George Berkeley

1. Life and philosophical works

Berkeley was born in 1685 near Kilkenny, Ireland. After several years of schooling at Kilkenny College, he entered Trinity College, in Dublin, at age 15. He was made a fellow of Trinity College in 1707 (three years after graduating) and was ordained in the Anglican Church shortly thereafter. At Trinity, where the curriculum was notably modern, Berkeley encountered the new science and philosophy of the late seventeenth century, which was characterized by hostility towards Aristotelianism. Berkeley’s philosophical notebooks (sometimes styled the Philosophical Commentaries), which he began in 1707, provide rich documentation of Berkeley’s early philosophical evolution, enabling the reader to track the emergence of his immaterialist philosophy from a critical response to Descartes, Locke, Malebranche, Newton, Hobbes, and others.

Berkeley’s first important published work, An Essay Towards a New Theory of Vision (1709), was an influential contribution to the psychology of vision and also developed doctrines relevant to his idealist project. In his mid-twenties, he published his most enduring works, the Treatise concerning the Principles of Human Knowledge (1710) and the Three Dialogues between Hylas and Philonous (1713), whose central doctrines we will examine below.

In 1720, while completing a four-year tour of Europe as tutor to a young man, Berkeley composed De Motu, a tract on the philosophical foundations of mechanics which developed his views on philosophy of science and articulated an instrumentalist approach to Newtonian dynamics. After his continental tour, Berkeley returned to Ireland and resumed his position at Trinity until 1724, when he was appointed Dean of Derry. At this time, Berkeley began developing his scheme for founding a college in Bermuda. He was convinced that Europe was in spiritual decay and that the New World offered hope for a new golden age. Having secured a charter and promises of funding from the British Parliament, Berkeley set sail for America in 1728, with his new bride, Anne Forster. They spent three years in Newport, Rhode Island, awaiting the promised money, but Berkeley’s political support had collapsed and they were forced to abandon the project and return to Britain in 1731. While in America, Berkeley composed Alciphron, a work of Christian apologetics directed against the “free-thinkers” whom he took to be enemies of established Anglicanism. Alciphron is also a significant philosophical work and a crucial source of Berkeley’s views on language.

Shortly after returning to London, Berkeley composed the Theory of Vision, Vindicated and Explained, a defense of his earlier work on vision, and the Analyst, an acute and influential critique of the foundations of Newton’s calculus. In 1734 he was made Bishop of Cloyne, and thus he returned to Ireland. It was here that Berkeley wrote his last, strangest, and best-selling (in his own lifetime) philosophical work. Siris (1744) has a three-fold aim: to establish the virtues of tar-water (a liquid prepared by letting pine tar stand in water) as a medical panacea, to provide scientific background supporting the efficacy of tar-water, and to lead the mind of the reader, via gradual steps, toward contemplation of God. Berkeley died in 1753, shortly after moving to Oxford to supervise the education of his son George, one of the three out of seven of his children to survive childhood.

2. Berkeley’s critique of materialism in the Principles and Dialogues

In his two great works of metaphysics, Berkeley defends idealism by attacking the materialist alternative. What exactly is the doctrine that he’s attacking? Readers should first note that “materialism” is here used to mean “the doctrine that material things exist”. This is in contrast with another use, more standard in contemporary discussions, according to which materialism is the doctrine that only material things exist. Berkeley contends that no material things exist, not just that some immaterial things exist. Thus, he attacks Cartesian and Lockean dualism, not just the considerably less popular (in Berkeley’s time) view, held by Hobbes, that only material things exist. But what exactly is a material thing? Interestingly, part of Berkeley’s attack on matter is to argue that this question cannot be satisfactorily answered by the materialists, that they cannot characterize their supposed material things. However, an answer that captures what exactly it is that Berkeley rejects is that material things are mind-independent things or substances. And a mind-independent thing is something whose existence is not dependent on thinking/perceiving things, and thus would exist whether or not any thinking things (minds) existed. Berkeley holds that there are no such mind-independent things, that, in the famous phrase, esse est percipi (aut percipere) — to be is to be perceived (or to perceive).

Berkeley charges that materialism promotes skepticism and atheism: skepticism because materialism implies that our senses mislead us as to the natures of these material things, which moreover need not exist at all, and atheism because a material world could be expected to run without the assistance of God. This double charge provides Berkeley’s motivation for questioning materialism (one which he thinks should motivate others as well), though not, of course, a philosophical argument against materialism. Fortunately, the Principles and Dialogues overflow with such arguments. Below, we will examine some of the main elements of Berkeley’s argumentative campaign against matter.

