Perception as a source of knowledge

Question 1

Explain direct realism

Answer 1

Direct realism is a theory of perception which argues that there is an external world existing independently of the mind which we perceive directly through our senses. Our senses detect the properties of these objects (such as colour, size, shape, smell etc..) exactly as they are in the external world and these objects retain these properties when unperceived. For example, when I perceive my desk, I directly perceive its size, shape, colour, smell and texture exactly as they are in the external world. When I leave my room, both the desk and its properties continue to exist independent of my perception.

Question 2

Explain the argument from illusion against direct realism

Answer 2

P1: When subject to an illusion an object appears to a perceiver to have a particular property (for example, a straw appears to be bent when refracted in water)

P2: The perceiver is directly aware of this apparent property

P3: But the object does not have this property in reality (i.e. the straw is not actually bent)

P4: So what the perceiver is directly aware of (the bent straw) and what exists in reality (a straight straw) are distinct

C: Therefore, direct realism is false; we do not perceive physical objects directly

Question 3

Explain the response to the argument from illusion

Answer 3

A possible response to the argument from illusion against direct realism is that the premise that ‘the perceiver is directly aware of an apparent property’ (e.g. the straw being bent) misrepresents the situation. Rather than being aware of the appearance of the straw, I am directly aware of the real straw, which happens to appear to be bent due to the circumstances. There is a difference between the property ‘looking bent’ and the property ‘being bent’. So, we still directly perceive physical objects and their properties.

Question 4

Explain the argument from perceptual variation against direct realism

Answer 4

P1: Direct realism claims that the immediate objects of perception are physical objects and their properties (such as colours, textures and shapes)

P2: But when we perceive physical objects, the appearance of their properties can very (for example, Betrand Russell posits the case of a table which appears to be rectangular or kite-shaped depending on where the perceiver is standing)

P3: The properties of the objects themselves don’t vary

C: Therefore, direct realism is false; the apparent properties are not the same as the real properties of physical objects

Question 5

Explain the response to the argument from perceptual variation

Answer 5

Direct realism can respond to the argument from perceptual variation by introducing the idea of relational properties (one which varies in relation to something else). For example, the property of being to the left or right or something (e.g. ‘the cupboard is to the left of the fridge’) is a real property that something can have but it varies in relation to other objects. Similarly, we could say that certain properties vary according to the perceiver. In terms of Russell’s example of the table, appearing kite-shaped is a relational property of the table which varies depending on where the perceiver is standing. Crucially, the table itself does not change.

(Indirect realist could respond to this by saying that relational properties are mind-dependent as they only exist when a mind is perceiving something. This contradicts the claim made by direct realism that we perceive mind-independent objects with their mind-independent properties)

Question 6

Explain the argument from hallucination against direct realism

Answer 6

P1: Hallucinations occur when a person perceives something which doesn’t exist in the mind

C1: So what they perceive, the hallucination, exists only in their mind

P2: Hallucinations can be subjectively indistinguishable from veridical perception

P3: But if hallucinations and veridical perceptions are subjectively indistinguishable, then the person must be aware of the same thing in both cases

C2: So what they are directly aware of during veridical perception must also be in the mind

C3: Hence, we perceive the world indirectly and direct realism is false

Question 7

Explain a response to the argument from hallucination

Answer 7

Direct realism is challenged by the argument from hallucination, which argues that, as we cannot effectively distinguish between hallucinations and veridical perception, we cannot perceive the world directly as direct realism claims. A potential response to this issue is that the fact that hallucinations are subjectively indistinguishable from veridical perceptions does not show that they are the same phenomenon in reality. Hallucinations have a very different causal history to veridical perceptions: veridical perceptions are caused by physical objects in the external world, but hallucinations are caused by a malfunction in the brain. This shows that hallucinations and veridical perceptions are not identical phenomena. Therefore, just because hallucinations are of mind-dependent sense data, it doesn’t follow that all perceptions are mind-dependent sense data too.

