Richard Sorabji – “Aristotle on Colour, Light, and Imperceptibles”

8 September, 2017 - MA Coursework

Richard Sorabji, “Aristotle on Colour, Light, and Imperceptibles,” Bulletin of the Institute of Classical Studies of the University of London 47 (2004): 129-140.

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I am afraid, as Sorabji here is doing little more than compiling and recounting Aristotle’s statements on the nature of light, color, and sight, that I can do little more, here, than recount Sorabji’s recounting, but we will see what I might extract otherwise, if anything.

“In On Sense Perception 3, a thing’s own colour is said to be a boundary or surface, but not the boundary of the body, rather the boundary of the transparency within the body.” What is this “transparency within the body?

“Where does the borrowed colour of the sea come from? Aristotle points out that with rigid bodies — and he is thinking of opaque ones — the appearance of colour, though not its own colour, can be changed by the surroundings.” This would seem to indicate that color is a property inherent to (rigid) bodies, and is constant. Thus something’s color cannot be changed, only our perception of that color in relation to colors of its surroundings.

Aristotle provides two definitions for light: a functional one, which is clear to Sorabji, and a material definition, which Sorabji considers problematic. Functionally, it is the state in which the transparent can actually be seen through. This seems to indicate that transparency always exists for transparent things, but their transparency is only a potentiality until they are lighted (derived from the perceived opacity of darkness, where the air itself is not any less transparent, but nonetheless cannot be seen through, as though opaque?). The material definition of light, “that is of illumination, not of brightness” (I have no idea what is meant by this distinction), is that it is the presence of fire or something fire-like. This emphasis on presence is complicated by the existence of shadows, including, even, night itself. If light was solely described as a presence, would it not be that case that everything were illuminated all the time (due to the omnipresence of the sun and other fire-like stuff around the earth).

This could be resolved by Aristotle’s conceding to Empedocles that light (like Aristotle believes of sound and odor already) travels. But he will not, so it is necessary to add to presence a second property of light — directionality — while maintaining, though, that this does not imply travel. Why was it that Aristotle could grant that sound and odor travel, but not allow for the travel of light (only its presence and directionality)? This insistence on the distinction between directionality and travel makes me wonder, even though no mention of such a demonstration is made here, if Aristotle’s insistence that light does not travel, but sound does, was determined empirically. There are ways to devise trials in which the travel time, and differences thereof, of sounds are perceptible and obvious, but the immense speed of light makes it logistically very difficult to observe the travelling of light (probably impossible without advanced and precise measurement apparatus, and thus to Aristotle).

But regardless how Aristotle came to insist that light cannot travel. He finds ways to circumvent the problems it creates. Perhaps light, as a property, cannot travel, but rays (material entities bearing light-like properties?) can travel, as from the sun or from our sense mechanism within the eye outward to the thing being seen and back to the eye.

The remainder of Sorabji’s overview deals with imperceptibles (of time, size, light, sound, distance, etc.). This seems to be a version of the philosophical concern of limits so interesting to medieval scholars. These conversations are complicated and rely upon distinctions between what is imperceptible, what is strongly perceptible (what might be called observable), and what is weakly perceptible (contributes to the observability of the sensory information it, in part, composes?) Aristotle denied imperceptible time. Sorabji probes this by wondering, given that Aristotle acknowledge that sound traveled, and that two sounds could originate from points that were imperceptibly distant from one another, shouldn’t the differences in arrival time likewise be imperceptible? I speculate that perhaps Aristotle could not grant this because it could be argued with sophistry that (knowing that Aristotle grants that sound travels, meaning that sound’s arrival is not instantaneous), if the time difference between two sounds, originating an imperceptible distance from one another were considered imperceptible, then the perception of the arrival time of a sound to travelling over a great distance could be said to be imperceptibly small, the distance being the sum of very many imperceptibly small differences. Sorabji also adds that Aristotle’s resistance to imperceptible times is that it could be used by proponents of the belief that one cannot perceive more than one sense object at a time. With the possibility of imperceptibly small amounts of time, those proponent could argue that we only think we are perceiving more than one sense object at a time, but we are actually perceiving individual sense objects in such quick perception as to seem simultaneous.

Much of this discussion of the nature of color, light, and imperceptibles, and the categories used to make distinctions, eluded me.

What is this difference between “strongly” and “weakly” perceptible? If light does not travel and Aristotle eventually abandoned the theory that “sight” leaves the eye to capture the impression of the object seen, what is sight? What explains shadows, in Aristotle’s conception? What are the implications for Aristotle granting imperceptible distances, but not sizes or times?








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