2.1 The attack on representationalist materialism

The starting point of Berkeley’s attack on the materialism of his contemporaries is a very short argument presented in Principles 4:

It is indeed an opinion strangely prevailing amongst men, that houses, mountains, rivers, and in a word all sensible objects have an existence natural or real, distinct from their being perceived by the understanding. But with how great an assurance and acquiescence soever this principle may be entertained in the world; yet whoever shall find in his heart to call it in question, may, if I mistake not, perceive it to involve a manifest contradiction. For what are the forementioned objects but the things we perceive by sense, and what do we perceive besides our own ideas or sensations; and is it not plainly repugnant that any one of these or any combination of them should exist unperceived?

Berkeley presents here the following argument (see Winkler 1989, 138):

(1) We perceive ordinary objects (houses, mountains, etc.).

(2) We perceive only ideas.

Therefore,

(3) Ordinary objects are ideas.

The argument is valid, and premise (1) looks hard to deny. What about premise (2)? Berkeley believes that this premise is accepted by all the modern philosophers. In the Principles, Berkeley is operating within the idea-theoretic tradition of the seventeenth and eighteenth centuries. In particular, Berkeley believes that some version of this premise is accepted by his main targets, the influential philosophers Descartes and Locke.

However, Berkeley recognizes that these philosophers have an obvious response available to this argument. This response blocks Berkeley’s inference to (3) by distinguishing two sorts of perception, mediate and immediate. Thus, premises (1) and (2) are replaced by the claims that (1′) we mediately perceive ordinary objects, while (2′) we immediately perceive only ideas. From these claims, of course, no idealist conclusion follows. The response reflects a representationalist theory of perception, according to which we indirectly (mediately) perceive material things, by directly (immediately) perceiving ideas, which are mind-dependent items. The ideas represent external material objects, and thereby allow us to perceive them.

Whether Descartes, Malebranche, and Locke were representationalists of this kind is a matter of some controversy (see e.g. Yolton 1984, Chappell 1994). However, Berkeley surely had good grounds for understanding his predecessors in this way: it reflects the most obvious interpretation of Locke’s account of perception and Descartes’ whole procedure in the Meditations tends to suggest this sort of view, given the meditator’s situation as someone contemplating her own ideas, trying to determine whether something external corresponds to them.

Berkeley devotes the succeeding sections of the Principles to undermining the representationalist response to his initial argument. In effect, he poses the question: What allows an idea to represent a material object? He assumes, again with good grounds, that the representationalist answer is going to involve resemblance:

But say you, though the ideas themselves do not exist without the mind, yet there may be things like them whereof they are copies or resemblances, which things exist without the mind, in an unthinking substance. I answer, an idea can be like nothing but an idea; a colour or figure can be like nothing but another colour or figure. (PHK 8)

Berkeley argues that this supposed resemblance is nonsensical; an idea can only be like another idea.

But why? The closest Berkeley ever comes to directly addressing this question is in his early philosophical notebooks, where he observes that “Two things cannot be said to be alike or unlike till they have been compar’d” (PC 377). Thus, because the mind can compare nothing but its own ideas, which by hypothesis are the only things immediately perceivable, the representationalist cannot assert a likeness between an idea and a non-ideal mind-independent material object. (For further discussion, see Winkler 1989, 145–9.)

If Berkeley’s Likeness Principle, the thesis that an idea can only be like another idea, is granted, representationalist materialism is in serious trouble. For how are material objects now to be characterized? If material objects are supposed to be extended, solid, or colored, Berkeley will counter that these sensory qualities pertain to ideas, to that which is immediately perceived, and that the materialist cannot assert that material objects are like ideas in these ways. Many passages in the Principles and Dialogues drive home this point, arguing that matter is, if not an incoherent notion, at best a completely empty one.

One way in which Berkeley’s anti-abstractionism comes into play is in reinforcing this point. Berkeley argues in the “Introduction” to the Principles[1] that we cannot form general ideas in the way that Locke often seems to suggest—by stripping particularizing qualities from an idea of a particular, creating a new, intrinsically general, abstract idea.[2] Berkeley then claims that notions the materialist might invoke in a last-ditch attempt to characterize matter, e.g. being or mere extension, are objectionably abstract and unavailable.[3]

Berkeley is aware that the materialist has one important card left to play: Don’t we need material objects in order to explain our ideas? And indeed, this seems intuitively gripping: Surely the best explanation of the fact that I have a chair idea every time I enter my office and that my colleague has a chair idea when she enters my office is that a single enduring material object causes all these various ideas. Again, however, Berkeley replies by effectively exploiting the weaknesses of his opponents’ theories:

