Muhammad bin Idris Al-Shafi'i (d. 204AH) is reputed to be the one who delineated the principles of deduction (usul al-istinbat) and regulated it with general comprehensive principles. Thus, he was the originator of the science of usul al-fiqh (principles of jurisprudence), even though many people came after him who were more knowledgeable about usul al-fiqh and its definitions. The Fuqaha (jurists) before al-Shafi'i used to perform ijtihad without having defined parameters for ijtihad. Rather, they used to depend on their understanding of the Shari'a meanings and purpose of the ahkam, their aims, whatever its texts point to and whatever its objectives (maqasid) indicated. Due to the experience of those Fuqaha (jurists) in their study of the Shari'a and their thorough familiarity with the Arabic language, this has caused them to be acquainted with their meanings, to comprehend their aims (ghayat) and objectives (maqasid). They used to reconcile its concepts and objectives in deducing rules from the texts without having any recorded defined parameters.
Yes, the Fuqaha before al-Shafi'i, from the time of Sahaba, Tabi'un and those after them, used to deal with issues of usul al-fiqh and educe and oppose (evidences). Such as the narration about 'Ali b' Abi Talib (r.a.) that he spoke about the mutlaq (absolute), muqayyad (restricted), khas (specific), 'amm (general), abrogator (nasikh) and the abrogated (mansukh). However, that was not in a defined, set out manner. And those Fuqaha who dealt with certain issues of usul al-fiqh did not possess general and comprehensive principles to which they referred in order to understand the indication of the Shari'a or to know how to oppose or outweigh them. But when al-Shafi'i came, he derived the science of usul al-fiqh. And he laid down comprehensive laws to which reference is made in knowing the levels of the Shari'a evidences. It has become widely known to people that al-Shafi'i set out the science of usul in his book entitled al-Risala, a work which is famous. But the reality is that the al-Risala contains only a part of the science of usul outlined by al-Shafi'i. Anyone who examines the books of al-Shafi'i will find that al-Risala contains only some of the topics in the science of usul al-fiqh, but it does not contain all of al-Shafi'i's discussion in usul. Al-Shafi'i has other books which contain discussions (on usul), such as the book of ‘The refutation of Istihsan’ (Ibtaal ul Istihsaan) and the book Jamma' al-'ilm. Even the book al-Umm within its pages there are discussion on the science of usul. In these he has mentioned comprehensive principles amidst the detailed rules.
What helped al-Shafi'i to lay down the science of usul was that he came at a time when Islamic jurisprudence had started to greatly flourish. In the Islamic lands juristic groups of mujtahidin began to take shape and they began to form into mazhabs (schools). The debate between the Mujtahidin and the proponents of mazahibs took various perspectives in fiqh and the evidences. So he plunged into debates with those who engaged in the debate, these discussions were what guided him to think about general and comprehensive principles, as regulatory criterions which should be the basis of study and inference. He brought together these principles as one body of knowledge which was the science of usul al-fiqh. The impressive thing about the usul of al-Shafi'i is that he proceeds, in the discussion of usul, in a legislative and not in a logical manner. Because, one of the greatest dangers for study and for the Ummah's revival especially in fiqh and usul, is the path of logic. Al-Shafi'i clearly distanced himself from the course of logic and adhered to the legislative course. He was not interested in theoretical methods or suppositions. He wanted to regulate real and existing issues i.e. he took the Shari'a texts and stopped at the limit of the text and at the limit of the reality which the text indicated and the people themselves witnessed. Regarding the issue of abrogation (nasikh wal mansukh), he established the principles of abrogation from the issues which, for him had been proven to contain abrogation’s, taken from what has been mentioned in the ayah or hadith itself, or from the indication (dilala) of abrogation, or what has been narrated about the Messenger (saw) in terms of hadith which indicate abrogation, or whatever has been reported about the Companions of the Messenger of Allah in terms of reports and judgements. Not like many who came after him, when they saw a contradiction between two verses or hadiths, they immediately moved to say that one has abrogated the other. To the point they ended up making terrible errors. When al-Shafi'i came with a principle he did not bring it from a logical premise (muqaddima mantiqiyya), rather he showed you the sources from which he took it. Either from a report about the Prophet (saw) or from legal verdicts (fatwas) of the Sahaba. His approach in extracting regulatory (qawa'd dabita) principles was a practical one, in which he relied on the reality, the evidences, and on the application of those things on tangible facts.
