WEBVTT 00:00.360 --> 00:02.850 Professor Shelly Kagan: Today we're going to take up the 00:02.846 --> 00:04.446 discussion where we left it last time. 00:04.450 --> 00:08.260 We were talking about two main positions with regard to the 00:08.262 --> 00:10.302 question, "What is a person?" 00:10.300 --> 00:12.620 On the one hand, we have the dualist view; 00:12.620 --> 00:16.860 that's the view that we spent a fair bit of time sketching last 00:16.856 --> 00:18.696 meeting. The dualist view, 00:18.699 --> 00:22.109 according to which a person is a body and a soul. 00:22.110 --> 00:25.460 Or perhaps, strictly speaking, what we should say is the only 00:25.459 --> 00:28.249 part that's essential to the person is the soul, 00:28.250 --> 00:31.120 though it's got a rather intimate connection to a 00:31.115 --> 00:34.215 particular body. That's the dualist view. 00:34.220 --> 00:37.480 In contrast to that, we've got the physicalist view, 00:37.480 --> 00:40.230 according to which there are just bodies. 00:40.230 --> 00:43.830 A person is just a body, as we might put it. 00:43.830 --> 00:46.810 Now, the crucial point here, the point I was turning to as 00:46.811 --> 00:50.191 we ended last time, is that although a person on 00:50.186 --> 00:54.976 the physicalist view is just a body, a person isn't just any 00:54.984 --> 00:59.354 old body. A person is a body that has a 00:59.352 --> 01:05.202 certain set of abilities, can do a certain array of 01:05.202 --> 01:08.802 activities. People are bodies that can 01:08.800 --> 01:12.270 think, that can communicate, that are rational, 01:12.268 --> 01:15.388 that can plan, that can feel things, 01:15.392 --> 01:19.432 that can be creative, and so forth and so on. 01:19.430 --> 01:25.060 Now, we might argue about what's the exact best list of 01:25.055 --> 01:28.115 those abilities. For our purposes, 01:28.120 --> 01:32.040 I think that won't be crucial, and so I'll sometimes talk 01:32.040 --> 01:35.680 about this set of abilities without actually having a 01:35.680 --> 01:39.340 canonical list. Just think of them as the set 01:39.342 --> 01:44.022 of abilities that people have, the things that we can do that 01:44.024 --> 01:50.024 other physical objects--chalk, radios, cars--those things 01:50.016 --> 01:54.026 can't do. Call those the abilities that 01:54.031 --> 01:56.361 make something a person. 01:56.360 --> 02:00.120 To just introduce a piece of jargon, we could call those the 02:00.116 --> 02:02.786 P abilities, P for person. 02:02.790 --> 02:05.060 Or we could talk about the various kinds of ways--this is 02:05.064 --> 02:07.384 the physicalist way of thinking about it--according to the 02:07.380 --> 02:10.780 physicalist, a person is just a body that 02:10.784 --> 02:16.594 has the ability to fulfill the various P functions. 02:16.590 --> 02:20.290 And we can talk, then, about a person as a 02:20.291 --> 02:22.821 P-functioning body. 02:22.819 --> 02:27.139 Or we could say that a person is a body that is 02:27.139 --> 02:29.299 P-functioning. 02:29.300 --> 02:32.290 It's important to see that the idea is, although it's a body, 02:32.293 --> 02:33.743 it's not just any old body. 02:33.740 --> 02:35.630 Indeed, it's not just any old human body. 02:35.629 --> 02:39.629 After all, if you rip out your gun, shoot me in the heart, 02:39.634 --> 02:42.874 I bleed to death, we still have a human body in 02:42.865 --> 02:45.695 front of us. But we don't have a 02:45.695 --> 02:47.485 P-functioning body. 02:47.490 --> 02:50.500 We don't have a body that's able to think, 02:50.496 --> 02:53.576 a body that's able to plan, to communicate, 02:53.576 --> 02:56.066 to be creative, to have goals. 02:56.069 --> 03:00.849 So the crucial thing about having a person is having a 03:00.853 --> 03:03.383 P-functioning body. 03:03.380 --> 03:08.110 Now, what's a mind on this view? 03:08.110 --> 03:11.300 On the physicalist view, it's still perfectly legitimate 03:11.302 --> 03:12.582 to talk about minds. 03:12.580 --> 03:14.990 The point, though, is that from the physicalist 03:14.992 --> 03:17.092 perspective, the best thing to say is, 03:17.090 --> 03:23.670 talk about a mind is a way of talking about these various 03:23.674 --> 03:27.324 mental abilities of the body. 03:27.320 --> 03:30.240 We nominalize it. 03:30.240 --> 03:33.320 We talk about it using a noun, the mind. 03:33.319 --> 03:38.669 But talk of the mind is just a way of talking about these 03:38.671 --> 03:44.501 abilities that the body has when it's functioning properly. 03:44.500 --> 03:49.670 This is similar, let's say, to talking about a 03:49.670 --> 03:51.950 smile. We believe that there are 03:51.953 --> 03:53.913 smiles. Physicalists don't deny that 03:53.914 --> 03:56.044 there are minds. Just like we don't deny, 03:56.043 --> 03:58.003 we all believe, that there are smiles. 03:58.000 --> 03:59.820 But what is a smile? 03:59.819 --> 04:05.589 Well, a smile is just a way of talking about the ability of the 04:05.589 --> 04:07.729 body to do something. 04:07.729 --> 04:13.009 This characteristic thing we do with our lips exposing our teeth 04:13.012 --> 04:15.152 and so forth. It's a smile, 04:15.154 --> 04:18.084 a rather dorky smile, but there's a smile. 04:18.079 --> 04:21.379 Now, if you were listing the parts of the body, 04:21.379 --> 04:25.109 you would list the teeth, you would list the lips, 04:25.110 --> 04:28.720 you would list the gums, you would list the tongue, 04:28.723 --> 04:31.183 but you wouldn't list the smile. 04:31.180 --> 04:34.110 So, should we conclude, as dualists, 04:34.111 --> 04:38.891 that smiles are these extra nonphysical things that have a 04:38.886 --> 04:42.736 special intimate relationship with bodies? 04:42.740 --> 04:45.450 Well, you could imagine a view like that, but it would be 04:45.446 --> 04:46.506 rather a silly view. 04:46.509 --> 04:53.779 Talk about a smile is just a way of talking about the body's 04:53.779 --> 04:56.119 ability to smile. 04:56.120 --> 04:58.660 There's no extra part. 04:58.660 --> 05:03.740 Even though we have a noun, the smile, that if you're not 05:03.735 --> 05:08.985 careful might lull you into thinking there must be a thing, 05:08.991 --> 05:11.661 the smile. And then you'd have all these 05:11.661 --> 05:12.871 metaphysical conundrums. 05:12.870 --> 05:14.890 Where is the smile located? 05:14.889 --> 05:17.939 It seems to be in the vicinity of the mouth. 05:17.940 --> 05:20.370 But the smile isn't the lips. 05:20.370 --> 05:21.810 The smile isn't the teeth. 05:21.810 --> 05:23.620 So it must be something nonphysical. 