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Berkeley, Principles 1-24

Immaterialism

You were represented in last night’s conversation, as one who maintained the most extravagant opinion that ever entered into the mind of man, to wit, that there is no such thing as material substance in the world.

– Hylas (a character in Berkeley’s Three Dialogues between Hylas and Philonous)

Berkeley’s thesis that there is no material world might seem so absurd that it does not need to be taken seriously. In part this is because it is easily misunderstood. Berkeley did not deny that there is an external world, if by that we mean that there are other things distinct from the self and its ideas. He did maintain, however, that the only things that exist are spiritual things and their ideas. We might represent this by saying that Berkeley maintained that only minds exist and that there are no bodies, but even this would not be entirely correct. It all depends what we mean by “body.” Berkeley maintained that bodies are nothing more than collections of ideas, existing in the minds of perceivers. If that is what we take bodies to be, then Berkeley did not even deny the existence of bodies. Similarly, if we take bodies to be physical things, then Berkeley did not deny the existence of physical things. “Physical thing” is just another name for body, so in whatever sense bodies exist, physical things also exist. If, on the other hand, we take bodies to be mind-independent, unthinking substances, possibly possessing such characteristic qualities as extension, mobility, and solidity, then Berkeley did deny the existence of body. However, he was quick to add that all anybody really thinks of when they think of bodies is their own ideas. A few philosophers, corrupted by scholastic jargon, speak of bodies as being “material substances,” but no one has any clear idea of what it means to be material or what it means to be a substance. Berkeley went so far as to maintain that ordinary people, uncorrupted by the dogmas of philosophy, think just the way he did. They consider bodies to be just collections of their own ideas. His conviction that ordinary people are on his side was so deep that, after seeing his thoughts widely scorned and condemned subsequent to their initial publication, he formulated the project of moving to America and founding a university in Bermuda, convinced that native Americans, uncorrupted by European ideas, would be more open to the truth of what he had to say.

There is nonetheless something strikingly counterintuitive about Berkeley’s position, even when it is correctly understood. If bodies are just collections of our ideas, then they come into existence and go out of existence as our ideas come into and go out of existence. If I am looking at a body, and then I turn my back, my ideas of the body cease to exist. But if the body just is the collection of my ideas, then it ceases to exist as well. So bodies exist only when they are being perceived.

This is not consistent with common sense, whatever Berkeley might have thought. At Principles 3 Berkeley claimed that when ordinary people speak of something they are not currently perceiving, such as the books in their study, as existing, all they mean to say is that they were perceived in the past and would be perceived again were they to go back there. But this is not all that ordinary people believe. Ordinary people believe that we are located in space and that bodies occupy locations in space outside of us and exist independently of being perceived by us, so that when we turn away from them, they continue to exist outside us.

Berkeley based his position on the rejection of the ability to form abstract ideas. He claimed that we can have no thought of the existence of a body apart from perceiving or thinking of the body we think to exist, so that to attempt to distinguish between the existence of a body and the perception of it, as we must do when we claim that bodies can exist unperceived, is to attempt to form an abstract idea. If abstract ideas are impossible we cannot even think that bodies can exist apart from being perceived, and we use words that have no meaning if we say that they do.

Unfortunately for Berkeley, common folk do speak of bodies that exist unperceived all the time. This would be an oddity if they cannot even form the ideas of what they are talking about. To further defend his position, he claimed that even though bodies are just collections of ideas, they are not collections of ideas of imagination made up by us, but collections of ideas of sense, imposed on us by God. God works in supremely regular ways in bringing about these ideas in us. For example, if I put the corn in the silo, God will not give me ideas of corn unless I go into the silo — and will give me ideas of corn whether I want them or not if I do so. Counting on God to keep on acting in this supremely regular way is tantamount to counting on landmarks to continue to be perceived in the same places, on immobile objects to be perceived again at the places where we left them, and on bodies in motion to be perceived at those places where the laws of motion should dictate them to be at later times. When farmers and merchants say that bodies continue to exist unperceived when they talk about the corn enclosed in silos, this is all they really mean. They think of the bodies they say exist to either be perceived by some other mind or to be things they would perceive were they or some other spirit to go into the silo, or would have perceived had they or some other spirit done so. We get all the same ideas we would get if there were an external world of independently existing bodies that act on our sense organs to bring about ideas in us. Only there is no such world. There is only God, acting to bring about ideas in us in the same way.

