Copernicus and His Islamic Predecessors: Some Historical Remarks

These are: Al-Battānī, al-Biṭrūjī, al-Zarqāllu, Ibn Rushd, and Thābit ibn Qurra. Copernicus also refers to al-Battānī in his Commentariolus, which remained unpublished during his lifetime. “Islamic” here refers to the civilization of Islam, not the religion, since a number of “Islamic” astronomers, such as Thābit, were not Muslims.

Dreyer J. L. E. , History of the planetary systems from Thales to Kepler (Cambridge, 1906), 269. Dreyer knew of Ṭūsī's work from the translation by Carra de Vaux of a chapter of his al-Tadhkira fi ^cilm al-hay'a (“Les sphères célestes selon Nasīr Eddin-Attusī” in Paul Tannery, Recherches sur l'histoire de l'astronomie ancienne (Paris, 1893), Appendix VI, pp. 337–61).

These have been conveniently collected in Kennedy E. S. Ghanem Imad (eds), The life & work of Ibn al-Shāṭir: An Arab astronomer of the fourteenth century (Aleppo, 1976), and in Kennedy E. S. , Studies in the Islamic exact sciences (Beirut, 1983), 50–107. The most important of these is Kennedy E. S. , “Late medieval planetary theory”, Isis, lvii (1966), 1966–97.

See, for example, the very critical remarks, most likely by the Banū Mūsā (ninth century), in Morelon Régis , Thābit ibn Qurra: Œuvres d'astronomie (Paris, 1987), 61.

Ragep F. J. , Naṣīr al-Dīn al-Ṭūsī's memoir on astronomy (2 vols, New York, 1993), i, 48–51.

Ragep F. Jamil , “Ibn al-Haytham and Eudoxus: The revival of homocentric modeling in Islam”, in Studies in the history of the exact sciences in honour of David Pingree, ed. by Burnett C. (Leiden, 2004), 786–809.

Saliba George , “Ibn Sīnā and Abū ^cUbayd al-Jūzjānī: The problem of the Ptolemaic equant”, Journal for the history of Arabic science, iv (1980), 376–403; reprinted in idem, A history of Arabic astronomy: Planetary theories during the golden age of Islam (New York, 1994), 85–112.

See Nūr al-Dīn abū Isḥāq al-Biṭrūjī, On the principles of astronomy, ed. and transl. by Goldstein B. (2 vols, New Haven, 1971). Cf. Sabra A. I. , “The Andalusian revolt against Ptolemaic astronomy: Averroes and al-Biṭrūjī”, in Transformation and tradition in the sciences, ed. by Mendelsohn E. (Cambridge, 1984), 133–53.

Copernicus Nicholas , De revolutionibus orbium coelestium, transl. by Rosen E. as On the revolutions (Baltimore, 1978), 18.

Good overviews can be found in Saliba George , “The astronomical tradition of Maragha: A historical survey and prospects for future research”, Arabic science and philosophy, i (1991), 67–99 (reprinted in idem, History (ref. 7), 258–90), and George Saliba, “Arabic planetary theories after the eleventh century AD”, in Encyclopedia of the history of Arabic science, ed. by Rashed R. (3 vols, London, 1996), i, 58–127.

Today we would say that these mathematical tools were equivalent to linkages of constant-length vectors rotating at constant angular velocities; but it is important to remember that Islamic astronomers conceived of their devices as physical and not simply mathematical. Cf. Ragep , op. cit. (ref. 5), ii, 433–7.

Ragep F. Jamil , “The two versions of the Ṭūsī couple”, in From deferent to equant: Studies in honor of E. S. Kennedy, ed. by King D. Saliba G. (The annals of the New York Academy of Sciences, d (1987)), 329–56.

Swerdlow N. M. Neugebauer O. , Mathematical astronomy in Copernicus's De revolutionibus (2 parts, New York and Berlin, 1984), i, 47.

Swerdlow N. M. , “The derivation and first draft of Copernicus's planetary theory: A translation of the Commentariolus with commentary”, Proceedings of the American Philosophical Society, cxvii (1973), 423–512, p. 434.

Admittedly, this is a grossly simplified version of a fuller and much more careful exposition that one may find in Swerdlow and Neugebauer, op. cit. (ref. 13), i, 41–64. A good summary is also provided by Shank Michael H. , “Regiomontanus on Ptolemy, physical orbs, and astronomical fictionalism: Goldsteinian themes in the ‘Defense of Theon against George of Trebizond’”, Perspectives on science: Historical, philosophical, social, x (2002), 179–207.

