Medieval Optics, Scholasticism and Neutrality

Abstract

If value judgments are a known source of scientific error, there are cases where the error comes from an indirect lack of neutrality, i.e. by simple adherence to a way of thinking, be it based on a thinking routine, an analogy (Bachelard), a presupposition (Holton), a model (Granger) or a paradigm (Kuhn). This article proposes to study the influence of scholasticism on medieval optics, and to show how it hindered the development of optics. By adhering to the idea of the primacy of argumentation over demonstration, Roger Bacon and John Pecham obtained poor results in optics, because, paradoxically enough, they aimed at reconstructing geometric optics without geometry.