05:23.620 --> 05:27.870 No, that would just be a silly way to think about smiles. 05:27.870 --> 05:33.820 Talk of smiles is just a way of talking about the ability of the 05:33.822 --> 05:36.942 body to smile, to form a smile. 05:36.940 --> 05:40.930 That's an ability that we have, our bodies have. 05:40.930 --> 05:43.930 Similarly, then, according to the physicalist, 05:43.925 --> 05:47.115 talk of the mind, despite the fact that we have a 05:47.121 --> 05:51.181 noun there, is just a way of talking about 05:51.177 --> 05:56.067 the abilities of the body to do various things. 05:56.069 --> 06:01.219 The mind is just a way of talking about the fact that our 06:01.221 --> 06:04.351 body can think, can communicate, 06:04.350 --> 06:08.560 can plan, can deliberate, can be creative, 06:08.555 --> 06:12.345 can write poetry, can fall in love. 06:12.350 --> 06:16.660 Talk of all of those things is what we mean by the mind, 06:16.659 --> 06:21.119 but there's no extra thing, the mind, above and beyond the 06:21.124 --> 06:22.874 body. That's the physicalist view. 06:22.870 --> 06:25.720 So it's important, in particular, 06:25.717 --> 06:30.607 to understand that from the physicalist's point of view, 06:30.610 --> 06:33.280 the mind is not the brain. 06:33.279 --> 06:35.629 You might think, "Look, according to 06:35.634 --> 06:38.194 physicalists minds are just brains." 06:38.190 --> 06:41.740 And that wouldn't be a horrendously misleading thing to 06:41.742 --> 06:45.692 say, because according to the best science that we've got, 06:45.690 --> 06:51.190 the brain is the part of the body that is the seat or house 06:51.185 --> 06:56.585 or the underlying mechanical structure that gives us these 06:56.585 --> 06:58.665 various abilities. 06:58.670 --> 07:02.130 These P functions are functions that we have by virtue 07:02.125 --> 07:05.675 of our brain. So that might tempt you into 07:05.677 --> 07:10.287 saying the mind on the physicalist view is just a 07:10.286 --> 07:13.266 brain. But we probably shouldn't say 07:13.271 --> 07:15.051 that. After all, if you shoot me, 07:15.051 --> 07:16.941 there's my corpse lying on the stage. 07:16.940 --> 07:19.130 Well, there's my brain. 07:19.129 --> 07:22.139 My brain is still there in my head. 07:22.140 --> 07:24.720 But we no longer have a person. 07:24.720 --> 07:26.420 The person has died. 07:26.420 --> 07:29.090 The person, it seems, no longer exists. 07:29.089 --> 07:31.629 Whether strictly that's the best thing to say or not is a 07:31.630 --> 07:34.080 question we'll have to come to in a couple of weeks. 07:34.079 --> 07:37.709 But it seems pretty clear that the mind has been destroyed, 07:37.709 --> 07:40.149 even though the brain is still there. 07:40.149 --> 07:42.469 So I think, at least when there's the need to be 07:42.465 --> 07:45.515 careful--maybe we don't normally have a need to be careful--but 07:45.519 --> 07:47.489 when there's the need to be careful, 07:47.490 --> 07:51.460 we should say, talk of the mind is a way of 07:51.455 --> 07:55.605 talking about the P-functioning of the 07:55.610 --> 07:58.860 body. Our best science suggests that 07:58.860 --> 08:02.860 a well-functioning body can perform these things, 08:02.860 --> 08:06.710 can think and plan and fall in love by virtue of the fact that 08:06.714 --> 08:08.994 the brain is functioning properly. 08:08.990 --> 08:11.590 That's the physicalist view. 08:11.589 --> 08:16.059 On the dualist view, what was death? 08:16.060 --> 08:19.490 Death is presumably the separation of the mind and the 08:19.492 --> 08:23.312 body, perhaps the permanent separation, with the destruction 08:23.313 --> 08:26.193 of the body. What's death on the physicalist 08:26.193 --> 08:29.733 view? Well, there is no extra entity, 08:29.733 --> 08:32.593 the soul. The mind is just the proper 08:32.592 --> 08:34.902 P-functioning of the body. 08:34.899 --> 08:40.149 So, the mind gets destroyed when the ability of the body to 08:40.154 --> 08:43.964 function in that way has been destroyed. 08:43.960 --> 08:47.750 Death is, roughly, the end of this set of 08:47.752 --> 08:49.082 functioning. 08:49.080 --> 08:52.150 08:52.149 --> 08:55.799 Again, this probably should be cleaned up and in a couple of 08:55.800 --> 08:58.770 weeks we'll spend a day or half period trying, 08:58.769 --> 09:00.989 to clean it up and make it somewhat more precise. 09:00.990 --> 09:04.140 But there's nothing mysterious about death from the physicalist 09:04.144 --> 09:06.334 point of view, at least about the basic idea 09:06.331 --> 09:07.961 of what's going on in death. 09:07.960 --> 09:11.230 I've got a stereo. 09:11.230 --> 09:15.070 Suppose I hold up my boombox for you and it's playing music. 09:15.070 --> 09:16.650 It's one of the things it can do. 09:16.649 --> 09:20.549 And I drop in on the ground, smashing it. 09:20.549 --> 09:24.139 Well, it no longer can function properly. 09:24.140 --> 09:28.750 It's broken. There's no mystery why it can't 09:28.748 --> 09:31.288 function once it's broken. 09:31.289 --> 09:35.409 Death is basically just the breaking down of the body, 09:35.414 --> 09:39.544 on the physicalist point of view, so that it no longer 09:39.539 --> 09:41.329 functions properly. 09:41.330 --> 09:44.890 One other point worth emphasizing and sketching the 09:44.894 --> 09:46.824 physicalist view is this. 09:46.820 --> 09:49.400 So, as I said, physicalists don't deny that 09:49.395 --> 09:52.035 there are minds. Even though we say "we're just 09:52.041 --> 09:54.971 bodies," that doesn't mean that we're just any old body. 09:54.970 --> 09:57.640 It's not as though the physicalist view is, 09:57.644 --> 10:01.024 "we're bodies that have some illusion of thinking." 10:01.019 --> 10:04.539 No, we're bodies that really do think. 10:04.540 --> 10:07.920 So there really are minds. 10:07.919 --> 10:11.079 We could, on the physicalist point of view, 10:11.080 --> 10:12.510 call those souls. 