Swerdlow Neugebauer , op. cit. (ref. 13), i, 47. Cf. Neugebauer's earlier remark that “The mathematical logic of these methods is such that the purely historical problem of contact or transmission, as opposed to independent discovery, becomes a rather minor one” ( Neugebauer O. , “On the planetary theory of Copernicus”, in Vistas in astronomy, x (1968), 89–103, p. 90; reprinted in idem, Astronomy and history (New York, 1983), 491–505, p. 492).

Swerdlow N. , “Copernicus, Nicolaus (1473–1543)”, in Encyclopedia of the scientific revolution from Copernicus to Newton, ed. by Applebaum W. (New York and London, 2000), 165.

Swerdlow and Neugebauer claim that it is a translation. The recent editors and translators of the text argue that it is an original Byzantine work that is simply influenced to some degree by Arabic or Persian sources ( Paschos E. A. Sotiroudis P. , The schemata of the stars (Singapore, 1998), 11–18). The closeness to Islamic sources, however, and the use of the standard Arabic corruption Kakkaous rather than the Greek Cepheus argue for a greater dependence than the authors wish to admit. Clearly more research on this question is needed.

See Swerdlow N. , “Aristotelian planetary theory in the Renaissance: Giovanni Battista Amico's homocentric spheres”, Journal for the history of astronomy, iii (1972), 36–48, and Di Bono Mario , “Copernicus, Amico, Fracastoro and Ṭūsī's device: Observations on the use and transmission of a model”, Journal for the history of astronomy, xxvi (1995), 1995–54. In a passage in III.4 of De revolutionibus that was deleted prior to publication, Copernicus himself speaks of others who had used the Ṭūsī device; see Ragep , op. cit. (ref. 5), ii, 431.

Hartner Willy , “Copernicus, the man, the work, and its history”, Proceedings of the American Philosophical Society, cxvii (1973), 413–22, p. 421.

A session at a recent American History of Science Society annual meeting was entitled: “The late, great scientific revolution”. Cf. Osler Margaret J. (ed.), Rethinking the scientific revolution (Cambridge, 2000).

Two recent examples are Peter Dear's Revolutionizing the sciences: European knowledge and its ambitions, 1500–1700 (Princeton, 2001), and Steven Shapin's The scientific revolution (Chicago, 1996). Both ignore Islamic science entirely and scarcely discuss medieval European contributions to the scientific revolution.

Copernicus's conservatism was emphasized in 1959 both in a scholarly and in a popular context. As for the former, Derek de Solla Price's “Contra-Copernicus” provided a technical account that showed that Copernicus was really still part of ancient and medieval astronomy. As Price concludes: “… Copernicus made a fortunate philosophical guess without any observation to prove or disprove his ideas, and … his work as a mathematical astronomer was uninspired. From this point of view his book is conservative and a mere reshuffled version of the Almagest” ( de S. Price Derek J. , “Contra-Copernicus: A critical re-estimation of the mathematical planetary theory of Ptolemy, Copernicus, and Kepler”, in Critical problems in the history of science, ed. by Clagett M. (Madison, 1969), 197–218, p. 216). The popular presentation of this viewpoint was made by Arthur Koestler in his The sleep walkers: A history of man's changing vision of the universe (London, 1959), where Copernicus is referred to as the “timid canon”. How Copernicus can be “saved” despite this conservatism and/or his connection to Islamic astronomy is well-illustrated by Erna Hilfstein's remarks regarding the significance of Copernicus's achievement: “Copernicus may have used the geometrical devices of his Greek or Arab predecessors (for example, from the ‘Maragha school’), yet his system, and the perception of the cosmos it established, was entirely novel” (“Introduction to the softcover edition” of Nicholas Copernicus, On the revolutions, transl. and comm. by Rosen E. (Baltimore, 1992), p. xiii.

