3.1.2 Perception as a source of knowledge

What is the main belief of direct realism?

The immediate objects of perception are mind-independent objects and their properties.

Philosophers argue that gaining knowledge involves … with reality

Philosophers argue that gaining knowledge involves ‘cognitive contact’ with reality

What are our senses?

 The empirical data I see, hear, taste, touch, smell

How do realist and idealists views differ?

Realists argue that that which we perceive is mind-independent whereas idealists disagree

What is direct realism?

The idea that our senses provide us with knowledge of reality as it really is as I have a direct causal relationship with the world.

Agrees with the laws of science.

Says that the world we perceive is mind-independent, and

Also known as common sense realism or naive realism.

• We perceive objects in the world immediately 

• When we perceive objects we are directly aware of the objects themselves

For example, the table that I am sat at is there in the external world

Outline Bertrand Russell’s case for direct realism

‘It seems to me that I am now sitting in a chair, at a table of a certain shape, on which I see sheets of paper with writing or print. …’

What are Micheal Huemer’s 5 precepts to summarise direct realism (these are the essential ideas found in direct realism) ?

1. The world is made up of physical objects (realist view)

2. Physical objects can be known through sense experience

3. Physical objects and their properties exist independent of our perception (realist view)

4. The objects we perceive continue to exist even when we cease to perceive them (materialist theory)

5. As our perceptions are generally accurate, we have good reason to claim the world is as we perceive it (differs from indirect realism)

What are the arguments in support of direct realism?

• In tune with common sense - hence why it is sometimes called common sense realism

  • In problems of philosophy Russel argues we should accept the common sense opinions/beliefs we are inclined to by instinct unless they lead to inconsistency

• It avoids scepticism and gives a clear account of how we come to have knowledge of the world 

  • because our senses provide immediate access to its true nature

• Easily explain how we can execute practical actions on a daily basis 

  • through interactions with objects in the external world

• Explains why I perceive what I do - 

  • I see the tree as green because it is green, my perception of it is regular and predictable because there actually is a green tree causing my perception

• Explains why individuals agree about what they perceive

  • e.g. if me and a friend look at the same tree, we describe it in the same way because there is an actual tree

Explain the argument from perceptual variation

Using the example of colour, it appears different under different conditions, like colour blindness, tinted glasses etc.

Russell uses the example of observing a table … ‘it appears to be of different colours from different points of view, and there is no reason for regarding some of these as more really its colour than others.’

Russell concludes that we do not perceive things in the world, we only perceive sense data - when I look at a table, I don’t see the actual table as it really is, merely my perceptions/my sense data (what I see, smell, hear, etc.) of the table so what I am perceiving is mind dependent.

Sense data therefore provides an appearance of reality - it shows me something about the appearance of the world but the world that I perceive is not necessarily the world as it is so the sense data is somehow separate from the world I see - there is a veil of perception

What are the examples of perceptual variation?

Russell’s table

Sapir wharf hypothesis

• Argues that the way we has no concept of the colour blue and therefore cannot apparently perceive the colour blue

• Shows how our perceptions are altered by the language available to us

• Iris Murdoch takes it further by asking the question of ‘Are there things that exist which we don’t know exist as we don’t have a word for them?’

Berkeley’s water

• Uses Locke’s example of water - if you place a hot hand and a cold hand in a bowl of lukewarm water, you will feel two different temperatures

• If material objects possess mind independent properties (as DR claims), then how can one object have contradictory/incompatible properties - hot and cold

  • In reality an object cannot possess incompatible properties as this is contradictory

• So material objects cannot have mind-independent properties and the DR argument falls apart

What is a bona fide reality?

A genuine/real reality

Explain the responses to the argument from perceptual variation

• Perceptual variation merely critiques the view that we perceive the properties of objects as they really are

• But with the water example, the water is still really lukewarm (and we have empirical methods to prove this) even if it appears cold 

• This is because one of the properties of lukewarm water is that it can appear different temperatures 

• So it doesn’t follow that there must be something between the objects we perceive and ourselves (e.g. sense data)

• BR’s claim that we observe many different colours on the table-top does not actually refute the claim that the table-topis a form colour.

