WEBVTT 00:00.960 --> 00:04.000 Professor Shelly Kagan: We've been looking at Plato's 00:04.000 --> 00:07.200 arguments for the immortality of the soul, and so far I have to 00:07.195 --> 00:10.025 say I haven't found them very compelling arguments. 00:10.030 --> 00:11.320 In a minute, I'm going to turn to an 00:11.318 --> 00:13.378 argument that at least strikes me as more interesting. 00:13.380 --> 00:16.490 It's more difficult to pin down where it goes wrong. 00:16.490 --> 00:19.330 But before we do, I want to make a last couple of 00:19.330 --> 00:22.880 comments about the argument we were considering at the end of 00:22.882 --> 00:25.062 last class. That was the argument from 00:25.063 --> 00:27.863 recollection. You recall the basic idea was 00:27.862 --> 00:31.852 that although objects in the ordinary familiar empirical 00:31.850 --> 00:35.460 world are not perfectly just, perfectly round, 00:35.458 --> 00:38.838 what have you, they're able to remind us of 00:38.840 --> 00:42.120 perfect justice, perfect roundness and the like. 00:42.120 --> 00:45.640 And when Plato asked himself, "How could that be?" 00:45.640 --> 00:48.710 the answer he gives is, "Well, it's got to be that we 00:48.710 --> 00:52.200 were previously acquainted with the forms before our life in 00:52.195 --> 00:55.305 this world." And that shows that the soul 00:55.308 --> 00:59.798 must be something that existed prior to the creation of the 00:59.800 --> 01:01.340 body. That's the argument from 01:01.342 --> 01:03.992 recollection. And at the very end of class I 01:03.992 --> 01:07.162 suggested that, look, even if we were to grant 01:07.160 --> 01:10.610 to Plato that in order to think about justice, 01:10.610 --> 01:12.510 circularity, what have you, 01:12.510 --> 01:16.600 we had to somehow grasp the forms, and even if we were to 01:16.603 --> 01:21.143 grant to Plato that nothing in this world is perfectly round or 01:21.135 --> 01:25.065 perfectly just, it's not necessarily correct to 01:25.069 --> 01:29.409 say, "So the only possible explanation of what's going on 01:29.405 --> 01:33.965 is that these things in the empirical world remind us of our 01:33.973 --> 01:37.073 prior acquaintance with the forms." 01:37.069 --> 01:41.559 It could be that what goes on is, when we bump up against 01:41.563 --> 01:46.063 something that's partially just or partially beautiful or 01:46.056 --> 01:50.546 partially round--imperfectly round--what happens is, 01:50.550 --> 01:56.400 those things sort of trigger our minds in such a way that we 01:56.399 --> 02:02.049 begin to think about the forms for the very first time. 02:02.049 --> 02:04.479 So it might be, in order to think about justice 02:04.482 --> 02:06.812 and roundness, we have to grasp the forms. 02:06.810 --> 02:12.640 But it could be that we only grasp the forms in this life, 02:12.640 --> 02:15.300 for the very first time. 02:15.300 --> 02:20.460 Exposure to the things that participate in the forms may 02:20.461 --> 02:25.531 nudge our minds or our souls in such a way that at that 02:25.529 --> 02:31.159 point--given that exposure--we begin to grasp the forms. 02:31.159 --> 02:35.179 It's as though the ordinary earthly objects, 02:35.181 --> 02:40.981 we bump into them or they bump into us, and they get us to look 02:40.978 --> 02:44.998 upwards to the heavenly Platonic realm. 02:45.000 --> 02:46.120 I don't mean literally upwards. 02:46.120 --> 02:49.740 It's not as though these things--the number three--is up 02:49.743 --> 02:52.853 there. But if you accept the metaphor, 02:52.845 --> 02:57.495 running into things in the empirical world gets our minds 02:57.497 --> 03:01.567 to start thinking about, for the first time, 03:01.567 --> 03:06.567 the heavenly realm of the Platonic forms and ideas. 