Islamic Science

Healers with some kind of hospital training and adepts of alchemy were already active in the time of the Prophet and under the Umayyad dynasty (661–750) of Damascus. The earliest preserved fragments of and references to Arabic astronomical and astrological texts are from 679 and 735. Historians of science, medicine, and philosophy, however, disagree as to whether all writings ascribed to the alchemist and Sufi Jabir ibn Hayyan (c. 721–c. 815) were indeed his own or rather composed by later authors.

Translation movement.

The major breakthrough as far as philosophy and the ancient sciences are concerned occurred from the mid-eighth to the first third of the ninth centuries under the Abbasid dynasty (750–1258). During these decades, the extraordinary "translation movement" started and gained solid footing. The movement covered different kinds of scholarly heritage (Iranian, Indian, Byzantine, Hellenistic, Hellenic) whose transfer into Arabic flourished over different periods.

Translations were a major aspect of scholarly culture in several Islamic societies until the early eleventh century. Previous scholarship saw the reasons for this movement primarily in practical needs of physicians, astrologers, and patrons as well as in an intellectual superiority of the non-Muslim communities that persuaded the Muslims to acquire their knowledge and standards of debate. Dmitri Gutas proposes a different view in Greek Thought, Arabic Culture (1998). He points to the suppression of intellectual activities in the centers of the Byzantine Empire after the sixth century and the preservation of the heritage among persecuted and marginalized Christian minorities, whose status and liberty of movement changed drastically after the conquest of their lands by Arab Muslim armies. The second factor Gutas emphasizes is the need for legitimacy-creating measures by Abbasid caliphs at two points of their dynastic history (after 750 when they had successfully conquered the Umayyad empire and after 819 when al-Ma'mun decided to return to Baghdad after his successful overthrow of his brother, the caliph al-Amin in 813). In both instances, Gutas believes, the two caliphs, al-Mansur (r. 754–775) and al-Ma'mun (r. 813–833), chose to implement a cultural politics that favored translations of foreign knowledge. In the case of al-Mansur the emphasis was on Persian knowledge, although the caliph had already commissioned the acquisition of Greek scientific manuscripts, while in the case of al-Ma'mun the translation of Greek texts was primary. The purpose of this politics was to lend al-Mansur the legitimizing aura of Sassanian royalty and to bind his Persian allies more closely to his rule. Al-Ma'mun, on the other hand, strove to foster the alliances he deemed necessary by means of devaluating the reputation of the only surviving pre-Islamic enemy of substantial power, Byzantium, and hence this enemy's right to claim imperial rule in the Mediterranean world.

Astrologers and physicians.

The first known scholars of the Abbasid court were astrologers and physicians, mostly from western Persia. They lent their expertise for determining the auspicious day for building Baghdad in 762 and for treating sick caliphs and their wives. They calculated horoscopes and composed astrological histories. They were the first translators mostly of Pahlavi (a group of Iranian languages and dialects used from 300 B.C.E. and 900 C.E.) but also of some Greek and Syriac texts on astrology, logic, medicine, astronomy, mathematics, ethics, and wisdom sayings.

Descendants of Byzantine nobles, clergymen of various Orthodox churches in Mesopotamia (present-day Iraq) and Syria, and members of the Sabian communities of northern Mesopotamia began to participate in these translations during the later decades of the eighth century. Until the end of the ninth century, many books were translated twice, or even three times, because of conflicting approaches to what constituted a good translation and what or who mattered more—language or scientific content, the author or the translator. These translations were executed and interpreted within the set of ideas and practices that developed during the eighth and the early ninth centuries. An example is Qusta ibn Luqaal-Ba'labakki's (fl. 860–900) rendering of Diophantes' number theory in the technical language of algebra found in the book of Abu Ja'far Muhammad ibn Musa Al-Khwarizmi (fl. c. 780–840). On the other hand, the translations were a major component of a process that transformed the set of earlier ideas and practices into new, often hybrid forms. An example is the combination of Indian and Ptolemaic concepts, methods, and parameters in astronomical handbooks of the so-called Sindhind tradition—that is, the tradition based indirectly on the Brahma-sphutasiddhanta (628) by Brahmagupta (598–c. 665).

Science at court.

