Certainty in George Berkeley’s Theory of Vision and Immaterialism

george berkeley

George Berkeley is one of the greatest and most influential philosophers of the early modern period. In defending the immaterialism for which he is most famous, he redirected modern thinking about the nature of objectivity and the mind’s capacity to come to terms with it. Along the way, he made striking and influential proposals concerning the psychology of the senses, the workings of language, the aim of science, and the foundations of mathematics. In this Companion volume, a team of distinguished authors examines not only Berkeley’s best-known achievements, but his writings on economics and development, his neglected contributions to moral and political philosophy, and his defense of religious commitment and religious life. The volume places Berkeley in the context of the many social and intellectual traditions of  philosophical, scientific, ethical, and religious  to which he fashioned a distinctive response.


Berkeley was born on 12 March 1685 in or near Kilkenny, a relatively small city within the eastern region of Ireland that had been anglicized most successfully during the seventeenth century ‘plantations’. He was educated at Kilkenny College, a residential school for Church of Ireland boys, and subsequently matriculated in 1700 at Dublin University, to which he remained attached until 1724. Following graduation in 1704, he was appointed a Fellow of Trinity College in 1707, and began work on his early philosophical publications. Some initial thoughts or reactions to what he read in other philosophers are recorded in notebooks that were published posthumously as the Philosophical Commentaries. These included often very brief, discrete notes and suggestions, some of which were subsequently expanded and defended in his published work. Berkeley published A New Theory of Vision and The Principles of Human Knowledge (Part I) in Dublin, in 1709 and 1710 respectively, but neither one attracted much critical attention. Although the Principles had been scheduled to appear in at least two parts, Berkeley seems to have deferred publication of Part II in favour of reworking his central philosophical theses in dialogue form, which he published in London, following his arrival there in 1713, as Three Dialogues between Hylas and Philonous. Berkeley wasn’t transparent; he sometimes did mask himself and his views. There was, in other words, a greater than usual split between his appearance and reality. Of course this is not to deny that Berkeley very often was as he appeared. However, in certain crucial matters concerning his highest hopes, he was able and willing to present himself in a strategic way in order to further admirable as he saw them long-term aims.

One of the most remarkable documents in the history of philosophy is a set of two notebooks Berkeley kept in his early twenties, probably between 1706 and 1708, as a rising scholar at Trinity College, Dublin. Originally published in the nineteenth century as his “Commonplace Book of Occasional Metaphysical Thoughts,” the notebooks were renamed “Philosophical Commentaries” by A. A. Luce, who saw them as “commentaries on the arguments for immaterialism which Berkeley had in his mind, and probably on paper also, before he began to make the entries” (Works 1: 3. Because there is less-than-powerful evidence for Luce’s view, the contributors to this Companion usually refer to these manuscripts simply, and more neutrally, as Berkeley’s “notebooks”). The notebooks are a unique record of an early modern philosopher just beyond his student days, working out the arguments and rhetorical strategies of what were to become his most seminal books, An Essay towards a New Theory of Vision (1709) and the Principles of Human Knowledge (1710). Robert McKim outlines the contents of the notebooks, offers guidelines for reading them, and interprets Berkeley’s developing views on a wide range of themes central to his published works: his arguments for immaterialism; the distinction between primary and secondary qualities; the divisibility of matter; the boundaries between species, sorts, or kinds; the nature of extension; the existence of unperceived objects; and the nature of spirit, mind, or soul.

Berkeley’s philosophisizing comes out, for example, in the final sections of the Principles. Of course, it may be objected that his talk of being in “the intimate presence” of God, on whom we have “a most absolute and immediate dependence” is just conventional preacher’s talk, which should not be taken too seriously. Yet I don’t think that Berkeley’s strategic manipulation in the New Theory of Vision can be dismissed so lightly. For it is clear from the changes he made in subsequent editions that he wanted to move his readers by stages to a radically theistic view, according to which God literally communicates to us through vision. Originally, in the first two editions of 1709, Berkeley gives little hint that the book has a theological message: He speaks of the “language of nature,” which he later changed in the 1732 editions to “the language of the author of nature.” Indeed, in the Theory of Vision Vindicated, Section 38, he explains that “the conclusion [of the New Theory is] that Vision is the Language of the Author of Nature.” Of course, it might be thought that Berkeley changed his mind, or came to see sometime before 1732 that his new theory of vision had a theological dimension. But that seems extremely unlikely, given what Berkeley says in Principles 44 and in his 1710 letter to Percival, where he notes that something is missing from the New Theory, “but in time I hope to make what is there laid down subservient to the ends of morality and religion.”