10:12.509 --> 10:15.699 Just like there's no danger in talking of the mind from the 10:15.703 --> 10:18.623 physicalist perspective, there wouldn't be any serious 10:18.622 --> 10:20.552 danger in talking about a soul. 10:20.549 --> 10:24.529 And so, in certain contexts, I'm perfectly comfortable--in 10:24.531 --> 10:26.981 my physicalist moods, I am perfectly 10:26.977 --> 10:30.467 comfortable--talking about this person's soul. 10:30.470 --> 10:33.640 He's got a good soul, a bad soul, how the soul soars 10:33.642 --> 10:36.382 when I read Shakespeare, or what have you. 10:36.379 --> 10:40.379 There's nothing upsetting or improper about the language of 10:40.375 --> 10:43.815 the soul, even on the physicalist point of view. 10:43.820 --> 10:46.890 But in this class, just to try to keep us from 10:46.887 --> 10:49.887 getting confused, as I indicated before and I 10:49.886 --> 10:52.946 want to remind you, I'm going to save the word 10:52.953 --> 10:55.253 "soul"; I'm going to at least try to 10:55.251 --> 10:58.181 save the word "soul" for when I'm talking about the dualist 10:58.176 --> 11:00.616 view. So we might put it this way. 11:00.620 --> 11:04.270 The neutral term is going to be "mind." 11:04.269 --> 11:10.139 We all agree that people have minds, sort of the house or the 11:10.140 --> 11:12.880 seat of our personalities. 11:12.879 --> 11:16.129 The question is, "What is a mind?" 11:16.129 --> 11:22.329 The dualist position is that the mind is a soul and the soul 11:22.328 --> 11:25.058 is an immaterial object. 11:25.059 --> 11:29.459 So when I use the word "soul," I will try to reserve it for the 11:29.460 --> 11:32.730 metaphysical view, according to which souls are 11:32.725 --> 11:34.495 something immaterial. 11:34.500 --> 11:37.920 In contrast to that, we've got the physicalist view. 11:37.919 --> 11:40.889 Physicalists also believe in minds. 11:40.889 --> 11:44.699 But minds are just a way of talking about the abilities of 11:44.703 --> 11:47.863 the body. So physicalists do not believe 11:47.862 --> 11:52.792 in any immaterial object above and beyond the body that's part 11:52.788 --> 11:56.208 of a person. Just to keep things clear, 11:56.208 --> 11:59.778 I will say that physicalists, materialists, 11:59.776 --> 12:02.066 do not believe in souls. 12:02.070 --> 12:07.140 Because, for the purposes of this class, I'm going to reserve 12:07.143 --> 12:11.713 the word "soul" for the immaterialist conception of the 12:11.709 --> 12:15.739 mind. In other contexts--no harm in 12:15.735 --> 12:18.095 talking about souls. 12:18.100 --> 12:22.080 So these are the two basic positions: the dualist view on 12:22.078 --> 12:24.918 the one hand, the physicalist view on the 12:24.919 --> 12:27.369 other. The question we need to turn 12:27.372 --> 12:31.172 to--I take it that just as the dualist view is a familiar one, 12:31.167 --> 12:34.337 so it's true that the physicalist view is a familiar 12:34.340 --> 12:36.350 one. Whether or not you believe it, 12:36.352 --> 12:39.162 you are familiar with the fact that some people believe it, 12:39.159 --> 12:41.289 or at least you wonder whether it's true. 12:41.289 --> 12:44.799 Does science require that we believe in the physicalist view 12:44.795 --> 12:45.325 or not? 12:45.330 --> 12:48.680 12:48.679 --> 12:51.589 The question we want to turn to, then, is, 12:51.591 --> 12:54.651 "Which of these two views should we believe: 12:54.645 --> 12:58.475 the dualist position or the physicalist position?" 12:58.480 --> 13:01.660 And the crucial question, presumably, is, 13:01.662 --> 13:05.562 "Should we believe in the existence of a soul?" 13:05.560 --> 13:09.340 Both sides believe in bodies. 13:09.340 --> 13:12.480 As I say, the dualist position, as we're understanding it, 13:12.477 --> 13:14.897 is not a view that says there are only minds, 13:14.899 --> 13:16.219 there are no bodies. 13:16.220 --> 13:17.730 Dualists believe that there are bodies. 13:17.730 --> 13:20.900 They believe that there are souls as well as bodies. 13:20.899 --> 13:23.259 Physicalists believe there are bodies but no souls. 13:23.259 --> 13:26.839 So there's an agreement that there are bodies. 13:26.840 --> 13:29.670 Here is one. Each one of you is sort of 13:29.672 --> 13:31.662 dragging one around with you. 13:31.659 --> 13:33.099 There's agreement that there's bodies. 13:33.100 --> 13:36.610 The question is, "Are there anything beyond 13:36.613 --> 13:39.003 bodies?" Is there anything beyond the 13:38.998 --> 13:40.158 body? Is there a soul? 13:40.160 --> 13:43.900 Are there souls? That's the question that's 13:43.902 --> 13:46.422 going to concern us for a couple of weeks. 13:46.420 --> 13:50.490 13:50.490 --> 13:53.620 If we ask ourselves, "What reasons do we have to 13:53.621 --> 13:55.021 believe in a soul?" 13:55.019 --> 13:58.639 we might start by asking, what reasons do we have to 13:58.638 --> 14:00.198 believe in anything? 14:00.200 --> 14:02.530 How do we prove the existence of things? 14:02.529 --> 14:08.929 For lots of familiar everyday objects, the answer is fairly 14:08.932 --> 14:12.492 straightforward. We prove their existence by 14:12.491 --> 14:13.831 using our five senses. 14:13.830 --> 14:16.540 We just see them. 14:16.539 --> 14:20.509 How do I know that there are chairs? 14:20.509 --> 14:23.229 Well, there are some chairs in front of me. 14:23.230 --> 14:25.150 Open my eyes, I see them. 14:25.149 --> 14:27.419 How do I know that there is a lectern? 14:27.420 --> 14:30.910 Well, I see it. I can touch it. 14:30.910 --> 14:35.430 I feel it. How do I know that there are 14:35.429 --> 14:36.719 trees? I see them. 14:36.720 --> 14:37.770 How do I know that there are birds? 14:37.770 --> 14:38.940 I see them. I hear them. 14:38.940 --> 14:40.550 How do I know that there are apples? 14:40.550 --> 14:42.060 I see them. I taste them. 14:42.060 --> 14:45.260 So forth and so on. 14:45.259 --> 14:50.649 That approach pretty clearly isn't going to work for souls, 14:50.648 --> 14:54.538 because a soul--and again, we've got in mind this 14:54.539 --> 14:56.889 metaphysical view, according to which its 14:56.885 --> 14:59.695 something immaterial--isn't something we see. 14:59.700 --> 15:04.720 It's not something we taste or touch or smell or hear. 15:04.720 --> 15:12.460 We don't directly observe souls with our five senses. 15:12.460 --> 15:15.630 You might wonder, well, don't I sort of directly 15:15.633 --> 15:18.473 observe it in myself that I have a soul? 15:18.470 --> 15:21.070 Although I guess there have been people who've made that 15:21.066 --> 15:22.856 sort of claim, it seems false to me. 15:22.860 --> 15:26.110 I can only ask each of you to sort of introspect for a second. 15:26.110 --> 15:29.360 Turn your mind's eye inward and ask. 15:29.360 --> 15:34.320 Do you see a soul inside you? 15:34.320 --> 15:35.470 I don't think so. 15:35.470 --> 15:38.980 I see things outside me. 15:38.980 --> 15:42.700 I feel certain sensations in my body, but it doesn't seem as 15:42.700 --> 15:44.340 though I observe a soul. 15:44.340 --> 15:46.020 Even if I believe in a soul, I don't see it. 15:46.020 --> 15:49.640 15:49.639 --> 15:55.149 How do we prove the existence of things we can't see or hear 15:55.149 --> 15:57.389 or taste and so forth? 