Question 8

Explain the time lag argument against direct realism

Answer 8

Explain the time lag argument against direct realism (5 marks)

P1: The light from distant objects (such as stars) takes time to reach our eyes

C1: So what we are perceiving now may no longer exist

C2: So what we perceive and what exists in reality are different

P2: This is no less true for physical objects at any distance

C3: Therefore, what we directly see may not correspond to physical objects existing in the external world, therefore the claims made by direct realism are false

Question 9

Explain a response to the time lag argument against direct realism

Answer 9

The time lag argument against direct realism argues that the claims made by direct realism are false as we cannot be sure that what we are perceiving still exists in the external world. A direct realist could respond to this by suggesting that there is nothing in the direct realist view that commits it to the claim that the moment at which we perceive an object must be simultaneous with the object perceived. So, the time-lag argument does not mean that we are seeing objects indirectly, we are just seeing them as they were.

Question 10

Essay plan - ‘how convincing is direct realism’

Answer 10

Intent - unconvincing

1. Time lag
   Response - direct perception does not mean instantaneous perception, just that the object is present at the time of perception
   Counter-response - doesn’t work for objects like stars which likely won’t exist anymore
   Judgement - time lag makes direct realism less conv
2. Percep var
   Response - Galen Strawson ‘real’ properties under ‘optimal conditions’
   Counter-response - DR fails to offer any way to say what these ‘real’ properties are
   Judgement - this issue makes DR less conv
3. Hallucination
   Response - hallucinations are not perceptions but imaginations
   Counter-response - DR offers no way to distinguish between perceptions and hallucinations
   Judgement - crucial arg against DR

Question 11

Explain indirect realism

Answer 11

Indirect realism is the view that the immediate objects of perception are a mind-dependent representation of the external world which is caused by mind-independent physical objects. As a realist theory, it maintains the belief that material objects exist independently of the mind. Sense-data (the ‘content’ of our immediate sensory perception) is perceived directly, whereas physical objects are perceived indirectly.

Question 12

Explain Locke’s distinction between primary and secondary qualities

Answer 12

Primary qualities, such as size, shape, motion and number, are properties inherent in the object itself (what Locke calls ‘utterly inseparable’ from the object). These are objective and analogous to the mind-independent external world. On the other hand, secondary qualities, such as colour, taste, smell and feel, are qualities that physical objects have that are, according to Locke ‘nothing but powers to produce various sensations in us’. These are subjective and analogous to sense data.

Question 13

Explain the issue of scepticism about the existence of mind-independent objects for indirect realism

Answer 13

Indirect realism claims that the objects of perception are mind-dependent sense data that represents and is caused by mind-independent objects. However, if all we perceive directly are sense-data, mere representations of the external world, then we never perceive the mind independent objects in the external world. This is known as the ‘veil of perception’ between our sense data and the external world. The issue here is that it seems that we cannot know for certain that mind-independent objects exist at all, let alone whether sense data represents them as they are. This gives rise to a great deal of scepticism, reducing the credibility of indirect realism as a theory of perception.

Question 14

Explain Russell’s best hypothesis response to the issue of scepticism for indirect realism

Answer 14

Bertrand Russell argues that the existence of a mind-independent external world is the best hypothesis, attempting to negate the issue of scepticism for indirect realism. He posits the example of a cat. When you first glance, it is in the corner of the room. The next time you look, it is on the sofa. If there is no external world, then the cat just disappeared from one place in perceptual experience then appeared in another. However, that does not provide an explanation of the experience. If we take the other hypothesis, that there is an external world, so the cat is a mind-independent object which continues existing when unperceived, then we have an explanation of our sense data of the cat having moved to the sofa. Since this hypothesis actually explains our experience, it is, according to Russell, the best hypothesis.

