Electromagnetic

Qushji [d. A.D. 1474] was the son of Prince Ulugh Beg’s falconer and grew up in or close to the Timurid court in Samarqand in the fifteenth century. Samarqand at the time, with its observatory, large scientific staff, brilliant individuals, and scientifically accomplished patron Ulugh Beg, was without a doubt the major center of science in the world and certainly could rival its thirteenth-century predecessor that had been established by [Nasir al-Din] Tusi [d. A.D. 1274] in Maragha under Mongol patronage. After the assassination of his patron Ulugh Beg, Qushji traveled through Iran and Anatolia and eventually assumed a chair in astronomy and mathematics at the college (madrasa) of Aya Sofia in the newly Islamic city of Istanbul. It should be emphasized that the teaching of science in the religious schools, and later the establishment of an observatory in Istanbul, were opposed, sometimes bitterly, by the religious establishment. Qushji, writing his commentary on Tusi’s “Epitome of Belief” after the assassination but before assuming his chair, was no doubt mindful of this religious opposition and sought to answer the objection to astronomy that I have previously quoted from him.

Let us summarize some of the key points he makes. (The entire Arabic text, with my translation, is in the Appendix.) Qushji is clearly sensitive to the Ash’arite position on causality, and he makes the interesting observation that part of their objection to it, at least as regards astronomy, has to do with the astrological contention of a causal link between the positions of the orbs and terrestrial events (especially “unusual circumstances”). To get around such objections, Qushji insists that astronomy does not need philosophy, since one could build the entire edifice of orbs necessary for the astronomical enterprise using only geometry, reasonable suppositions, appropriate judgments, and provisional hypotheses. These premises allow astronomers to

conceive {takhayyalu} from among the possible approaches the one by which the circumstances of the planets with their manifold irregularities may be put in order in such a way as to facilitate their determination of the positions and conjunctions of these planets for any time they might wish and so as to conform with perception {hiss} and sight {‘iyan}.

What this will allow us to do is make presumptions that best explain or “save the phenomena.” Of course God might, by His will, cause the phenomena directly; Qushji gives the example of God darkening the Moon without the Earth’s shadow and causing an eclipse. But just as we go about our everyday lives using what he calls ordinary (‘adiyya) and practical (tajribiyya) knowledge, thus should we proceed in science. Here he allows himself a bit of sarcasm, arguing that we could (for example) claim that after we had left our house one day, God turned all the pots and pans into human scholars who took to investigating the sciences of theology and geometry; insofar as we feel confident in assuming that this has not happened, so also should we have confidence that the heavens normally follow a regular pattern that we have the capacity to explain. We do not, however, need to make the further claim that our explanation represents the only possible one; in this way, Qushji believes he has made astronomy independent of philosophy.

What makes Qushji’s position especially fascinating are some of the repercussions it had for his astronomical work. Since he claims to be no longer tied to the principles of Aristotelian physics, he feels free to explore other possibilities, including the Earth’s rotation. Clearly within the tradition of the debate that we outlined earlier, he agrees with Tusi, thus countering Ptolemy and [Qutb al-Din] Shirazi [A.D. 1236-1311], and argues that the question of the Earth’s motion cannot be determined by observation. But unlike Tusi, he refuses to settle the matter by appealing to Aristotelian natural philosophy. Instead he states that “it is not established that what has a principle of rectilinear inclination is prevented from [having] circular motion.” He then ends with a startling conclusion: “Thus nothing false (fasid) follows [from the assumption of a rotating Earth].

Ragep, Jamil F. and Ali al-Qushji. “Freeing Astronomy from Philosophy: An Aspect of Islamic Influence on Science” (p. 61-62) in Osiris, 2nd Series, Vol. 16, Science in Theistic Contexts: Cognitive Dimensions, University of Chicago Press on behalf of The History of Science Society, 2001, pp. 49-64+66-71. Note: I have removed Ragep’s footnotes and diacritics. Square brackets [...] are mine.