We should note, though, that recently Michał Kokowski, in defending Copernicus's originality, has also conceded that the Islamic models are also somehow revolutionary according to his “correspondence principle” inasmuch as they supersede those of Ptolemy by overcoming the problematic equant (Copernicus's originality: Towards integration of contemporary Copernican studies (Warsaw, 2004), 75–77). Here he follows George Saliba, who maintained that the Marāgha school astronomers were revolutionary because of their “realization that astronomy ought to describe the behaviour of physical bodies in mathematical language, and should not remain a mathematical hypothesis, which would only save the phenomena” (“The rôle of Maragha in the development of Islamic astronomy: A scientific revolution before the Renaissance”, Revue de synthèse, cviii (1987), 361–73, p. 372; reprinted in idem, History (ref. 7), 245–57, p. 256). It is not clear how Saliba reconciles this position with his later claim that the sixteenth-century astronomer al-Khafrī had reached “unparalleled heights” in this tradition by “realiz[ing] that all mathematical modeling had no physical truth by itself and was simply another language with which one could describe the physical observed reality” (George Saliba, “Arabic versus Greek astronomy: A debate over the foundations of science”, Perspectives on science, viii (2000), 2000–41, p. 339). For a contrary view, see Sabra A. I. , who has argued that this Islamic scientific tradition was not revolutionary but should be regarded as “normal science” in the Kuhnian sense (“Configuring the universe: Aporetic, problem solving, and kinematic modeling as themes of Arabic astronomy”, Perspectives on science, vi (1998), 1998–330, pp. 292, 321–3). As should be clear in what follows, I believe that the emphasis on the mathematical models — Whether revolutionary or not — Has distracted us from what is the most significant and innovative part of Islamic theoretical astronomy.

Recent books by two mediaevalists, A. C. Crombie and Edward Grant, advocate the European nature of modern science, thus reverting to the more traditional viewpoint. See Crombie's Styles of scientific thinking in the European tradition: The history of argument and explanation especially in the mathematical and biomedical sciences and arts (London, 1994), and Grant's The foundations of modern science in the Middle Ages: Their religious, institutional, and intellectual contexts (Cambridge, 1996) and idem, God and reason in the Middle Ages (Cambridge, 2001). This view is held by both Western and Islamic scholars so cannot be simply ascribed to some biased antagonism towards Islamic civilization. For example, the Iranian expatriate S. H. Nasr has stated that although “all that is astronomically new in Copernicus can be found essentially in the school of al-Ṭūsī”, Islamic astronomers were prescient enough not to break with the traditional Ptolemaic cosmology “because that would have meant not only a revolution in astronomy, but also an upheaval in the religious, philosophical and social domains” ( Nasr S. H. , Science and civilization in Islam, 2nd edn (Cambridge, 1987), 174).

Cf. Brentjes Sonja , “Between doubts and certainties: On the place of history of science in Islamic societies within the field of history of science”, N.T.M., xi (2003), 65–79.

Dobrzycki J. Kremer R. L. , “Peurbach and Marāgha astronomy? The ephemerides of Johannes Angelus and their implications”, Journal for the history of astronomy, xxvii (1996), 187–237, p. 211.

Veselovsky I. N. , “Copernicus and Naṣīr al-Dīn al-Ṭūsī”, Journal for the history of astronomy, iv (1973), 128–30. This turns out to be implausible since Copernicus probably did not know of the Proclus theorem (actually the converse of the Ṭūsī couple) until many years after he used the device; see Ragep , op. cit. (ref. 5), ii, 430–1.

Di Bono , op. cit. (ref. 19), 153–4.

Swerdlow , op. cit. (ref. 14), 434–5.

Recently B. R. Goldstein (“Copernicus and the origin of his heliocentric system”, Journal for the history of astronomy, xxxiii (2002), 219–35) has sought to undermine Swerdlow's reconstruction of the origins of Copernicus's heliocentric system by emphasizing a passage in De revolutionibus (I.10). In it Copernicus points to the distance—period relationship of the planets to justify his system, which Goldstein takes to be the initial motivation. But again, it is odd that this is hardly mentioned in the Commentariolus.

For this Spanish episode in Islamic astronomy, see Sabra , op. cit. (ref. 8), 133–53.

It is difficult, if not impossible, to prove a negative, but it is highly suggestive that one does not find the word “equant” in Edward Grant's monumental (816-page) Planets, stars, and orbs: The medieval cosmos, 1200–1687 (Cambridge, 1994). Even in the generation immediately before Copernicus, there seems to have been no precedent for what was a commonplace in Islamic astronomy. As stated in Dobrzycki and Kremer, op. cit. (ref. 27), 211: “We know of no extant text by Peurbach or Regiomontanus in which the Ptolemaic models are criticized explicitly on the grounds that they violate uniform, circular motion”.