15:57.389 --> 16:00.319 The usual method, maybe not the only method, 16:00.317 --> 16:03.447 but the usual method is something like this. 16:03.450 --> 16:09.010 Sometimes, we posit the existence of something that we 16:09.012 --> 16:15.102 can't see so as to explain something else that we all agree 16:15.100 --> 16:16.780 takes place. 16:16.780 --> 16:20.420 16:20.419 --> 16:25.529 Why do I believe in the existence of atoms? 16:25.530 --> 16:28.450 I don't see individual atoms. 16:28.450 --> 16:31.360 Why do I believe in the existence of atoms so small that 16:31.363 --> 16:32.373 I can't see them? 16:32.370 --> 16:38.080 Because atomic theory explains things. 16:38.080 --> 16:42.130 When I posit the existence of atoms with certain structures 16:42.126 --> 16:46.026 and certain sort of ways of interacting and combining and 16:46.033 --> 16:48.923 building up, when I posit atoms, 16:48.916 --> 16:53.656 suddenly I can explain all sorts of things about the 16:53.656 --> 16:59.046 physical world. So, I infer the existence of 16:59.048 --> 17:06.878 atoms based on the fact that doing that allows me to explain 17:06.883 --> 17:11.003 things that need explaining. 17:11.000 --> 17:17.240 This is a kind of argument that we use all the time. 17:17.240 --> 17:20.210 How do I posit--why do I believe in x-rays, 17:20.214 --> 17:22.414 even though I don't see them? 17:22.410 --> 17:25.630 Because doing that allows me to explain certain things. 17:25.630 --> 17:30.930 Why do I believe in certain planets too far away to be 17:30.930 --> 17:34.930 observed directly through a telescope? 17:34.930 --> 17:38.890 Because positing them allows you explain things about the 17:38.889 --> 17:42.709 rotation of the star or the gravitational fluctuations, 17:42.707 --> 17:46.147 what have you. We make inferences to the 17:46.149 --> 17:51.359 existence of things we can't see, when doing that helps us to 17:51.355 --> 17:55.515 explain something we can't otherwise explain. 17:55.519 --> 18:00.519 This pattern of argument, which is ubiquitous, 18:00.518 --> 18:05.848 is called "inference to the best explanation." 18:05.849 --> 18:10.939 I want to emphasize this bit about "best explanation." 18:10.940 --> 18:14.660 What we're justified in believing are those things that 18:14.660 --> 18:18.520 we need, not simply when they would offer us some kind of 18:18.517 --> 18:21.997 explanation, but when they offer us the best 18:22.004 --> 18:24.624 explanation that we can think of. 18:24.619 --> 18:27.119 So look, why am I justified in believing in germs, 18:27.118 --> 18:30.228 various kinds of viruses that I can't see, or bacteria or what 18:30.229 --> 18:31.809 have you, that I can't see? 18:31.809 --> 18:39.669 Because doing that allows me to explain why people get sick. 18:39.670 --> 18:41.710 But there's other things that would allow me to explain that 18:41.713 --> 18:44.373 as well. How about demons? 18:44.369 --> 18:48.149 I could believe in demons and say, "Why does a person get sick 18:48.150 --> 18:49.880 and die? Well, it is demonic possession." 18:49.880 --> 18:52.950 18:52.950 --> 18:57.210 Why aren't I justified in believing in the existence of 18:57.210 --> 19:00.910 demons? It's a possible explanation. 19:00.910 --> 19:04.640 But what we seem to be justified in believing is not 19:04.643 --> 19:08.673 just any old explanation, but the "best explanation." 19:08.670 --> 19:10.550 So we've got two rival explanations. 19:10.549 --> 19:13.349 We've got, roughly, germ theory and we've got demon 19:13.346 --> 19:15.666 theory. We have to ask ourselves, 19:15.665 --> 19:19.725 "Which of these does a better job of explaining the facts 19:19.732 --> 19:22.952 about disease?" Who gets what kinds of diseases? 19:22.950 --> 19:26.550 How diseases spread, how they can be treated or 19:26.554 --> 19:29.144 cured, when they kill somebody. 19:29.140 --> 19:34.120 The fact of the matter is, demon theory doesn't do a very 19:34.122 --> 19:39.282 good job of explaining disease, while germ theory does do a 19:39.283 --> 19:43.563 good job. It's the better explanation. 19:43.559 --> 19:48.589 So we're justified in believing in germs, but not demons. 19:48.589 --> 19:52.079 It's a matter of inference, not just to any old 19:52.084 --> 19:56.114 explanation, but inference to the best explanation. 19:56.109 --> 19:59.359 All right, so, what we need to ask ourselves, 19:59.364 --> 20:01.884 then, is, "What about the soul?" 20:01.880 --> 20:04.170 We can't observe souls. 20:04.170 --> 20:07.710 But here's a possible way of arguing for them. 20:07.710 --> 20:13.140 Are there things that need to be explained that we could 20:13.140 --> 20:17.880 explain if we posited the existence of a soul, 20:17.880 --> 20:21.420 an immaterial object, above and beyond the body? 20:21.420 --> 20:25.590 Are there things that the existence of a soul could 20:25.594 --> 20:30.604 explain and explain better than the explanation that we would 20:30.602 --> 20:34.612 have if we had to limit ourselves to bodies? 20:34.610 --> 20:38.580 20:38.579 --> 20:41.249 You might put it this way as sort of the easiest version of 20:41.253 --> 20:43.193 this kind of argument, for our purposes. 20:43.190 --> 20:49.280 Are there things about us that the physicalist cannot explain? 20:49.279 --> 20:54.349 Are there mysteries or puzzles about people that the 20:54.351 --> 21:00.021 physicalist just draws a blank, but if we become dualists, 21:00.019 --> 21:03.399 we can explain these features? 21:03.400 --> 21:08.800 Suppose there was a feature like that, feature F. 21:08.799 --> 21:11.839 Then we'd say, "Look, although we can't see 21:11.835 --> 21:15.445 the soul, we have reason to believe in the soul, 21:15.450 --> 21:19.930 because positing the existence of a soul helps us to explain 21:19.928 --> 21:26.038 the existence of feature F, which we all agree we've got." 21:26.039 --> 21:29.369 Suppose it was true that you couldn't explain love from the 21:29.368 --> 21:30.858 physicalist perspective. 21:30.859 --> 21:33.069 But we all know that people do fall in love, 21:33.069 --> 21:35.279 but souls would allow us to explain that. 21:35.279 --> 21:40.449 Boom, we'd have an argument for the existence of a soul. 21:40.450 --> 21:42.250 It would be an example of "inference to the best 21:42.254 --> 21:42.834 explanation." 