From the ninth to the eleventh centuries, most students of the ancient sciences earned their living as scholars at courts, as itinerant scholars, and as merchants, or they lived from their family fortunes. Mathematicians were often either astrologers or physicians. Occasionally they also served as secretaries and historians. The social and cultural acceptance of the ancient sciences is expressed by the high ranks given to several leading scholars at various courts in the center of the Abbasid empire and its provinces. They acted as teachers of princes, table companions of caliphs and viziers, courtly ambassadors, and heads of delegations of city notables charged to negotiate credits, war, and peace with their feuding sovereigns. In the ninth century, they presented their scientific results as letters to princely students and viziers, as answers to friends and critics, as interpolations to and comments on translated pre-Islamic books, and as treatises that focused on a particular set of research questions. Cross-confessional cooperation was another major feature of scholarly life and applied to both scholars and patrons.

Beginning in the second half of the tenth century, new Islamic dynasties evolved inside and outside the Abbasid empire. This political, religious, and cultural diversification produced more possibilities for patronage and scholarship. Scientists introduced new forms of communication, such as the exchange of letters between scholars in far away towns through riding messengers. Long-distance cooperation also included shared research activities, such as observations of eclipses. The mobility of scientists increased too. They wandered between regions as far away as modern Uzbekistan and Syria and worked at several courts and for different patrons.

The new forms of scholarly life spread the sciences over the large territories of the Islamic world and enabled other dynasties to formulate their own cultural politics. In al-Andalus on the Iberian Peninsula, for instance, the heirs of the only Umayyad prince who had survived the Abbasid massacre of his family supported scientific activities as part of their anti-Abbasid foreign politics. At their court, the relationship between the newly arriving sciences and the previously established Maliki branch of Sunni jurisprudence was tense. Since the early ninth century, poets, sponsored by the emirs, had espoused astrology disapproved by Maliki scholars. As Mònica Rius has shown, the conflicts between poets and jurists were not motivated solely by legal concepts of right and wrong but included power struggles, issues of reputation, and courtly politics. She believes that despite Maliki condemnations, astrology became an obligatory element in the courtly educational canon.

In the late tenth and early eleventh centuries, a new type of scholar emerged in Andalusia who taught parts of Maliki law together with number theory. Maslama ibn Ahmad al-Majriti (d. 1008) is the first known scholar of this group. He and his students recalculated, edited, modified, and criticized astronomical tables devised in Baghdad, in particular those by al-Khwarizmi and al-Battani (c. 858–929). Their successors, such as the judge Sa'id al-Andalusi (1029–1070) and his collaborator al-Zarqallu (c. 1030–1099), compiled and calculated new astronomical handbooks such as the Toledan Tables, the Alphonsine Tables, and many others. One of the multiple changes that these Andalusian scientists introduced was a new longitude of Cordoba, which shortened the Ptolemaic length of the Mediterranean Sea almost to its correct size. Other changes included theoretical and conceptual innovations such as cycles that regulate the obliquity of the ecliptic or a corrected Ptolemaic lunar model.

Fine arts.

The ancient sciences and their proponents in Islamic societies also stimulated the fine arts. Illuminated Byzantine manuscripts on pharmacy, medicine, and mechanics as well as illustrated Sassanian historical books inspired the art of the book in Islamic societies. The first preserved illuminated Arabic manuscripts on medicine, pharmacology, astrology, astronomy, and natural history are from the twelfth and early thirteenth centuries. But astrologers of previous centuries, such as 'Abd al-Jalil al-Sijzi (c. 950–c. 1025) or 'Abd al-Rahman al-Sufi (903–998), already had persuaded central Asian and Persian princes to sponsor the scientific treatises and occasionally also their illumination.

Philosophers and mathematicians.

The relationship between philosophers and mathematicians was rather strained during the ninth century, mainly due to the conflicts that raged between the philosopher al-Kindi (d. c. 870) and the three Banu Musa: Muhammad, Ahmad, and al-Hasan. The conflicts concerned questions of content and style as much as they revolved around issues of patronage, courtly power, and cultural superiority. Notwithstanding, a few mathematicians of the ninth century, such as Thabit ibn Qurrah (d. 901), wrote about philosophical subjects. Al-Kindi, as did philosophers in antiquity, applied Aristotelian notions to his discussions of mathematics. Other, anonymous writers strove to harmonize Euclid's (fl. c. 300 B.C.E.) geometry with Nicomachus of Gerasa's (fl. c. 100 C.E.) number theoretical philosophy by reinterpreting book 2 of the Elements as dealing with mixed arithmetical-geometrical objects (bricks) rather than lines and surfaces, which were in this view objects of a lower ontological status.