(Possible response – why is the cat having its own mind independent existence really a better explanation of our experience? It may make more sense to us, but that could just be because of our habit of thinking that there is an external world)

Question 15

Explain Locke’s argument from the involuntary nature of our experience

Answer 15

Locke attempts to negate the issue of scepticism for indirect realism by arguing that there must be an external world due to the involuntary nature of our experience. If there were no external world, then everything must be in our mind. In that case, we should expect to have choice over perceptions from sense experience. However, for example, if I stepped outside and looked directly at the sun, I involuntarily squint in response to the bright light. Since we respond involuntarily to sensory experience, it follows that perceptions from sensory experiences do not originate from our mind but from an external world.

(Possible response – Locke hasnt proven that there is an external world of material objects, he has merely presented a reason as to how it makes sense for there to be one. There may be some reason unknown to us why sense data originating from our mind isn’t under our control.)

(Possible counter-response – indirect realism can still be justifed using the ‘best hypothesis’ argument. The existence of the external world is the best explanation of lack of choice over perceptions)

Question 16

Explain the argument from the coherence of various kinds of experience (Locke and Cockburne)

Answer 16

Locke argues that sense data from different senses back each other up, proving that there must be an external world from which these corresponding sensory experiences derive. He uses the example of changing how paper looks by writing on it – in this case, sight and the sense of your hand moving cohere. Furthermore, if somebody were to read out what you had written, there would be a coherence between your auditory sense data and what you thought to write. Locke argues that this ‘leaves little room for doubt’ that there is an external world. Catherine Trotter Cockburn developed this argument by pointing to the fact that we can make an inference from one sense to another. If we are walking on a mountain and hear a waterfall, we can infer and accurately predict what it will look like (and vice versa). The fact that we can accurately infer and predict our experience suggests that there is some mind-independent object which both senses perceive.

Question 17

Explain the argument from Berkeley that mind dependent ideas cannot be like mind independent objects

Answer 17

P1: My idea of, for example, a tree, has certain sensible (perceptible) qualities, such as being green.

P2: But these sensible qualities depend on the mind

P3: To say that my idea of a tree resembles the real material tree is like saying that something visible can resemble something invisible, or that a sound can resemble something inaudible.

P4: Furthermore, ideas are fleeting and changing, whereas material objects should be permanent and immutable.

C1: Thus, anything outside of the mind (like matter) cannot have any such qualities.

C2: It follows that a supposed material object could not resemble my idea of it.

(Possible response – an indirect realist could argue that Berkeley incorrectly assumes that representation requires resemblance. For example, the word ‘chair’ represents a chair but bears no resemblance to it. So, mind-dependent ideas can be ‘like’ mind-independent objects if we take ‘like’ to mean representation without resemblance)

(Possible counter-response – we could defend Berkeley by arguing that if we restrict ‘likeness’ to representation, our perceptions may not even represent the mind-independent world. If we take the indirect realist response as true, then we cannot know whether our perceptions represent mind-independent objects at all, leading us to a place of scepticism)

Question 18

Essay plan - ‘is indirect realism convincing?’

Answer 18

1. Exp IDR
2. Issue of scepticism
3. Russell’s best hypothesis (w/ response that it is not conv to say it is the best hypothesis)
4. Involuntary nature of exp (hasn’t proven an external world as there may be some other reason why our senses correspond - cd use best hypothesis - but then back to issue that it may not be best hypothesis)

J - not conv as it cannot successfully defeat scepticism

Question 19

Explain Berkeley’s idealism

Answer 19

The central claim of Berkeley’s idealism is that all that exists are minds and their ideas. This means that mind-independent material objects do not exist independently of our perception (‘Esse est percipi’ - to be is to be perceived) and are no more than collections of ideas appearing in our minds. Berkeley also argues that the universe is sustained in its existence through being perceived by the infinite mind of God, who directly causes our ideas.