Explain the argument from illusion

The commonly used example is the stick appearing bent in a glass of water which shows that we perceive some objects in a way that isn’t consistent with its actual properties.

So our perceptions of objects are not always consistent with the reality of things.

So we must not be perceiving objects directly.

What is the syllogism for the argument from illusion?

Micheal Huemer’s argument from illusion:

P1. When viewing a straight stick half-submerged in water, one is directly aware of something bent.

P2. No relevant physical thing is bent in this situation.

C1. Therefore, in this situation, one is directly aware of something non-physical.

P3. What one is directly aware of in this situation is the same kind of thing that one is directly aware of in normal, non-illusory perception.

C2. Therefore, in normal perception, one is directly aware of non-physical things.

Explain the response to the argument from illusion

• Simply, our sense data observes a bent stick but there are obvious conditions affecting the sense data (here it's the way light is refracted when passing through water 

  • I am directly aware of the real straw, but it appears bent due to the circumstances ( the way light is refracted when passing through water)

  • This is not a third thing mediating my perception of the straw but just the manner of its appearance

  • So realists don’t need to suppose that objects have to appear directly as they are

  • And indirect realists shouldn’t explain illusions by positing entities like ‘appearances’ or ‘sense data’ which are directly observed

Explain the argument from hallucination

As given by Michael Huemer:

• Imagine two people, Sally and Sam, each of whom is having an experience of seeming to see a pineapple. Sally is simply perceiving a pineapple in the normal way. Sam, however, is having an incredibly realistic hallucination of a pineapple, induced by brain scientists

• Their perceptions of the pineapple are indistinguishable, yet one is a veridical (truthful/accurate) perception and the other is a hallucination 

• So if the hallucination of the pineapple is merely perceptions in the mind

• What we are directly aware of during veridical perception must only be in the mind

• So veridical perception involves sense data and we perceive the world indirectly

As both Sally and Sam are experiencing the same perceptions, we can conclude that our sense data is independent of the real world so direct realism can’t distinguish between differing perceptions of reality

What is the syllogism for the argument from hallucination?

• P1: Perceptions from hallucinations are indistinguishable from veridical perceptions 

• P2:Perceptions from hallucinations are entirely mind-dependent

• P3: So veridical perceptions must also be mind-dependent

• C1: therefore, we must not be perceiving mind-independent objects directly

• C2:  and we are unable to distinguish whether our perceptions are actually caused by mind-independent objects

• C2: direct realism fails

Explain the response to the argument from hallucination using reliabilism

• The argument from hallucination says that perceptions from hallucinations are indistinguishable from perceptions from reality. 

• However, direct realists may argue that even though hallucinations are a possibility, they do not necessarily disregard the fact that our perception is generally reliable and  it allows us to navigate the external world correctly (hence why DR forms the basis of natural sciences) 

• Even though we cannot fully trust our perceptions due to the likes of hallucinations and such, our perceptions do allow us to correctly operate within the world (most of the time) so they are therefore a reliable source of perception

Explain the time lag argument

• We experience time-lags in everyday life

  • e.g. hearing thunder after seeing lightning in a storm (referred to by Bertrand Russel)

  • e.g. when looking at constellations of stars we are looking at objects from millions of years ago that may have even ceased to exist by now

  • e.g. we see the smoke of a starting pistol before hearing its sound

• The time difference between the real phenomenon and our perceptions of it demonstrates that we are only perceiving things through our senses, not experiencing the world as it actually is

Explain the response to the time lag argument

The direct realist can argue that this response confuses what we perceive with how we perceive it. 

Yes, we perceive objects via light and sound waves and, yes, it takes time for these light and sound waves to travel through space. 

But what we are perceiving is still a mind-independent object – it’s just we are perceiving it as it was moments ago rather than how it is now.

What is the main belief of indirect realism?

The immediate objects of perception are mind-dependent objects (sense-data) that are caused by and represent mind-independent objects

What is sense data?

Objects we are aware of when we perceive the world

Sense data are the things we are directly aware of in perception

Sense data are dependent on the mind

Sense data have the properties that perceptually appear to us

What do indirect realists say about the external world?

