Visione, percezione e cognizione nelle teorie medico-filosofiche in Francia nel secolo XVIII

It’s in the medical an physiological research field that in XVIIIth century France the most interesting solutions concerning sight perception and its spin-off for philosophy have been presented. As for life sciences, it’s up to philosophers to define the theoretical coordinates providing a sense for the experimental study. Anyway, it’s in early XVIIth century that the connection between optics, physics and philosophy achieves its better results, results which are the object of our analysis – from Keplero to Gassendi and Berkeley – in view of the turning point represented by XVIIIth century biological theories developed by Georges-Louis Leclerc de Buffon, Julien Offroy de La Mettrie and Denis Diderot. From the ancient times to modern age, the old question about the condition for human understanding, the function of sight perception and its cognitive significance – a part from the well restricted world of philosophy – concern competences of interdisciplinary value that are the main topic the debate about the origins of knowledge developed in XVIIth and XVIIIth centuries focused on in the wake of Keplero’s theory (Paralipomena ad Vitellionem) first, and, later on, of Descartes’ (Discours de la méthode e Dioptrique) and Locke’s famous achievement in Essay Concerning Human Understanding (1690) referring to the so called «Molyneux’s question». It is a matter dealing both with physiology and medicine chiefly rather than with philosophy. The example of the born blind man who, once had his sight regained, tries to recognize, through the simple act of naming, the objects previously experienced and known only through his touch belongs to a very old tradition. A twenty-five centuries old tradition, «twenty-five centuries of research and experiment concerning how sight works» (A. De Cola), during which the experience of blindness and multi-sensory sight perception played a not secondary part, paving the way to the development of lively debates about the nature of human mind in relation to sense organs. The XVIIIth century represents the link between the ancient and the modern theories dealing with the question of sight, knowledge and its legitimacy for the achievement of sensible truth. According to the Ancients, knowledge – since Aristotle’s Book A in Metaphysics where sight is celebrated as the knowledge sense – is based on the direct view of things and on a substantialistic concept of the act of viewing, traditionally deriving from the different metaphysical conceptions of reality developed from time to time (from Greeks to Arabs) and, accordingly, from the Weltanschauungen they gave rise. As far as the mechanics in medicine field is concerned, for pre-modern scholars studying how sight work means investigate the eye functions (and crystalline functions) with reference to the different species of things. Sight and knowledge are both strictly connected to another reality, an upper level reality, that transcends and stands for their cause. After Keplero and Descartes, modern speculation focuses on the cognitive processes and on the functions of the mind, spirit and soul, throughout the investigation, in the viewing experience, of real, material basis of subjectivity, namely the different ways subjectivity materially develops (memory, imagination, will, passions, desire etc.). The key-concepts paving the way to investigation, from Keplero and Descartes to Diderot and La Mettrie, are a) pictura (the material image reflecting on the eye ground) and b) imago (the rational entity human mind has to understand and interpret). As far as the mechanics in medicine field is concerned, in XVIIth and XVIIIth centuries, studying the sight work means investigate the connection between the eye, its physico-physiological phantasmata (Hobbes) and the mind. The Enlightenment is the age when the crux of this threefold question, concerning the connection between sight/perception/cognition – on the background of the post-cartesian modern theories of knowledge, from the empirical, philosophical, aesthetical perspective to the XVIIIth century medical and language theory - urges to be solved. So, it’s in Molyneux’ question that a synthesis of the most striking and different solutions proposed by philosophers, Diderot and Kant included, to the problem of knowledge and its connections with sensitivity can be found.