Descartes, contemplating this possibility, had declared that a God who would behave in such a fashion would be a deceiver for creating us with such a strong inclination to suppose that bodies continue to exist independently of being perceived. But Locke had already observed that as long as we feel real pain when we stub a toe on a stone or real pleasure when we bite into an apple, it doesn’t matter whether the stone or the apple is an independently existing external body or a dream existing only in us. If there is no external world containing a fire, but moving your idea of your hand into your idea of the fire causes the same pain that it would if you had a hand in the fire, and leaves you forever afterward unable to give yourself an idea of that hand whole, or give yourself ideas of it moving and doing things you used to be able to do with that idea, then where is the deception in getting ideas of painful heat from fire? Either way, whether there is a material external world or only an ideal world, the effects are the same and you are warned in advance not to do that thing on account of those effects. As long as the idea comes and goes independently of your will, and you get the pleasure or pain accordingly, the thing is as real for you as anything needs to be, and has to be treated as such. Berkeley not only took this lesson from Locke but tried to make the further point that far from deceiving us, God is actually giving us certain ideas in order to advise us what will happen next, depending on how we move and otherwise act. Far from being a remote and disinterested creator, God is constantly with us, and constantly speaking to us in his own language of ideas, warning us what is about to happen next. As for being a deceiver, since unperceived existence is unthinkable, all our references to bodies that are not currently being perceived are just references to collections of ideas that are or might under other circumstances be perceived by ourselves or others, and there is no error in that. The belief in the unperceived existence of material substances is not the belief of ordinary people but the belief of a few philosophers, who have corrupted themselves by bad reasoning and sought to employ this bizarre belief for atheistic and sceptical purposes, seeking to substitute the agency of blind matter for that of God and introduce a universal doubt about all things.

Even with these clarifications, Berkeley’s position might still seem too absurd to be taken seriously. But those who have bothered to study his arguments have found his position to be less easy to refute than we might expect.

QUESTIONS ON THE READING

1. What are the objects of human knowledge?

2. Is there anything said by Berkeley in Principles 1 that Locke would have disagreed with?

3. What is required in order for an idea to exist?

4. What do I really mean when I say that something I am not now in a position to perceive exists?

5. What are the limits on my power of abstraction?

6. Why should the fact that extension in general (i.e., Cartesian intelligible extension like that the understanding finds in the wax) is inconceivable unless it is supposed to have some specific shape, size and velocity entail that extension in general cannot exist outside of the mind?

7. Why should we suppose that neither sense nor reason informs us of the existence of solid, extended corpuscles located in space outside of the mind?

8. What is wrong with supposing that it is at least plausible that our sensations are caused by some sort of solid, extended substance existing in space outside of the mind and acting on our sense organs when we come into contact with it?

NOTES ON THE READING

Though Berkeley devoted all of Principles 1-24 to arguing that material substances do not exist, his main argument is over by the end of Principles 6 — indeed, by the end of Principles 3. Principles 1-3 survey the objects of human knowledge and argue that they are all collections of ideas perceived by us. It follows that none of them can exist unperceived, though this startling conclusion is only first drawn in Principles 4. Principles 4-6 charge that those who think otherwise are caught in a “manifest contradiction” and explain how this could have happened to so many people. Principles 7-24 mount arguments for the complementary conclusion that there can be no material things.

Principles 1-3. Why sensible objects cannot exist apart from being perceived. Principles 1 could have been written by Locke, and Berkeley likely intended it to sound as if it had come from the pages of Locke’s widely respected Essay. Anyone who surveys the objects of human sensory experience, Berkeley claimed (following Locke), will find that they consist either of ideas of sensation, coming from the five senses, or ideas of reflection obtained by attending to the operations of the mind or the passions aroused in it by the pleasing or displeasing aspects of its ideas of sense. All the things that we call objects and consider to exist around us are collections of ideas. At least, this is all we experience objects to be, and all we have in mind when we talk about things. An apple or a book is just a collection of ideas. Some of these ideas are ideas of sensation or memory; others may be ideas of imagination. (For example, I may only imagine the taste of an apple while looking at it.) But there is nothing more to objects.