They argue there is an external world but the world I perceive is not necessarily the world as it is

This is because we perceive the external world only through our senses - all our knowledge about the world comes through our senses

We perceive the external world indirectly through our senses

Veil of perception

A being without the philosophy of mind would not be able to conceive such an indirect relationship with the world

In indirect realism there is no innate knowledge

What is empiricism?

Empiricism argues that all our knowledge starts with the senses. That means that we come to know about the world through empirical observations (our experience of the world).

Empirical knowledge is acquired a posteriori. Such knowledge is not necessarily true. Empirical knowledge is inductive and is assessed according to probability.

A posteriori, empirical observations of the world are contingent. The word ‘contingent’ means ‘dependent on other thing’

Empiricism says all a priori knowledge is of analytic truths.

Knowledge that is mind-dependent (or perceived though the senses) = knowledge of ‘particulars’

Knowledge which is true independent of the mind = knowledge of ‘universals’

Locke argues that we reach conclusions about the world based on probabilities rather than proofs

• Because empiricism is based on probability rather than proof, the conclusions about the world cannot be ‘true or false’, ‘valid or invalid’, or ‘necessary or impossible’.

• These inductive arguments are either strong or weak, according to how probable it is that the conclusion is true.

Empirical observations about the world are contingent

• contingent = dependent on other things

What did Locke claim about the mind of a new-born?

Locke said that the mind of a new-born is tabula rasa

Tabula rasa translates to ‘clean slate’ and is the idea that we born without any innate ideas

Sensations and reflections are the only sources of knowledge available to us

An unborn child 'differs not much from the state of a vegetable', and passes the greatest part of its time without perception or thought. It need not seek for food, it is always the same heat, surrounded by fluid, the eyes have no light, there is no sound: there is no variety to move the senses. The mind thinks in proportion to the matter it gets from experience to think about. This is why a child makes alterations as the mind by the sense comes more and more to be furnished with ideas, and comes to be more and more awake’

Explain the distinction between primary and secondary qualities

Sensations are divisible into primary and secondary qualities:

Primary qualities;

• Primary qualities can’t be separated from objects of experience

• They are more reliable than secondary ones

• E.g. number, size, shape, hardness

• Our perception of primary qualities like shape are more certain

Secondary qualities;

• Secondary qualities are properties produced by the perceiver of an object, an aspect of the object itself

• They are less reliable than primary ones

• E.g. colour, taste, temperature

• Our perception of secondary qualities like temperature or colour may vary

Explain how sensations and reflections differ

Sensations;

• More immediate to us than reflections

• Sense-dependent

• E.g. the taste of raspberries

• Involuntary

• Simple and unanalysable

Reflections;

• Complex, derived from our empirical experiences of the world

• The ideas of our own mental operations

• E.g. I like the taste of raspberries

• E.g. remembering/comparing

Explain the argument that indirect realism leads to scepticism about the existence of mind-independent objects

Scepticism = Doubting aspects of the external world

Solipsism = The rejection of the existence of everything except our own consciousness

• If the world we perceive isn’t necessarily the world as it is

• there is a veil of perception which separates us from the objects we perceive

• if there is a veil of perception and our senses are unreliable then we begin to doubt our empirical senses

• I don’t know if my perceptions are accurate (as Hume’s says ‘the senses alone are not to be depended on’) but all my knowledge comes from my senses

• due to Philosophy of Mind, I can’t confirm that others perceive what I perceive

• I also can’t confirm that other minds exist

• If other minds don’t exist then does an external world exist?

Hume’s exploration of scepticism in his Enquiry Concerning Human Understanding:

‘The mind never has anything present to it but the perceptions, and can't possibly experience their connection with objects. The belief in such a connection, therefore, has no foundation in reasoning because reasoning would have to start from something known through experience.’