…though we give the materialists their external bodies, they by their own confession are never the nearer knowing how our ideas are produced: since they own themselves unable to comprehend in what manner body can act upon spirit, or how it is possible it should imprint any idea in the mind. Hence it is evident the production of ideas or sensations in our minds, can be no reason why we should suppose matter or corporeal substances, since that is acknowledged to remain equally inexplicable with, or without this supposition. (PHK 19)

Firstly, Berkeley contends, a representationalist must admit that we could have our ideas without there being any external objects causing them (PHK 18). (This is one way in which Berkeley sees materialism as leading to skepticism.) More devastatingly, however, he must admit that the existence of matter does not help to explain the occurrence of our ideas. After all, Locke himself diagnosed the difficulty:

Body as far as we can conceive being able only to strike and affect body; and Motion, according to the utmost reach of our Ideas, being able to produce nothing but Motion, so that when we allow it to produce pleasure or pain, or the Idea of a Colour, or Sound, we are fain to quit our Reason, go beyond our Ideas, and attribute it wholly to the good Pleasure of our Maker. (Locke 1975, 541;Essay 4.3.6)

And, when Descartes was pressed by Elizabeth as to how mind and body interact,[4] she rightly regarded his answers as unsatisfactory. The basic problem here is set by dualism: how can one substance causally affect another substance of a fundamentally different kind? In its Cartesian form, the difficulty is particularly severe: how can an extended thing, which affects other extended things only by mechanical impact, affect a mind, which is non-extended and non-spatial?

Berkeley’s point is thus well taken. It is worth noting that, in addition to undermining the materialist’s attempted inference to the best explanation, Berkeley’s point also challenges any attempt to explain representation and mediate perception in terms of causation. That is, the materialist might try to claim that ideas represent material objects, not by resemblance, but in virtue of being caused by the objects. (Though neither Descartes nor Locke spells out such an account, there are grounds in each for attributing such an account to them. For Descartes see Wilson 1999, 73–76; for Locke see Chappell 1994, 53.) However, PHK 19 implies that the materialists are not in a position to render this account of representation philosophically satisfactory.

2.2 Contra direct realist materialism

As emphasized above, Berkeley’s campaign against matter, as he presents it in the Principles, is directed against materialist representationalism and presupposes representationalism. In particular, Berkeley presupposes that all anyone ever directly or immediately perceives are ideas. As contemporary philosophers, we might wonder whether Berkeley has anything to say to a materialist who denies this representationalist premise and asserts instead that we ordinarily directly/immediately perceive material objects themselves. The answer is ‘yes’.

However, one place where one might naturally look for such an argument is not, in fact, as promising as might initially appear. In both the Principles (22–3) and the Dialogues (200), Berkeley gives a version of what has come to be called “The Master Argument”[5] because of the apparent strength with which he endorses it:

… I am content to put the whole upon this issue; if you can but conceive it possible for one extended moveable substance, or in general, for any one idea or any thing like an idea, to exist otherwise than in a mind perceiving it, I shall readily give up the cause…. But say you, surely there is nothing easier than to imagine trees, for instance, in a park, or books existing in a closet, and no body by to perceive them. I answer, you may so, there is no difficulty in it: but what is all this, I beseech you, more than framing in your mind certain ideas which you call books and trees, and at the same time omitting to frame the idea of any one that may perceive them? But do not you your self perceive or think of them all the while? This therefore is nothing to the purpose: it only shows you have the power of imagining or forming ideas in your mind; but it doth not shew that you can conceive it possible, the objects of your thought may exist without the mind: to make out this, it is necessary that you conceive them existing unconceived or unthought of, which is a manifest repugnancy. When we do our utmost to conceive the existence of external bodies, we are all the while only contemplating our own ideas. But the mind taking no notice of itself, is deluded to think it can and doth conceive bodies existing unthought of or without the mind; though at the same time they are apprehended by or exist in it self. (PHK 22–23)

The argument seems intended to establish that we cannot actually conceive of mind-independent objects, that is, objects existing unperceived and unthought of. Why not? Simply because in order to conceive of any such things, we must ourselves be conceiving, i.e., thinking, of them. However, as Pitcher (1977, 113) nicely observes, such an argument seems to conflate the representation (what we conceive with) and the represented (what we conceive of—the content of our thought). Once we make this distinction, we realize that although we must have some conception or representation in order to conceive of something, and that representation is in some sense thought of, it does not follow (contra Berkeley) that what we conceive of must be a thought-of object. That is, when we imagine a tree standing alone in a forest, we (arguably) conceive of an unthought-of object, though of course we must employ a thought in order to accomplish this feat.[6] Thus (as many commentators have observed), this argument fails.