In the second half of the tenth and early eleventh centuries, things started to change. The Persian mathematician and astronomer Abu al-Wafa' al-Buzajani (940–998) lent his support to the secretary and philosopher Abu Hayyan al-Tawhidi (d. 1023) at the Buyid court in Baghdad. Ibn al-Haytham (965–1042) in Basra and Cairo and Omar Khayyám (1048–1131) in Balkh, Bukhara, and Samarkand engaged in serious philosophical study and writing.

Science and religion.

The relationship between the ancient sciences and religious disciplines covered conceptual as well as practical aspects. In the eighth century, a newly emerging faction among the religious scholars, the Mu'tazilites, began to use mathematical and philosophical arguments in discussions of matter and movement. Representatives of Ash'ari kalam, founded against Mu'tazili doctrines in the early tenth century, participated in debates about number theory, physics, astronomy, and astrology and wrote about such themes. Mathematicians in the ninth century such as al-Khwarizmi tried to relate their fields of knowledge to religion. Opening his book on algebra by advertising the new discipline as an appropriate tool for merchants, he ended it with an exposé of algebraic solutions for legal problems. While this is usually seen as a further aspect of applied mathematics, it also reflects the mathematician's participation in the not-yet-finished process of codifying Abu Hanifa's (699–767) school of law. Anonymous readers of Euclid's Elements added to the definition of a solid in book 11 that "it is all that has a corpse" (kull ma lahu juththa), alluding to discussions of whether God was or had a body.

The cornerstone of the efforts to apply mathematics and astronomy to Muslim religious practice was to find the qibla, the direction toward Mecca, and to determine the prayer times. Ahmad b. 'Abdallah al-Marwazi called Habash al-Hasib (c. 770–c. 870), Abu l-'Abbas al-Fadl al-Nayrizi (d. c. 922), and al-Battani (c. 850–929) used methods such as the analemma of Hellenistic geometry to find exact solutions or spherical triangles and the Indian sine function to find approximate solutions. The visibility of the new moon and possibly the issue of the beginning of the world also belong in this context. Ibn al-Nadim ascribed a lost treatise touching on the latter question to Muhammad (d. 872), the eldest of the Banu Musa.

Mathematicians, astronomers, and astrologers.

Mathematicians, astronomers, and astrologers held different views about what was important, valuable, and feasible in their disciplines. Thabit ibn Qurrah interpreted al-Khwarizmi's algebra in terms of book 2 of Euclid's Elements on particular geometrical constructions. Al-Karaji (d. c. 1030), like Thabit ibn Qurrah, placed geometry over algebra because he regarded it as the science that guaranteed certain knowledge. Al-Hasan ibn Musa (d. after 870) was accused of inventing solutions to mathematical problems without having done what was proper—reading all books of the Elements. Ibrahim b. Sinan (908–946, a grandson of Thabit ibn Qurrah), Abu Sahl al-Kuhi (tenth–eleventh centuries), al-Sijzi, Abu l-Jud b. al-Layth (tenth–eleventh centuries), al-Biruni (973–1048), and others struggled with one another about the appropriate methods for solving difficult mathematical problems and the deficiencies of certain forms of analysis and synthesis, two major geometrical methods since antiquity.

