: To honor Bernard Goldstein, this article highlights in the "Defense of Theon against George of Trebizond" by Regiomontanus (1436-1476) themes that resonate with leading strands of Goldstein's scholarship. I argue that, in this poorly-known work, Regiomontanus's mastery of Ptolemy's mathematical astronomy, his interest in making astronomy physical, and his homocentric ideals stand in unresolved tension. Each of these themes resonates with Gold- stein's fundamental work on the Almagest, the Planetary Hypotheses, and al-Bitruji's Principles of Astronomy. I flesh out these (...) tensions with an intriguing interpretation of the history of astronomy, in which Regiomontanus contrasts the two-dimensional "eccentric astronomy" attributed to the Almagest and the Arabs with the three-dimensional spheres of the "later" astronomers. A similar contrast reappears when Regiomontanus portrays as a "fictitious art" an astronomy that does not go beyond the accommodation of computations to the appearances. To conclude, I use Regiomontanus's expression to reinstate (pace Goldstein and Barker in this journal, 1998) fictionalism as an actor's category in Osiander and sixteenth-century astronomy. (shrink)

The change from ancient and medieval to modern natural science, called Wende , must be associated with the work of Johannes Kepler and not that of Nicolaus Copernicus. Copernicus merely showed the way, introducing heliocentricity as the order of the planets. This Wende resulted from the synthesis of several disciplines formerly isolated from each other, namely mathematical astronomy, new physics, mathematical harmony, astrology, new physical optics, and natural theology. Whereas Copernicus united mathematical astronomy and peripatetic physics, Kepler was first to (...) see the necessity for providing a physical explanation and an ontological foundation to the heliocentric system. He was the first to consider and measure the movement of the planets in depth. The elements for his new physics Kepler obtained not from newly observed data, but from a harmonic archetypus of the regular polyhedra fitted in between excentric planetary spheres. On the basis of this archetypus he accepted the new heliocentric planetary system as a physical reality. That is why astronomy, by way of taking into account stereometric quantities, is, in Kepler's eyes, a kind of divine worship. Later, the best empirical data had also to be taken into consideration as a means of proving this a priori archetypus .The result was, on the one hand, a universal natural science able to explain natural processes in grater abundance than ever before or since in the history of science. Although accepted only in parts, it resulted in founding a new natural science with adherent mathematical and empirical methods. It also led Kepler to establish, step by step, the elliptical path of the planets, thereby overcoming, for the first time, the two axioms of ancient astronomy, requiring uniform and circular planetary motion.It has been shown that this Keplerian Wende was possible only within the Historischen Erfahrungsraum of Renaissance Humanism , which came about itself as the result of reactivating the scientific and philosophical thinking of the ancient Greeks and was accomplished by three steps relating to the revival of original ancient writings, the ancient knowledge of natural facts and data, and the ancient scientific and philosophical ideas and mentalities. (shrink)

The paper considers the development of physics‐teaching at the universities of Königsberg (founded 1544) and Helmstedt (founded 1576). The question is: How many teachers of physics professed Aristotelianism and how long? and why did most of them reject Copernicanismus? The paper suggests that Melanchthon, not only the founder of early German philosophy ‘was also the propounder of a form of, modern Aristotelianism’ which proved very valuable in mediating between theologians and philosophers on the one side and between philosophers and experimentalists (...) on the other side. (shrink)