An Essay Towards a New Theory of Vision by George Berkeley
"An Essay Towards a New Theory of Vision" by George Berkeley, published in 1709, delves into the nature of visual perception, positioning itself within the realm of experimental psychology rather than traditional philosophy. Berkeley examines how humans perceive distance and size, challenging the geometric explanations prevalent in his time, which suggested that distance perception was based on angles of light. Instead, he argues that our understanding of distance is rooted in immediate sensations and experiences, such as eye strain and the blurred appearance of nearby objects. His work also explores the distinction between visual and tactile perception, asserting that true understanding of size and distance comes from touch, not sight.
Berkeley posits that when we perceive an object at a distance, we are actually responding to visual signs that have habitual associations with tangible experiences. This leads to a critical examination of how we interpret visual information and its relationship to the tangible world. Importantly, he notes that a person lacking tactile experience cannot accurately identify objects visually, underscoring the intricate link between perception and experience. While the essay seems to contradict some of his later philosophical assertions about the existence of objects outside the mind, it serves as a foundational exploration of his ideas on perception and knowledge that would influence his subsequent works.
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An Essay Towards a New Theory of Vision by George Berkeley
First published: 1709
Type of work: Psychological study of perception
Critical Evaluation:
Berkeley is most importantly a philosopher, the second of the three British Empiricists, following John Locke and preceding David Hume. AN ESSAY TOWARDS A NEW THEORY OF VISION was published in 1709, one year before his first important philosophical work, A TREATISE CONCERNING THE PRINCIPLES OF HUMAN KNOWLEDGE. Yet the ESSAY is not primarily a philosophical work. It is a study of visual perception which is best classed with experimental psychology. Its major objective is to show how we perceive the distance and size of objects and their spatial relation to other objects. In so doing, Berkeley manages to criticize most of the accepted views on the topic. The last part of the ESSAY is a consideration of the difference between perception by sight and by touch and of whether we ever perceive the same thing by both faculties. It is in his treatment of this latter issue that Berkeley hints at the philosophical doctrines which he soon elaborated.
Most of the standard discussions of vision in Berkeley’s day were couched in terms of geometric diagrams showing how light rays converged and diverged when they passed through lenses or were reflected from surfaces of varying curvature. It was claimed that distance was estimated on the basis of the angle at which light entered the eye. His criticisms of such views give the first insight into the special character of Berkeley’s concern. He says that the perception of distance cannot be explained by lines and angles because we never perceive any such things and those who know nothing of optics perceive distance without ever thinking of such lines and angles. Berkeley wants to know what we perceive immediately which allows us to say that something is near or far away. Nor will he allow us to say we perceive the distance between us and an object. We estimate it on the basis of our immediate perceptions. There are three we typically use: first, the sensation we get when we cross our eyes to see something very close; second, the confused appearance of an object as it gets close to the eye, and third, the muscular strain involved in preventing, temporarily, the confused appearance of an object close to the eye. In addition to these we use our knowledge of the size, number, kind, and so on, of the objects in question. There is no necessary connection between these perceptions and the distance of objects. We have found the connection in experience and this gives rise to a habitual or customary connection between these two kinds of ideas. Visual perceptions are signs of distance and are related to it in the way a blush is to shame, or a word to the idea it stands for.
The more usual features of Berkeley’s doctrine come to the fore when he explains how it is that we experience the visual sign and its connection with the distance it signifies. The idea of distance comes from touch. He insists that what we really mean when we say that an object is at a distance is that certain movements will result in certain sensations of touch. Not only do we not visually perceive distance—we do not visually perceive that which we claim to be at a distance. We say that the moon is at a great distance from us, but what we see is a small luminous disk. That is certainly not what we would find if we traversed the distance between us and the moon. What is really at a distance from us is the object of touch, not the object of sight. What we actually see is merely light and colors and these are only ideas, or sensations, and are not outside the mind at all, much less at some distance or other from us. Berkeley says that we no more see distance or distant objects than we hear distance or distant objects when we say on the basis of a clatter that the coach is a block away. In experience, certain visual perceptions are always connected with certain objects at certain distances, and one learns to infer what objects are at what distances on the basis of these perceptions. A man blind from birth and newly given sight could not tell, visually, what objects were in front of him or how far away they were. He sees neither them nor the distance and has not had the experience which will permit him to infer what the visual signs signify.
Berkeley’s theory of the basis of judgments of magnitude is much the same as that for distance. Geometric explanations are rejected, and three immediate visual perceptions are offered. The first is the magnitude of the visual object; the second its confusion or distinctness, and the third its faintness or vividness. On the basis of these, singly and in combination, and the general perceptual situation, we judge the size of objects. Here Berkeley makes another distinction between visible and tangible objects. When we speak of the size of an object, it is almost always the tangible size we refer to. Visual magnitude is used as a sign and is not really noticed. Insofar as a given object is thought to have a determinate size, this is tangible size, for visible size changes with location of the perceiver.
Failure to distinguish between visible and tangible objects is easy to explain as well as the source of much confusion. Our foremost concern with the size and distance of objects is to gain the pleasant ones and to avoid the painful ones. Pleasure and pain are much more tactual than visual matters; thus, for reasons of economy, our speech and ordinary thoughts are directed to tactual magnitude and location. We so seldom have occasion to focus on visible objects in their own right that we forget they are distinct entities. Failure to distinguish them is what makes certain visual phenomena puzzling. By not confusing them, Berkeley claims to remove the anomalies connected with the moon when it appears large on the horizon, and with the fact that the retinal image of what we see is inverted.
The final quarter of the ESSAY is a negative answer to the question whether we can see and touch the same kinds of things; that is, shapes and sizes. Berkeley’s final judgment is that one who had no tactual experience of a certain shape or size could not identify it visually. A visible square and a tangible square have nothing more in common than do a man and his name, and only the regularity of our experience justifies us in taking the visible to be a sign of the tangible. He goes so far as to say that a being which could think and see but not touch could not do geometry.
The ESSAY seems to contradict Berkeley’s philosophy at one crucial point: it says tangible objects exist outside the mind, a view his philosophy explicitly denies. In Section 44 of the PRINCIPLES, Berkeley says that he realized this to be a vulgar error, but that it was beside the point to refute it in the ESSAY. Whether or not this represents complete candor, Berkeley’s ESSAY is interesting on its own and as an anticipation of his later views.