Epistemology Flashcards
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?
- We perceive something having some property F (e.g a stick in water is crooked).
- When we perceive something having some property F, then there is something that has this property.
- In an illusion, the physical object does not have the property F (the stick is not crooked).
- Therefore, what has the property F is something mental, a sense-datum.
- Therefore, in illusions, we see sense data, and not physical objects, immediately.
- Illusions can be ‘subjectively indistinguishable’ from veridical perception.
- Therefore, we see the same thing (sense-data) in both illusions and veridical perception.
- Therefore, in all cases, we see sense-data, and not physical objects, immediately.
- Therefore, direct realism is false.
What is the argument from perceptual variation?
- There are variations in perception.
- 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).
- Therefore, the properties physical objects have and the properties they appear to have are not identical.
- Therefore, what we are immediately aware of in perception is not exactly the same as what exists independently of our own minds.
- Therefore, we do not perceive physical objects directly.
Who came up with the argument from perceptual variation?
Bertrand Russell.
What is the argument from hallucination?
- In hallucination, we perceive something having some property F.
- When we perceive something having some property F, then there is something that has this property.
- We don’t perceive a physical object at all (unlike the case of illusion).
- Therefore, what we perceive must be mental - sense-data.
- Hallucinations can be experiences that are ‘subjectively indistinguishable’ from veridical perceptions.
- Therefore, we see the same thing, namely sense-data, in both hallucinations and veridical perception.
- Therefore, in all cases, we see sense-data, and not physical objects, immediately.
- 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:
- Either physical objects exist and cause my sense-data or physical objects do not exist nor cause my sense-data.
- I can’t prove either claim is true or false.
- Therefore, I have to treat them as hypotheses.
- 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).
- Therefore, physical objects exist and cause my sense-data.
Who responded saying the external world is the bets hypothesis?
Bertrand Russell.
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?
John Locke.
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.
- 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.
- 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.
- 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?
Bertrand Russell.
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?
John Locke.
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.