1 00:00:10,690 --> 00:00:17,660 OK, let's move on to consider the issue of perception and in a little more detail. 2 00:00:17,660 --> 00:00:27,950 I've suggested that realism can be defended. It can be defended as long as we're prepared to relax the requirement of intelligibility. 3 00:00:27,950 --> 00:00:34,130 But that's not the only way in which realism can be attacked. 4 00:00:34,130 --> 00:00:39,410 So Locke famously is an indirect realist when I see the tree. 5 00:00:39,410 --> 00:00:48,390 There's an idea in my mind that's what's directly I directly perceive in the sense that I'm directly aware of the idea of the tree in my mind. 6 00:00:48,390 --> 00:00:54,530 And I assume that there is a material object, which is the cause of this idea. 7 00:00:54,530 --> 00:00:57,950 This naturally brings the so-called veil of perception problem. 8 00:00:57,950 --> 00:01:03,890 How do we know that there really is a material object, as it were, beyond the veil of my ideas? 9 00:01:03,890 --> 00:01:10,610 Does this trap me within my ideas? Well. 10 00:01:10,610 --> 00:01:18,570 It can seem to do so, particularly if you're tempted by what I shall call the unacceptable interpretation. 11 00:01:18,570 --> 00:01:23,070 Now it is possible to parody indirect realism like this. 12 00:01:23,070 --> 00:01:28,380 Okay. There's a tree out there. I'm looking at the tree. How do we explain it? 13 00:01:28,380 --> 00:01:35,520 Well, we explain it by postulating an idea in my mind, an idea of a tree, which is in my mind. 14 00:01:35,520 --> 00:01:40,330 OK, so I see the tree by seeing the idea in my mind. 15 00:01:40,330 --> 00:01:43,780 Now, what you're seeing, the idea in my mind, amount to. 16 00:01:43,780 --> 00:01:51,790 Well, maybe there's a little homunculus, a little me in there looking at a screen and on the screen is image of a tree. 17 00:01:51,790 --> 00:02:00,960 And that's the idea of the tree. So I see the tree by the homunculus in here seeing the image of the tree. 18 00:02:00,960 --> 00:02:10,750 Now, that clearly is not explanatory because it's explaining perception of the tree in terms of perception of the idea of a tree. 19 00:02:10,750 --> 00:02:18,140 That's. Not got us anywhere. It's replaced one mystery by another mystery. 20 00:02:18,140 --> 00:02:23,880 So. That interpretation, I think it is clearly wrong. 21 00:02:23,880 --> 00:02:29,260 And certainly that can that can naturally lead to the following sort of puzzle, you know, 22 00:02:29,260 --> 00:02:35,300 if you think about it, what happens when you see a tree, the image on your retina is upside down. 23 00:02:35,300 --> 00:02:43,690 Right. Because of the way the eye works as a camera. And it can seem really puzzling that we don't see the tree is upside down. 24 00:02:43,690 --> 00:02:48,830 Why? If you think about it, shouldn't be so puzzling at all. 25 00:02:48,830 --> 00:02:55,010 Why should you expect it to appear upside down unless you are trapped by the unacceptable interpretation, 26 00:02:55,010 --> 00:03:04,090 unless you're thinking that somehow that image has to be seen? The projection of that image onto the retina just is part of the process of seeing. 27 00:03:04,090 --> 00:03:12,340 And by some intricate mechanism that we vaguely understand, but not very well, hopefully in the next 50 hundred years. 28 00:03:12,340 --> 00:03:14,810 We'll get to understand it a lot better. 29 00:03:14,810 --> 00:03:26,720 We are aware of the tree through by means of this physical process, but it is not because there is some little man in there looking at the screen. 30 00:03:26,720 --> 00:03:33,230 Now, 20th century philosophers have tended to prefer to talk about census data rather than ideas. 31 00:03:33,230 --> 00:03:41,960 But beware, when you read stuff about census data, there's always this temptation to think of it in terms of the unacceptable interpretation. 32 00:03:41,960 --> 00:03:48,320 It's much better to say that awareness of a sense datum counts as perception of an external object. 33 00:03:48,320 --> 00:03:54,080 So it's not that you perceive a sense datum and thus perceive an external object. 34 00:03:54,080 --> 00:04:03,120 Rather, you are aware of the Senate state and think of the sense datum is simply the way in which the object appears to you. 35 00:04:03,120 --> 00:04:11,150 But how can we know that there really is an object out there, as it were, beyond what we are immediately aware of? 36 00:04:11,150 --> 00:04:22,120 How can we prove that causal link? Well, here is David Hume presenting the problem in his characteristically pithy way. 37 00:04:22,120 --> 00:04:29,750 It is a question of fact whether the perceptions of the senses be produced by external objects resembling them. 38 00:04:29,750 --> 00:04:39,940 How shall this question be determined by experience? Shirley Hume says experience is the only way by which we can establish any causal connexion. 