interested in practicing ijtihad. Beginning in the 9th century, jurists began to make more restrictions on who could practice ijtihad and the kinds of qualifications necessary. Therefore, the practice of ijtihad became limited to a qualified scholar and jurist otherwise known as a mujtahid. Abu'l-Husayn al-Basri provides the earliest and most expansive outline for the qualifications of a mujtahid, they include:
- Enough knowledge of Arabic so that the scholar can read and understand both the Qur'an and the Sunnah.
- Extensive comprehensive knowledge of the Qur'an and the Sunnah. More specifically, the scholar must have a full understanding of the Qur'an's legal contents. In regards to the Sunnah the scholar must understand the specific texts that refer to law and also the incidence of abrogation in the Sunnah.
- Must be able to confirm the consensus (Ijma) of the Companions, the Successors, and the leading Imams and mujtahideen of the past, in order to prevent making decisions that disregard these honored decisions made in the past.
- Should be able to fully understand the objectives of the sharia and be dedicated to the protection of the Five Principles of Islam, which are life, religion, intellect, lineage, and property.
- Be able to distinguish strength and weakness in reasoning, or in other words exercise logic.
- Must be sincere and a good person.
From the declaration of these requirements of mujtahid onwards, legal scholars adopted these characteristics as being standard for anyone looking to practice ijtihad. In order for the reasoning of these mujtahids to be accepted as law multiple mujtahids had to reach ijma. This allowed for mujtahids to openly discuss their particular views and reach a conclusion together. The interaction required by ijma allowed for mujtahids to circulate ideas and eventually merge to create particular Islamic schools of law (madhhabs). This consolidation of mujtahids into particular madhhabs prompted these groups to create their own distinct authoritative rules. These laws reduced issues of legal uncertainty that had been present when multiple mujtahids were working together with one another. However, with this introduction of common laws for each madhhab, legal scholars began to dismiss the practice of independent ijtihad and instead maintained the title of mujtahid only for the founders of the four main schools of Islamic law (Hanafiyya, Malikiyya, Shafiyya, Hanbaliyya). Therefore, from the 12th century onwards jurists could occupy the position of a mujtahid or access ijtihad in only two cases, when distinguishing between the manifest and the obscure views of their particular schools or when they served as "imitators" of mujtahids, expressing the views of the more qualified mujtahids before them. Therefore, the practice of ijtihad was restricted in favor of taqlid.
The Shi'a Muslims understand the process of ijtihad as being the independent effort used to arrive at the rulings of sharia. Following the death of the Prophet and once they had determined the Imam as absent, ijtihad evolved into a practice of applying careful reason in order to uncover the knowledge of what Imams would have done in particular legal situations. The decisions the Imams would have made were explored through the application of the Qur'an, Sunnah, ijma and 'aql (reason). It was not until the end of the eighteenth century that the title of mujtahid became associated with the term faqih or one who is an expert in jurisprudence. From this point on religious courts began to increase in number and the ulama were transformed by Shi'i Islamic authorities into the new producer of ijtihad. In order to produce perceptive mujtahids that could fulfill this important role, principles of Shi'i jurisprudence were developed to provide a foundation for scholarly deduction of Islamic law. Shaykh Murtada Ansari and his successors developed the school of Shi'i law, dividing the legal decisions into four categories of certainty (qat), valid conjecture (zann), doubt (shakk), and erroneous conjecture (wahm). These rules allowed mujtahids to issue adjudications on any subject, that could be derived through this process of ijtihad, demonstrating their great responsibility to the Shi'i community Furthermore, according to Shi'i Islamic Jurisprudence a believer of Islam is either a Mujtahid (one that expresses their own legal reasoning), or a Muqallid (one performing Taqlid of a Mujtahid) and a Muhtat (one who acts with precaution). Most Shi'i Muslims qualify as Muqallid, and therefore are very dependent on the rulings of the Mujtahids. Therefore, the Mujtahids must be well prepared to perform ijtihad, as the community of Muqallid are dependent on their rulings. Not only did Shi'i Muslims require:
- Knowledge of the texts of the Qur'an and Sunnah
- Justice in matters of public and personal life
- Utmost piety
- Understanding of the cases where Shi'i mujtahids reached consensus
- Ability to exercise competence and authority
However, these scholars also depended on further training that could be received in religious centers called Hawza. At these centers they are taught the important subjects and technical knowledge a mujtahid need be proficient in such as:
- Arabic grammar and literature
- Extensive knowledge of the Qur'anic sciences and Hadith
- Science of narrators
- Principle of Jurisprudence
- Comparative Jurisprudence
Therefore, Shi'i mujtahids remain revered throughout the Shi'i Islamic world. The relationship between the mujtahids and muqallids continues to address and solve the contemporary legal issues. Participating in ijtihad, however, has been cautioned by scholars for those not properly educated in interpretation of the Qu'ran. This is narrated by Ali ibn Husayn Zayn al-Abidin, the great grandson of Muhammad, when he cautioned Aban ibn abi-Ayyash, a fellow companion, saying, "Oh brother from 'Abd Qays, if the issue becomes clear to you, then accept it. Otherwise remain silent and defer to Allah because your interpretation from the truth will be as far from the Earth as the sky."