Samuel Bailey introduces his book on Berkeley’s theory of vision, published in 1842, by saying: The doctrine contained in “An Essay towards a new Theory of Vision,” which was first published in 1709 by the celebrated Bishop of Cloyne, seems to have become the established creed of philosophers almost from the moment of its appearance. In the last century, Hartley, Reid, Adam Smith, Condillac, Voltaire, Dugald Stewart (not to mention less eminent authors), all in succession adopted, extolled and enforced it; and a further proof of its extensive prevalence is furnished by the sanction more or less explicit, which it met with from such writers as Diderot, Buffon, and D’ Alembert.

Not surprisingly, perhaps, a closer examination of the facts about the reception of Berkeley’s theory of vision shows things are actually more complicated. When we ask what it is about Berkeley’s theory that was so generally accepted, we find that the area given approval was considerably narrower than the theory Berkeley put forward. It also becomes clear that the account of Berkeley’s theory as silencing all opposition must be tempered by recognizing the considerable reservations expressed about the theory. Finally, the view that Berkeley’s work achieved two opposing reputations also must be reexamined. It is possible to identify a strain of Berkeley commentary that not only takes a broader look at the theory of vision, but, in so doing, provides grounds for a generally positive response to Berkeley’s overall theory.

I do not have space here to give a complete history of the reception of Berkeley’s New Theory. What I intend to do first is give an account of Berkeley’s theory of vision, in order to make plain both the richness of Berkeley’s actual theory and to explain something of what Berkeley hoped to accomplish. Second, I will give a flavor of the complexity of the response to the New Theory by dipping into the history of its reception at a number of different points.  Berkeley’s writings took the form of tracts. He produced a further work on vision. This was written to elucidate and justify his previous views and to reinforce his work against the deists; it is important as a framework for his early psychology, but it contained none of the scientific quality of that great early work. Then he was soon involved in the mathematical controversy about fluxions, in which he was right and many of the mathematicians of the day were wrong; he showed that there was a fundamental flaw in Newton’s method. The importance of this great negative achievement has been inadequately recognized.

Berkeley’s theory of vision

Berkeley begins the New Theory quite baldly, with an introductory paragraph telling his readers what the book is about: “My design is to show the manner wherein we perceive by sight the distance, magnitude, and situation of objects. Also to consider the difference there is betwixt the ideas of sight and touch and whether there be any idea common to both senses”. What this paragraph does not tell us is why Berkeley considered this investigation into space perception worth doing, and in particular why Berkeley thought a consideration of the difference between the ideas of sight and touch was peculiarly relevant. These deficiencies, however, are amply made up in Berkeley’s later summary of his theory, Theory of Vision Vindicated and Explained. In that work, Berkeley tells us that instead of following the synthetical method of the New Theory, “wherein, from false and popular suppositions, men do often arrive at truth”, he will now follow the reverse order: Starting from the conclusion of the New Theory he will deduce from it the truth it supports. In Theory of Vision Vindicated, then, we find an unequivocal statement of what Berkeley set out to prove through his investigation of vision in the New Theory: It is that “Vision is the Language of the Author of Nature”. Berkeley undertook his investigation of distance, size, and situation perception in order to demonstrate the truth of the conclusions he draws in New Theory 147:

Upon the whole, I think we may fairly conclude that the proper objects of vision constitute an universal language of the Author of nature, whereby we are instructed how to regulate our actions in order to attain those things that are necessary to the preservation and well-being of our bodies, as also to avoid whatever may be hurtful and destructive of them. It is by their information that we are principally guided in all the transactions and concerns of life. And the manner wherein they signify and mark unto us the objects which are at a distance is the same with that of languages and signs of human appointment, which do not suggest the things signified by any likeness or identity of nature, but only by an habitual connection that experience has made us to observe between them.

