One can only assert that such problems were philosophical problems, if one were to think of them only in the medieval sense of natural philosophy, where such cosmological issues were properly discussed. But they also did matter to the scientists who were also trying to make sense of the physical phenomena around them, and who would have demanded that their scientific disciplines did not contradict each other. In that sense, those problems became real scientific problems, and did not remain only in the domain of philosophical speculation.
Take, for example, the physical spheres that were supposed to constitute the Aristotelian universe, and which were simply represented by circles by Ptolemy in the text of the Almagest. If one were to limit himself to philosophical speculations only, then those spheres would pose no serious problem if they were understood as mere mathematical representations that had no connection to reality. But if at the end of the day one used those spheres to account for the motion of planets and used them to predict the positions of those planets for a specific time, then one had to face their reality in a much deeper sense than is already admitted. And when that reality was reiterated in the Planetary Hypotheses, the contradictions became much more serious. Again, there would be no problem if one were only using those models of spheres to compute positions of planets only. But when one says that those spheres were actually physical in nature, in the Aristotelian sense of physical, it would become then impossible to think of them, for example, as being able to move uniformly, in place, around an axis that did not pass through their centers.
This was the most important impossibility in the whole of Greek astronomy, or at least it was so perceived. Such glaring absurdities that were embedded in almost every model of the Almagest could not pass unnoticed by astronomers, who were not only being watched over by their opponents in the society, who in turn did not want them to bring those "ancient" sciences into the Islamic domain in the first place, but they were also being watched by their own fellow astronomers who definitely believed, as al-Ḥajjāj must have done, that they could outsmart their fellow astronomers if they could cleanse the imported system from those blemishes.
That people were really thinking along those lines is best illustrated by one of the earliest texts to address the sheer physicality of the spheres: the text of Muḥammad b. Mūsā b. Shākir (d. 873), who was not only one of the major patrons of the translation of Greek scientific and philosophical texts, but was also himself a scientist in his own right. In his capacity as a practicing scientist, he devoted a treatise to the absurdity of assuming the existence of a ninth sphere, as Ptolemy had done. According to Ptolemy that last ninth sphere was responsible for the motion of the eighth sphere, which, in turn, carried the fixed stars. And yet Ptolemy had both spheres share the same center of the universe. The problem was then reduced to the impossibility of having two concentric spheres move one another without assuming a phenomenon like friction, which could not be allowed in the celestial realm of the Aristotelian universe where celestial spheres, by their very ethereal nature, did not allow friction to take place.[183]
That Ptolemy himself was thinking along the same lines is evident from the preface of the Almagest, where he says that the celestial motions should not be compared to the motions that we observe around us, for they belonged instead to some form of a deity. To which one could respond: if that were the case, and if the deities were responsible for the motion of the planets, then there would be no need for the science of astronomy, nor would there be any need for scientific observations, for who are the humans who could predict the behavior of deities? The readers of the Ptolemaic texts in their Arabic translation saw a different world, and could not simply resort to such whimsical deities in the midst of a competitive society that was watching every step they took.
This incompatibility between the mathematics of the Almagest and the physics of the Planetary Hypotheses would not have been noticed had those two books not been read together. And in the tense environment in which they were thrust their coming into conflict with one another was simply unavoidable. In addition, if one were to remember that those problems were being raised by Muḥammad b. Mūsā b. Shākir toward the middle of the ninth century, when the first translation of the Almagest by al-Ḥajjāj was barely two decades old, and the translation of Isḥāq b. Ḥunain (d. 911) had not yet taken place, one can then begin to appreciate the sophistication with which the Greek astronomical tradition was being received as it was being translated, a sophistication that could not be explained by the classical narrative. Furthermore, it is a kind of sophistication that could only come from this comprehensive understanding of the Greek philosophical tradition, where cosmology was read together with observational science, a reading that was nowhere to be found in any other civilization up till that time.
In later centuries, as other contradictions began to appear, further sophistication began to be necessary. But all the basic problems still focused around this major issue of the lack of consistency in the imported Greek astronomical tradition. In a word they still dealt with these foundational issues of science.
Once those issues were widely recognized by the various sectors of the society, they began to develop a tradition of their own. The various treatises that began to appear in the later centuries, and in which those issues were recounted, began to constitute a scientific genre of their own normally referred to with such titles as Shukūk (doubts). And because of the social dynamics within which those doubts were expressed, they were by no means restricted to the field of astronomy alone.
The similar text by Abū Bakr al-Rāzī (Latin Rhazes, d. 925) called al-Shukūk 'alā Jālīnūs (Doubts Against Galen), falls in this category as well, and with it we can easily detect a general cultural trend that has yet to be elaborated. Only skeletal sketches of these developments and of the major issues that were raised in those texts could be attempted at this time. Of course the astronomical tradition still received the lion's share of those discussions, and can only be used here as a representative model of the other discussions that were obviously taking place in the other disciplines.
If one were to disregard the earlier objections to the Ptolemaic observational parameters, or even the cosmological questions by Muḥammad b. Mūsā b. Shākir, just mentioned, as early expressions of doubts that had not yet developed into a genre of their own, then one will have to say that the genre was born with Rāzī's book, which was expressly called Shukūk, despite the fact that in the case of Rāzī his book was restricted to medical and philosophical doubts. Astronomical Shukūk were soon to follow, even though they seem to have taken a slightly different route.
During the eleventh century, possibly in the latter half of that century, an Andalusian astronomer, whose name is yet to be identified, has left us a treatise called Kitāb al-Hay'a (A Book on Astronomy), which is still preserved in an apparently unique copy at the Osmania library at Hyderabad (Deccan, India). In this treatise the author had several comments to make about the problems in the received Greek astronomy. But almost every time he made such comments he would quickly say that he had gathered those problems in a book that he called al-Istidrāk ['alā Baṭlamyūs] (which could be freely translated as: Recapitulation Regarding Ptolemy). This book has yet to be located. But from the context in which it is mentioned, and the problems it seems to refer to, it sounds like it was of the same nature as the other shukūk texts under discussion.[184]
184
Saliba,