Explain Locke’s argument from the involuntary nature of experience (part of Locke’s resemblance thesis)

This is a part of Locke’s resemblance theory - the theory that our perceptions resemble the outside world

The argument from the involuntary nature of our experience says that as we can’t control our perceptions, their causes must be external to our minds - an external world must exist 

• Sense experiences are involuntary

• e.g if you touch a flame, you cannot NOT feel pain/burn

• So whatever causes our perceptions must be external to our minds

• However, our complex reflections of memory and imagination somehow allow us to choose our experiences

• So Locke ‘proves’ there is an external world, but doesn’t prove that sense data is an accurate representation of the external world

• So sceptics can still argue that the external world could be completely different from what we perceive

Explain Locke’s argument from coherence of various kinds of experience (part of Locke’s resemblance thesis) as developed by Locke and Catharine Trotter Cockburn

• The idea that different senses often confirm information of each other

  • e.g. if I were to throw a ball to you, you would experience a range of sensations from your different senses which separately would confirm the sensations of other senses. You would be able to see the ball moving in space towards you. You might be able to hear it moving through the air, and you would be able to feel and smell it once you catch it.

  • So all your senses confirm that a ball is being thrown to you

  • So we can conclude that there is indeed a ball is being thrown to you

• Locke also uses ‘Molyneux’s Problem’ suggesting that a blind man would be able to distinguish a globe and cube by sight if his vision were to miraculously appear

  • This is because our senses cohere with each other and his other sense experiences would be consistent with the objects being a globe and a cube

  • They don’t exist in isolation 

  • So they give an accurate description of the world when combined

Explain how Catharine Trotter Cockburn supports Locke’s theory

• Cockburn questions Berkeley's theory of perception and defends Locke by arguing that the combination of our sense experiences creates a cumulative case which offers us a coherent and consistent view of the external world

• She argued that such coherence demonstrates that the external world is independent of the mind. 

• She emphasises this point by considering a person with only one sense. Such a person would have such a limited experience of the external world that they might question its existence or even veer towards a conclusion of solipsism. 

• However, with the additional senses we are provided with an ever more detailed and coherent perception of the external world.

• Cockburn argues that our sense experiences are consistent (with one another) and regular. 

  • e.g Imagine you were blindfolded and given a dice to feel. Imagine also that you had never seen a dice before. It is highly likely that when the blindfold is removed the dice would look very similar to what you were expecting it to look like.

• So not only does the external world exist, it resembles what our perceptions show us

• However we can’t actually prove that the world we perceive is the world as it really is so the resemblance theory is just the most likely explanation

Explain Bertrand Russell’s argument that the external world is the ‘best hypothesis’

• Bertrand Russell provided a famous response to this problem of scepticism in his Problems of Philosophy. 

• He considers the most common response to scepticism which can be written as follows:

  • P1. Because sense experiences are private to individuals it follows that no two people can actually experience exactly the same perceptions of the world. 

  • P2. Two people in the same place and at the same time can have identical perceptions of the world. 

  • P3. The best explanation is that there must be physical objects in the world which correspond to those perceptions. 

  • C. Therefore physical objects exist.

Explain how Russell contradicts his argument from ‘best hypothesis’

Because he is producing an inductive a posteriori argument, he must follow the rules of inductive a posteriori arguments. 

These rules tell us we can only reach probabilities about the objects of perception and so, he argues, he cannot actually prove the existence of other minds. 

This makes the above argument internally inconsistent.

(P2 doesn’t work because of the theory of mind)

Explain Russell’s reformulation of his best hypothesis argument

‘The way in which simplicity comes in from supposing that there really are physical objects is easily seen. If the cat appears at one moment in one part of the room, and at another in another part, it is natural to suppose that it has moved from the one to the other, passing over a series of intermediate positions. But if it is merely a set of sense-data, it cannot have ever been in any place where I did not see it; thus we shall have to suppose that it did not exist at all while I was not looking, but suddenly sprang into being in a new place. If the cat exists whether I see it or not, we can understand from our own experience how it gets hungry between one meal and the next; but if it does not exist when I am not seeing it, it seems odd that appetite should grow during non-existence as fast as during existence. And if the cat consists only of sense-data, it cannot be hungry, since no hunger but my own can be a sense-datum to me. Thus the behaviour of the sense-data which represent the cat to me, though it seems quite natural when regarded as an expression of hunger, becomes utterly inexplicable when regarded as mere movements and changes of patches of colour, which are as incapable of hunger as triangle is of playing football.’

