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Perception 2016 revision 2. indirect realism part 1

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Perception 2016 revision 2. indirect realism part 1

  1. 1. Indirect Realism Definition, first set of problems
  2. 2. The Syllabus: Indirect Realism • the immediate objects of perception are mind- dependent objects that are caused by and represent mind- independent objects. • Issues, including: – it leads to scepticism about the ‘existence’ of the external world (attacking ‘realism’) – responses to this (external world is the ‘best hypothesis’ (Russell); coherence of the various senses and lack of choice over our experiences (Locke)) – it leads to scepticism about the ‘nature’ of the external world (attacking ‘representative’) - responses (sense data tell us of ‘relations’ between objects (Russell); the distinction between primary and secondary qualities (Locke)) – problems arising from the view that mind-dependent objects represent mind-independent objects and are caused by mind-independent objects.
  3. 3. Indirect Realism • Indirect realism: the immediate objects of perception are mind-dependent objects that are caused by and represent mind- independent objects. • Indirect Realists: John Locke, Rene Descartes, David Hume, Bertrand Russell etc
  4. 4. Indirect Realism (Possibly) helpful illustrations
  5. 5. Descartes’ Indirect Realism taken from ‘Meditation 3’ (1641) To discover the nature of our ideas the better, and to discourse of them intelligibly, it will be convenient to distinguish them, as they are ideas or perceptions in our minds, and as they are modifications of matter in the bodies that cause such perceptions in us; that so we may not think (as perhaps usually is done) that they are exactly the images and resemblances of something inherent in the subject; most of those [of sensation] being in the mind no more the likeness of Something existing without us… Whatsoever the mind perceives in itself, or is the immediate object of perception, thought, or understanding, that I call idea; and the power to produce any idea in our mind, I call the quality of the subject wherein that power is. Explain Descartes’ distinction between ideas and qualities
  6. 6. Locke’s Indirect Realism taken from his ‘An Essay Concerning Human Understanding’ (1690) 8. [Ideas and Qualities] Whatsoever the mind perceives in itself, or is the immediate object of perception, thought, or understanding, that I call idea; and the power to produce any idea in our mind, I call a quality of the subject wherein that power is. Thus a snowball having the power to produce in us the ideas of white, cold, and round, as they are in the snowball, I call qualities; and as they are sensations or perceptions in our understandings, I call them ideas. Explain Locke’s distinction between ideas and qualities.
  7. 7. Hume’s Indirect Realism From ‘Enquiry concerning Human Understanding’, section 12 (1748) It seems clear that we humans are naturally, instinctively inclined to trust our senses, and that without any reasoning—indeed, almost before the use of reason—we take it that there is an external universe that doesn’t depend on our perceiving it and would have existed if there had never been any perceiving creatures or if we had all been annihilated. Even the animals are governed by a similar opinion, and maintain this belief in external objects in all their thoughts, plans and actions. It also seems clear that when men follow this blind and powerful instinct of nature they always suppose that the very images that their senses present to them are the external objects that they perceive; it never crosses their minds that sensory images are merely representations of external objects. This very table that we see as white and feel as hard is believed to exist independently of our perception, and to be something external to our mind, which perceives it. Our presence doesn’t bring it into existence, and our absence doesn’t annihilate it. It stays in existence (we think), complete and unchanging, independent of any facts about intelligent beings who perceive it or think about it. But the slightest philosophy is enough to destroy this basic belief that all men have. For philosophy teaches us that images (or perceptions) are the only things that can ever be present to the mind, and that the senses serve only to bring these images before the mind and cannot put our minds into any immediate relation with external objects. The table that we see seems to shrink as we move away from it; but the real table that exists independently of us doesn’t alter; so what was present to the mind wasn’t the real table but only an image of it. These are the obvious dictates of reason; and no-one who thinks about it has ever doubted that when we say ‘this house’ and ‘that tree’ the things we are referring to are nothing but perceptions in the mind—fleeting copies or representations of other things that are independent of us and don’t change. To that extent, then, reason compels us to contradict or depart from the basic instincts of nature, and to adopt a new set of views about the evidence of our senses. Explain Hume’s view of our ‘basic belief’ and why it is that the ‘slightest philosophy’ destroys it.
  8. 8. Russell’s Indirect Realism: sense-data From ‘The Problems of Philosophy’ (1912) Take Russell to be explaining, pace Hume, what Hume then goes on to say… ‘Let us give the name of 'sense-data' to the things that are immediately known in sensation: such things as colours, sounds, smells, hardnesses, roughnesses, and so on. We shall give the name 'sensation' to the experience of being immediately aware of these things. Thus, whenever we see a colour, we have a sensation of the colour, but the colour itself is a sense-datum, not a sensation. The colour is that of which we are immediately aware, and the awareness itself is the sensation. It is plain that if we are to know anything about the table, it must be by means of the sense-data--brown colour, oblong shape, smoothness, etc. – which we associate with the table; but, for the reasons which have been given, we cannot say that the table is the sense-data, or even that the sense-data are directly properties of the table. Thus a problem arises as to the relation of the sense-data to the real table, supposing there is such a thing.’ In other words, Russell uses the perceptual variation problem as an argument for indirect realism, by (re-)introducing the notion of sense-data.