39 00:04:39,940 --> 00:04:43,630 But here, experience is and must be entirely silent. 40 00:04:43,630 --> 00:04:51,520 The mind has never anything present to it but the perceptions and cannot possibly reach any experience of their connexion with objects. 41 00:04:51,520 --> 00:04:57,080 The supposition of such a connexion is therefore without any foundation in reasoning. 42 00:04:57,080 --> 00:05:07,190 So here's the challenge. Once you accept that there is a difference between the object out there and your perception of the object. 43 00:05:07,190 --> 00:05:12,880 However you interpret that. A sceptical question can be raised. 44 00:05:12,880 --> 00:05:22,870 How do we know that there are any objects there? And what humans are saying is we only directly perceive or we're only directly aware. 45 00:05:22,870 --> 00:05:25,420 All of those perceptions of things as they appear. 46 00:05:25,420 --> 00:05:33,520 How can we ever establish a reliable causal connexion between the supposed objects out there and our perceptions? 47 00:05:33,520 --> 00:05:42,070 If we are only ever acquainted with our own perceptions, we never get the God's eye view to see this correlation between objects and perceptions. 48 00:05:42,070 --> 00:05:53,360 So how can we know that there are any objects? Well, one attempt that was made, particularly in the 20th century to get around this, though. 49 00:05:53,360 --> 00:06:00,660 You can see very much themes of this in Barclays' work is so-called phenomenal ism. 50 00:06:00,660 --> 00:06:07,080 Phenomenal ism is the view that physical objects are logical constructions out of census data. 51 00:06:07,080 --> 00:06:15,300 So statements about physical objects are to be interpreted in terms of statements about census data. 52 00:06:15,300 --> 00:06:24,540 So saying that an object is in a particular place is like making a statement about what you would perceive in certain circumstances. 53 00:06:24,540 --> 00:06:35,070 So saying that there is a lectern here is making a statement about the perceptions that I or you would have if we made certain movements. 54 00:06:35,070 --> 00:06:41,580 Those perceptions would correspond with the apparent experience of elected and maybe the 55 00:06:41,580 --> 00:06:49,280 physical existence of the lectern just is to be analysed in terms of those perceptions. 56 00:06:49,280 --> 00:06:56,330 Well, that's trying to get round the sort of Berkely an argument Berkeley wants to say 57 00:06:56,330 --> 00:07:01,010 that you can't make sense of physical objects in abstraction from perceptions. 58 00:07:01,010 --> 00:07:07,260 Here is an account that actually aims to analyse physical object as perceptions. 59 00:07:07,260 --> 00:07:12,610 It also is trying to get round the veil of perception problem. If. 60 00:07:12,610 --> 00:07:20,380 If I am acquainted with my own perceptions and if physical objects just are to be analysed in terms of my perceptions, 61 00:07:20,380 --> 00:07:29,080 then it looks as though we can get round that sceptical worry. Or at least it might look like that. 62 00:07:29,080 --> 00:07:33,760 Here again, just as we saw we've seen before. 63 00:07:33,760 --> 00:07:44,470 The problem of horizontal scepticism can be raised just as effectively phenomenal ism is trying to get round a kind of vertical scepticism by saying, 64 00:07:44,470 --> 00:07:50,410 well, if we can't prove this exists, the existence of this different kind of thing, the physical objects. 65 00:07:50,410 --> 00:07:55,720 Let's just analyse those in terms of what we do know about, namely our own perceptions. 66 00:07:55,720 --> 00:08:00,160 But again, we can raise the problem of induction. 67 00:08:00,160 --> 00:08:07,510 Suppose you do analyse the existence of a physical object in terms of perceptions that you would perceive in certain circumstances. 68 00:08:07,510 --> 00:08:17,420 You've still got the problem of justifying the claim that those predictions are actually true. 69 00:08:17,420 --> 00:08:24,800 Well, phenomenal ism was very popular in the in the mid 20th century, it hasn't been so popular since. 70 00:08:24,800 --> 00:08:34,070 Much more popular since Jay lost in NPF. Straughan has been to insist that we perceive objects directly. 