A more charitable reading of the argument (see Winkler 1989, 184–7; Lennon 1988) makes Berkeley’s point that we cannot represent unconceivedness, because we have never and could never experience it.[7] Because we cannot represent unconceivedness, we cannot conceive of mind-independent objects. While this is a rather more promising argument, it clearly presupposes representationalism, just as Berkeley’s earlier Principles arguments did.[8] (This, however, is not necessarily a defect of the interpretation, since the Principles, as we saw above, is aimed against representationalism, and in the Dialogues the Master Argument crops up only after Hylas has been converted to representationalism (see below).)[9]

Thus, if we seek a challenge to direct realist materialism, we must turn to the Three Dialogues, where the character Hylas (the would-be materialist) begins from a sort of naïve realism, according to which we perceive material objects themselves, directly. Against this position, Philonous (lover of spirit—Berkeley’s spokesperson) attempts to argue that the sensible qualities—the qualities immediately perceived by sense—must be ideal, rather than belonging to material objects. (The following analysis of these first dialogue arguments is indebted to Margaret Wilson’s account in “Berkeley on the Mind-Dependence of Colors,” Wilson 1999, 229–242.[10])

Philonous begins his first argument by contending that sensible qualities such as heat are not distinct from pleasure or pain. Pleasure and pain, Philonous argues, are allowed by all to be merely in the mind; therefore the same must be true for the sensible qualities. The most serious difficulties with this argument are (1) whether we should grant the “no distinction” premise in the case of the particular sensory qualities invoked by Berkeley (why not suppose that I can distinguish between the heat and the pain?) and (2) if we do, whether we should generalize to all sensory qualities as Berkeley would have us do.

Secondly, Philonous invokes relativity arguments to suggest that because sensory qualities are relative to the perceiver, e.g. what is hot to one hand may be cold to the other and what is sweet to one person may be bitter to another, they cannot belong to mind-independent material objects, for such objects could not bear contradictory qualities.

As Berkeley is well aware, one may reply to this sort of argument by claiming that only one of the incompatible qualities is truly a quality of the object and that the other apparent qualities result from misperception. But how then, Berkeley asks, are these “true” qualities to be identified and distinguished from the “false” ones (3D 184)? By noting the differences between animal perception and human perception, Berkeley suggests that it would be arbitrary anthropocentrism to claim that humans have special access to the true qualities of objects. Further, Berkeley uses the example of microscopes to undermine the prima facie plausible thought that the true visual qualities of objects are revealed by close examination. Thus, Berkeley provides a strong challenge to any direct realist attempt to specify standard conditions under which the true (mind-independent) qualities of objects are (directly) perceived by sense.

Under this pressure from Philonous, Hylas retreats (perhaps a bit quickly) from naïve realism to a more “philosophical” position. He first tries to make use of the primary/secondary quality distinction associated with mechanism and, again, locatable in the thought of Descartes and Locke. Thus, Hylas allows that color, taste, etc. may be mind-dependent (secondary) qualities, but contends that figure, solidity, motion and rest (the primary qualities) exist in mind-independent material bodies. The mechanist picture behind this proposal is that bodies are composed of particles with size, shape, motion/rest, and perhaps solidity, and that our sensory ideas arise from the action of such particles on our sense organs and, ultimately, on our minds. Berkeley opposes this sort of mechanism throughout his writings, believing that it engenders skepticism by dictating that bodies are utterly unlike our sensory experience of them. Here Philonous has a two-pronged reply: (1) The same sorts of relativity arguments that were made against secondary qualities can be made against primary ones. (2) We cannot abstract the primary qualities (e.g. shape) from secondary ones (e.g. color), and thus we cannot conceive of mechanist material bodies which are extended but not (in themselves) colored.[11]

When, after some further struggles, Hylas finally capitulates to Philonous’ view that all of existence is mind-dependent, he does so unhappily and with great reluctance. Philonous needs to convince him (as Berkeley needed to convince his readers in both books) that a commonsensical philosophy could be built on an immaterialist foundation, that no one but a skeptic or atheist would ever miss matter. As a matter of historical fact, Berkeley persuaded few of his contemporaries, who for the most part regarded him as a purveyor of skeptical paradoxes (Bracken 1965). Nevertheless, we can and should appreciate the way in which Berkeley articulated a positive idealist philosophical system, which, if not in perfect accord with common sense, is in many respects superior to its competitors.