The sharp debates that surrounded the twin disciplines of astronomy and astrology ranged from the two standard challenges of lacking reliability and religious heterodoxy to the kinds of philosophical foundations necessary for a well-functioning astrology, the appropriate demonstrative methods, and the relationship to astronomy. George Saliba argues that these debates motivated astronomers in the ninth century to set up a new kind of astronomy or mathematical cosmography, 'ilm al-hay'a, that aimed at drawing clear fences between a mathematically sound discipline of the heavens and astrology (2002). Similarly, F. Jamil Ragep, who thinks that two different kinds of 'ilm al-hay'a emerged, sees the more general type aiming at setting a mathematical science of the heavens apart from ancient astronomia or 'ilm al-nujum (science of the stars) that included astrology. The other, more restricted project of 'ilm al-hay'a evolved as a specific genre that strove to harmonize physical, that is, philosophical, principles and mathematical models of planetary movements and included the mathematical description of the earth (1993). As the works of Thabit ibn Qurrah and al-Hasan al-Nawbakht (d. c. 920) illustrate, a third realm of debate focused on Ptolemy's (second century C.E.) work and the various new astronomical tables, in particular the Zij al-Mumtahan (The corrected tables). These and other tables were calculated by al-Ma'mun's court astronomers Yahya b. Abi Mansur (d. c. 830), Khalid b. 'Abd al-Malik al-Marwarrudhi (first half of the ninth century), al-'Abbas al-Jawhari (first half of the ninth century), Habash al-Hasib, and others on the basis of astronomical observations. While Thabit ibn Qurrah explained and propagated specific theories and methods from Ptolemy's Almagest, he apparently held the "Corrected Tables" in less esteem.

David A. King, Julio Samsó, and B.R. Goldstein believe that the debates that surrounded and permeated the new tables caused the gradual elimination of Persian and Indian elements from Islamic astronomy in favor of Ptolemaic theory. The debates also led to the replacement of some Ptolemaic parameters such as the obliquity of the ecliptic by new observational results and to the abandonment of certain Ptolemaic beliefs, such as the immobility of the solar apogee or the impossibility of annular solar eclipses. Al-Hasan al-Nabawkht, in contrast, wrote a disputation against Ptolemy's planetary models as well as against the Platonic stance that the cosmos was a living, rational being. His rejection of Ptolemy and Plato may have been linked to his political-religious preference of the quietist Shia in opposition to the Shii revolutionary wing of the period, the Batiniyya.

Major themes and achievements.

Major mathematical, astronomical, mechanical, and optical themes and achievements of these four centuries concern the gradual emergence of a new, distinctly Islamic trigonometry; the use of analysis and synthesis; the construction of the side of a regular heptagon; the study of conic sections; efforts to solve specific problems of number theory such as the so-called theorem of Fermat; the creation of a geometrical as well as a numerical theory of cubic equations; the determination of centers of gravity as well as of specific weights; the study of the law of the lever and the construction of balances; the introduction of a new theory of seeing, reflection, and refraction; the interpretation of the moon's light; the construction of burning mirrors; and the physical foundation of mathematical astronomy. This vibrant pursuit of theoretical themes fostered an atmosphere in which claims to invention, innovation, and novelty thrived. Experimentation was regarded as a means to achieve new insights and build new theories. Ibn al-Haytham carried out experiments for solving optical questions, for deciding between alternative explanatory approaches, and for modeling astronomical processes. Abu Sahl al-Kuhi used thought experiments for finding new results for geometrical questions related to mechanics. Criticizing predecessors and compatriots was a favored stylistic means to establish credibility and claims to priority and to propagate new results.

Parallel to the attention directed toward theoretical aspects of science, much work went into practical fields such as calculating calendars and horoscopes; determining geographical coordinates; teaching the basics for calculating exchange rates, wages, business transactions, and the hire of labor; surveying fields and properties; and determining surfaces and volumes used in architecture and for ornamental decorations. Leading mathematicians such as Abu al-Wafa and Ibn al-Haytham wrote about these practical subjects, as did a number of religious scholars, such as the founder of the Ash'ari kalam, Abu al-Hasan 'Ali al-Ash'ari (873 or 874–935 or 936) and his eminent follower 'Abd al-Qahir al-Baghdadi (d. 1038). The two mathematicians also contributed to the new field of magic squares—that is, squares filled with numbers in a way that the sum of each column equals the sum of each row as well as each diagonal. Abu l-Wafa', Ibn al-Haytham, and later writers created methods for constructing pair and impair magic squares of higher order, partitioned magic squares, or bordered magic squares. Over the centuries, magic squares attracted the attention of scholars who were interested in mathematics as well as that of writers, mystics, artisans, sultans, military leaders, and ordinary people who applied magic squares—from the most elementary to the very large and fairly complex—to protect themselves from all sorts of misfortunes.