But ideas only exist in minds and they only exist insofar as they are perceived by those minds. If objects are just collections of ideas, then the same must be true of them. They can exist only insofar as they are perceived. Moreover, Berkeley claimed, this is all that people ever mean when they claim that something exists. They mean that the thing is perceived by someone. Or, if there is no one around, they mean either that there was someone around at an earlier time who perceived it at that earlier time or that if someone were to perform certain actions (those followed by our getting ideas of our bodies moving to occupy a certain place) then they might perceive it. (On this account, we never claim to know that something now exists if no one is perceiving it. If we are not ourselves perceiving something, we must rely on the testimony of others to be assured of its existence. And if no one is now perceiving it, we can get no further than thinking it existed once, when someone did perceive it, or that it might be perceived by someone who is appropriately positioned. Recall, in this context, that Locke himself denied that we can be assured of the existence of objects that are not currently being perceived.)

The entire argument is nicely summed up at the close of Principles 4:

1. Sensible objects are things we perceive by sense.

2. The only things we perceive by sense are our own sensations.

3. Our sensations cannot exist independently of being perceived.

Sensible objects cannot exist independently of being perceived.

What does it mean to have an idea? Perhaps the most serious objection to Berkeley’s argument is that it rests on a particular view of what it means to have a sensation or idea — a view that need not be accepted. On Berkeley’s view, an idea is a mental state. At the same time, however, it is an object of perception. Combining these two claims results in the view that an idea is a kind of object that exists in the mind and that the mind somehow looks at or perceives this object.

There is much to recommend this view (it accounts for what we are perceiving when we misperceive; it accounts for how different people can perceive the same object in different ways; it accounts for how we can perceive objects that are at a distance from us; and it accounts for what we are thinking about when we think about objects that do not exist), but there are also problems with it. One is that it is threatened with an infinite regress. If we perceive objects by having ideas, then how do we perceive ideas? By having ideas of our ideas? But then how do we perceive those ideas? Berkeley would have responded to these questions by saying that for an idea to be perceived by a mind just is for it to exist in that mind. After all, for Berkeley, the being of an idea cannot be separated from its being perceived.

But there is another way to avoid the regress that does not lead to Berkeley’s immaterialist conclusions. This is to maintain that ideas are not objects that are perceived by minds but acts or operations that are performed by minds. When the mind perceives an object it performs an act, the act of perceiving. This act exists in the mind and it exists only when the mind performs it. But the object that is perceived through performing this act is distinct from the act. Just because the act of perceiving exists in the mind and exists only when the mind performs it, it does not follow that the object perceived by performing this act is similarly located in the mind and dependent on it.

This view, too, has much to recommend it. The chief among its advantages is that the qualities that we perceive are not very good candidates for being mental states. We perceive things like redness, hardness, squareness, and rotten smells. But we do not think that the mind that perceives red turns red, that the mind that perceives hardness turns hard, that the mind that perceives squareness takes on a square shape, or that the mind that smells something rotten itself has a rotten smell. Instead, we are more inclined to suppose that if there are such things as ideas of redness or hardness, or squareness, or rotten smells, and those ideas are mental states, then they must be distinct from the things they are “of.” To have an idea of red cannot be the same thing as to be red, but must be something more like performing the act of thinking about red, so that the act of thinking exists in the mind, but without the mind taking on the redness thought about. And the same would have to hold for hardness, squareness, rottenness, and so on. But then the idea is one thing, and the object the idea is of is something else, and it ought to be in principle possible that the one could exist when the other does not — so I can think of objects that do not exist, and objects can exist even though they are not thought of or perceived.

Berkeley was aware of this objection, and at different points in his work he said things that might be taken to address it. Chief among them is Principles 49:

… it may perhaps be objected, that if extension and figure exist only in the mind, it follows that the mind is extended and figured; since extension is a mode or attribute, which (to speak with the Schools) is predicated of the subject in which it exists. I answer, 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; and it no more follows that the soul or mind is extended because extension exists in it alone, than it does that it is red or blue, because those colours are on all hands acknowledged to exist in it, and nowhere else.

It might be objected that this is tantamount to giving in to the objection, and accepting that ideas must be distinct from the things they are of, from which it would seem to follow that idea and object must be different things. But Berkeley’s claim here was that the only way that things like redness or extension can exist is as the object of ideas. It makes no sense to consider them to have an alternative mode of being, independent of the ideas that are of them.