21:42.830 --> 21:46.220 21:46.220 --> 21:50.340 Now, the crucial question, of course, is, 21:50.343 --> 21:54.573 "What's the relevant feature F?" 21:54.569 --> 21:59.569 Is there some feature that the physicalist can't explain and so 21:59.565 --> 22:04.555 we need to appeal to something extra-physical to explain it? 22:04.559 --> 22:09.409 Or the physicalist can only do a rotten job of explaining, 22:09.408 --> 22:11.448 like demon theory did? 22:11.450 --> 22:15.200 And then, if we were to appeal to something nonphysical, 22:15.196 --> 22:17.986 we would do a better job of explaining. 22:17.990 --> 22:21.410 If we could find the right F, and make out the 22:21.411 --> 22:25.491 argument, the physicalist can't explain it or does a bad job of 22:25.490 --> 22:29.440 explaining it and the dualist does a better job of explaining 22:29.437 --> 22:32.457 it, we'd have reason to believe in 22:32.460 --> 22:35.240 the soul. Like all arguments in 22:35.238 --> 22:39.548 philosophy, it would be a tentative argument. 22:39.549 --> 22:43.159 We'd sort of have some reason to believe in the soul until we 22:43.155 --> 22:46.335 sort of see what next argument comes down the road. 22:46.339 --> 22:48.219 But at least it would give us some reason to believe in the 22:48.222 --> 22:48.452 soul. 22:48.450 --> 22:52.020 22:52.019 --> 22:58.169 What I want to do is ask, "What might feature F 22:58.173 --> 23:00.773 be?" Is there any such feature 23:00.769 --> 23:03.009 F? It's probably also worth 23:03.006 --> 23:06.386 underlining the fact that what I've really been doing is 23:06.388 --> 23:08.908 running through a series of arguments. 23:08.910 --> 23:12.710 "Inference to the best explanation" is not a single 23:12.714 --> 23:14.544 argument for the soul. 23:14.539 --> 23:18.699 It's rather the name for a kind of argument. 23:18.700 --> 23:22.410 Depending on what F you fill in the blank with, 23:22.414 --> 23:26.694 what pet feature or fact you're trying to explain by appeal to 23:26.688 --> 23:30.048 the soul, you get a different argument. 23:30.049 --> 23:34.679 So let's ask ourselves, "Are there things that we need 23:34.683 --> 23:39.843 to appeal to the soul in order to explain these things about 23:39.840 --> 23:42.900 us?" Here's a first try. 23:42.900 --> 23:46.130 Actually, let me start by saying I'm going to distinguish 23:46.128 --> 23:49.128 two broad families of characteristics we might appeal 23:49.126 --> 23:51.266 to. We might say, 23:51.268 --> 23:57.818 one set of approaches focus on ordinary, familiar, 23:57.819 --> 24:01.429 everyday facts about us. 24:01.430 --> 24:04.440 The fact that we love, the fact that we think, 24:04.442 --> 24:08.262 the fact that we experience emotions, what have you--these 24:08.257 --> 24:10.397 are ordinary features of us. 24:10.400 --> 24:13.280 I'm going to start with those and then I'll turn, 24:13.279 --> 24:16.879 eventually, to another set of possible things that might need 24:16.880 --> 24:19.700 explaining, which we might think of as 24:19.704 --> 24:22.374 extraordinary, supernatural things. 24:22.369 --> 24:25.239 Maybe there are certain supernatural things about 24:25.237 --> 24:28.937 communication from the dead or near-death experiences that need 24:28.940 --> 24:31.390 to be explained in terms of the soul. 24:31.390 --> 24:35.400 We'll get to those, but we'll start with ordinary, 24:35.396 --> 24:38.336 everyday, hum-drum facts about us. 24:38.339 --> 24:40.399 Even though they're ordinary and familiar, 24:40.403 --> 24:43.573 it still could turn out that we need to appeal to souls in order 24:43.573 --> 24:49.133 to explain them. So, to start, how about this? 24:49.130 --> 24:52.980 Start with a familiar fact, which I've already drawn your 24:52.983 --> 24:57.253 attention to a couple of times, that you can have a body that's 24:57.250 --> 25:00.270 dead. You could have a corpse, 25:00.265 --> 25:03.555 and that's clearly not a person. 25:03.560 --> 25:04.600 It's not a living being. 25:04.600 --> 25:06.410 It's not a person. 25:06.410 --> 25:07.370 It doesn't do anything. 25:07.370 --> 25:11.440 It just lies there; whereas your body, 25:11.436 --> 25:13.936 my body is animated. 25:13.940 --> 25:18.110 I move my hands around, my mouth is going up and down, 25:18.106 --> 25:22.736 it walks from one part of the stage to the other part of the 25:22.743 --> 25:27.613 stage. Maybe we need to appeal to the 25:27.608 --> 25:34.268 soul in order to explain what animates the body. 25:34.269 --> 25:38.199 The thought would be, when the soul and the body have 25:38.200 --> 25:42.960 been separated--such the dualist explains--the soul has lost its 25:42.961 --> 25:46.061 ability to give commands to the body. 25:46.059 --> 25:47.979 So the body is no longer animated. 25:47.980 --> 25:51.440 So we've got a possible explanation of the difference 25:51.436 --> 25:55.226 between an animated and an unanimated or an inanimate body 25:55.225 --> 25:58.095 to it. Is the soul in contact of the 25:58.099 --> 26:00.079 right sort with the body? 26:00.080 --> 26:02.570 There's a possible explanation. 26:02.569 --> 26:04.749 You might say, "Look, the physicalist can't 26:04.746 --> 26:06.966 tell us that, because all the physical parts 26:06.974 --> 26:09.414 are still there when you've got the corpse, 26:09.410 --> 26:15.850 at least if it's a fresh corpse before the decay has set in. 26:15.849 --> 26:20.149 So, we need to appeal to the existence of a soul in order to 26:20.145 --> 26:24.435 explain the animation of bodies like the ones that you and I 26:24.441 --> 26:27.871 have." Well, I said I was going to run 26:27.871 --> 26:33.101 through a series of arguments but that doesn't mean that--the 26:33.098 --> 26:39.238 lights have just turned off; I don't know why--that doesn't 26:39.244 --> 26:44.644 mean that I think the arguments will all work. 26:44.640 --> 26:47.710 I announced on the first day of class that I don't, 26:47.713 --> 26:50.483 myself, believe in the existence of a soul. 26:50.480 --> 26:53.070 As such, it shouldn't be any surprise to you that what I'm 26:53.070 --> 26:55.710 going to do as we run through each of these arguments is to 26:55.706 --> 26:58.046 say, "I'm not convinced by it and 26:58.050 --> 27:00.490 here's why." Now since I think that the 27:00.490 --> 27:03.470 arguments I'm about to sketch--and I've just started 27:03.473 --> 27:07.163 sketching the first of is--fails I hope you'll think it over and 27:07.158 --> 27:09.788 you'll eventually come to agree with me, 27:09.789 --> 27:12.059 yeah, these arguments don't really work after all. 27:12.059 --> 27:16.409 But what's more important to me is that you at least think about 27:16.413 --> 27:18.213 each of these arguments. 