03:06.569 --> 03:11.529 That would be just as likely a possibility as the alternative 03:11.533 --> 03:16.333 explanation that what's going on is that ordinary empirical 03:16.330 --> 03:20.880 objects are reminding us of our prior acquaintance. 03:20.879 --> 03:24.719 Perhaps these ordinary objects act like letters of 03:24.720 --> 03:26.840 introduction, getting us to, 03:26.836 --> 03:30.206 helping us to, think about the forms for the 03:30.205 --> 03:33.445 very first time. Well, if that's right, 03:33.445 --> 03:36.475 then of course, we don't have any good reason 03:36.475 --> 03:40.625 to follow Plato when he says, "It must be the case that the 03:40.626 --> 03:43.576 soul existed prior to the--prior to birth." 03:43.580 --> 03:47.260 03:47.259 --> 03:50.899 Now, the objection I've just raised is not an objection that 03:50.899 --> 03:52.939 Plato raises in the Phaedo, 03:52.935 --> 03:55.645 but he does raise a different objection. 03:55.650 --> 03:58.690 Remember our concern isn't, strictly speaking, 03:58.686 --> 04:01.926 with the question, "Did the soul exist before our 04:01.925 --> 04:04.045 birth? Did the soul exist before our 04:04.050 --> 04:06.230 bodies?" but rather, "Is the soul 04:06.228 --> 04:09.058 immortal?" And so, having now given the 04:09.061 --> 04:12.631 argument from recollection, Plato envisions two of 04:12.633 --> 04:15.903 Socrates' disciples, Simmias and Cebes, 04:15.895 --> 04:19.325 responding, objecting, by saying, "Look, 04:19.329 --> 04:22.939 even if the soul existed before birth, 04:22.939 --> 04:26.649 it doesn't follow that it exists after death. 04:26.649 --> 04:28.359 And that's, after all, what we really want, 04:28.356 --> 04:29.246 are wondering about. 04:29.250 --> 04:31.910 We want to know, will we survive our deaths? 04:31.910 --> 04:33.370 Is the soul immortal? 04:33.370 --> 04:37.410 And you haven't yet shown that Socrates," they object. 04:37.410 --> 04:40.330 Could be that it existed before, but won't exist 04:40.331 --> 04:42.791 afterwards. But very nicely--it's quite 04:42.790 --> 04:46.090 elegant structure at this point--Socrates puts together 04:46.090 --> 04:49.330 the two arguments that we've just been rehearsing--the 04:49.330 --> 04:52.940 argument from recollection and the argument that came before 04:52.936 --> 04:55.126 that, the one that I dubbed "the 04:55.125 --> 04:56.575 argument from recycling." 04:56.579 --> 04:59.059 Remember, the argument from recycling says, 04:59.060 --> 05:02.250 when you build something, you build it out of parts, 05:02.250 --> 05:07.790 and when that thing falls apart you go back to the parts. 05:07.790 --> 05:13.460 All right. So the prior parts get recycled. 05:13.459 --> 05:17.909 The soul, we now say--based on the argument from 05:17.905 --> 05:22.725 recollection--the soul is one of our prior parts. 05:22.730 --> 05:25.150 The soul existed before we were put together, 05:25.147 --> 05:27.837 or before we were put together with our bodies. 05:27.839 --> 05:31.139 If you then combine the argument from recycling and say, 05:31.135 --> 05:34.845 the parts that existed before are going to exist afterwards, 05:34.850 --> 05:39.000 it must follow that if the soul existed before, 05:38.995 --> 05:42.145 it will exist afterwards as well. 05:42.149 --> 05:45.999 And so we've got the immortality of the soul after 05:45.998 --> 05:48.698 all. Now, bracket the fact that, 05:48.700 --> 05:52.250 as I just explained, I don't myself find the 05:52.252 --> 05:55.642 argument from recollection persuasive. 