The most prominent aspect by which Shafi'is usul is distinguished, is that it contains general principles for the deduction (istinbat) of rules, regardless of what his specific methodology was. Rather, his usul is suitable for any methodology however different they may be. Thus, it is a measure by which one can know which opinions are correct and which are not correct. It is a comprehensive law which must be adhered to when deducing new rules, whatever methodology a person may set himself, in order to measure opinions and regulate the inference of rules by a comprehensive law. The usul of al-Shafi'i was not intended to be an usul for his mazhab (school) only, even though the mazhab adhered to it. It was not written to defend his mazhab and clarify its viewpoint. Rather, it contains general and comprehensive principles for istinbat (inference). The motive was not to tend towards a particular mazhab but rather it was a desire to regulate the procedures of ijtihad and put in place limits and guidelines for the mujtahidin. He was sincere in his intentions and he had the correct understanding when devising the science of usul al-fiqh, thereby influencing, without exception, those mujtahidin and Ulama that came after al-Shafi'i, whether they opposed or supported his opinions. Until, despite their different tendencies, they saw themselves proceeding according to the path al-Shafi'i had taken, in terms of setting out comprehensive principles (qawa'id kulliyya) and proceeding in fiqh and istinbat (inference) in a regulated manner according to comprehensive laws and general principles. Fiqh (Islamic jurisprudence) after him came to be based on established foundations not as an assortment of fatwas and individual judgements (aqdiya) as was the case before him.
Even though all of the 'Ulama proceed in the footsteps of al-Shafi'i in terms of the notion of usul al-fiqh, however the way in which they received what al-Shafi' had arrived at was different according to their different juristic approaches. There were those who followed his opinions and began to explain and expand on them and disagree with them. And they are like the followers of al-Shafi'i himself. There were those who took the major part of what al-Shafi'i had brought despite their disagreement with certain details of usul and but not the actual body of usul. Since they had no disagreements in terms of the body, framework and course of al-Shafi'is usul, like the Hanafis and those who followed their method. And there were those who disagreed with al-Shafi'i in this usul, like the Zahiris and Shi'a. Those who followed al-Shafi'i in his opinions were: the Hanbalis. They adopted the usul of al-Shafi'i even though they said the only (recognised) ijma' (consensus) is that of the Sahaba. The Malikis who came after al-Shafi'i combined their methodology with much of what was in al-Shafi'is usul though they took the practise of the people of Madina as proof and differed with him in certain details. As for those who proceeded according to his method and embraced his opinions. They are the followers of his mazhab, who were very active in the science of usul al-fiqh and wrote prolifically about the subject. Books were written according to the methodology of al-Shafi'i in usul al-fiqh which were, and still are, the pillars and support of this science. Of the most important three books that are known to be written by the old scholars: First, the book al-Mutamad of Abu al-Husayn Muhammad b. al-Basri (d.413 A.H.). Second, the book al-Burhan of 'Abd al-Malik b.'Abd Allah al-Juwayni commonly known as Imam al-Haramayn (d.478 A.H.). And third, the book al-Mustasfa of Abu Hamid al-Ghazali (d.505 A.H.). After them came Abu al-Husayn 'Ali otherwise known as al-Amidi (d. 631 A.H.), he brought together all three books and expanded on it in his book al-ihkam fi usul al-ahkam. It is one of the most important works written in usul al-fiqh. As for those who adopted the major part of what al-Shafi'i brought and differed in some of the details, they are the Hanafis. That is because their method of istinbat (inference) agreed with the usul of al-Shafi'i, though the way in which they approached the science of usul was influenced by the furu' (branches of fiqh). They studied the principles of usul in order to support the furu'. So they made the furu' the basis. The general principles were based on it and made to support it. Perhaps what pushed them towards this approach was that their study of usul was for the purpose of supporting their mazhab and not in order to produce principles according to which their school should deduce rules. That is because Abu Hanifa, who had preceded al-Shafi'i, died the year in which al-Shafi'i was born. And his inferences were not according to general and comprehensive principles. Likewise after him came his students Abu Yusuf, Muhammad b. al-Hasan al-Shaybani and Zufar. They did not concern themselves with writing about usul al-fiqh but it fell to the scholars of the Hanafi mazhab afterwards to pursue the inference of principles which would serve the furu' of the Hanafi mazhab. The principles came later than the furu' and did not precede it. Nevertheless, the Hanafi usul, on the whole, has been extracted from the usul of al-Shafi'i. And what they differed on with the Shafi'is in terms of the 'amm (general) being qat'i (definite) like the khas (specific), and the consideration is not for the understanding of the condition (shart) and description (wasf), and that there is no tarjeeh (outweighing) due to the great number of transmitters. They are detailed issues and not comprehensive principles. That is why it is possible to consider the Hanafi and Shafi'i usuls as one usul for fiqh. Its approach towards the furu' and disagreements in certain details is not another usul but they are one usul in its comprehensiveness, generality and principles. You hardly ever see any difference between a book in shafi'i usul and a book in Hanafi usul. Rather, all of them are a study of the same principles (usul) of al-fiqh. One of the most important books of usul for the Hanafis is the usul al-Bazdawi compiled by Fakhr al-Islam 'Ali b. Muhammad al-Bazdawi (d.483 A.H.)
