The Doubts Concerning Ptolemy

After the 3rd century Hijri, when the most intense and original works on science and art in the Islamic world were revealed, Ibn al-Haytham (d. 1040) wrote works in the fields of geometry, physics, astronomy, especially optics. His scientific studies influenced not only his own period but also his successors. Therefore, it is necessary to convey the scientific personality and method of Ibn al-Haytham to today’s readers in order to transfer our ancient heritage to future generations. This book is an analysis, a text and a translation study of Ibn al-Haytham’s work called al-Shukûk alâ Ptolemy. The aforementioned work is the critique of three books written by Ptolemy on Mathematike Syntaxis/ Almagest (al-Macistî), PlanetaryHypotheses (al-Iqtisâs), and Optics (al-Manâzır). According toIbn al-Haytham, the inconsistencies that disrupted Ptolemy’sastronomy stem from the inconsistency between the mathematical theory of planets and cosmology. Although Ptolemy’sGeocentric system uses Aristotle’s physics, the concept of the displacement of the Earth from the center, the epicycle circle, and the equinant is contrary to Aristotelian physics. For this reason, Ibn al-Haytham desires to put Ptolemy’s astronomy on a more solid ground by clearing out its internal inconsistencies. In addition, in order to reach the truth in science, he aimed to eliminate the prejudices and the pressure of the authority. For this reason, Ibn al-Haytham criticized the planetary models of Ptolemy, who is considered an authority in astronomy, ensured that these models were reconsidered and he started the “tradition of doubt”.After the criticisms of Ibn al-Haytham, Islamic astronomy made progress in efforts to reconstruct the mathematical structure of Ptolemy’s astronomy, on the one hand, and to put this mathematical structure on a physical basis, on the other.