Principles 4-6. Why so many have failed to recognize the impossibility of the unperceived existence of sensible things. Having argued that sensible objects cannot exist unperceived because they are just collections of ideas received by sense, and ideas of sense cannot exist independently of being perceived, Berkeley proceeded to claim that anyone who supposes the contrary is caught in a “manifest contradiction.” The contradiction, of course, is maintaining that something that cannot exist unperceived, namely our ideas, nonetheless can exist unperceived. The contradiction is so blatant that Berkeley had to wonder how anyone could have missed seeing it. His answer was that it happens because of a widespread acceptance of the belief that we are able to form abstract ideas. To briefly review what was discussed in the previous chapter, Berkeley was of the view that his predecessors and contemporaries, particularly Locke, had believed that we can form separate and distinct ideas of things that cannot exist separately, such as shapeless extension and colourless shapes. If you think we can do that, Berkeley observed, then you will not balk at the view that we can form separate and distinct ideas of the existence of a sensible object and the perception of a sensible object. And because you think you can conceive the two separately, you will maintain that it is possible for the one to occur without the other. In fact, Berkeley insisted, things are the other way around. The only ideas that can be abstracted or separated are ideas of things that can in fact exist separately. But our ideas of sense cannot exist apart from being sensed. Therefore we cannot form abstract ideas of sensible qualities existing apart from being perceived. And anyone who tries to do so will see that they cannot bring it off.

Principles 7-24. Why material things that are distinct from sensible things, though perhaps resembling them, cannot exist unperceived. Even if we grant that Berkeley has established that sensible things, the things we perceive by means of our senses, cannot exist apart from being perceived, we might still wonder whether other things also exist — and not just other minds, but other unthinking, material things. Berkeley turned to consider this possibility over Principles 7-24. Over these sections he did not just argue that we couldn’t know that material things exist. He argued instead that it is impossible that they could exist. This is because the very notion of a material thing is empty, meaningless, and even self-contradictory. Insofar as we think of material things, we think only of our ideas, which cannot exist independently of being perceived. If we attempt to describe what the term “material thing” might refer to, we end up describing it in terms of qualities like extension, motion, solidity, and colour, which are qualities of our ideas and things that cannot in fact exist independently of being perceived. If we give up on the attempt and take material things to be indescribable, then we don’t know what we are talking about when we claim that they might exist. We aren’t in fact saying anything when we say that material things might exist.

Principles 7-15. The meaninglessness of “material.” The educated opinion of Berkeley’s day was that the sensible qualities of colour, smell, taste, are sensations, not qualities of bodies. As such they can only exist in minds, not in material things. This was the view of Hobbes, Galileo, Descartes, Locke, and Bayle, and Berkeley was happy to help himself to it without supplying any further justification (though the first part of his Three dialogues between Hylas and Philonous argues for it in some detail). He added, however, that not only could material things not have colour or smell, or taste, etc., they could not have qualities that are anything like what we experience as our sensations of colour, taste, smell, etc. His reason was that, as he put it, “an idea can be like nothing but an idea” (Principles 8). Consider heat. Heat is a feeling that we experience when we touch hot things. But a feeling can’t be like anything other than a feeling and feelings can only exist in minds. To suppose that an unthinking, material thing could have anything in it like our feeling of heat would be like supposing that an unthinking material thing could have something in it like our feelings of pain or pleasure. This is absurd. The same could be said of colour. If we accept that colour does not exist outside of us, on the surfaces of mind-independent material things, then it too is just a sensation or a way of feeling.

In addition to appealing to this “likeness principle” to deny that material things could have qualities resembling what we experience as heat, colour, smell, taste, etc., Berekeley added something else. He included figure and motion on the list of sensible qualities (Principles 7). In other words, he rejected the distinction between primary and sensible qualities. This was something Bayle had done, following Foucher, and Berkeley endorsed their arguments while adding a powerful one of his own. He claimed that it is impossible for the primary qualities to exist apart from sensible qualities like colours, heat and cold, tickles. If they can’t exist apart from one another, and we accept that the sensible qualities are just feelings that can only exist in minds, then the primary qualities can only exist in minds as well.

Berkeley’s reason for holding this view was a specific application of his claim about the impossibility of forming abstract ideas. We can’t abstract the idea of solidity from the idea of extension, because the idea of solidity is just the idea of resisting another body that tries to move into the space you occupy, and so involves the idea of extension. But we can’t abstract the idea of extension from the idea of shape. Every extension must be the extension of some shape or other. And for there to be shape there must be edges that define the shape. But for there to be edges there must be contrasting sensible qualities. What makes an edge is a difference in colour or a difference in tactile feelings of pressure. So where there are no colours or tactile feelings there can be no edges, hence no shape, hence no extension, hence no solidity. But colours and tactile feelings are ideas that exist only when they are perceived. So solidity and extension must be only ideas, that exist only when they are perceived.