27:18.210 --> 27:22.870 Is this a convincing argument for the existence of a soul? 27:22.869 --> 27:26.539 If you think so, what response do you want to 27:26.543 --> 27:30.053 offer to the objections that I'm giving? 27:30.049 --> 27:33.799 If this argument doesn't work, is there another argument for 27:33.803 --> 27:37.433 the existence of a soul that you think is a better one? 27:37.430 --> 27:40.670 First argument, you need the soul in order to 27:40.674 --> 27:43.334 explain the animation of the body. 27:43.329 --> 27:46.669 From the physicalist point of view, of course, 27:46.665 --> 27:49.625 the answer is going to be "too quick." 27:49.630 --> 27:54.510 To have an animated body, you need to have a functioning 27:54.509 --> 27:57.969 body. It's true that when you've got 27:57.967 --> 28:03.637 a corpse, you've got all the parts there, but clearly they're 28:03.641 --> 28:06.291 not functioning properly. 28:06.289 --> 28:11.159 But all that shows us is, the parts have broken. 28:11.160 --> 28:13.250 Remember my stereo? 28:13.250 --> 28:15.490 I dropped my stereo. 28:15.490 --> 28:16.930 It falls on the stage. 28:16.930 --> 28:18.290 It doesn't work anymore. 28:18.290 --> 28:20.530 It stops giving off music. 28:20.529 --> 28:24.229 My boombox stops giving off music. 28:24.230 --> 28:28.150 That's not because previously--we had a CD inside 28:28.148 --> 28:30.678 of it, we had some batteries. 28:30.680 --> 28:31.920 We dropped the whole thing. 28:31.920 --> 28:37.730 It's not as though previously there was something nonmaterial 28:37.734 --> 28:40.704 there. We've got all the same parts 28:40.698 --> 28:43.588 there, but the parts are now broken. 28:43.589 --> 28:46.519 They're not connected to each other in the right way. 28:46.519 --> 28:50.279 The energy is not flowing from the batteries through the wires 28:50.275 --> 28:51.625 to the CD component. 28:51.630 --> 28:55.720 28:55.720 --> 29:00.450 There's nothing mysterious from the physicalist perspective 29:00.445 --> 29:04.515 about the idea that a physical object can break. 29:04.519 --> 29:08.759 Although we need to offer a story about what makes the parts 29:08.761 --> 29:13.151 work when they're connected with each other and interacting in 29:13.146 --> 29:16.426 the right way, there's no need to appeal to 29:16.433 --> 29:18.573 anything beyond the physical. 29:18.569 --> 29:21.049 Suppose we try to refine the argument. 29:21.049 --> 29:25.239 Suppose we say, "You need to appeal to the soul 29:25.237 --> 29:30.237 in order to explain not just that the body moves around, 29:30.244 --> 29:34.254 flails, but the body acts purposefully." 29:34.250 --> 29:40.250 We need something to be pulling the strings, to be directing the 29:40.252 --> 29:44.022 body. That's what the soul does, 29:44.017 --> 29:46.517 so says the dualist. 29:46.519 --> 29:48.989 In response, the physicalist is going to 29:48.991 --> 29:52.981 say, "Yes it's true that bodies don't just move around in random 29:52.982 --> 29:55.632 patterns." Human bodies don't do that. 29:55.630 --> 30:02.090 So we need something to direct it, but why couldn't that just 30:02.092 --> 30:08.122 be, one particular part of the body plays the part of the 30:08.123 --> 30:15.273 command module? Suppose I've got a heat-seeking 30:15.266 --> 30:21.346 missile which tracks down the plane. 30:21.349 --> 30:26.029 As the plane tries to dodge it, the missile corrects its 30:26.033 --> 30:28.973 course. It's not just moving randomly, 30:28.974 --> 30:30.864 it's moving purposefully. 30:30.859 --> 30:33.869 There had better be something that explains, 30:33.865 --> 30:37.285 that's controlling, the motions of the missile. 30:37.289 --> 30:39.789 But for all that, it could just be a particular 30:39.786 --> 30:41.736 piece of the missile that does it. 30:41.740 --> 30:45.200 30:45.200 --> 30:49.930 More gloriously, we could imagine building some 30:49.928 --> 30:54.758 kind of a robot that does a variety of tasks. 30:54.759 --> 30:59.779 It's not moving randomly, but the tasks are all 30:59.777 --> 31:04.247 controlled by the CPU within the robot. 31:04.250 --> 31:07.980 The physicalist says we don't need to appeal to anything as 31:07.976 --> 31:11.896 extravagant as a soul in order to explain the fact that bodies 31:11.896 --> 31:16.606 don't just move randomly, but they move in purposeful 31:16.607 --> 31:19.347 ways that are controlled. 31:19.349 --> 31:21.589 For each objection, there's a response. 31:21.589 --> 31:25.269 You could imagine the dualist coming back and saying, 31:25.269 --> 31:28.949 "Look, in the case of the heat-seeking missile or the 31:28.950 --> 31:32.330 robot for that matter, although it's doing things, 31:32.328 --> 31:33.808 it's just obeying orders. 31:33.809 --> 31:39.859 And the orders were given to it from something outside itself." 31:39.859 --> 31:43.139 Something programmed the robot or the missile. 31:43.140 --> 31:47.880 So don't we need there to be something outside the body that 31:47.882 --> 31:49.492 programs the body? 31:49.490 --> 31:49.910 That could be the soul. 31:49.910 --> 31:53.500 31:53.500 --> 31:54.810 That's a harder question. 31:54.809 --> 31:59.179 Must there be something outside the body that controls the body? 31:59.180 --> 32:01.460 One possibility, of course, is, 32:01.456 --> 32:05.776 why not say that people are just robots as well and we get 32:05.783 --> 32:08.063 our commands from outside? 32:08.059 --> 32:14.139 On a familiar religious view, God built Adam out of dirt, 32:14.140 --> 32:17.720 out of dust. Adam is just a certain kind of 32:17.717 --> 32:20.777 robot then. God breathes into Adam. 32:20.780 --> 32:23.490 That's sort of turning it on. 32:23.490 --> 32:28.090 Maybe people are just robots commanded from outside by God. 32:28.089 --> 32:29.839 But that doesn't mean that there's anything more to us than 32:29.844 --> 32:30.574 there is to the robot. 32:30.570 --> 32:34.070 32:34.070 --> 32:38.350 That's one possible response. 32:38.349 --> 32:41.779 A different response, of course, is why couldn't we 32:41.784 --> 32:44.674 have robots that just build more robots? 32:44.670 --> 32:48.250 Then, if you ask, "Where did the commands come 32:48.253 --> 32:49.783 from?" the answer is, 32:49.780 --> 32:53.020 "When they were built, they were built in such a way 32:53.023 --> 32:57.223 as to have certain instructions that they begin to follow out." 32:57.220 --> 32:59.500 Just like people have a genetic code, perhaps, 32:59.498 --> 33:02.028 that gives us various instructions that we begin to 33:02.030 --> 33:05.520 follow out, or certain innate psychology or 33:05.519 --> 33:09.769 what have you. The argument quickly becomes 33:09.767 --> 33:11.647 very, very messy. 