A woman can be a mujtahid and there are dozens who have attained the rank in the modern history of Iran (for instance, Amina Bint al-Majlisi in the Safavid era, Bibi Khanum in the Qajar era, Lady Amin in the Pahlavi era, and Zohreh Sefati during the time of the Islamic Republic). There are diverging opinions as to whether a female mujtahid can be a marjaʻ or not. Zohreh Sefati and some male jurists believe a female mujtahida can become a marja‘, —in other words, they believe that believers perform taqlid (emulation) of a female mujtahid— but many male jurists believe a marjaʻ must be male.
- Biblical Hermeneutics
- Grand Ayatollahs
- Islamic Golden Age
- Liberal movements within Islam
- List of Islamic terms in Arabic
- After the eleventh century, Sunnī legal literature developed rankings of jurists according to their ability to practice ijtihād. One predominant classification credited the founders of the legal schools with the distinction of being absolute mujtahids (mujtahid muṭlaq) who were capable of laying down a methodology of the law and of deriving from it the positive doctrines that were to dominate their respective schools. Accordingly, each legal school represented a different methodology for ijtihād. Next came the mujtahids who operated within each school (mujtahid muntasim or mujtahid fī al-madhhab), who followed the methodology of the school's founder but proffered new solutions for novel legal cases. The lowest rank belonged to the muqallid, the jurist-imitator who merely followed the rulings arrived at by the mujtāhids without understanding the processes by which these rulings were derived. Between the ranks of mujtahids and muqallids there were distinguished other levels of jurists who combined ijtihād with taqlīd. [...] The settling of the major areas of Islamic law gave rise to the perception, prevalent among many modern Western scholars and Sunnī lay Muslims, that jurists had come to a consensus that the so-called "gate of ijtihād" (باب الاجتهاد bāb al-ijtihād) was closed at the beginning of the tenth century. 
- In the eleventh century, jurists defined a jurisconsult as being a mujtahid (i.e., one who has the ability to independently reason; the highest rank of a jurist). By the middle of the thirteenth century, however, it appears that the prerequisites were lowered, and jurisconsults were expected – by most, but not all scholars – to be muqallids (i.e., able to articulate a legal opinion based on the precedents and methodology of a particular legal school; a lower rank than mujtahid).
- The leading European authority on Islamic law in the mid-twentieth century, Joseph Schacht, declared in a phenomenally influential survey that [...] Since the 1990s, a large and growing body of research has demonstrated the continuing creativity and dynamism of Islamic legal thinking in the post-formative period, as well as probed the lively dialectic between legal rulings and social practice. While it is no longer possible to assert that "the door of ijtihad was closed" after the tenth (or, indeed, any other) century, however, there is still lively debate over the extent of legal change and the mechanisms by which it occurred.
- Rabb, Intisar A. (2009). "Ijtihād". In John L. Esposito (ed.). The Oxford Encyclopedia of the Islamic World. Oxford: Oxford University Press.
- John L. Esposito, ed. (2014). "Ijtihad". The Oxford Dictionary of Islam. Oxford: Oxford University Press.
- John L. Esposito, ed. (2014). "Taqlid". The Oxford Dictionary of Islam. Oxford: Oxford University Press.
- Marion Katz (2015). "The Age of Development and Continuity, 12th–15th Centuries CE". The Oxford Handbook of Islamic Law. Oxford University Press.
- Hallaq, Wael (2005). The Origins and Evolution of Islamic Law. Cambridge University Press.
- Kayadibi, Saim (2017). Principles of Islamic Law and the Methods of Interpretation of the Texts (Uṣūl al-Fiqh). Kuala Lumpur: Islamic Book Trust. p. 349. ISBN 978-967-0526-33-1.
- Kayadibi, Saim (2017). Principles of Islamic Law and the Methods of Interpretation of the Texts (Uṣūl al-Fiqh). Kuala Lumpur: Islamic Book Trust. p. 350. ISBN 978-967-0526-33-1.
- "The Office of the Judge (Kitab Al-Aqdiyah). Book 24, Number 3585". University of Southern California. Center for Muslim-Jewish Engagement. Retrieved 28 September 2016.
- ALI ENGINEER, ASGHAR (1 February 2013). "Is Sharia immutable?". Dawn. Retrieved 27 September 2016.