05:55.639 --> 05:59.189 I don't think we've got any good reason to believe--based on 05:59.191 --> 06:02.741 the sort of things that Plato is drawing our attention to--I 06:02.742 --> 06:06.412 don't think we've got any good reason to believe that the soul 06:06.413 --> 06:08.463 existed before we were born. 06:08.459 --> 06:13.309 But even if we grant him that, we shouldn't be so quick to 06:13.305 --> 06:17.725 conclude, on the basis of combining the argument from 06:17.725 --> 06:21.885 recollection and the argument from recycling, 06:21.889 --> 06:26.679 that the soul will continue to exist after the death of our 06:26.677 --> 06:29.357 bodies. After all, take a more 06:29.364 --> 06:31.754 familiar, humdrum example. 06:31.750 --> 06:36.970 Cars are built out of non-cars, right? 06:36.970 --> 06:41.030 Cars get built out of engines and tires and steering wheels. 06:41.030 --> 06:46.570 And the engine is not a car; the steering wheel is not a car. 06:46.569 --> 06:50.479 So you build the car out of its parts. 06:50.480 --> 06:54.440 Now, the engine is a prior-existing part. 06:54.440 --> 06:58.420 So can we conclude then that from the fact that--argument 06:58.421 --> 07:00.911 from recycling: parts get reused, 07:00.910 --> 07:03.120 get rebuilt, when cars get destroyed, 07:03.117 --> 07:06.797 the parts are still around--can we conclude from the argument 07:06.796 --> 07:10.596 from recycling and the fact that the engine is a prior-existing 07:10.597 --> 07:13.047 part from which the car was built, 07:13.050 --> 07:18.540 that the engine will continue to exist forever after the 07:18.543 --> 07:21.043 destruction of the car? 07:21.040 --> 07:23.280 No, obviously you can't conclude that at all. 07:23.279 --> 07:27.169 Sometimes when cars get destroyed the engine gets 07:27.173 --> 07:29.773 destroyed right along with it. 07:29.769 --> 07:33.529 And of course, even if--in many cases--the 07:33.531 --> 07:39.131 engine continues to exist for a while after the destruction of 07:39.128 --> 07:41.548 the car, it certainly doesn't follow 07:41.550 --> 07:44.190 that the engine is immortal, that it continues to exist 07:44.191 --> 07:47.021 forever. Engines will eventually 07:47.022 --> 07:50.612 decompose and turn back into atoms. 07:50.610 --> 07:56.090 So from the mere fact that the engine was a part that existed 07:56.087 --> 08:00.277 before the car existed, and the further fact that when 08:00.276 --> 08:03.576 the car breaks down, it decomposes back into parts, 08:03.579 --> 08:07.039 it certainly doesn't follow that all of the parts that 08:07.038 --> 08:10.628 existed prior to the existence of the car will be around 08:10.627 --> 08:14.267 forever. That would just be false. 08:14.269 --> 08:18.929 So even if we were to give Socrates the assumption 08:18.927 --> 08:24.337 that--the thesis that--the soul existed before we were put 08:24.344 --> 08:27.434 together, before we were born, 08:27.431 --> 08:32.991 it still wouldn't follow that the soul will continue to exist 08:32.987 --> 08:35.947 after we're taken back apart. 08:35.950 --> 08:42.270 The soul might eventually decay just like the engine will 08:42.274 --> 08:44.424 eventually decay. 08:44.419 --> 08:47.779 What we need, to really become convinced of 08:47.784 --> 08:52.434 the immortality of the soul, is not the mere suggestion, 08:52.429 --> 08:56.109 even it was--even if we were convinced--is not the mere 08:56.110 --> 08:59.860 suggestion that the soul was around before our birth. 08:59.860 --> 09:06.480 We need to believe that the soul, unlike an engine, 09:06.476 --> 09:12.956 can't itself be destroyed, can't itself decompose, 09:12.961 --> 09:15.741 can't fall apart. 