33:11.650 --> 33:16.240 The fan of the soul begins to want to protest, 33:16.244 --> 33:19.414 "Look, we're not just robots. 33:19.410 --> 33:22.680 We're not just robots with some sort of program in our brain 33:22.676 --> 33:23.946 that we're following. 33:23.950 --> 33:27.510 We've got free will. 33:27.510 --> 33:29.290 Robots can't have free will. 33:29.289 --> 33:31.399 So there's got to be something more to us than robots. 33:31.400 --> 33:35.160 We can't just be physical things." 33:35.160 --> 33:38.930 This is an interesting argument, and I think it's a new 33:38.931 --> 33:41.871 argument. We started with the idea you 33:41.870 --> 33:46.210 needed to appeal to souls in order to roughly explain why 33:46.211 --> 33:49.861 human bodies move, why we're animated or why we 33:49.864 --> 33:51.604 move in nonrandom ways. 33:51.599 --> 33:56.649 I think it's fairly clear that you don't need to appeal to 33:56.649 --> 33:59.129 souls in order to do that. 33:59.130 --> 34:02.380 Appeal to a physical body suffices, I think, 34:02.382 --> 34:06.392 to have an explanation as to the difference between an 34:06.392 --> 34:10.352 animated and an inanimate body, how bodies will move in 34:10.349 --> 34:13.139 nonrandom ways. If the brain is our CPU, 34:13.135 --> 34:17.195 then we'll behave in deliberate, purposeful ways just 34:17.199 --> 34:21.809 like a robot will behave in deliberate, purposeful ways. 34:21.809 --> 34:26.209 So this initial argument, I think, is not compelling. 34:26.210 --> 34:29.970 Still, we might wonder, what about this new argument? 34:29.969 --> 34:33.679 What about the fact that--We said there's a family of 34:33.679 --> 34:37.459 arguments, all of which have the general structure, 34:37.460 --> 34:40.360 inference to the best explanation, you need souls in 34:40.361 --> 34:42.411 order to explain feature F. 34:42.409 --> 34:45.479 Plug in a different feature F and you get a new 34:45.482 --> 34:48.032 argument. The one we started with--you 34:48.030 --> 34:51.780 need the soul to explain the animation of the body--that 34:51.782 --> 34:54.172 argument, I think, doesn't work. 34:54.170 --> 34:55.760 Now we've got a new one. 34:55.760 --> 35:01.050 You need the soul in order to explain free will. 35:01.050 --> 35:03.840 Let me come back to that argument later. 35:03.840 --> 35:04.520 It's a good argument. 35:04.519 --> 35:06.739 It's an argument well worth taking seriously, 35:06.736 --> 35:08.446 but let's come back to it later. 35:08.449 --> 35:12.129 First, let's run through some other things that might be 35:12.130 --> 35:15.410 appealed to as candidates for feature F. 35:15.409 --> 35:18.689 Suppose somebody says, "Look, it's true that we don't 35:18.688 --> 35:22.348 need to appeal to souls in order to explain why bodies move 35:22.346 --> 35:24.486 around in a nonrandom fashion. 35:24.489 --> 35:28.609 But people have a very special ability"--and so the argument 35:28.610 --> 35:32.520 goes--"that mere bodies couldn't have, physicalists can't 35:32.521 --> 35:36.951 explain. That's the ability to think. 35:36.950 --> 35:39.780 It's the ability to reason. 35:39.780 --> 35:44.380 People have beliefs and desires. 35:44.380 --> 35:50.640 And based on their beliefs about how to fulfill their 35:50.639 --> 35:53.889 desires, they make plans. 35:53.890 --> 35:55.400 They have strategies. 35:55.400 --> 35:59.450 They reason about what to do. 35:59.449 --> 36:04.449 This tightly connected set of facts about us--beliefs, 36:04.448 --> 36:07.748 desires, reasoning, strategizing, 36:07.750 --> 36:14.490 planning--you need to appeal to a soul"--so the argument 36:14.492 --> 36:17.682 goes--;"to explain that. 36:17.680 --> 36:22.580 No mere machine could believe. 36:22.580 --> 36:25.970 No mere machine has desires. 36:25.970 --> 36:32.840 No mere machine could reason." 36:32.840 --> 36:37.990 It's easy to see why you might think that sort of thing when 36:37.986 --> 36:40.686 you stick to simple machines. 36:40.690 --> 36:43.640 It's pretty clear that there are lots of machines that it 36:43.644 --> 36:46.864 doesn't seem natural to ascribe beliefs or desires or goals or 36:46.863 --> 36:49.633 reasoning to. My lawnmower, 36:49.634 --> 36:55.984 for example, doesn't want to cut the grass. 36:55.980 --> 36:58.820 Even though it does cut the grass, it doesn't have the 36:58.818 --> 37:01.688 desire. It doesn't think to itself, 37:01.687 --> 37:07.167 "How shall I get that blade of grass that's been eluding me?" 37:07.170 --> 37:12.490 So it's easy to see why we might be tempted to say no mere 37:12.491 --> 37:18.001 machine could think or reason or have beliefs or desires. 37:18.000 --> 37:22.610 That argument's much less compelling nowadays than I think 37:22.607 --> 37:25.837 it would have been 20 or 40 years ago. 37:25.840 --> 37:32.590 In an era of computers with quite sophisticated computer 37:32.591 --> 37:36.971 programs, it seems, at the very least, 37:36.974 --> 37:42.594 natural to talk about beliefs, desires, and reasoning and 37:42.586 --> 37:46.566 strategizing. So suppose, for example, 37:46.570 --> 37:50.140 we've got a chess-playing computer. 37:50.139 --> 37:53.709 On my computer at home I've got a program that allows my 37:53.708 --> 37:55.328 computer to play chess. 37:55.330 --> 37:58.550 I, myself, stink at chess. 37:58.550 --> 38:04.380 This program can beat me blind. 38:04.380 --> 38:12.020 I move my bishop, the computer moves its queen. 38:12.019 --> 38:14.709 What do we say about the computer? 38:14.710 --> 38:19.230 Why did the computer move its queen, or virtual queen? 38:19.230 --> 38:21.220 Why did the computer move its queen? 38:21.219 --> 38:27.459 The natural thing to say is, it's worried about the fact 38:27.456 --> 38:33.576 that the king is exposed and it's trying to block me by 38:33.578 --> 38:36.298 capturing my bishop. 38:36.300 --> 38:40.940 That is what we say about computer-playing programs. 38:40.940 --> 38:43.100 Think about what we're doing. 38:43.099 --> 38:46.949 We're ascribing desires to the program. 38:46.949 --> 38:50.389 We're saying it's got an ultimate desire to win the game. 38:50.389 --> 38:54.049 A certain subsidiary desire is to protect its king, 38:54.051 --> 38:55.591 to capture my king. 38:55.590 --> 38:57.560 A certain other subsidiary desire is, no doubt, 38:57.561 --> 38:59.791 to protect its various other pieces along the way. 38:59.789 --> 39:04.569 It's got beliefs about how to do that by blocking certain 39:04.574 --> 39:09.364 paths or by making other pieces on my side vulnerable. 