Question 20

Explain Berkeley’s attack on the primary/secondary quality distinction

Answer 20

In his ‘Three Dialogues Between Hylas and Philonous’, Berkeley argues against the distinction drawn by Locke between primary and secondary qualities by suggesting that secondary qualities cannot be separable from primary qualities. This argument can be laid out as such:

P1: It is impossible to imagine an object with only the primary qualities of shape, size, movement etc…

C1: So the ideas of the secondary qualities of an object cannot be separated from those of its primary qualities

C2: It follows that they must exist together

P2: Indirect realists accept that our ideas of secondary qualities are mind-dependent

C3: It follows that our ideas of primary qualities must also be mind independent as primary and secondary qualities cannot exist separately

Question 21

Explain Berkeley’s master argument

Answer 21

Berkeley’s ‘master’ argument attempts to show that the very idea of a mind-independent material world is contradictory and thus impossible. He asks us to consider a tree which exists outside of any mind, which nobody has any awareness of. In doing so, the tree is being conceived in your mind. Berkeley argues that any thought of an object that exists outside of one’s mind can only take place within someone’s mind. Therefore, the idea of a mind-independent object in a mind-independent material world is contradictory and thus, idealism must be correct

(Possible response – In ‘Problems of Philosophy’, Russell argues that Berkeley is making an error by confusing the mental act of conceiving a thing with the thing being conceived. It may be true that my idea of a tree is in my mind, but it doesn’t follow that what my idea is about (the tree itself) exists in my mind)

Question 22

Explain the issues with the role played by God in Berkeley’s idealism

Answer 22

P1: My perceptions and sensations are part of my mind. What I perceive and feel is in my mind, not God’s mind

P2: God cannot have the sorts of perceptual experiences I have – God does not perceive as I do, nor can He undergo sensations, such as pain (which would undermine his nature as a perfect being)

P3: The ordinary objects of my perception change and go out of existence, but God’s mind is said to be unchanging and eternal

C1: Therefore, what I perceive and feel cannot be part of God’s mind: this notion is contradictory and incoherent

Question 23

Explain the arguments from illusion and hallucination against Berkeley’s idealism

Answer 23

Berkeley’s idealism is based on the idea that material objects do not exist independently of our perception – they are merely ‘ideas’ in our minds. Since we perceive ideas, how can we distinguish between ideas of ‘real’ objects and illusions or hallucinations? If there is no mind-independent reality, then illusions and hallucinations would appear to be no different from veridical perceptions. For example, there is no way to distinguish between the idea of the ‘real’ straight pencil and the illusion of a crooked pencil, nor is there any way to tell whether hallucinations (such as Macbeth’s vision of a dagger) are real. The issue here is that this is incompatible with common sense, damaging the credibility of idealism.

(Possible response – Berkeley’s response could be that we can distinguish objects of the imagination because they are subject to the will of the perceiver who is able to conjure or extinguish them from existence)

(Possible counter-response – Berkeley’s response fails as it still offers no way to tell what is ‘real’, especially in cases where the perceiver cannot control their perceptions, such as if they have a fever causing hallucinations)

Question 24

Explain the issue of solipsism for Berkeley’s idealism

Answer 24

Berkeley’s idealism argues that the objects of perception are mind dependent ideas. When we perceive a mountain or a tree, they have no mind-independent existence. If this is true, then it seems that I cannot know that other minds exist either. Perception gives us no reason to believe that anything exists beyond our own experience, including other minds. This clearly leads us to a place of solipsism, the view that one’s mind is the only thing that exists. This undermines the credibility of Berkeley’s idealism.

(Possible response – this doesn’t provide evidence that Berkeley’s idealism is false. It only shows that idealism leads to scepticism/ Berkeley does provide an argument for at least one other mind: God’s)

(Possible counter-response – makes it a less credible theory nonetheless)

Question 25

Essay plan - ‘is idealism convincing?’

Answer 25

Intent- unconvincing

1. Explain idealism
2. Master argument (and Russell’s response)
3. Issue with illusion and hallucination (+response and counter-response)
4. Issue with solipsism (+ response and counter-response)