The ArgumentThe publication of Johannes Kepler's brilliant and revolutionary Astronomia nova has hitherto been viewed as somehow inevitable. This paper argues that, on the contrary, the book's very existence and a measure of its unusual form and content are in fact highly contingent, and derive from a legal dispute between Kepler and Tycho's heirs over the right to capitalize on his astronomical legacy. On Tycho's death, Kepler rather accidentally found himself in charge of Tycho's posthumous astronomical publications, especially the highly (...) prestigious Rudol phine Tables. Tycho's legal heirs, not having been paid by the emperor for Tycho's astronomical assets and feigning Kepler's unworthiness as his successor, wrested this mandate back. Ordered in turn to justify his employment, Kepler contrived the Astronomia nova as an interim announcement of the fruits of his astronomical research. In an effort to block Kepler's continuing exploitation of Tycho's observations, the heirs obtained the legal right to censor his publications, which severely threatened his philosophical freedom. The threat of editorial interference was responsible in part for Astronomia nova's unusual narrative form. (shrink)

For historical epistemology to succeed, it must adopt a defensible set of categories to characterise scientific activity over time. In historically orientated philosophy of science during the twentieth century, the original categories of theory and observation were supplemented or replaced by categories like paradigm, research program and research tradition. Underlying all three proposals was talk about conceptual systems and conceptual structures, attributed to individual scientists or to research communities, however there has been little general agreement on the nature of these (...) structures. Recent experimental research in cognitive science has considerably refined the theory of concepts. Drawing upon the results of that research, philosophers can construct more concrete and empirically defensible representations of conceptual systems. I will suggest that this research supports a modest and useful sense of both normal and revolutionary science, not as epistemological continuities or discontinuities, but as particular patterns of conceptual change. (shrink)

This paper argues that Kepler considered his work in optics as part of natural philosophy and that, consequently, he aimed at change within natural philosophy. Back-to-back with John Schuster’s claim that Descartes’ optics should be considered as a natural philosophical appropriation of innovative results in the tradition of practical and mixed mathematics the central claim of my paper is that Kepler’s theory of optical imagery, developed in his Paralipomena ad Vitellionem (1604), was the result of a move similar to Descartes’ (...) by Kepler. My argument consists of three parts. First, Kepler borrowed a geometrical model and experiment of optical imagery from the mélange of mixed and practical mathematics provided in the works of the sixteenth-century mathematicians Ettore Ausonio and Giovanni Battista Della Porta. Second, Kepler criticized the Aristotelian theory of light and he developed his own alternative metaphysics. Third, Kepler used his natural philosophical assumptions about the nature of light to re-interpret the model of image formation taken from Della Porta’s work. Taken together, I portray Kepler’s theory of optical imagery as a natural philosophical appropriation of an innovative model of image formation developed in a sixteenth-century practical and mixed mathematical tradition which was not interested in questioning philosophical assumptions on the nature of light. (shrink)

A few years ago, a manuscript by Jost Bürgi (1552–1632) was brought to scholarly attention, which included an ingenious sine calculation method. The purpose of this paper is to discuss two aspects of this manuscript. First, we wish to improve the current understanding of Bürgi’s method of sine calculation, especially with respect to the calculation of sines at a resolution of 1 min. Second, we wish to suggest a possible transfer of knowledge between India’s Kerala School of mathematical astronomy and (...) Bürgi. The evidence for the latter seems to be stronger than the evidence for other available case studies, but still revolves mainly around analogies, and can therefore not be considered as conclusive proof of transmission. We also append a translation of the relevant chapter of Bürgi’s treatise. (shrink)