Scholars of the Islamic Golden Age and What They Actually Wrote

The scholars gathered under the heading "Islamic Golden Age" wrote specific books, and reading what is actually in them is more interesting than either of the two summaries usually on offer — that the period merely preserved Greek learning for Europe, or that it invented everything. Al-Khwarizmi wrote a manual of equation-solving aimed at inheritance disputes and trade. Ibn Sina wrote a medical encyclopaedia that organised the whole field. Ibn al-Haytham argued that vision works by light entering the eye and set out how to test it. Ibn Khaldun wrote a theory of why states rise and fall. Those are four different projects, four centuries apart in places, and lumping them together is where most of the confusion starts.

The label, and why it is argued about

Two problems with "Islamic Golden Age", both worth stating before the names.

The first is geography. Al-Khwarizmi worked in Baghdad. Ibn Sina was born near Bukhara in Central Asia and died at Hamadan in what is now Iran. Ibn al-Haytham did his optical work in Cairo under the Fatimids — a rival caliphate. Ibn Khaldun was born in Tunis in 1332 and wrote his major work in the 1370s. A Baghdad-centred golden age places most of these people in the wrong city and several of them in the wrong century.

The second is the built-in decline. A golden age has to end, and the usual ending — that religious conservatism strangled enquiry sometime after the eleventh century — has been argued against directly. George Saliba's Islamic Science and the Making of the European Renaissance traces continuing and original astronomical work long after the supposed collapse, and connects it to what European astronomers were doing later.

The House of Wisdom has a similar problem. The familiar account, which the MacTutor History of Mathematics Archive gives in its biography of al-Khwarizmi, describes an academy founded by the caliph al-Ma'mun where Greek scientific and philosophical works were translated, with a library assembled alongside it. Dimitri Gutas's study of the translation movement argues that the institution itself was much narrower than the legend, and that the astonishing scale of the translation effort is better explained by demand running right through Abbasid elite society than by any single foundation. Both positions are in print; what a reader should not do is treat the legend as settled.

Al-Khwarizmi, and a book with a practical purpose

Even the basic facts are contested. MacTutor gives his dates as roughly 780 to 850 and then spends several paragraphs on the disagreement about where he came from — whether the name points to Khwarazm south of the Aral Sea, whether an epithet in al-Tabari indicates Zoroastrian ancestry, and whether that epithet refers to al-Khwarizmi at all or to a second person whose name was merged with his by a copying error. The archive's own comment on one reconstruction is that it was built "with naive confidence" on an error.

That is a useful reminder about biography at this distance: the evidence is a handful of later references, and confident life stories are usually inference dressed up.

What survives is the work. His treatise on al-jabr and al-muqabala — restoring and balancing — gives English the word algebra; the Latinised form of his name gives us algorithm. MacTutor describes it, carefully, as a text that can in a certain sense be considered the first book written on algebra, which is a more defensible claim than the flat superlative you usually see.

What was genuinely new in it was not the solving of individual problems, which older traditions had done, but the systematic reduction of problems to a small number of standard forms, each with a general procedure and a geometric justification. And the purpose was stated plainly. In Rosen's translation, quoted by MacTutor, al-Khwarizmi says he intended to teach what is easiest and most useful in arithmetic, such as men constantly require in cases of inheritance, legacies, partition, lawsuits, and trade. Islamic inheritance law generates hard fractional problems; a general method for solving them was worth having.

Ibn Sina, and an autobiography that is also an argument

Ibn Sina — Avicenna in the Latin tradition — was born in 980 near Bukhara and died at Hamadan in June 1037. He lived through the collapse of the Samanid dynasty and worked for a succession of unstable courts, which is part of why his career reads as a series of relocations.

His Canon of Medicine organised medical knowledge into a structured whole: general principles, simple drugs, diseases by part of the body, diseases affecting the whole body, and compound remedies. It was used as a teaching text in Europe for centuries after its translation into Latin. His Book of Healing did something comparable for philosophy and the sciences.

The provenance point here is unusually neat. We know a great deal about his life because he wrote an autobiography and a student continued it. MacTutor's caution is exactly right: the autobiography is not simply an account of a life but a demonstration of how a person reaches the ultimate truth, and it has to be interpreted accordingly. A first-person source is not automatically a transparent one — which is the general lesson of primary and secondary sources applied to the friendliest kind of evidence there is, and the reason how we know what historical figures actually did treats autobiography as a category needing its own handling.