3. Berkeley’s positive program: idealism and common sense

3.1 The basics of Berkeley’s ontology

The basics of Berkeley’s metaphysics are apparent from the first section of the main body of the Principles:

It is evident to any one who takes a survey of the objects of human knowledge, that they are either ideas actually imprinted on the senses, or else such as are perceived by attending to the passions and operations of the mind, or lastly ideas formed by help of memory and imagination, either compounding, dividing, or barely representing those originally perceived in the aforesaid ways. By sight I have the ideas of light and colours with their several degrees and variations. By touch I perceive, for example, hard and soft, heat and cold, motion and resistance, and of all these more and less either as to quantity or degree. Smelling furnishes me with odours; the palate with tastes, and hearing conveys sounds to the mind in all their variety of tone and composition. And as several of these are observed to accompany each other, they come to be marked by one name, and so to be reputed as one thing. Thus, for example, a certain colour, taste, smell, figure and consistence having been observed to go together, are accounted one distinct thing, signified by the name apple. Other collections of ideas constitute a stone, a tree, a book, and the like sensible things; which, as they are pleasing or disagreeable, excite the passions of love, hatred, joy, grief, and so forth.

As this passage illustrates, Berkeley does not deny the existence of ordinary objects such as stones, trees, books, and apples. On the contrary, as was indicated above, he holds that only an immaterialist account of such objects can avoid skepticism about their existence and nature. What such objects turn out to be, on his account, are bundles or collections of ideas. An apple is a combination of visual ideas (including the sensible qualities of color and visual shape), tangible ideas, ideas of taste, smell, etc.[12] The question of what does the combining is a philosophically interesting one which Berkeley does not address in detail. He does make clear that there are two sides to the process of bundling ideas into objects: (1) co-occurrence, an objective fact about what sorts of ideas tend to accompany each other in our experience, and (2) something we do when we decide to single out a set of co-occurring ideas and refer to it with a certain name (NTV 109).

Thus, although there is no material world for Berkeley, there is a physical world, a world of ordinary objects. This world is mind-dependent, for it is composed of ideas, whose existence consists in being perceived. For ideas, and so for the physical world, esse est percipi.

Berkeley’s ontology is not exhausted by the ideal, however. In addition to perceived things (ideas), he posits perceivers, i.e., minds or spirits, as he often terms them. Spirits, he emphasizes, are totally different in kind from ideas, for they are active where ideas are passive. This suggests that Berkeley has replaced one kind of dualism, of mind and matter, with another kind of dualism, of mind and idea. There is something to this point, given Berkeley’s refusal to elaborate upon the relation between active minds and passive ideas. At Principles 49, he famously dismisses quibbling about how ideas inhere in the mind (are minds colored and extended when such sensible qualities “exist in” them?) with the declaration that “those qualities are in the mind only as they are perceived by it, that is, not by way of mode or attribute, but only by way of idea”. Berkeley’s dualism, however, is a dualism within the realm of the mind-dependent.

The last major item in Berkeley’s ontology is God, himself a spirit, but an infinite one. Berkeley believes that once he has established idealism, he has a novel and convincing argument for God’s existence as the cause of our sensory ideas. He argues by elimination: What could cause my sensory ideas? Candidate causes, supposing that Berkeley has already established that matter doesn’t exist, are (1) other ideas, (2) myself, or (3) some other spirit. Berkeley eliminates the first option with the following argument (PHK 25):

(1) Ideas are manifestly passive—no power or activity is perceived in them.

(2) But because of the mind-dependent status of ideas, they cannot have any characteristics which they are not perceived to have.

Therefore,

(3) Ideas are passive, that is, they possess no causal power.

It should be noted that premise (2) is rather strong; Phillip Cummins (1990) identifies it as Berkeley’s “manifest qualities thesis” and argues that it commits Berkeley to the view that ideas are radically and completely dependent on perceivers in the way that sensations of pleasure and pain are typically taken to be.[13]

The second option is eliminated with the observation that although I clearly can cause some ideas at will (e.g. ideas of imagination), sensory ideas are involuntary; they present themselves whether I wish to perceive them or not and I cannot control their content. The hidden assumption here is that any causing the mind does must be done by willing and such willing must be accessible to consciousness. Berkeley is hardly alone in presupposing this model of the mental; Descartes, for example, makes a similar set of assumptions.

This leaves us, then, with the third option: my sensory ideas must be caused by some other spirit. Berkeley thinks that when we consider the stunning complexity and systematicity of our sensory ideas, we must conclude that the spirit in question is wise and benevolent beyond measure, that, in short, he is God.