Christoph Scheiner’s The Eye, that is, The Foundation of Optics (1619): The Role of Contrived Experience at the Intersection of Psychology and Mathematics

Abstract

AbstractAccounts of the development of experimental methods (including controls, broadly understood) in the seventeenth century have tended to overlook Aristotelians. Until recently the consensus was that, because of the art-nature distinction and a focus on final causes, Aristotelianism had significant issues incorporating experiments and contrived experiences into the natural sciences, including “middle” sciences such as optics.I argue that this picture relies, in part, on misreading Aristotle’s Posterior Analytics as a treatise on epistemology. In particular, book 2 chapter 19 has been seen as an account of how Aristotle justified grasping the principles of a science based on so-called “common sense” experience. Recent Aristotle scholars have challenged this, instead arguing that this notorious chapter on “Aristotelian induction” is, instead, just a general psychological description of how sensation leads to memory, from memory to experience, and from there to the grasping the universal first principles of either an art or a science. The epistemic justification for those principles, for any particular art or science, is rather more complex and domain-specific.What, then, did early modern Aristotelians in fact present as an account of how to actually grasp the first principles of any particular science? This contribution examines the Jesuit polymath Christoph Scheiner’s 1619 work, The Eye, that is, The Foundation of Optics, in which he argues for the revolutionary position that the retina, not the crystalline lens, is the seat of visual sensation. Scheiner relies on first-hand anatomy, contrived experiences, and experiments to establish at the axioms of optics, but I argue that his Aristotelianism presented no special obstacles to this. What Scheiner means by sensation, memory, and experience in this treatise are complex, and Scheiner’s implementation of control practices is rather sophisticated for the time. In this he was part of a general trend in the seventeenth century, most noticed in anti-Aristotelians such as Francis Bacon, in which we see scientific methodology being examined critically and experimental precepts, including control strategies, developed explicitly.