If vision is a language, our visual ideas work as signs suggesting to us the various tangible and other meanings that come to be associated with them in our experience. The importance of the heterogeneity thesis – the claim that ideas of sight are of a different kind than ideas of touch also is spelled out clearly in Theory of Vision Vindicated. Language is a kind of symbol system in which there is a purely arbitrary connection between the signs and what they signify. Language thus provides a model whereby we can understand how visual signs can suggest, and hence call to mind, information supplied by touch. As in a language, visual signs can lead the mind to their meanings through what Berkeley calls “suggestion.” Vision need not resemble the non-visual for it to inform us of what it stands for, nor need there be a necessary connection between what we see and what it signifies so that we can reason our way from one to the other. Berkeley spends considerable amounts of time establishing the truth of the heterogeneity thesis. His basic claim is that if we pay attention to the nature of the objects of our various senses, we are forced to conclude that the proper objects of each sense are different one from another, that by sight we apprehend light and colors but not solidity, by touch we apprehend solidity, distance, and so forth, but not sounds, by hearing we are aware of sounds but not smells, and so on. Berkeley identifies the theories against which he is arguing as being committed to a homogeneity thesis, the claim that ideas of sight look like or are conceptually connected to what they signify. Both Berkeley and the theories of which he is critical assume we see only visual qualities. The theories Berkeley rejects, however, take seeing to be successful only to the extent that what we see resembles or can be connected conceptually with what it stands for. Because what we see often is not very much like what it stands for (as when the apparent moon we see, for example, is very much smaller than the real moon), vision is held to be frequently unsuccessful in providing information.

Berkeley’s New Theory of Vision did not lead him to adopt, or perhaps even to appreciate, the theory in its entirety. He was not interested in those aspects of Berkeley’s account where Berkeley spelled out the way his view differed from those of the geometric theory. To Reid, the real dangers of skepticism are represented by Hume and not by Malebranche. Reid is not willing to follow Berkeley into the heterogeneity thesis because for Reid, this would cut off a sensory world from the “real” world. Reid’s reading of the New Theory is significantly colored by his fears of immaterialism. He retains only that portion of the New Theory   the account of distance that presents the least obvious threat to realist ontology.

Towards the middle of the nineteenth century, a work appeared aimed explicitly to refute Berkeley’s New Theory of Vision. Samuel Bailey, in his A Review of Berkeley’s Theory of Vision, published in 1842, set himself to break what he took to be a hitherto unbroken chain of praise for Berkeley’s theory. Bailey’s account of Berkeley was influential immediately, and has been subsequently admired, but almost instantly it was the subject of a rebuttal by the Scottish philosopher J. F. Ferrier. Ferrier’s response is especially interesting, not only because it is able and sympathetic, but because of the pains Ferrier takes to locate Berkeley’s theory of vision within Berkeley’s broader theory, which Ferrier calls idealism. His attack on Berkeley reveals that Bailey prefers a very different approach to the theory of vision. Bailey is convinced an appeal to consciousness plainly shows that what we perceive by sight are external, spatially organized objects. His position is that physiological facts about retinas, optic nerves, or anything else are irrelevant to determining the nature of the deliverances of consciousness. It is perfectly obvious that we do indeed see external, solid objects. If information about our physiology does not explain this, then the most we are entitled to conclude is that we don’t know how it is done. Bailey’s position is that we have no need of tactual information in order to see objects in space. Indeed, our tactual information in general is inferior to that provided by vision.