39:09.360 --> 39:12.720 It's got beliefs about how to achieve its goals. 39:12.719 --> 39:17.679 Then, it puts those combinations of beliefs and 39:17.680 --> 39:24.580 desires into action by moving in a way that's a rational response 39:24.582 --> 39:28.152 to my move. It looks as though the natural 39:28.150 --> 39:31.270 thing to say about the chess-playing computer is, 39:31.269 --> 39:32.829 it does have beliefs. 39:32.830 --> 39:34.410 It does have desires. 39:34.410 --> 39:36.090 It does have intentions. 39:36.090 --> 39:37.520 It does have goals. 39:37.520 --> 39:41.260 It does reason. It does all of this. 39:41.260 --> 39:45.900 It's rational to this limited extent. 39:45.900 --> 39:47.480 It's only able to play chess. 39:47.480 --> 39:51.120 But to that extent, it's doing all these things and 39:51.117 --> 39:55.477 yet we're not tempted to say, are we, that the computer has a 39:55.482 --> 39:57.012 nonphysical part? 39:57.010 --> 40:02.860 We can explain how the computer does all of this in strictly 40:02.855 --> 40:06.765 physical terms. Of course, once you start 40:06.769 --> 40:11.499 thinking of it this way, it's natural to talk this way 40:11.495 --> 40:16.845 across a variety of things that the computer may be trying to 40:16.846 --> 40:17.556 do. 40:17.560 --> 40:21.110 40:21.110 --> 40:25.750 It's perfectly open to you, as dualists, 40:25.750 --> 40:31.340 to respond by saying, "Although we personify the 40:31.343 --> 40:35.803 computer, we treat it as though it was a 40:35.798 --> 40:41.518 person, as though it had beliefs and desires and so forth, 40:41.519 --> 40:45.309 it doesn't really have the relevant beliefs and desires, 40:45.312 --> 40:48.762 because it doesn't have any beliefs and desires, 40:48.760 --> 40:56.890 because no physical object could have beliefs and desires." 40:56.889 --> 41:00.579 In response to that, I just want to say, 41:00.575 --> 41:03.405 "Isn't that just prejudice?" 41:03.409 --> 41:09.209 Of course, it is true that if we simply insist no physical 41:09.209 --> 41:13.889 object could really have beliefs or desires, 41:13.889 --> 41:18.009 then it will follow that when we are tempted to ascribe 41:18.009 --> 41:21.899 beliefs and desires to my chess-playing computer, 41:21.900 --> 41:25.230 we're falling into an illusion. 41:25.230 --> 41:30.680 That will follow once we assume that no physical object has 41:30.684 --> 41:32.664 beliefs or desires. 41:32.659 --> 41:38.159 But what reason is there for saying it has no beliefs or 41:38.159 --> 41:42.229 desires? What grounds are there for 41:42.233 --> 41:48.383 withholding ascriptions of beliefs and desires to the 41:48.381 --> 41:51.371 computer? That's far from obvious. 41:51.370 --> 41:56.970 41:56.970 --> 42:01.750 Here's a possibility. 42:01.750 --> 42:08.200 Desires, at the very least, seem to be, at least in typical 42:08.199 --> 42:13.869 cases, very closely tied to a series of emotions. 42:13.869 --> 42:20.619 You get excited when you're playing chess at the prospect of 42:20.624 --> 42:24.864 capturing my queen and crushing me. 42:24.860 --> 42:32.080 You get worried when your pieces are threatened. 42:32.079 --> 42:36.209 Of course, more generally, you get excited, 42:36.209 --> 42:41.129 your heart goes pitter-pat, when your girlfriend or 42:41.125 --> 42:44.365 boyfriend says they love you. 42:44.369 --> 42:48.669 Your stomach sinks, you have that sinking feeling 42:48.668 --> 42:53.678 in the pit of your stomach, when you get a bad grade on a 42:53.683 --> 42:58.583 test. Maybe what's really going on is 42:58.578 --> 43:05.698 the thought that there's an aspect of desire that has a 43:05.700 --> 43:11.190 purely behavioral side, that's moving pieces around in 43:11.192 --> 43:14.632 a way that would make sense if you had this goal. 43:14.630 --> 43:18.010 And maybe machines can do that. 43:18.010 --> 43:23.120 But there's an aspect of desires, the emotional side, 43:23.124 --> 43:28.144 that machines can't have, but we clearly do have. 43:28.139 --> 43:33.799 Maybe we want to build that emotional side into talk of 43:33.801 --> 43:36.521 desires. So maybe if we want to say 43:36.524 --> 43:40.324 machines don't have a mental life and couldn't have a mental 43:40.324 --> 43:43.034 life, what we really mean is no 43:43.025 --> 43:46.605 machine could feel anything emotionally. 43:46.610 --> 43:50.140 43:50.140 --> 43:51.650 So let's distinguish. 43:51.650 --> 43:56.590 Let's say there's a way of talking about beliefs and 43:56.588 --> 44:01.718 desires which is just going to be captured in terms of 44:01.719 --> 44:07.819 responding in a way that makes sense given the environment. 44:07.820 --> 44:11.810 Maybe computers and robots could do that. 44:11.809 --> 44:15.619 But there's clearly a side of our mental life, 44:15.619 --> 44:19.599 the emotional side, where we might really worry, 44:19.599 --> 44:21.969 could a robot feel love? 44:21.970 --> 44:26.900 Could it be afraid of anything? 44:26.900 --> 44:31.180 Again, our question was, "Do we need to appeal to souls 44:31.182 --> 44:33.802 to explain something about us?" 44:33.800 --> 44:37.250 The physicalist says "no"; the dualist says "yes." 44:37.250 --> 44:42.050 If what we mean is the mental, but that the aspect, 44:42.051 --> 44:45.701 the behavioral aspect of the mental, 44:45.699 --> 44:49.079 where even a chess-playing computer probably has it, 44:49.084 --> 44:52.074 then that's not a very compelling argument. 44:52.070 --> 44:54.560 The physicalist will say, "Look, that aspect of the 44:54.556 --> 44:55.796 mental is pretty clear. 44:55.800 --> 44:58.770 We can explain it in physical terms." 44:58.769 --> 45:00.559 But let's just switch the argument. 45:00.560 --> 45:04.560 What about emotions? 45:04.560 --> 45:10.090 Can a robot feel emotions? 45:10.090 --> 45:16.330 Could a purely physical being fall in love? 45:16.330 --> 45:18.860 Could it be afraid of things? 45:18.860 --> 45:21.630 Could it hope for something? 45:21.630 --> 45:27.440 The latest version of our argument then is, 45:27.443 --> 45:31.323 "People can feel emotions. 45:31.320 --> 45:35.080 But if you think about it, it's pretty clear no robot 45:35.079 --> 45:36.669 could feel emotions. 45:36.670 --> 45:40.150 No merely physical thing could feel emotions. 45:40.150 --> 45:45.290 So there must be more to us than a merely physical thing." 45:45.289 --> 45:47.999 That's the argument we'll start with next time.