- see also: Hannan, Shah Abdul. "Islamic Jurisprudence (Usul Al Fiqh): Ijtihad". Muslim tents. Retrieved 27 September 2016.
- Esposito, John. "Ijtihad". The Islamic World: Past and Present. Oxford Islamic Studies Online.
- Esposito, John. "Ijtihad". The Islamic World: Past and Present. Oxford Islamic Studies Online. Retrieved April 28, 2013.
- DeLong-Bas, Natana J. (2004). Wahhabi Islam: From Revival and Reform to Global Jihad (First ed.). Oxford University Press, USA. p. 106. ISBN 0-19-516991-3.
- Intisar A. Rabb (2009). "Ijtihād". The Oxford Encyclopedia of the Islamic World. Oxford University Press.
- Lapidus, Ira M. (2014). A History of Islamic Societies. Cambridge University Press. p. 218. ISBN 978-0-521-51430-9.
- Schacht, Joseph (1964). An Introduction to Islamic Law. Clarendon Press. pp. 70–71.
- Wael B. Hallaq, "On the origin of the Controversy about the Existence of Mutahids and the Gate of Ijtihad," Studia Islamica, 63 (1986): 129
- Esposito, John. "Ijtihad". The Islamic World: Past and Present. Oxford Islamic Studies Online. Retrieved April 28, 2013.[permanent dead link]
- "Ijtihad: Reinterpreting Islamic Principles for the 21st Century" (PDF). United States Institute of Peace Special Report. United States Institute of Peace. Retrieved May 3, 2013.
- "Voices of a New Ijtihad". Center for Dialogues. NYU. Archived from the original on 2016-01-05. Retrieved May 2, 2013.
- Hussain, Tanveer (16 November 2013). "Immutability of the Islamic Laws". quranicteachings.org. Retrieved 12 April 2018.
- Ungureanu, Daniel. "Wahabism, Salafism, and the Expansion of Islamic Fundamentalist Ideology" (PDF). Ai.I.Cuza University of Iasi. Retrieved May 2, 2013.
- Indira Falk Gesnik (June 2003). ""Chaos on the Earth": Subjective Truths versus Communal Unity in Islamic Law and the Rise of Militant Islam". The American Historical Review. Oxford University Press. 108 (3): 710–733. doi:10.1086/529594. JSTOR 10.1086/529594.
- "Mujtahid". The Oxford Dictionary of Islam. Retrieved 1 May 2013.
- El Shamsy, Ahmed. "Ijtihad bi al-Ray". The Oxford Encyclopedia of the Islamic World. Oxford Islamic Studies Online. Retrieved 1 May 2013.
- Kamali, Mohammad Hashim (1991). Principles of Islamic Jurisprudence. Cambridge: Islamic Texts Society. p. 389. ISBN 0946621241.
- Kamali, Mohammad Hashim (1991). Principles of Islamic Jurisprudence. Cambridge: Islamic Texts Society. pp. 374–377.
- Momen, Moojan (1985). An Introduction to Shi'i Islam: The History and Doctrines of Twelver Shi'ism. New Haven: Yale University Press. p. 186.
- Mutahhari, Murtada. "The Principle of Ijtihad in Islam". Retrieved 1 May 2013.
- Mutahhari, Murtada. "The Principles of Ijtihad in Islam". Retrieved 1 May 2013.
- al-Kulayni, Muhammad ibn Ya‘qub (2015). Al-Kafi (Volume 6 ed.). NY: Islamic Seminary Incorporated. ISBN 9780991430864.
- See: Mirjam Künkler and Roja Fazaeli, “The Life of Two Mujtahidas: Female Religious Authority in 20th Century Iran”, in Women, Leadership and Mosques: Changes in Contemporary Islamic Authority, ed. Masooda Bano and Hilary Kalmbach (Brill Publishers, 2012), 127-160. SSRN 1884209
Books, articles, etc.
- Wael Hallaq: “Was the Gate of Ijtihad Closed?”, International Journal of Middle East Studies, 16, 1 (1984), 3–41.
- Glassé, Cyril, The Concise Encyclopaedia of Islam, 2nd Edition, Stacey International, London (1991) ISBN 0-905743-65-2
- Goldziher, Ignaz (translated by A And R Hamori), Introduction to Islamic Theology and Law, Princeton University Press, Princeton New Jersey (1981) ISBN 0-691-10099-3
- Kamali, Mohammad Hashim Principles of Islamic Jurisprudence, Islamic Texts Society, Cambridge (1991) ISBN 0-946621-24-1.
- Carlos Martínez, “Limiting the Power of Religion from Within: Probabilism and Ishtihad,” in Religion and Its Other: Secular and Sacral Concepts and Practices in Interaction. Edited by Heike Bock, Jörg Feuchter, and Michi Knecht (Frankfurt/M., Campus Verlag, 2008).