The Ontological Status of Light and Color in St. Thomas Aquinas | Prof. John Boyer
Oct 7, 2024
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John Boyer, a Ph.D. candidate specializing in medieval Aristotelian scholasticism at the University of St. Thomas, takes listeners on an enlightening journey through St. Thomas Aquinas's views on light and color. He explores the ontological importance of light in perception, referencing Aristotle's theories, and highlights contrasts with ancient thoughts on visibility and color. Boyer also discusses how these philosophical ideas have influenced our understanding of reality and perception through the lens of causal explanation.
The lecture distinguishes between emission and intro mission theories of vision, highlighting St. Thomas Aquinas's preference for Aristotle's perspective on light and color perception.
Aquinas critiques the materialistic understanding of light, proposing it as a modifying quality in transparent media essential for transmitting color perceptions to the observer's eye.
Deep dives
Ancient Theories of Vision
Two primary theories of vision are discussed, namely the emission and intro mission theories. Emission theory, championed by Plato, posits that the eye sends out light, likened to fire, to engage with objects, whereas intro mission theory, supported by Aristotle, suggests that light enters the eye from outside sources. St. Thomas Aquinas adopts Aristotle’s view and builds upon it, recognizing the contextual differences that arose in understanding Aristotle's original concepts in light of subsequent philosophical commentary, particularly by Arabic thinkers. This sets the stage for a deeper exploration into the role of light and color in the process of seeing.
The Nature of Light and Color
Light is characterized as the actuality of a transparent body, revealing its critical role in vision by making colors perceivable. St. Thomas distinguishes between light as an active quality of both light sources like the sun and illuminated mediums like air or water. He asserts that color, while visible, is not inherently present in objects until light activates the potential for color perception, thus emphasizing that colors exist in a dark environment only in a latent form. This relationship highlights how light and color serve various functions in perceptual experiences, with light being a prerequisite for the visibility of colors.
Light's Ontological Status
St. Thomas argues against the notion of light as a physical body by critiquing the atomist view of light as composed of particles, emphasizing that light is a property of transparent media rather than a substance. He provides logical proofs to support that light must be understood as a modifying quality that illuminates a medium instantaneously, as opposed to having a physical presence that requires transportation and motion. The distinction between lux and lumen is made, where lux pertains to the light of a source, like the sun, while lumen refers to the radiant light seen in the medium. This elucidation establishes light in a metaphysical framework, transcending simple materialistic definitions.
The Interplay of Light, Color, and Perception
Light is understood to be necessary for sight not only as an illuminative agent but also as a medium that carries the color perceptions from objects to the observer's eye. St. Thomas's insights delineate that colors do not affect sight unless there is an illuminated medium present to bridge the gap between the object and sense perception. He explores how the air conveys color into our vision without itself altering, supporting the notion of immaterial conveyance of information as a means of sight. This duality of the material properties of light and the immateriality of color presentation in perception underscores the complexity of sensory experiences.
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Exploring the Ontological Status of Light and Color
Professor John Boyer explores how St. Thomas Aquinas differentiated himself from Aristotle through arguing that light is not a body or spiritual entity, but an active quality of transparent mediums, enabling vision and color perception.
This lecture was given on July 18th, 2024, at The Dominican House of Studies.
John Boyer's training is in the History of Philosophy, specifically medieval Aristotelian scholasticism. His philosophical interests include issues in philosophy of science and philosophy of nature (e.g. causality, explanation, time, quantum physics), with an emphasis on their treatment in the Aristotelian-Thomistic tradition.
His current research focuses on Aristotle's philosophy of science (especially his theory of causal explanation) and how it was built upon by scholastic thinkers such as Albert the Great and Thomas Aquinas.
John is a Ph.D. Candidate in Philosophy at the Center for Thomistic Studies, University of St. Thomas (Houston). Prior to coming to Loyola, he taught philosophy at the University of St. Thomas (Houston). He earned an MA in philosophy at the Center for Thomistic Studies and a BA in liberal arts from Thomas Aquinas College (California).
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