  9. 9. The Qualities of Sense-Data 1. Sense-data are purely mental objects. Seemings. Appearances. The content of your experience. The ‘Raw Feel’ of the world as it appears to you. They are only as they seem or appear. They have no further or deeper reality. – So if our knowledge of physical objects is intermediated by sense-data, objects can appear differently from how they really are, and perceptions can vary between individuals, and illusions, hallucinations etc. can be explained away. 2. Sense-data, as mental objects, only exist while they are being experienced. In contrast, physical objects exist when no one experiences them. 3. Sense-data, as mental objects, are private to you. No one else can experience your sense-data, as only you have access to your collection of mental objects. In contrast, physical objects are public: the same object is experienced/perceived by all perceivers.
  10. 10. Issues with Indirect Realism 1. Can we be sure the external world exists? – Attacks ‘realism’ of RR: scepticism about the ‘existence’ of the external world – Response: external world is the ‘best hypothesis’- Russell. – Responses: physical objects explain sensory coherence/ lack of choice over our experiences - Locke 2. Can we know the external world as it really is? – Attacks ‘representative’: scepticism about the ‘nature’ of the external world that indirect realism lets us know. – Response: ‘Sense data’ explain ‘relations’ between objects – Russell – Response: The distinction between primary and secondary qualities explains the nature of the external world – Locke. 3. There are problems arising from the view that mind-dependent objects represent mind- independent objects and are caused by mind-independent objects. (These I am collapsing into 2., above, and our discussion of Berkeley, to follow)
  11. 11. ‘Realism’ sceptically attacked Does the external world actually exist? Accusation 1: Indirect Realism leads to scepticism about the ‘existence’ of the external world. • Notion of three components being involved in perception is too complex. • Given that the Indirect Realist admits that we can know only mind-dependent objects, what arguments can we offer that in fact there are mind-independent objects? • How can we get beneath or beyond sense-data to prove that objects in fact exist? • We can only point to sense-data in our proof of the existence of physical objects: we cannot logically prove that they exist in the realist’s sense. ‘You say, though the ideas themselves do not exist without the mind, yet there may be things like them, whereof they are copies or resemblances, which things exist without the mind in an unthinking substance. I answer, an idea can be like nothing but an idea; a colour or figure can be like nothing but another colour or figure. …I appeal to any one whether it be sense to assert a colour is like something which is invisible; hard or soft, like something which is intangible; and so of the rest.’ - Berkeley, responding to Locke
  12. 12. The Sceptical Issue This is nicely explained by Russell, in Ch. 2 of ‘The Problems of Philosophy’ The problem we have to consider is this: granted that we are certain of our own sense-data, have we any reason for regarding them as signs of the existence of something else, which we can call the physical object? When we have enumerated all the sense-data which we should naturally regard as connected with the table, have we said all there is to say about the table, or is there still something else--something not a sense-datum, something which persists when we go out of the room? Common sense unhesitatingly answers that there is. What can be bought and sold and pushed about and have a cloth laid on it, and so on, cannot be a mere collection of sense-data. If the cloth completely hides the table, we shall derive no sense-data from the table, and therefore, if the table were merely sense-data, it would have ceased to exist, and the cloth would be suspended in empty air, resting, by a miracle, in the place where the table formerly was. This seems plainly absurd; but whoever wishes to become a philosopher must learn not to be frightened by absurdities.
  13. 13. Other Minds and Shared Objects Here Russell weighs up an argument that since other minds exist and are in agreement with us, there must be underlying physical objects. ‘One great reason why it is felt that we must secure a physical object in addition to the sense-data, is that we want the same object for different people…it is the fact that different people have similar sense-data, and that one person in a given place at different times has similar sense-data, which makes us suppose that over and above the sense-data there is a permanent public object which underlies or causes the sense-data of various people at various times...yet when we are trying to show that there must be objects independent of our own sense-data, we cannot appeal to the testimony of other people, since this testimony itself consists of sense-data, and does not reveal other people's experiences unless our own sense-data are signs of things existing independently of us. We must therefore, if possible, find, in our own purely private experiences, characteristics which show, or tend to show, that there are in the world things other than ourselves and our private experiences. His response is that we cannot be sure that other minds exist…this is called the Problem of Other Minds
  14. 14. Writing task • Outline and explain the argument that indirect realism leads to scepticism about the existence of the external world.
  15. 15. Explanatory Power • The three arguments that follow perhaps are really all arguments that rely on the notion of ‘explanatory power’. • Explanatory power simply means: ‘this hypothesis, if true, explains lots of things’. • For each of the arguments that follow, pick out: – What the things that are explained are. – The key example that is used.