As for those who disagreed with al-Shafi'i in usul, they are the Zahiris and Shi'a. They disagreed with al-Shafi'is usul in some of its basic elements and not just in the details. As for the Zahiris, they rejected Qiyas (analogical deduction) completely and depended solely on the apparent (zahir) (meaning) of the texts. Even what is termed as the qiyas jali (clear analogy), they did not consider it as a part of Qiyas but as text. Their consideration of the text is nothing other than a consideration of the apparent (zahir) (meaning) of the text. The imam of this mazhab is Abu Sulayman Dawud b. Khalaf al-Isfahani (d.270 A.H.) He was from the Shafi'iyya. He learnt fiqh from the students of al-Shafi'i. Then he left the mazhab of al-Shafi'i and chose a special mazhab for himself where he would only rely on the text. It is called the Zahiri mazhab (literalists), Ibn Hazm is one of the most well known scholars from amongst them. Certain people made him popular and gave a glowing description about him until people became interested in his books even though they were below the level of the books of fiqh and other usuls in terms of the jurisprudential discussion and angle of educing evidences.
As for the Shi'a, they disagreed with al-Shafi'is usul in a significant way, for they made the sayings of their imams a Shari'a daleel like the Kitab and Sunnah. For them it is considered a proof which follows the proof of the Kitab and that of the Sunnah at the very least. They permitted the speech of the imams to specify the Sunnah. They say: 'The wisdom (hikma) of legislation demands the exposition of a body of ahkam and requires the concealment of a body of ahkam. But he (Allah's peace be upon him) entrusted (the body of ahkam that is concealed) to his guardians (awsiya). Each guardian (wasi) delegates the other to spread it when it is appropriate for him, according to Hikma (wisdom), in terms of an 'amm (general) which is specified (mukhassas), a mutlaq (absolute) which is restricted (muqayyad) or a mujmal (ambivalent) which is clarified (mubayyan). So the Prophet (saw) may mention something which is 'amm (general) and mentions the specific after a while in his life. Or, he may not mention it originally, rather leaving his guardian (wasi) to do it on his behalf.' The Imami Shi'as place their imams in a position close to the Sunnah. Ijtihad for them is restricted to the mazhab. It is not permitted for the mujtahid to contradict the views of the mazhab i.e. it is not permitted for the mujtahid to make ijtihad with what contradicts the sayings of the Imam al-Sadiq. They rejected hadiths except if it came via their imams. They do not take Qiyas. It has been recurrently reported (tawatara) about their imams, as they have narrated in their books, that when analogy is made to the Shari'a the deen is destroyed.
This is the situation of the course of Muslim Ulama in the science of usul al-fiqh after al-Shafi'i in terms of their agreement or opposition to him. As for the science itself, after al-Shafi'i, it was discussed at great length and it had many commentators and writers. It is strange that in the ages that followed the age al-Shafi'i, ijtihad diminished and there was a scarcity of mujtahidin. And in the ages that followed that age, the door of ijtihad was closed. However, the science of usul al-fiqh thrived and flourished, the study of its principles increased and its issues became more elaborate. But all of this was from a theoretical and not practical perspective. As a result, it was ineffective in creating mujtahidin and breaking the notion of the closing of the door of ijtihad and bringing it to an end. Perhaps the reason for that is that usul al-fiqh, during those later periods, took a purely theoretical approach, where the theoretical discussion prevailed, and studies were inserted into it that had no relationship to usul al-fiqh. The attention of researchers was directed to examining and revising the principles, supporting them with evidences, and selecting the one with the strongest evidence regardless of whether there was a reality for it or not. Their theoretical assumptions multiplied and they studied the concept of dalala (textual implications) and classified it according to the classifications of the scholars of mantiq (logic). They raised discussions which had nothing to do with usul al-fiqh like husn (pretty) and qubh (ugly), or are they rational or legal? Or discussion such as; is thanking (shukr) the benefactor (mun'im) an obligation due to the Shari'a or the mind. They initiated studies that were from the science of Kalam (theology) and not from usul al-fiqh. Such as the infallibility of the Prophets, permissibility of the Prophets to make mistakes or forget in issues relating to (conveying) the Message. They made studies relating to the Arabic language and not to usul al-fiqh. The studied the origin of languages and studied particles (huruf) and nouns (asma). In that manner they made the science of usul al-fiqh rigid and transformed it from its legislative aspect, which produced mujtahidin and enriched fiqh, into a theoretical and philosophical study in which the scholar is unable to deduce the simplest of rules. Until, its usefulness was almost lost and it had not effect in legislation or deduction of rules (istinbat). And since the science of usul al-fiqh is indispensable, in relation to the deduction of rules and the growth of the legislative aspect. That is why it is essential to attend to the study of usul al-fiqh as a study which is based on reality and not theoretical. It is enough to undertake studies that relate to the deduction of rules, which are studied accompanied by evidences indicating the rules, and realities which apply to their meanings until mujtahidin are produced and a legislative wealth is generated to treat new issues which come up each day, in the Muslim world and in the rest of the world.
