The Mathematics of Plato's Psychophysics of Colour

Aristotle is often looked to as providing a potentially appropriate model for a naturalistic human psychology that is able to reconcile the commonly opposed normative or “manifest” and factual or “scientific” images of the world. In contrast, this paper argues for the greater relevance of Plato’s comparatively neglected approach, exploring this in the context of a psychophysics of colour perception—a topic still resistant to formalization in modern science. While Plato’s natural philosophy is often dismissed as caught up in a fanciful pre-scientific approach based on the “harmonies” of Pythagorean music theory (the so-called “music of the spheres”), it is argued that such Pythagorean harmony theory had actually provided Plato with the rudiments of contemporary mathematical tools useful for the study of colour phenomena, tools such as projective geometry, linear algebra, algebraic topology, and graph theory. It is argued that Plato’s approach to the psychophysics of colour underlies the colour phenomena discovered by Goethe in the nineteenth century, phenomena that are consistent with modern mathematical analyses of order. It is Plato, not Aristotle, whose work is suggestive of a successful psychophysical approach to colour.