As he couldn’t effectively defeat the sceptical argument he suggested that accepting the idea of a mind-independent external world was the ‘best hypothesis’

Summarise Berkeley’s idealism

• Immaterialism (attacks all forms of materialism)

• All that exists are minds and their ideas 

• So-called physical objects don’t exist mind-independently

• They are no more than collections of ideas or sense data appearing in minds

• But they continue to exist when not being perceived by finite human minds (esse est percipi) - the universe is sustained in existence through being perceived by the infinite mind of God

• God directly causes our ideas/sense data

How does Berkeley expand on Locke’s argument from the resemblance theory?

• Argues that the resemblance theory is inconsistent

• He agreed with Locke that the immediate objects of perception are ideas in the mind but goes on to argue that you cannot maintain the resemblance thesis (that our ideas of primary qualities resemble primary qualities)

  • The idea of resemblance only works if two things are said to be similar to each other

  • e.g. You can’t compare a sense of colour with a sense of smell, given their differences,

  • so how can we compare mental ideas and material qualities given that only the former can be perceived

  • An idea can only be like another idea - ‘I answer, an idea can be like nothing but an idea; a colour or figure can be nothing but another colour or figure’

Explain the response to Berkeley’s developments of Locke’s resemblance thesis

• He’s guilty of epistemic hyperbole (Jonathan Jenkins Ichikawa) 

• Just because an idea might not resemble something mind dependent doesn’t mean it definitely doesn’t

Explain Berkeley’s criticisms of Locke’s primary and secondary quality distinction

• He claimed Locke had no justification for distinguishing between our ideas of secondary and primary qualities 

• both are only ideas in the mind and as such are equally susceptible to illusions

• So there is no reason to think that one type fundamentally resembles the qualities of material objects

  • He argues this by saying we can't imagine an object without secondary qualities so they must be just as essential to the object as primary ones

  • We can’t think of a shape (primary quality) without colour (secondary quality)

  • So you can’t separate primary and secondary qualities

  • Both are mind-dependent (as secondary qualities are mind-dependent) and just as susceptible to illusion 

  • ‘But I desire any one to reflect and try whether he can, by any abstraction of thought, conceive the extension and motion of a body without all other sensible qualities. For my own part, I see evidently that it is not in my power to frame an idea of a body extended and moving, but I must withal give it some colour or other sensible quality which is acknowledged to exist only in the mind. In short, extension, figure, and motion, abstracted from all other qualities, are inconceivable.’

Explain the response to Berkeley’s criticism of Locke’s distinction between primary and secondary qualities

• Secondary qualities aren’t mind dependent

• Locke just says that they can cause mind-dependent sensations in us - the qualities themselves are still mind-independent

• So just because you can’t separate primary and secondary qualities, doesn’t mean they are mind-dependent

• Only the sense of these qualities exist in the mind but the qualities themselves exist mind-independently

Explain the argument for idealism that follows the idea of immaterialism

• Immaterialism (attacks all forms of materialism)

  • Argues that direct and indirect realism fail as they cannot prove that the external world exists as a material entity

• Asserts that what we think of as the external world is inseparable from our perceptions and perceptions are dependent on the mind therefore, the external world we perceive is mind-dependent and so is the product of an idea

• It is inconceivable that the external world which we perceive might be a product of my mind and so, the external world which we perceive must be the product of the divine or God’s mind

What is the syllogism for the argument for idealism following the idea of immaterialism?

P1: What we think of as the external world is inseparable from our perceptions

P2: Perceptions are dependent on the mind (mind-dependent)

C1: The external world is the product of a idea

P3: It is inconceivable that the idea of the external world could be the product of my mind

C2: The external world which we perceive must be the product of God’s mind

Explain the criticisms of Berkeley’s idealism

• Berkeley writes in defence of his belief in God (he’s led by a conclusion not by the evidence) making him an apologist and the argument corrupt

• It also does not necessarily follow that the external world is the product of an idea as P1 and 2 (veil of perception) leave other possibilities

  • That there is an external world and it is the one we perceive (direct realism)

  • That there is an external world but it is not the one we perceive (indirect realism)

  • That there is no external world (solipsism, although this can be discounted as we cannot conceive or perceive of the external world not existing)

  • That the external world is the product of an idea (idealism)

• Berkeley’s philosophy means that that which I perceive through my sense experience exists only because I  (and God)am perceiving it 

  • Esse est percipi 

  • To be is to be perceived

• Idealism leads to solipsism: 

  • All I perceive are ideas

  • So what if other minds are simply ideas

  • And what if i am not a mind but simply an idea

  • God could also simply be an idea

  • So with idealism not only can I not make sense of the idea of anything existing outside of my mind but i am unsure whether my mind is more than an idea

• But if everything I perceive is the product of God’s mind, then my perception of pain is a product of God’s mind and so God must experience pain, implying a contradiction.