In 1956, D. M. Armstrong published a discussion note commenting on a paper of C. M. Turbayne’s, “Berkeley and Molyneux on Retinal Images.” While this note is the only point of contact between the two, the issues raised in it are symptomatic of the much wider differences to be found in their more extended treatments of the New Theory – Armstrong’s Berkeley’s Theory of Vision and Turbayne’s Myth of Metaphor and his editor’s commentary on Berkeley’s Works on Vision. These works illustrate, each in an admirably clear manner, elements of the different approaches we have seen taken towards Berkeley’s theory of vision. For Armstrong, on the one hand, Berkeley is most centrally an idealist, while Turbayne, on the other, stresses the importance of the language analogy for a realist reading of Berkeley. While Armstrong makes several points in his note, the one most clearly expressing the contrast between himself and Turbayne concerns their differing views about the goals of the New Theory. Armstrong criticizes Turbayne for endorsing Berkeley’s own account of the relationship between the New Theory and the Principles as a halfway house to immaterialism. Turbayne claims the account of vision worked out in the New Theory provided Berkeley with an important principle enabling him to establish the immaterialism of whose truth Berkeley was already convinced. For Turbayne, the importance of the New Theory is it allowed Berkeley to demonstrate that the proper objects of sight are not “images of external things,” as Berkeley puts it in Principles 44.

Finally, it should be clear that Armstrong and Turbayne not only have different versions of the point of the New Theory, they also have different versions of the immaterialism they take to be Berkeley’s ultimate aim to establish. For Armstrong, the New Theory would have been a halfway house to immaterialism if Berkeley had been able to demonstrate the mind-dependence of visual objects. Thus, a full-blown immaterialism presumably seeks to establish the mind-dependence of all sensible objects. Immaterialism is a view that says things exist “in the mind” and not “out there.” Turbayne, on the other hand, ties immaterialism to a rejection of claims of seventeenth-century materialists, in particular, that our ideas can stand for or represent mind-independent matter. Turbayne sees Berkeley as developing an alternative theory of how ideas represent.

Several years later George Berkeley produced the most extraordinary work ever written by a modern philosopher, Siris, an investigation of the medical and divine properties of tar-water. He was in search of a panacea, partly because of the conditions of health in his neighbourhood, but also because certain troubles of his own, which had dogged him for a number of years, had now come to a head. Fantastic though the ideas of this work are, it should not be thought that he had become senile. It remains to say a few words about Berkeley’s personality. Everything that comes down to us, including a fair-sized correspondence, reveals him as a man of unusual charm, possessing the great majority of those character-traits we admire and almost none of us have ever did. Berkeley does not therefore contend that such doctrines have no “assertoric” significance. On the contrary, although he emphasizes the importance of “worship in spirit & in truth … not lip worship, not will-worship, but inward and Evangelical”, his point is rather that we should be moved by what we also understand.


  1. Cf. Works, 6: 90, where Jessop drew attention to the 67 queries which conclude The Analyst (1734); T. W. Hutchison, “Berkeley’s Querist and its Place in the Economic Thought of the Eighteenth Century,” British Journal of the Philosophy of Science: 4 (1953–4): 52–77, 54. For an interesting discussion of what Berkeley may have intended in adopting such a format, see C. George Caffentzis, “Querying the Querist,” Maine Scholar 3 (1990): 287–307.
  2. Joseph Johnston, “The Irish currency in the Eighteenth Century,” reprinted as Berkeley’s Querist in Historical Perspective, chapter 6. Cf. Queries 94, 485, 573.
  3. A. A. Luce, The Life of George Berkeley, London and Edinburgh, 1949.
  4. See G. W. Leibniz, “A New System of Nature,” in Philosophical Essays, trans. and ed. Roger Ariew and Daniel Garber (Indianapolis: Hackett Publishing Co., 1989), 139.
  5. Harry M. Bracken, The Early Reception of Berkeley’s Immaterialism, 1710–1733, revised edition (The Hague: Martinus Nijhoff, 1965).
  6. William Porterfield, A Treatise on the Eye, The Manner and Phaenomena of Vision (London and Edinburgh: A. Miller, G. Hamilton, and J. Balfour, 1759).
  7. Samuel Bailey, A Review of Berkeley’s Theory of Vision, Designed to Show the Unsoundness of That Celebrated Speculation (London: James Ridgway, 1842), reprinted in Berkeley on Vision: A Nineteenth Century Debate, ed. George Pitcher (New York: Garland Publishing Company, 1988)

Bionote: Working as an Assistant Professor in History, CUHP. My area of interests was Cultural Theory, Social Theory and Contemporary History.


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