Perception as a source of knowledge Flashcards
1
Q
what is direct realism?
A
the immediate objects of perception are mind independent objects and their properties.
- the external world exists independently of the mind
- and we perceive the external world directly
- whatever you look at, you are also perceiving its properties
- objects retain these properties even when you are not looking at it, they continue to exist e.g. if you leave an apple in a draw it will rot
-often thought of as common sense theory of perception - no third mediator between us and objects
1
Q
how is the argument from illusion an issue for direct realism?
A
- when we experience illusions, our perceptions distort the true nature of physical reality, so that what we perceive is not the same as what is actually out there
- reality is DIFFERENT to our perception of it
-e.g. when looking at a half-immersed straw in a glass of water it may appear bent/crooked when it is NOT actually crooked - if direct realism was true, the external world would be exactly how we perceive it
- BUT in illusions there is an obvious difference between reality and our perceptions
2
Q
how can direct realist respond to the argument from illusion?
A
- we are directly aware of the straw BUT it APPEARS bent because of the circumstances
- it has the relational property of looking crooked
- this appearing is not another thing mediating between us and the straw
- direct realists don’t have to suppose that objects have to appear exactly as they are
3
Q
explain the issue of perceptual variation for direct realism
A
- the appearance of physical objects can vary depending on the conditions which they are perceived in
-e.g. Russels table example: when I stand on one side of the room, a shiny wooden table may have a white spot on it because of reflection of light, but to someone standing on the other side there may be no white spot - we can’t privilege one colour over the other, so the table cannot be said to have a particular colour
- the spot is either there or it isn’t - so one of us is not perceiving the table DIRECTLY AS IT IS
-russel also says the shape of the table may change: when I look from a birds eye view it is rectangular, but when I look from a few metres away it is kite shaped: it can’t be both shapes!
-the apparent properties of the objects are not the same of their real properties, there are differences in our perception and of the table and the table itself; DR says there should be no such difference
4
Q
explain a response to the argument from perceptual variation
A
- objects may appear differently to perceivers but they are still directly perceived
- things have RELATIONAL PROPERTIES: one that varies in relation to something else
- e.g. lukewarm water can appear cold to the perceiver because the temperature of our hands is RELATIVE to the temperature of the water
- similarly a table can appear white or brown from different angles; the table has the (mind-independent) relational property of appearing brown to some people while appearing white to others
- the table has both of these mind-independent properties but which one you perceive varies depending on where you are
- we can explain scientifically why the water feels different, or why the table appears different: agreed methods of determining
5
Q
explain the argument from hallucination against direct realism
A
- during hallucinations (being ill or taking drugs) we perceive things that aren’t actually there
e.g. I may see a goblin on my sofa but there is no goblin on my sofa in reality
-often a person cannot distinguish their hallucinations from a veridical perception - if a hallucination and veridical perception are indistinguishable, then the person must be aware of the same thing in both cases
-if what a person is aware of in a hallucination is in the mind, then what we are aware of in veridical perception is also in the mind; it is all SENSE DATA - we perceive the world indirectly and direct realism is false
6
Q
explain a response to the argument from hallucination
A
- hallucinations are not perceptions they are imaginations
- in cases on hallucinations we confuse imagination for perception
- they are not the same phenomenon
- hallucinations have a very different causal history; produced by malfunction in the brain
7
Q
explain the time lag argument as an issue for direct realism
A
- it takes 8 minutes for light from the sun to reach the earth
- when you look at the sun you are not seeing the sun as it is now, you are seeing it as it was 8 mins ago; there is a difference between the sun itself and your perception of it
- we are NOT directly perceiving it
- if the sun ceased to exist in the last 8 mins, we would not know about it yet
- if what we are seeing may no longer exist, then we cannot really be seeing it; what we are seeing must be sense data
- this is also true of objects close to us; the time lag is just shorter
- so we can generalise ad say that immediate objects of perception are sense data and all our perception of physical objects is indirect
8
Q
explain a response to the time lag argument
A
- there is nothing in the direct realist view that says that what we perceive must be simultaneous with the object perceived
- it confuses WHAT we perceive with HOW we perceive it
- what we are perceiving is still a mind-independent object –> it’s just we are perceiving the object as it was a few moments ago rather than now
9
Q
what is indirect realism
A
-The immediate objects of perception are mind-dependent objects (sense-data) that are caused by and represent mind-independent objects.