09:15.740 --> 09:19.910 That's what we need if we're really going to become convinced 09:19.914 --> 09:22.214 of the immortality of the soul. 09:22.210 --> 09:25.820 Now, as I remarked previously, one of the amazing things--not 09:25.818 --> 09:29.428 amazing but one of the really attractive things about Plato's 09:29.427 --> 09:32.737 dialogues is, you raise an objection and it 09:32.737 --> 09:36.917 often seems as though Plato himself, whether or not he 09:36.918 --> 09:41.858 explicitly states the objection, seems aware of the objection, 09:41.864 --> 09:46.164 because he'll go on to say something that is responsive to 09:46.158 --> 09:48.398 it. And again, that makes sense if 09:48.400 --> 09:51.980 you think of these dialogues as a kind of pedagogical tool to 09:51.982 --> 09:54.432 help you get better at philosophizing. 09:54.429 --> 09:58.759 So the very next argument that Plato turns to can be viewed, 09:58.756 --> 10:03.006 I think, as responding to this unstated objection--well, 10:03.009 --> 10:05.299 I stated it, but Plato doesn't state it in 10:05.302 --> 10:08.602 the dialogue--the worry that even if the soul was one of the 10:08.600 --> 10:10.940 parts, even if the soul was already 10:10.943 --> 10:14.453 around before we were born, how do we know it can't come 10:14.446 --> 10:16.996 apart? How do we know the soul can't 10:17.002 --> 10:19.902 be destroyed? Since what we want to know is 10:19.903 --> 10:23.993 whether the soul is immortal, how do we know it can't break? 10:23.990 --> 10:28.600 Plato's next argument then tries to deal directly with this 10:28.602 --> 10:32.342 worry, and it's a quite interesting argument. 10:32.340 --> 10:36.600 I'll give it another--a new label--I'll call it the 10:36.599 --> 10:39.069 "argument from simplicity." 10:39.070 --> 10:46.000 Socrates turns to a discussion of what kinds of things can 10:46.004 --> 10:51.484 break and what kinds of things can't break; 10:51.480 --> 10:54.160 what kinds of things can be destroyed, and what kinds of 10:54.157 --> 10:55.517 things can't be destroyed. 10:55.520 --> 10:59.490 He thinks about examples; he surveys examples and tries 10:59.486 --> 11:02.626 to extract a kind of metaphysical principle from 11:02.625 --> 11:04.225 this. And then, as we'll see, 11:04.226 --> 11:06.676 he's going to use this principle to convince us--or to 11:06.684 --> 11:08.774 try to convince us--that the soul is immortal, 11:08.770 --> 11:09.930 it's indestructible. 11:09.929 --> 11:14.279 Well, lots of things can be destroyed. 11:14.280 --> 11:16.430 Here's a piece of paper. 11:16.430 --> 11:18.290 It can be destroyed Right? 11:18.290 --> 11:23.850 11:23.850 --> 11:26.390 Why was it that this was the sort of thing that could be 11:26.394 --> 11:28.824 destroyed? Well, the straightforward 11:28.823 --> 11:31.823 answer is the piece of paper had parts. 11:31.820 --> 11:34.450 And in breaking it, in ripping it, 11:34.445 --> 11:39.055 what I literally did was I ripped one part from another. 11:39.059 --> 11:43.719 To destroy the piece of paper, I take its parts apart. 11:43.720 --> 11:49.310 11:49.310 --> 11:52.020 Here's piece of chalk. 11:52.019 --> 11:56.549 The piece of chalk can be broken. 11:56.550 --> 11:59.920 What am I doing? Taking its parts apart. 11:59.919 --> 12:07.019 The kinds of things that can be destroyed have parts. 12:07.020 --> 12:09.340 They are composite. 12:09.340 --> 12:13.150 They are composed of their parts. 12:13.149 --> 12:19.589 Bodies can be destroyed because you can take a sword to it and 12:19.593 --> 12:24.773 go sweep, sweep, sweep and chop it into pieces. 12:24.769 --> 12:28.039 Composite things can be destroyed. 12:28.039 --> 12:31.129 Things that have parts can be destroyed. 12:31.129 --> 12:34.199 Now, what kind of things can't be destroyed? 12:34.200 --> 12:37.680 Well, it won't surprise you that when Plato looks for an 12:37.676 --> 12:41.276 example of something that's eternal and indestructible, 12:41.279 --> 12:45.249 his mind immediately starts thinking about the Platonic 12:45.251 --> 12:48.841 forms. Take the number three. 