71 00:08:34,070 --> 00:08:38,990 So the claim is that instead of being in direct realist's in the way of Locke, 72 00:08:38,990 --> 00:08:44,550 instead of saying that we perceive objects, as it were, by having ideas of them. 73 00:08:44,550 --> 00:08:50,290 We should say instead that we perceive them directly. What does that mean? 74 00:08:50,290 --> 00:08:56,650 What does it mean to say that we perceive objects directly? 75 00:08:56,650 --> 00:09:03,560 Well, in one sense, it seems definitely right. In so far as it counters, the unacceptable interpretation. 76 00:09:03,560 --> 00:09:11,130 If somebody thinks that we see objects by means of a little man in the head seeing a screen that's dead wrong. 77 00:09:11,130 --> 00:09:17,510 We do not perceive our ideas. We perceive objects. 78 00:09:17,510 --> 00:09:24,440 So when I look at a tree, it's the tree that I see. It's not an image of a tree. 79 00:09:24,440 --> 00:09:28,170 However, and this is the problem with it. 80 00:09:28,170 --> 00:09:36,900 There is no question that my seeing the tree is mediated by a physical process which involves things like like raise and so on, 81 00:09:36,900 --> 00:09:40,440 impacting on my retina involves signals going up. 82 00:09:40,440 --> 00:09:49,060 The optic nerve involves the brain doing all sorts of clever jiggery pocari, which somehow makes me aware of the tree. 83 00:09:49,060 --> 00:09:54,280 Simply insisting that the only thing I see is the tree, while in the sense that's true. 84 00:09:54,280 --> 00:10:00,220 I do see the tree. I don't see an idea of the tree and anything like the same sense. 85 00:10:00,220 --> 00:10:04,540 That doesn't actually, unfortunately, help the sceptical problem, 86 00:10:04,540 --> 00:10:10,330 because the sceptic can still perfectly well say, look, the experience that you're having. 87 00:10:10,330 --> 00:10:18,850 I grant you, if it is caused by the existence of the tree in the appropriate way, then I grant that you're seeing the tree. 88 00:10:18,850 --> 00:10:22,600 I'll even grant that you're seeing it directly, if that's the language you want to use. 89 00:10:22,600 --> 00:10:28,990 Fine. But how do you know that it is, in fact caused by the existence of a tree? 90 00:10:28,990 --> 00:10:33,560 How do you know you're not a brain in a VAT, etc.? So. 91 00:10:33,560 --> 00:10:38,020 The insistence on direct perception, though, it does have some point, I think, 92 00:10:38,020 --> 00:10:44,620 particularly in countering the unacceptable interpretation, doesn't really help against the sceptic. 93 00:10:44,620 --> 00:10:55,520 It merely gives a verbal solution, as it were, rather than a genuine one. 94 00:10:55,520 --> 00:11:01,950 Well, can we move back to a sort of Lockean and position? 95 00:11:01,950 --> 00:11:10,780 A Lockean position which accepts that there is a difference between the object itself and how the object appears to us. 96 00:11:10,780 --> 00:11:12,190 We have to draw that distinction. 97 00:11:12,190 --> 00:11:20,890 We have to be aware that there are potential sceptical worries here that it is possible logically to distinguish the one from the other and 98 00:11:20,890 --> 00:11:29,050 therefore that it's not a logical impossibility for me to be in the situation as of seeing a tree without there actually being a tree there. 99 00:11:29,050 --> 00:11:35,330 I could be hallucinating. I could be a brain in a vat and so on. 100 00:11:35,330 --> 00:11:41,620 Well. To get rid of the unacceptable interpretation. 101 00:11:41,620 --> 00:11:49,780 Instead of thinking of an idea as a little image of a tree, instead think of the idea as what we might call an intentional object. 102 00:11:49,780 --> 00:11:54,440 So it's not like a little tree in the mind. It's rather. 103 00:11:54,440 --> 00:12:02,260 How a tree appears to me. Well, that's a bit difficult to pin down. 104 00:12:02,260 --> 00:12:07,420 It's not exactly an image. It's not really an object at all. 105 00:12:07,420 --> 00:12:12,880 Nor is it really an explanatory thing within the. 106 00:12:12,880 --> 00:12:21,030 The causal story of how my perception comes around, rather, what we're saying is this When I perceive a tree, 107 00:12:21,030 --> 00:12:27,120 there is a characteristic experience of what it is like to perceive a tree. 108 00:12:27,120 --> 00:12:32,130 And since we can distinguish that experience from the actual being of a tree. 109 00:12:32,130 --> 00:12:36,690 Let us talk about the idea of a tree as capturing just that. 110 00:12:36,690 --> 00:12:42,100 It's not an object, but it's what it's like to see a tree. 111 00:12:42,100 --> 00:12:48,720 OK. Is that still a representative theory of perception? Well, who cares what we call it? 112 00:12:48,720 --> 00:12:52,470 A lot of Locke's language can plausibly be understood in that way, 113 00:12:52,470 --> 00:13:02,490 not in terms of ideas as little things projected on mental screens, but rather in terms of the way in which we encounter objects. 