Toomer G. J. , Ptolemy's Almagest (London, 1984), 36.

The translation is due to T. L. Heath in his Aristarchus of Samos (Oxford, 1913), 276; reprinted in Cohen Morris R. Drabkin I. E. , A source book in Greek science (Cambridge MA, 1948), 90–91. Cf. Lloyd G. E. R. , “Saving the appearances”, Classical quarterly, n.s., xxviii (1978), 1978–22, pp. 212–14 (reprinted with new introduction in idem, Methods and problems in Greek science (Cambridge, 1991), 248–77).

Ragep , op. cit. (ref. 5), i, 38–41, 106–7; ii, 386–8.

Much of what follows is elaborated in Ragep F. Jamil , “Freeing astronomy from philosophy: An aspect of Islamic influence on science”, Osiris, xvi (2001), 49–71.

Ragep , op. cit. (ref. 5), i, 44–46, 98–101; ii, 380–1.

Ragep , op. cit. (ref. 37), 61–63.

A discussion of this Islamic discourse on the Earth's possible rotation is in Ragep F. Jamil , “Ṭūsī and Copernicus: The Earth's motion in context”, Science in context, xiv (2001), 145–63.

Ibid., 157.

Ibid., 145–8.

In the fourteenth century, one finds Nicole Oresme and Jean Buridan discussing the Earth's rotation. The former, in particular, presents quite cogent reasons why one might believe in this motion. But in the end he rejects them for theological reasons. In both cases, it is clear that they have no interest in a reconceptualization of astronomy along the lines that occurred in Islamic astronomy (Ibid., 158–60). The possibility that such a discussion might have taken place in the fifteenth century in the circle of Peurbach and Regiomontanus is being investigated by M. Shank; cf. op. cit. (ref. 15).

Ragep F. Jamil , “^cAli Qūshjī and Regiomontanus: Eccentric transformations and Copernican revolutions”, Journal for the history of astronomy, xxxvi (2005), 359–71.

See Folkerts Menso , “Regiomontanus' role in the transmission and transformation of Greek mathematics”, in Tradition, transmission, transformation: Proceedings of two conferences on premodern science held at the University of Oklahoma, ed. by Ragep F. J. Ragep S. P. (Leiden, 1996), 89–113.

Byrne James Steven , “A humanist history of mathematics? Regiomontanus's Padua Oration in context”, Journal of the history of ideas, lxvii (2006), 41–61, p. 61.

Shank Michael H. , “The classical scientific tradition in fifteenth-century Vienna”, in Ragep F. J. Ragep S. P. (eds), Tradition, transmission, transformation (ref. 45), 115–36, p. 131.

Ibid., 126.

See above, ref. 18 (on the transmission of Islamic astronomy to Byzantium). And as Otto Neugebauer has remarked: “There is no reason to assume that there is any period in which Islamic astronomy was not known in Constantinople” (A history of ancient mathematical astronomy (3 parts, New York, 1975), i, 11). Cf. Mavroudi Maria , A Byzantine book on dream interpretation: The Oneirocriticon of Achmet and its Arabic sources (Leiden, 2002); Touwaide Alain , “Arabic urology in Byzantium”, Journal of nephrology, xvii (2004), 2004–9; and Touwaide Alain , “Arabic medicine in Greek translation: A preliminary report”, Journal of the International Society for the History of Islamic Medicine, i (2002), 2002–53.

Tihon Anne , “Les tables astronomiques persane à Constantinople dans la première moitié du xive siècle”, Byzantion, lvii (1987), 471–87. Reprinted in Tihon, Études d'astronomie Byzantine (Aldershot, 1994).

Ragep F. J. Ragep S. P. , (eds), Tradition, transmission, transformation (ref. 45), pp. xv–xviii.

A very important article that takes up the mathematical humanism of Samarqand is İhsan Fazlioǧlu's “Osmanli felsefe-biliminin arkaplani: Semerkand matematik-astronomi okulu”, Dîvân ilmî araştirmalar, xiv/1 (2003), 1–66. A revised version in English will appear in a forthcoming issue of the Journal for the history of Arabic science.

Makdisi George , The rise of humanism in classical Islam and the Christian West (Edinburgh, 1990), 349–50, p. 354.