12:48.840 --> 12:53.470 The number three can't be destroyed, right? 12:53.470 --> 12:58.650 Even if nuclear explosion took place and everything on Earth 12:58.645 --> 13:03.375 got atomized and destroyed through some bizarre science 13:03.381 --> 13:07.941 fiction chain reaction, like they're always doing in 13:07.940 --> 13:11.540 movies, the number three wouldn't be touched. 13:11.539 --> 13:13.319 The number three wouldn't be fazed. 13:13.320 --> 13:17.920 It would still be true that three plus one equals four. 13:17.920 --> 13:21.930 You can't hurt the number three. 13:21.929 --> 13:29.509 You can't alter or destroy perfect circularity. 13:29.510 --> 13:34.590 Why not? Well, it doesn't have any parts. 13:34.590 --> 13:36.660 That's the thought. 13:36.659 --> 13:42.509 Things like the Platonic forms are eternal, and they're 13:42.514 --> 13:46.384 eternal, changeless, and indestructible, 13:46.383 --> 13:50.913 because they are simple--simple here being the metaphysical 13:50.912 --> 13:54.662 notion that they're not composed of anything. 13:54.659 --> 13:57.579 Anything that's built up out of parts you could, 13:57.580 --> 14:00.690 at least in principle, worry about the parts coming 14:00.687 --> 14:03.667 apart and, hence, the thing being destroyed. 14:03.669 --> 14:09.079 But anything that's simple can't be destroyed in that way. 14:09.080 --> 14:10.660 It has no parts to take apart. 14:10.660 --> 14:15.200 14:15.200 --> 14:19.830 So the kinds of things that can be destroyed are the things with 14:19.831 --> 14:23.651 parts, and those are the sorts of things that change, 14:23.654 --> 14:26.184 right? Even if they're not destroyed, 14:26.182 --> 14:28.992 what's a tip off to something being composite? 14:28.990 --> 14:30.570 The fact that it changes. 14:30.570 --> 14:33.870 Suppose I take a bar of metal and I bend it. 14:33.870 --> 14:36.430 I haven't destroyed it, but I've changed it. 14:36.429 --> 14:40.579 I'm able to change it by rearranging the relationships 14:40.578 --> 14:42.768 between the various parts. 14:42.769 --> 14:46.679 My body is constantly changing because the relationships 14:46.679 --> 14:51.369 between my arms and my head and so forth, my muscles are moving. 14:51.370 --> 14:53.570 You rearrange the parts, the thing changes. 14:53.570 --> 14:55.830 Oh, but that means it's got parts and could be destroyed. 14:55.830 --> 14:59.870 So we've got some nice generalizations. 14:59.870 --> 15:05.920 Things that change have parts; things with parts can be 15:05.917 --> 15:08.877 destroyed. What are the kinds of things 15:08.879 --> 15:11.519 that you can change and destroy? 15:11.519 --> 15:15.859 Those are the familiar empirical objects that we can 15:15.855 --> 15:19.675 see: pieces of paper, bodies, pieces of chalk, 15:19.679 --> 15:22.219 bars of metal. In contrast, 15:22.224 --> 15:26.454 on the whole other side, you've got things that are 15:26.450 --> 15:31.100 invisible, like the number three--nobody sees the number 15:31.098 --> 15:34.308 three--things that are invisible, 15:34.310 --> 15:35.640 that never change. 15:35.639 --> 15:38.619 The number three never changes, right? 15:38.620 --> 15:41.950 The number three is an odd number. 15:41.950 --> 15:44.990 It's not as though, oh, today it's odd but maybe 15:44.985 --> 15:46.595 tomorrow it'll be even. 15:46.600 --> 15:49.490 It's eternally an odd number. 15:49.490 --> 15:54.790 Three plus one equals four today, yesterday and forever. 15:54.789 --> 15:57.449 These facts about the number three will never change. 15:57.450 --> 16:00.170 The number three is changeless. 16:00.170 --> 16:04.230 So the forms are eternal; they're invisible; 16:04.230 --> 16:06.540 they are changeless. 