al-Mustasfa min Ilm al-Usul

Al-Mustasfa min Ilm al-Usul is a work of legal theory by Abu Hamid Muhammad ibn Muhammad al-Ghazali (450-505 AH). ¹ In its editor's list of his works on the subject it comes last, after al-Mankhul, Shifa' al-Ghalil and Asas al-Qiyas. ^{2 3}

The editor quotes al-Ghazali's preface: when "God's decree led him back to teaching", a group of students of law asked him for a work on legal theory joining order and careful inquiry, steering between too little and too much, shorter than Tahdhib al-Usul, which tends to exhaustiveness, and longer than al-Mankhul, which tends to brevity; he agreed, using order for memorisation and inquiry for understanding. ⁴ Al-Ghazali says that a student who does not at the outset grasp the whole and the foundations of a science has no hope of reaching its secrets. ⁵

Al-Ghazali built the book on an introduction and four "poles", the introduction as preparation and the poles as the heart of the matter. ⁵ He likens rulings to fruit: every fruit has a nature of its own, something that bears it, someone who gathers it and a way of gathering. ⁶ The first pole is on rulings, that is obligation, recommendation, disapproval, permission, good and bad, performance out of time, validity and invalidity, placed first because they are the fruit sought; the second on the sources, the Book, the sunna and consensus; the third on the ways of deriving, the four modes in which the sources indicate: by explicit wording, by implication, by necessity and entailment, and by the understood rationale; the fourth on the one who derives, the mujtahid who rules by his best judgement, opposite whom stands the follower bound to follow him. ^{7 8} Al-Ghazali calls the third pole "the mainstay of legal theory", since it is the field in which mujtahids work to draw rulings from their sources. ⁹

Al-Ghazali opens with an introduction on definition and demonstration, saying it is not part of legal theory nor one of its special preliminaries but the introduction to all sciences, and that whoever does not master it has no reliable knowledge at all. ^{10 11} He makes theology (kalam) the highest science, which establishes the first principles of the religious sciences, and holds that the legal theorist takes from the theologian, on trust, that the Messenger's word is proof, and then studies how it indicates; mastering kalam is not a condition for being a legal theorist or jurist, though it is for being a scholar without qualification. ^{12 13}

The editor notes al-Ghazali's concern for careful inquiry, with phrases such as "the way to lift the veil, for us, is to say" and "our choice is to distinguish"; his attention to preliminaries and definitions; that he seldom names the holders of views, saying "some said" or "it was said", which the editor connects with his maxim "do not know the truth by men; know the truth and you will know its people" and with his discussion of backbiting in the Ihya'; his independence from any school, sometimes choosing against al-Shafi'i's view, as on whether a prohibition entails invalidity; and his care to record the views of the judge al-Baqillani, whose own books on legal theory have not been found. ^{14 10 11 15 16}

The editor notes that al-Mustasfa was first printed in 1324 AH in two volumes at the Amiriyya press at Bulaq, with Fawatih al-Rahamut in the margin, that in that print chapters and sections run together and there are omissions and errors, and that it was printed again in 1356 AH at the Tijariyya press, copied from it. ¹⁷ The museum's copy is the edition of Dr Hamza ibn Zuhayr Hafiz of the Islamic University of Medina, who dated his introduction 1 Ramadan 1413 AH. ^{1 18}

Volume 2 (the sources, including the discussion of istislah) and volume 4 were not read in this batch, and the date of composition is not given.

In Pole 2 al-Ghazali sets out four bases that are thought to be proofs but are not, which he calls "the supposed sources": the law of earlier prophets, the Companion's opinion, istihsan and istislah. ¹⁹ On the Companion's opinion he reports al-Shafi'i's old view of following the Companions and finds weak the view that a Companion's opinion is a proof when it spread without contradiction, since silence is not speech. ²⁰ On istihsan he rejects its interpretations one by one, accepting that what al-Karkhi and some Hanafis described - departing from a question's analogues because of a specific proof - is not objectionable, the objection being only to the name. ²¹ On istislah he divides interests into confirmed, cancelled and unattested, and defines interest as preserving the law's purpose in protecting religion, life, intellect, progeny and property; see Unattested interest. ^{21 22} In the Cairo Tijariyya printing (first printing 1356/1937) this falls in vol. 1. ²³