Galileo’s telescopic lunar observations, announced in Siderius Nuncius (1610), were a triumph of observational skill and ingenuity. Yet, unlike the Medicean stars, Galileo’s lunar “discoveries” were not especially novel. Indeed, Plutarch had noted the moon’s uneven surface in classical times, and many other renaissance observers had also turned their gaze moonward, even (in Harriot’s case) aided by telescopes of their own. Moreover, what Galileo and his contemporaries saw was colored by the assumptions they already had. Copernicans assumed the moon was (...) a terrestrial satellite, thus Galileo saw its mountains and Kepler “saw” the dwellings of its inhabitants. Aristotelians assumed the moon was a perfect sphere, so they saw differences in density and rarity in the lunar body. Theory corrected the results of observation, so Galileo’s lunar observations, like those that had come before, proved nothing. Yet this failure contained the germ of Galileo’s success, since the Siderius Nuncius gave observation a rhetorical force it did not have before. Observers on all sides set out to see for themselves what Galileo reported. Hence, all parties now had to answer to what they saw, whatever they believed. Thus, the Siderius Nuncius ultimately changed the grounds upon which natural philosophical argument and debate was carried out. In this new empirical arena, the Galilean science would eventually prevail. (shrink)

Science lies at the intersection of ideas and society, at the heart of the modern human experience. The study of past science should therefore be central to our humanistic attempt to know ourselves. Nevertheless, past science is not studied as an integral whole, but from two very different and divergent perspectives: the intellectual history of science, which focuses on the development of ideas and arguments, and the social history of science, which focuses on the development of science as a social (...) undertaking within its broader contexts. There is almost universal agreement that this bifurcation of the field is lamentable, and nearly universal disagreement about where, exactly, the problem lies. In order to identify the difficulty, this paper examines the institutional histories and disciplinary philosophies that have constituted the study of past science. I argue that science history, eventually allied itself with either History or Philosophy in order to find institutional support, thereby suffering the artificial imposition of the disciplinary prejudices of its allied fields, which lead science historians to adopt either the intellectual or the social perspective. Science history must reconcile its distinctions on its own terms, as an integrated unity with its own disciplinary bounds, and apart from History and Philosophy. As a catalyst for rapprochement, the historical and philosophical examination also yields a mapping of the field of science history that can be used to locate the problematic divisions in present scholarship and to draw new disciplinary bounds. (shrink)

In 1596, in the Mysterium Cosmographicum, a twenty-five-year-old Johannes Kepler rashly banished lines from the universe. They “scarcely admit of order,” he wrote, and God himself could have no use for them in this “well-ordered universe.” Twenty-five years later, though, Kepler had come to repent the temerity of his youth. “O male factum!” he lamented in a 1621 second edition of the Mysterium – “O what a mistake” it was to dismiss lines, for linearity is revealed in those most perfect (...) and divine motions – the revolutions of the heavenly orbs. Why did Kepler come to lament the rashness of his youth? The answer lies deep in the details of Kepler’s discovery of elliptical orbits in 1605. Kepler struggled to find an empirically adequate description and physically plausible explanation of Mars’s path through the heavens. He realized, though, that his originally spherical notion of location and direction were insufficient to reconcile descriptions and explanations of the planet’s motion. Crucially inspired by the “magnetic philosophy” of William Gilbert, Kepler adopted an oriented conception of space, which finally allowed a plausible mechanism to be constructed for elliptical motion – the true path of the planet. Yet, this oriented space required the stipulation of straight lines. Without straight lines, even God could not construct the planets’ elliptical orbits. (shrink)