Flashcards in Epistemology Deck (31):
What is direct realism?
Direct realism is the idea that the senses provide us with direct awareness of objects as they really are.
What are the four issues with direct realism?
The argument from illusion, the argument from perceptual variation (Russell), the argument from hallucination and the time-lag argument.
What is the argument from illusion?
1. We perceive something having some property F (e.g a stick in water is crooked).
2. When we perceive something having some property F, then there is something that has this property.
3. In an illusion, the physical object does not have the property F (the stick is not crooked).
4. Therefore, what has the property F is something mental, a sense-datum.
5. Therefore, in illusions, we see sense data, and not physical objects, immediately.
6. Illusions can be ‘subjectively indistinguishable’ from veridical perception.
7. Therefore, we see the same thing (sense-data) in both illusions and veridical perception.
8. Therefore, in all cases, we see sense-data, and not physical objects, immediately.
9. Therefore, direct realism is false.
What is the argument from perceptual variation?
1. There are variations in perception.
2. Our perception varies without corresponding changes in the physical object we perceive (for instance, a desk remains rectangular, even though the way it looks to me changes as I look at it from different angles).
3. Therefore, the properties physical objects have and the properties they appear to have are not identical.
4. Therefore, what we are immediately aware of in perception is not exactly the same as what exists independently of our own minds.
5. Therefore, we do not perceive physical objects directly.
Who came up with the argument from perceptual variation?
What is the argument from hallucination?
1. In hallucination, we perceive something having some property F.
2. When we perceive something having some property F, then there is something that has this property.
3. We don’t perceive a physical object at all (unlike the case of illusion).
4. Therefore, what we perceive must be mental - sense-data.
5. Hallucinations can be experiences that are ‘subjectively indistinguishable’ from veridical perceptions.
6. Therefore, we see the same thing, namely sense-data, in both hallucinations and veridical perception.
7. Therefore, in all cases, we see sense-data, and not physical objects, immediately.
8. Therefore, direct realism is false.
What is the time-lag argument?
It takes time for light/sound waves and smells to get from physical objects to our sense organs. For example, it takes 8 minutes for the light from the sun to reach the earth. If you look at the sun, you are seeing it as it was 8 minutes ago - if it blew up, you would see it normally for 8 minutes after it blew up even though it would no longer exist. Therefore, you could argue, you aren’t seeing it directly. However, this doesn't show you that what you perceive is actually sense-datum of the sun. The ‘image’ you see is physical, carried in light waves - the light waves exist during those 8 minutes. If you see the sun indirectly, it is because you are seeing the light waves directly. We can generalise: what we perceive is the physical medium by which we detect physical objects - so we don't perceive physical objects directly.
What are sense-data?
Sense-data are mental things which are the way we perceive them to be, they are appearances. They only exist while they are being experienced and are private.
What is indirect realism?
Indirect realism claims that we perceive physical objects which are mind-independent, but we do so via perceiving mind-dependent sense-data that are caused by and represent physical objects. We perceive sense-data immediately, and physical objects indirectly.
What are the three issues with indirect realism?
Scepticism about the existence of the external world, scepticism about the nature of the external world and problems arising from the view that mind-dependent objects are caused by mind independent objects.
How does indirect realism lead to scepticism about the existence of an external world?
If what we perceive directly are sense-data, then all we know about are sense-data. We believe that physical objects cause our sense-data. But how can we know this? To know that physical objects cause sense-data, we first have to know that physical objects exist.
How does indirect realism lead to scepticism about the nature of an external world?
We have assumed that in talking about the external world, we are talking about physical objects. But even if we can show that our sense-data are caused by something that is mind-independent, can we establish what kind of thing that cause is? For example, if all you knew was smoke, would you be able to work out that its cause is fire? The world is full of surprising relationships. Indirect realism claims that sense-data represent the external world - but is what we experience an accurate representation?
How does indirect realism lead to problems arising from the view that mind-dependent objects are caused by mind independent objects?
Physical objects casually affect our sense organs, which then affect our brains. But how does what happens in our brains casually affect our conscious perception? How can something physical and mind-independent possibly cause an idea in a mind? How could nerve signals in the brain produce sensations of sound and colour? Berkeley poses this as an objection to realism.
What are the two responses to scepticism about the existence of an external world?
The existence of the external world is the best hypothesis (Russell) and The lack of choice over our experiences and the coherence of the various senses (Locke).
Explain the response that says the external world is the best hypothesis.