  16. 16. Russell’s ‘Best hypothesis’ response From ‘The Problems of Philosophy’, chapter 2 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.
  17. 17. 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 a triangle is of playing football…
  18. 18. Thus every principle of simplicity urges us to adopt the natural view, that there really are objects other than ourselves and our sense-data which have an existence not dependent upon our perceiving them. [O]ur instinctive belief that there are objects corresponding to our sense-data...tends to simplify and systematize our account of our experiences, [and so] there seems no good reason for rejecting it. We may therefore admit--though with a slight doubt derived from dreams--that the external world does really exist, and is not wholly dependent for its existence upon our continuing to perceive it. A simple cat. Needs a simple explanation.
  19. 19. Russell’s Argument 1. Either the physical world exists or it doesn’t. 2. We cannot know for sure so we must hypothesise instead. 3. The hypothesis which best explains agreed features of the physical world is the one we should use. 4. The supposition that there are mind-independent physical objects best explains agreed features of the physical world like object permanence and unobserved causal processes (miaow!). 5. So the hypothesis that there are mind-independent physical objects is the one we should use.
  20. 20. Locke’s ‘Argument from Best Explanation’ 1 ‘Essay concerning Human Understanding’ (1690) (Book 4, chapter 11) Argument: our lack of choice over our experiences is only explained by the existence of physical objects: a rose, the taste of sugar, the sun. When my eyes are shut, I can choose to recall to my mind the ideas of light or the sun that former sensations have lodged in my memory, or choose to set such ideas aside and instead take into my imaginative view the idea of the smell of a rose or the taste of sugar. But if at noon I turn my eyes towards the sun, I can’t avoid the ideas that the light or sun then produces in me. So there is a clear difference between the ideas …that force themselves on me and that I can’t avoid having…the ones I have whether I want them or not must be produced in my mind by some exterior cause, and the brisk acting of some external objects whose power I can’t resist. Besides, everybody can see the difference in himself between having a memory of how the sun looks and actually looking at it. His perceptions of these two are so unalike [it is clear] that they are not both memory or products purely of his mind, and that actual seeing has an external cause.
  21. 21. Argument: the coherence of the various senses is only explained by the existence of physical objects, using the example of a letter to show this. …Here is an example of how the different senses confirm one another. [Consider the letter I am writing] Once those letters have been put onto the paper…they continue to affect my senses constantly and regularly according to the shapes that I put down on the page. A further point: the sight of those written letters will draw from someone who reads them aloud the very sounds that I planned them to stand for; and that leaves little reason for doubt that the words I write really do exist outside me. The sounds that they cause me to hear couldn’t come from my imagination or my memory. The letters will cause a long series of regular sounds to affect my ears—too long for my memory to be able to retain them in the right order; and because the sounds come to me whether I want them or not, they couldn’t be the effect of my imagination. (Bennett, ditto) Locke’s ‘Argument from Best Explanation’ 2 ‘Essay concerning Human Understanding’ (1690) (Book 4, chapter 11)
  22. 22. Issues with Indirect Realism 2 1. Can we know the external world as it really is? – Attacks ‘representative’: scepticism about the ‘nature’ of the external world that RR lets us know. – Response: ‘Sense data’ explain ‘relations’ between objects – Russell – Response: The distinction between primary and secondary qualities explains the nature of the external world – Locke. 2. There are problems arising from the view that mind-dependent objects represent mind-independent objects and are caused by mind- independent objects. (These I am collapsing into 2., above.)
  23. 23. Possible reply to Locke’s suggestions • Locke has only given us some more things that we have to explain about our senses, not an explanation about why physical objects exist. • He seems to be arguing that we must infer the existence of physical objects from the consistent and coherent existence of sense-data – that is to say, (negatively) then, that physical objects are really only an explanatory hypothesis at best. • So he doesn’t account for our strong intuitive sense that physical objects must exist. • And now, to Russell’s list of things to be explained, we now must also add explanations for: – How it is that our sense-data aren’t consciously controlled. – Why it is that our sense-data cohere. • Locke, of course, might well reply that an explanation has been asked for by the sceptic and he has given one – it is, therefore, the sceptic who seeks rational explanations of our intuitions and is, thus, committing a category error. (Locke’s mistake, then, if there is one, is only in taking the sceptic seriously.)
  24. 24. Can we know the external world as it really is? Some sceptical thoughts. • Assume, hypothetically, that the external world does exist: accept the argument from best explanation. – But what is the world’s nature? • Key Question: If we know it only through representations, could there be a gap between how we see the world and how it really is? – Re + Presentation – even the shape of this word shows there is a gap… – How representative is our view of the way the world really is? • [Worse: solipsism…If sense-data are private to the individual: could there be a gap between how the individual sees the world, and how others see it? • Might the world of representations have only one inhabitant?] How can you check the correctness of your mental image if you don’t have direct access to the real? How can you check the reality of the cinematic image, if you cannot leave the cinema?

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