Explain the argument for Idealism which says that realism promotes scepticism and atheism

• Due to the a-posteriori nature of realism it can theoretically lead to scepticism as we can’t demonstrate/prove that our senses aren’t misleading us

• It promotes atheism as  it describes the external world in a way that it can continue to exist without the assistance of God

• Berkeley starts his attack with the following argument as 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 fore-mentioned 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?'

So the things we perceive with our senses are mind-dependent ideas that represent external material objects allowing us to perceive them (Locke’s Theory of Resemblance)

What is the syllogism for the argument for idealism which says that realism promotes scepticism and atheism?

P1. We perceive ordinary objects

P2. We perceive only ideas

C1. Therefore, ordinary objects are ideas

Explain the likeness principle

This is an attack on the resemblance thesis

• In the same way that you can’t compare a smell with a texture, you can’t compare an idea with an object

• An idea can only be like another idea - ‘I answer, an idea can be like nothing but an idea;a colour or figure can be nothing but another colour or figure’

• Realists can’t assert a likeness between an idea and a material object

• If material objects have colour, size, shape, number, texture etc and these are all ideas, how can we base knowledge of material objects solely on ideas

• Realists claim that we only come to know of these ideas through material objects

  • So material objects are perceived first

  • But Berkey says realists must admit the possibility that ideas can exist without an external world 

  • so realism →  solipsism

  • Basically, their theory might be wrong so his might be right (baseless assumption)

Explain Berkeley’s master argument

• Berkeley regarded this as his winning argument and the term master argument was first used in 1974

• Here is asserts that the objects of perception cannot be mind-independent and must be ideas rather than material things 

  • But say you,surely there is nothing easier than to imagine trees,for instance,in a park, or books existing in a closet,and nobody 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 anyone that may perceive them? But do you not yourself 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.

  • Essentially all knowledge is mind dependent

What is the syllogism for Berkeley’s master argument?

• P1. We cannot think of a tree that is neither perceived nor conceived

• P2. We can think of the idea of a tree, but not of a tree that exists independently of the mind

• C1. So the tree doesn’t exist independently of the mind

Explain Lisa Downing’s criticisms of the master argument

• Lisa Downing points out that Berkeley confuses a thought with what a thought is about

• This can be presented as follows:

  • P1: My thoughts cannot exist outside my mind

  • C1: Therefore,according to Berkeley, my thought of a tree is mind-dependent. It is impossible that there can be a thought of a tree when no one is thinking of a tree. 

  • P2: But a thought about a tree is not the same thing as an actual tree

  • C2: Whilst my thought of a tree is mind-dependent, it does not follow that the actual tree is also mind-dependent. It is not impossible to think that a tree may exist when no one is thinking of it.

Explain Jonathan Jenkins Ichikawa’s criticisms of Berkeley’s idealism

• Jonathan Jenkins Ichikawa criticised Berkeley’s likeness principle for falling into the trap of ‘epistemic hyperbole’ (Berkeley also uses epistemic hyperbole in his argument for idealism)

• Ichikawa’s implication is that Berkeley starts reasonably, by acknowledging the veil of perception which separates me from the objects of my sense experience. However, whilst this is a valid starting point, it seems that moving to a conclusion that nothing  material actually exists is something of an exaggeration in Berkeley’s logic.

With regards to his likeness principle, suggesting that  ‘an idea can be like nothing but an idea; a colour or figure can be nothing but another colour or figure’ is an epistemic hyperbole as although an idea may not resemble a material object, it does not follow that it can be nothing like a material object

Explain Bertrand Russell’s criticism of Berkeley’s master argument

• Russell argued that Berkeley’s error is to confuse the mental act of conceiving a thing with the thing being conceived. So it is true that my idea of a tree must be in my mind, but it doesn’t follow that what my idea is about, namely the tree itself, must be in my mind.