Russell offers two responses. The first is this: the fact that sense-data are private means that no two people actually ever perceive the same thing, unless we can say that there are physical objects that they both perceive (indirectly). Russell rejects this argument because it assumes there are other people and that they have sense-data and their sense-data is similar to mine, and this is something we can’t know. To assume there are other people is to assume that there are physical objects, since people are physical objects. The second response is:
1. Either physical objects exist and cause my sense-data or physical objects do not exist nor cause my sense-data.
2. I can’t prove either claim is true or false.
3. Therefore, I have to treat them as hypotheses.
4. The hypotheses that physical objects exists and cause my sense-data is better (because it can explain why an experience is the way it is).
5. Therefore, physical objects exist and cause my sense-data.
Who responded saying the external world is the bets hypothesis?
Explain the response that says the coherence of the various senses and lack of choice over our experiences suggests there is an external world.
Locke offers two responses. Firstly, in perception, I cannot avoid having certain sense-data ‘produced’ in my mind. By contrast, if I shut my eyes, I find that I can choose what I experience. Perceptual experiences must be produced in my mind by some exterior cause. Secondly, our different senses confirm the information that each supplies. If I see a fire and doubt whether it is real, I can confirm its reality by touching it.
Lock brings the two responses together in an extended example. I know from experience that I can change the way a piece of paper looks by writing on it. I can plan what to write, and I can know in advance what the piece of paper will look like. But I cannot bring about the sense-data of seeing the piece of paper with the words on it just by imagination, the words must be already written. Finally, if someone reads aloud what I wrote on the paper - these words correspond with what I intended to write - this leaves little reason to doubt that the words exist outside my mind.
Who responded saying that the coherence of the various senses and lack of choice over our experiences suggests there is an external world?
What are the two responses to scepticism about the nature of the external world?
Sense-data tells us of relations between objects (Russell) and the distinction between primary and secondary qualities (Locke).
Explain the response that says sense-data tells us of relations between objects.
1. For objects in physical space to cause our sense-data, we must exist in physical space as well. In other words, we must have bodies that can be casually affected by physical objects.
2. The relative positions of physical objects in real space - near, far, left, right and so on - correspond to the relative positions of sense-data in apparent space. Thus, it will take us longer to walk through physical space to a house that appears further away than to a house that appears nearer.
3. All we can know about physical space, and the distribution of physical objects in physical space, is what secures this correspondence. For instance, we can’t know what ‘space’ or ‘distance’ are in themselves.
Who responded saying sense-data tells us of relations between objects?
Explain the response that distinguishes between primary and secondary qualities.
A ‘quality’ is a ‘power’ that a physical object has ‘to produce an idea in our mind’. Primary qualities are qualities that are ‘utterly inseparable’ from the object whatever changes it goes through. Primary qualities are: extension, size, shape, motion, solidity. Secondary qualities are qualities that physical objects have that are ‘nothing but powers to produce various sensations in us’. Locke lists colours, sounds, tastes, smells and temperature. The distinction between primary and secondary qualities is a distinction between qualities that physical objects have ‘in themselves’, and qualities they have that are related to how they are perceived.
Who responded by distinguishing between primary and secondary qualities?
What is Berkeley's Idealism?
Berkeley’s idealism claims that the ordinary objects of perception must be perceived in order to exist. The only things that exist are minds and what minds perceive.
Idealism is the claim that nothing mind-independent exists.
1. Through vision, we perceive colours, shapes, sizes, etc.; through hearing, sounds; through smell, odours - and so on. Each sense perceives particular types of qualities.
2. When we perceive physical objects, we don’t perceive anything in addition to its primary and secondary qualities.
3. Therefore, everything we perceive is either a primary or secondary quality.
4. Both primary and secondary qualities are mind-dependent.
5. Therefore, nothing that we perceive exists independently of the mind: the objects of perception are entirely mind-dependent.
What is Berkeley’s attack on the primary/secondary property distinction?
1. Hylas has not been persuaded that primary qualities are just as mind-dependent as secondary-qualities. Philonous tries another approach: a. a. A physical object will need to be of some size or other. b. What distinguishes one size from another size is something we perceive. c. Therefore, we can’t form an idea of size as something that exists independent of our perception. d. We can’t separate the idea of something having a size from ideas of secondary qualities. Try to picture something with size, and you will also picture something with a shape and a colour and other qualities that we sense. e. Therefore, we cannot coherently form a conception of a physical object that has primary properties alone.
2. Hylas argues that we need the idea of a ‘material substratum’ - the stuff or substance that possesses primary and secondary qualities and holds them together to make one physical object. Berkeley points out that it is never perceived, since it is distinct from its primary and secondary qualities - and primary and secondary qualities are all that we can perceive. When substance exists unperceived - it exists without any qualities at all.