In addition to making this ingenious appeal to the inseparability of the primary from the sensory qualities Berkeley reiterated the point Foucher had made and Bayle had alluded to: that the same arguments that are used to prove the ideality of the sensible qualities can also be used to prove that the primary qualities are merely ideas in us and not qualities of mind-independent things. These arguments were perceptual relativity arguments, which turn on the observation that the same object can appear differently, from which it is concluded that what we experience are just appearances, which exist only in us and not real qualities of the object. The same bucket of water, for example, will feel warm to a cold hand and cold to a warm hand. Because it cannot be both warm and cold at the same time, we conclude that these qualities must exist only in us — or, that if they do exist in the body, we do not know which, if any, of the qualities we experience is the one that is to be found in the body. But, just as feelings of temperature vary with the hand that feels them, so shapes and numbers vary with the conditions under which objects are viewed. Single objects look doubled to a person who is pressing on the side of their eyeball. A penny really looks elliptical when lying on a table but round when held up before the eye, as is demonstrated in painting. And so on. If in the one case we say that the heat and cold we feel are merely ideas in us and not real qualities of the bodies outside of us, then by parity of reasoning we should say that the shapes, sizes, numbers, and other modes of extension and solidity that we see and feel are merely ideas in us and not qualities in bodies. (It bears noting that Berkeley was not as pleased with this argument as he was with the earlier argument from the impossibility of abstracting the primary from the sensible qualities. This is because the argument allows that there might be extended, solid objects that exist independently of being perceived and only establishes that we do not know how their extension and solidity is modified. The earlier argument, in contrast, establishes that mind-independent, material things could not be extended or solid.)

Principles 16-17. The meaninglessness of “unthinking thing.” In proving that mind-independent material things could not be extended or solid, Berkeley established that we have no clear idea of what we mean by calling a mind-independent material thing a material thing. The term “material” could not mean “extended” nor could it mean “solid” since extension and solidity cannot exist apart from sensible qualities, which cannot exist apart from being perceived. But then it is not clear what “material” would mean, especially given that filling space is the quality that natural philosophers throughout the period had taken to be essential to matter. Having established this much, Berkeley turned to the other component of the idea of a mind-independent material thing: the notion of a “thing” or substance. Suppose we accept that material (i.e. spatially extended) things cannot exist independently of being perceived. Might we nonetheless suppose that some sort of unthinking thing exists outside of us? The trouble with this claim is that “unthinking” is a purely negative term. It tells us what the thing is not, but not what it is. So if there is any content to the claim that unthinking things might exist unperceived, that content must be carried by the residual notion of a thing. Berkeley charged that when this notion is stripped of all the sensible qualities and all the primary qualities, nothing is left of it but the notion of some substance or substratum in which non-mental qualities of some unknown sort might inhere. But what do we mean when we talk of a substance in which qualities inhere or a substratum that supports qualities? Literally, the Latin term “substance” means that which stands underneath something else and props it up. “Substratum” likewise refers to that which is spread under something else. But this cannot be what philosophers mean when they talk of substance and substratum, if for no other reason than that these are spatial relations, having to do with the extension and relative placement of things, and extension has already been proven to have no existence apart from being perceived. But far from anyone having explained what other meaning the terms “substance” and “substratum” might carry, philosophers like Locke had candidly confessed that they had no idea what the terms might mean. The terms refer to “something I know not what,” as Locke had put it. Berkeley drew the obvious conclusion: since neither the term “material” nor the term “substance” have any meaning, people do not know what they are talking about when they claim that material substance could exist independently of being perceived.

Principles 18-20. Why we can’t deduce that material things must exist even though we know nothing about them. There remains one recourse for a materialist. A materialist might claim that even if we cannot describe material things in any way, we can still infer that they must nonetheless exist. The inference is based on the claim that the best way to account for why our sensations exist is to suppose that material things exist apart from us, and cause us to feel sensations when we approach them. Berkeley had two main objections to this view. The first was that the case of dreams shows us that we don’t need to be affected by anything in order to get ideas that are so closely patterned on the ideas we get from waking experience as to be indistinguishable from waking experience. But we know the ideas we get in dreams are not produced by material things acting on us. Since the two sets of ideas, the dreaming and the waking, are so much alike as to be indistinguishable, the fact that the one is not caused by material things proves that the other need not be caused by material things either.