- the external world exists independently of the mind (realism)
- but we perceive the external world INDIRECTLY, via sense data
- there are 3 elements in perception; the perceiver, the real objects they perceive and the appearance of these objects to the perceiver
- the immediate objects of perception are sense-data –> which is caused by and represents the mind-independent external world
- sense-data are representations of reality + exists only in your mind
- because perception involves an inference, it is indirect
10
Q
what is John lock’s primary/secondary quality distinction?
A
- PRIMARY QUALITIES: sense data of certain properties of objects that resemble their real properties, they are OBJECTIVE
e.g. size, shape, motion, position - SECONDARY QUALITIES: ‘powers’ to produce a sensation in humans, they are SUBJECTIVE
e.g. colour, taste, sound, smell - when I look at a tree, my sense data of its size and shape correlate accurately with its true size and shape, but my sense data of it’s colour and smell do not
- whatever is causing me to see the leaves as green is not green itself
- an object can be imagined without its secondary qualities but not without its primary qualities
- this distinction explains the difference between reality (primary qualities) and our perception of it (secondary qualities)
11
Q
what is the issue for indirect realism that it leads to scepticism about the existence of mind-independent objects?
A
- it leads to scepticism about the external world, how can we be sure that there is a physical world at all?
- if we only perceive sense data, how can we be sure it is an accurate representation of the external world? or that there is an external world?
- our senses can deceive us
- our sense data may not represent any material reality; we may be a brain in a vat, or an evil demon is deceiving us
- since we cannot directly observe reality we cannot be sure it exists
- we cannot get beyond the ‘veil of perception’ to access the external world behind it
–> our sense-data constitutes a veil between us and reality which we cannot penetrate to discover the material world - how can indirect realism claim there is an external world if we can never actually perceive the external world?
12
Q
explain the response of the involuntary nature of our experience to the problem of scepticism (Locke)
A
- we cannot control what we see or hear
- e.g. if someone is speaking to you you can’t choose not to listen to them, you have to
- locke points out that we are unable to avoid certain sense-data
- by contrast, memory and imagination allow us to choose what we experience
- the fact that we cannot control our sensations/experiences suggests they must be made by some exterior cause
- sensations are not subject to our will
13
Q
explain the response of the coherence of various kinds of experiences to scepticism (Locke)
A
- our senses cohere with each other and back each other up
e.g. if you knock on a table touch backs up the sound - like two witnesses giving the same description of someone, if it matches up it is deemed as reliable
- the senses independently offer support for each other’s testimony, suggesting there is one external cause
- would be extremely coincidental if the different senses of sound and touch agreed about the geometric properties if those objects did not exist
14
Q
explain the response that the external world is the best hypothesis to scepticism (Russell)
A
- Russell accepts that there is no deductive proof of the external world, so we must treat it as a hypothesis
- we have an instinctive belief of a physical, external world that corresponds with our sense data and we should only reject these beliefs when they are shown to be incoherant
- imagine you see a cat sitting on the sofa, you go and make a cup of tea and when you come back the cat is sitting on the floor
- there are two possibly hypothesis
a) the cat exists independently of my mind and while I was making a cup of tea it walked from the sofa to the floor
b) the cat does not exist independently of my mind and stopped existing while I was making a cup of tea and sprung back into existence in a different location when I returned - russel says that hypothesis a is the better explanation because it connects the two perceptions whereas hypothesis b isn’t an explanation at all
- hypothesis a also explains why the cat gets hungry even when I’m not perceiving it
- even though we can’t prove the existence of mind-independent objects, Russell argues that we should believe in them since they are the best hypothesis