3. Berkeley argues that neither our senses nor reason are enough to support the idea that physical objects exist. a. All we perceive are primary and secondary qualities, not mind-independent physical objects.
b. Therefore, our experience cannot verify the hypothesis that there is a mind-independent physical world. c. Worse still, the hypothesis of ‘physical substance’ is not one that is even suggested by experience. d. So close attention to experience supports the claim that all there is (all we can say there is) is what we can experience. e. What we experience are ideas. f. Therefore, our experience supports idealism, not realism.
4. Supposing that the objects of perception can and do exist mind-independently leads to scepticism. How is it that we connect up our experiences to something beyond them - which, following the objection just made, we can’t even describe or understand? How can we know that ideas really do represent something that exists completely independently of them?
What is Berkeley’s master argument?
Philonous says, ‘I am willing to let our whole debate be settled as follows: If you can conceive it to be possible for any mixture or combination of qualities, or any sensible object whatever, to exist outside the mind, then I will grant it actually to be so’. Hylas responds that he is thinking of a tree existing unperceived by anyone. Philonous objects, what Hylas is thinking depends on his mind. He isn't actually thinking of a tree that exists independently of anyone’s mind; he is imagining a tree standing in a solitary place where no one perceives it. But all the time, he is thinking of such a tree. However, Berkeley seems to have confused a thought with what the thought is about.
1. Thoughts cannot exist outside the mind - thoughts are psychological events or states.
2. Therefore, my thinking of a tree is not mind-independent. It is impossible that there is a thought of a tree when no one is thinking of a tree.
3. But what a thought is about, e.g. a tree, is not the same thing as the thought itself.
4. Therefore, just because my thinking of a tree is mind-dependent, it does not follow that what I am thinking of is also mind-dependent. It is not impossible to think that a tree may exist when no one is thinking of it.
What are the four issues with Berkeley’s idealism?
It leads to solipsism, it does not give and adequate account of illusions and hallucinations, it cannot secure objective space and time and whether God can be used to play the role He does.
How does Berkeley’s idealism lead to solipsism?
Solipsism is the view that only oneself, one’s mind, exists. If all I perceive are ideas, what reason do I have to think that other minds exist? For that matter, what reason do I have to think that minds exist? After all, I do not perceive minds. Berkeley accepts that strictly speaking, I have no idea of a mind. But because I am a mind - a ‘thinking substance’ - I know I exist.
1. The mind is that which (actively) perceives, thinks and wills, while ideas are passive.
2. I am aware of myself as capable of this activity.
3. Therefore, I am not my ideas, but a mind.
4. Being a mind myself, I have a notion of what a mind is.
5. Therefore, it is possible that other minds exist.
6. My perceptions don't originate in my mind.
7. Therefore, they are caused by some other mind.
8. The complexity, regularity, ect., of my experience indicates that this mind is God.
How does Berkeley’s idealism not give an adequate account of illusions and hallucinations?
Hylas asks how idealism can explain illusions. For example, an oar half-submerged in water looks bent, however when you reach out and touch it it does not feel bent. Berkeley’s response is that we aren't misperceiving - what we perceive in the case of the half-submerged oar is crooked. However, this is misleading if we infer that the oar would feel crooked or would look crooked if we pulled it out of the water. Illusions mislead us regarding the ideas we might associate with what we perceive. This entails that the or is crooked when half-submerged. Berkeley responds that we should say ‘the oar looks crooked’ instead, because to say ‘the oar is crooked’ would mean that the oar is crooked under normal conditions, which is not true.
As for hallucinations, they are products of the imagination. Normally, imagination is voluntary and perception is not. Berkeley provides two other criteria that mark off hallucinations from perception. First, they are ‘dim, irregular, and confused’. Secondly, even if they were as ‘vivid and clear’ as perceptions, they are not coherently connected with the rest of our perceptual experience. In perception, you experience something outside your mind, in hallucination, you don’t.
How does Berkeley’s idealism not secure objective space and time?
Hylas objects that if you and I look at the same tree, the idea that exists in my mind is numerically different from the idea that exists in your mind. You see the tree that appears to you; I see the tree that appears to me. In that case, no two people ever see the same thing.
Berkeley responds that we see the same tree in the sense of ‘exactly resembling’. The tree you see is qualitatively identical to the tree I see. But this reply runs counter to common sense - surely you and I can look at one and the same tree.
Berkeley’s second response is better. You experience your sense-data of the tree, I experience mine. Idealism can say that we both perceive a copy of the idea of the tree in God’s mind - this is enough to say we perceive the same thing.
Idealism can secure objective space and time - in the mind of God. The ideas that make up physical objects and the relations of space and time between them exist in God’s mind. Russell says that ‘objective’ space and time is the space and time that characterise physical objects as science describes them. So, following Berkeley’s account of science, objective space and time are regularities in relations between what we experience, and these regularities are part of the mind of God.