• This is the same argument that Lisa Downing makes

Explain how reliabilism criticises Berkeley’s idealism

Reliability, suggests that we have good reasons to reject Berkeley’s position. It may not be hyperbolic to argue that the chair I am sitting on is only an idea and that it ceases to exist when I no longer perceive it, it seems far more coherent to assume that the evidence suggests that the chair continues to exist when it is not perceived.

Explain how idealism reacts to the challenges of illusions, hallucinations, and dreams

• Breaks down issues challenging direct realism and supporting indirect realism

  • E.g. when you half submerge a straw in a glass of water, it appears bent

  • According to Berkely’s idealism, it is actually bent 

  • This seems absurd

• Berkeley says its not absurd and we should say that the straw ‘looks bent’ rather than is bent to avoid confusion

• As for hallucinations and dreams…

  • With realism we understand that they appear in contrast to the real world and aren’t parts of the real world

  • With Idealism, they are no less real than the real world as both are simply ideas

• Berkeley provides two criteria that mark off hallucinations and dreams from perception. 

• First, they are ‘dim, irregular, and confused’. 

• Second, even if they were as ‘vivid and clear’ as perceptions, they are not coherently connected with the rest of our perceptual experience.

Explain how idealism leads to solipsism

• All I perceive are ideas

• So what if other minds are simply ideas

• And what if i am not a mind but simply an idea

• God could also simply be an idea

• So with idealism not only can I not make sense of the idea of anything existing outside of my mind but i am unsure whether my mind is more than an idea

Explain Berkeley’s response to the criticism that idealism leads to solipsism using a syllogism

P1: The mind is that which (actively) perceives, thinks and wills, while ideas are passive.

P2: I am aware of myself as capable of this activity.

C1: Therefore, I am not my ideas, but a mind.

P3: Being a mind myself, I have a ‘notion’ of what a mind is.

C2: Therefore, it is possible that other minds exist.

P4: My perceptions don’t originate in my mind.

C3: Therefore, they are caused by some other mind.

C4: The complexity, regularity, etc., of my experience indicates that this mind is God.

Explain the problem of God in Berkeley’s idealism using syllogism

In Berkeley’s Three Dialogues, he asserts that God “can suffer nothing, nor be affected with any painful sensation, or indeed any sensation at all”. 

But if everything I perceive is the product of God’s mind, then my perception of pain is a product of God’s mind and so God must experience pain, implying a contradiction.  

You can summarise this view in a formal way:

P1: what we perceive is in the mind of God

P2: The idea of pain must be in the mind of God

C1: Therefore God experiences pain

P3: If God experiences pain he is imperfect

C2: Therefore Berkeley’s views of God imply a contradiction

How does Berkeley respond to the problem of God in idealism?

• Berkeley responds to this by arguing that although our perceptions are a product of God’s ideas and mind, he does not experience them in the same way that we do. 

• We experience pain passively, in accordance with the laws of nature whereas God is immaterial and so does not suffer physical pain.

Explain the issue of only being able to conceive of objects which are mind-dependent as a problem with God

• According to Berkeley, we can only conceive of objects which are mind-dependent. 

• So it is impossible for us to conceive or perceive anything independent from our own minds and mind-independent objects are impossible or simply do not exist. 

• However, we are able to conceive of God, as Berkely himself does by asserting the existence of a Divine Being in his philosophy.

• So  cannot be mind-independent and so rather than the external world which we perceive being a product of God’s mind, it appears that God himself is merely an idea, the product of our mind.

  • P1: I cannot think of a God which is neither perceived nor conceived

  • P2: I can think of the idea of a God but not of a God that exists independently of the mind

  • C3: God is mind-dependent

Explain the response to the issue of only being able to conceive of objects which are mind-dependent as a problem with God using syllogism

• P1: I cannot think of a God which is neither perceived nor conceived

• P2: I can think of the idea of a God but not of a God that exists independently of the mind

• C3: God is mind-dependent

Take the original syllogism as presented above, and then add these following premises and conclusions

• P4: My perceptions don’t originate in my mind.

• C3: Therefore, they are caused by some other mind.

• C4: The complexity, regularity, etc., of my experience indicates that this mind is God.