Besides the aforementioned some of the other books written on the science of Usul ul Fiqh include:
• al-Usul by Imam Abu-al-Hasan al-Karkhi (died 340 AH)
• al-Usul by Imam Ahmad bin Ali known as Al-Jassas (died 370 A.H.)
• al-Usul by Imam Ubaid Allah bin Umar the Judge Abu-Zayd Al-Daboosi (from the areas of Samarqand in today's Uzbekistan he died 430 A.H.)
• al-Usul by Shams al-A'ima Abu-Bakr Muhammad bin Ahmad bin Abi Sahl Al-Sarkhasi (died 483 A.H.)
• al-Mahsul by Imam Fakhr ul-Deen Al-Razi Al-Shafi'(died 606 AH)
• al-Mukhtasar which summarised Muntaha al-Sa'ul wa al-Amal fi ilmay al-Usul wa al-Jadal which was summarised from Al-Aamidi's Ahkam by Imam Abu-'Amr Uthman bin Umar, known as Ibn-Hajib al-Maliki (died 646 AH)
• al-Minhaj by Imam Baydawi al-Shafi'(died 685 AH)
• al-Manar by Imam Abdullah bin Ahmad Al-Nasafi (died 710 A.H.)
• Badi'al-Nitham that gathered between the books of Bazdawi and al-Ahkam, by Imaam Muthafar al-Deen Ahmad bin Ali Al-Baghdadi Al-Hanafi
• Tanqih al-Usul Imam Sadr al-Shariah,Ubaid Allah bi n Mas'ud al-Bukhari al-Hanafi, who died (747 A.H.)
• Jam'al-Juwaami' by Imam Taj al-Deen Abdul-Wahab bin Ali al-Subki al-Shafi' (died 771 A.H)
• al-Muwafaqat Imam Abu-Ishaq Ibrahim bim Musa Al-Shatibi al-Maliki (ied 780A.H.)
• al-Tahrir by Imam Kamal al-Deen Muhammad bin Abdul-Wahad known as Ibn-Humam (died 861 A.H.)
• Muslim al-Tha-boot by Imam Muhib al-Deen bin Abdul Shakoor al-Hindi (died 1119 A.H.)
• Irshad al-Fuhul li Ilm al-Usul by Mohammad bin Ali Al-Shawkani (d.1255A.H./1839 CE)
• Taheel al-Wasul ila Ilm al-Usul by Sheikh Muhammad Abdul-Raahman Eid al-Muhlawi (died 1920 CE)
• Usul al-Fiqh by Sheikh Muhammad al-Khudri (died 1927 CE)
• Usul al-Fiqh by Abdul-Wahab Khalaf (died 1955 CE)
• Usul al-Fiqh by Muhammad Abu-Zahrah (died 1974 CE)
• Al-Shaksia al-Islamia by Sheikh Taqi ud-Deen al-Nabhani (died 1977 CE)
• Al-Waseet fi Usul al-Fiqh al-Hanafia by Sheikh Ahmad Fahmi Abu-Sinnah.
• Usul al-Fiqh al-Islami by Sheikh Shakir al-Hanbali printed in 1948 in Damascus.
Adapted from Chapter of Shaksiyyah Islamiyyah (The Islamic Personality) Volume 1 by Sheikh Taqiuddin an-Nabhani