114 00:13:02,490 --> 00:13:06,600 To read more on this, again, we're getting here into some quite deep issues. 115 00:13:06,600 --> 00:13:11,580 We're trying to cover them within the compass of a lecture is quite tricky. 116 00:13:11,580 --> 00:13:18,240 I think John Mackey's book, Problems from Locke, gives a pretty good discussion of this sort of approach. 117 00:13:18,240 --> 00:13:25,290 Pages 40, 47, 51, as I've indicated, they're. 118 00:13:25,290 --> 00:13:33,200 Well, in that case. What we end up doing is going back to a Locky, an indirect realism. 119 00:13:33,200 --> 00:13:40,250 In a sense, it's indirect, in a sense not. All right. We're not saying that they're there are these little ideas that are somehow intermediaries. 120 00:13:40,250 --> 00:13:48,320 We're rather reflecting the fact that when we perceive objects, there is an experience that it is like perceiving those objects. 121 00:13:48,320 --> 00:13:55,330 And one can draw this conceptual distinction between our awareness of them and the existence of them. 122 00:13:55,330 --> 00:13:59,230 So how do we justify the existence of those objects? 123 00:13:59,230 --> 00:14:06,040 How do we get round Hume's problem where he says you never experienced the link between the objects and the perceptions? 124 00:14:06,040 --> 00:14:10,510 So how can you justify the claim that there are any objects there? 125 00:14:10,510 --> 00:14:19,000 Well, we justify the existence of the external objects in terms of their scientific explanatory is how things 126 00:14:19,000 --> 00:14:28,700 appear to us is explicable in terms of mechanisms that attribute causal powers to these objects, 127 00:14:28,700 --> 00:14:36,620 that explain them in terms of physical intermediaries, like light rays, like sound waves and so on. 128 00:14:36,620 --> 00:14:41,990 And these explanations do actually enable us to predict the thing, the way that things behave. 129 00:14:41,990 --> 00:14:46,790 So as I mentioned earlier, we can think of physical properties, 130 00:14:46,790 --> 00:14:52,520 things like size and shape and so on, as corresponding structurally to our ideas of them. 131 00:14:52,520 --> 00:14:56,600 And we do find, in fact, that if we make predictions based on that, 132 00:14:56,600 --> 00:15:03,650 the predictions tend to be reliable by attributing a ball or a block or whatever with a particular 133 00:15:03,650 --> 00:15:08,930 size and shape and physical properties corresponding broadly to our conception of them. 134 00:15:08,930 --> 00:15:15,370 We can end up with predictions about what we will perceive that end up broadly right. 135 00:15:15,370 --> 00:15:23,110 So isn't the simplest explanation there, rather than going to Barclays' God, which is supposedly orchestrating the whole show, 136 00:15:23,110 --> 00:15:33,340 to suppose that there really are things out there, something like at least structurally, something like our conceptions of them. 137 00:15:33,340 --> 00:15:37,660 Now, these explanations, the causal explanations of how things behave. 138 00:15:37,660 --> 00:15:45,970 Of how things bring about our perceptions. Those explanations are going to be have to be in terms of the objects, real qualities. 139 00:15:45,970 --> 00:15:54,820 But. We can drop the requirement, as we've said, that those real qualities that we attribute must resemble our ideas. 140 00:15:54,820 --> 00:16:03,250 We are free to give explanations in terms of things like charge and spin and strangeness and whatever. 141 00:16:03,250 --> 00:16:11,500 We should not feel trapped by the paradigm of the 17th and 18th centuries when so many people were looking for a 142 00:16:11,500 --> 00:16:19,300 scientific explanation that would inevitably appeal to real qualities that had ultimately to resemble our ideas. 143 00:16:19,300 --> 00:16:24,700 We have to be prepared to accept that the world as it is out there is actually more 144 00:16:24,700 --> 00:16:30,560 radically different from our ideas than even the scientists of that time thought it to be. 145 00:16:30,560 --> 00:16:36,970 Thank you.