Berkeley’s second argument went further, and established that material things not only need not exist to cause our waking experiences, but that they could not possibly cause those experiences. Here again Berkeley’s job was easy, because his contemporaries all had to agree with his premise. They all accepted that matter is very different from mind — so different that it is impossible to understand how matter could act on mind to cause it to have sensations.

Berkeley’s Principles 20 backs these arguments up by offering an early version of what has since been referred to as the brain in the vat case. The case is of an amputated brain, kept alive in a vat and electronically stimulated by a scientist to receive all the same experiences it would obtain were it attached to a human body and living an ordinary human life. The only difference is that Berkeley’s example is not of an amputated brain but of a disembodied mind. Berkeley observed that a mind that is directly affected by God with all the same sensations that I receive because of the way I am acted on by what I suppose are external bodies would have experiences that are indistinguishable from mine. The example goes to show that there is nothing about my experiences that could entitle me to infer that they are even probably caused by external objects.

Principles 22-23. The “master argument.” After an obscure allusion, in Principles 21, to “errors and difficulties” that spring from materialism but are avoided by Berkeley’s immaterialist alternative (Berkeley was thinking of the atheism and scepticism discussed in the previous chapter) Berkeley turned to offer a final argument for his position. The argument is prefaced by the claim that he was “content to put the whole upon this issue” and “give up the cause” if this argument were successful. For this reason, it has come to be referred to as the “master” argument. The argument is neither clear nor uncontroversial, and has provided a great deal of amusement to formal logicians who like to fight over whether it involves an illegitimate shift in the scope of a modal operator. The argument takes the form of a challenge: if you can so much as conceive it possible for an extended movable substance, a sound, a figure, or a colour to exist outside of some mind that perceives that substance, Berkeley will give up his views and agree that you are correct. Berkeley was confident that you cannot do that, because anything you conceive of as possibly existing outside of the mind of any perceiver must of course be conceived by you, and so is not outside of the mind of any perceiver after all. The best you can do is conceive of an object that is not now being perceived by anyone else even though you are having ideas of it. The grain in the silo that I mentioned earlier is like this. Even though I suppose that the grain is enclosed in the silo, so that no one can perceive it, what I am talking about is a collection of ideas of imagination that are now existing in me and that I take to resemble ideas of perception that others would have if they were to do certain things (e.g., go into the silo).

Generations of scholars have been stunned by this apparently simple argument, and convinced that such a strong thesis as that of the impossibility of the unperceived existence of bodies could not be based on such an apparently trite observation as that conceiving something existing outside of all minds involves conceiving that thing. This has led them to look for some sophism concealed in the argument. It may be, however, that the master argument is not a special and particularly decisive argument at all, but merely a way of bringing people to appreciate that it is impossible for them to abstract the idea of the existence of a sensible thing from the idea of its being perceived. Berkeley had already claimed in Principles 5 that the main reason why people believe that bodies exist independently of being perceived is that they suppose that they can abstract the idea of being from the idea of being perceived. It is not surprising, therefore, that he should have decided to rest his case on a challenge to people to form such an idea. Supposing they cannot rise to the challenge would not prove that bodies cannot exist unperceived. It would merely remove people’s chief reason for thinking that they can.

ESSAY QUESTIONS AND RESEARCH PROJECTS

1. Was Berkeley successful in his attempt to claim that when ordinary people speak of things existing unperceived they do not really mean it but instead really mean something else?

2. On different occasions Berkeley said different things about what it properly means to say that something exists unperceived. Sometimes he said it means that the thing is being perceived by God, who sees all, but not by any other finite spirit. At other times he said it means that the thing was previously perceived by some spirit, from which we infer that had a spirit been placed in the appropriate circumstances, they would have perceived it. Examine the recent literature on Berkeley’s account of unperceived existence and review what can be said in favour of or against both of these accounts.

3. Was Berkeley ultimately successful in his attempt to answer the objection that ideas are acts of perceiving and not mental objects? In addressing this question consider what he had to say about the act/object distinction in the first part of his Three dialogues between Hylas and Philonous as well as Principles 49. Note that there is also a large body of secondary literature on this question. Consult some of the most recent of those discussions in giving your assessment.

4. Was Berkeley right to claim that nothing can be like an idea but another idea?

5. Was Berkeley right to reject the distinction between primary and secondary qualities?

6. Review some of the recent literature on Berkeley’s master argument and comment on whether that literature has demonstrated that the master argument rests on a fallacy.