16:06.539 --> 16:09.029 They're simple, and simple things can't be 16:09.030 --> 16:12.000 destroyed; forms can't be destroyed. 16:12.000 --> 16:15.570 You put all this together; these are the sorts of thoughts 16:15.573 --> 16:19.343 that Socrates assembles, and I've got the initial 16:19.341 --> 16:22.011 thoughts up there on the board. 16:22.010 --> 16:26.100 All right. So premise number one, 16:26.095 --> 16:29.865 only composite things can be destroyed. 16:29.870 --> 16:35.890 Premise number two, only changing things are 16:35.889 --> 16:39.279 composite. So if you put one and two 16:39.276 --> 16:42.616 together, you'd get: only changing things could be 16:42.622 --> 16:45.882 destroyed. And now add three, 16:45.875 --> 16:49.945 invisible things don't change. 16:49.950 --> 16:52.240 Well, if you've got to be the kind of thing that can change in 16:52.238 --> 16:54.598 order to be composite and you've got to be composite in order to 16:54.602 --> 16:57.812 be destroyed, invisible things don't change, 16:57.810 --> 17:01.070 follows four, invisible things can't be 17:01.066 --> 17:05.306 destroyed. That's the metaphysical thesis 17:05.310 --> 17:10.320 that Socrates comes to by thinking about cases. 17:10.319 --> 17:14.869 And that's the crucial premise or sub-conclusion for the 17:14.866 --> 17:19.246 immortality of the soul, because then Socrates invites 17:19.247 --> 17:21.807 us to think about the soul. 17:21.809 --> 17:25.939 Is the soul visible or invisible? 17:25.940 --> 17:31.000 He says, pretty obviously, "it's invisible." 17:31.000 --> 17:33.820 But if invisible things can't be destroyed, 17:33.817 --> 17:35.827 the soul can't be destroyed. 17:35.829 --> 17:41.929 So one, two and three got us four, invisible things can't be 17:41.928 --> 17:46.988 destroyed, but five, the soul is invisible so six, 17:46.992 --> 17:50.302 the soul can't be destroyed. 17:50.299 --> 17:54.869 That's my best attempt at reconstructing the argument from 17:54.868 --> 17:57.268 simplicity. It's not as though Plato 17:57.267 --> 18:00.377 himself spells it out with premises and conclusions like 18:00.377 --> 18:03.117 that, but I think this is fairly 18:03.123 --> 18:08.243 faithful to the kind of argument he means to put forward. 18:08.240 --> 18:11.820 And in a moment I'll turn to evaluating whether that's a good 18:11.824 --> 18:14.174 argument or not. But I think it's a pretty 18:14.165 --> 18:17.585 interesting argument; it's an argument worth taking 18:17.587 --> 18:19.017 fairly seriously. 18:19.019 --> 18:23.369 Except, I've got to confess to you that Socrates doesn't quite 18:23.365 --> 18:27.635 conclude the way I would've thought he would've concluded. 18:27.640 --> 18:30.220 So I've had the argument conclude six, 18:30.218 --> 18:32.308 the soul can't be destroyed. 18:32.309 --> 18:38.019 But what Socrates actually says is--his actual conclusion 18:38.020 --> 18:43.630 is--"And so the soul is indestructible or nearly so." 18:43.630 --> 18:47.750 That's rather an odd qualification, 18:47.750 --> 18:51.350 "or nearly so." The conclusion that Socrates 18:51.347 --> 18:54.697 reaches from his examination of change and invisibility and so 18:54.696 --> 18:57.416 forth and so on, and compositeness versus 18:57.420 --> 19:01.830 simplicity, is that "the soul is indestructible or nearly so." 19:01.829 --> 19:08.519 Now, adding that qualification opens the door to a worry. 19:08.519 --> 19:14.509 The worry gets raised by Cebes who says, even if we grant that 19:14.513 --> 19:17.763 the soul is nearly indestructible, 19:17.755 --> 19:22.565 that's not good enough to get us immortality. 19:22.569 --> 19:27.929 And he gives a very nice analogy of somebody who's--a 19:27.927 --> 19:33.797 coat, which could outlast the owner but isn't immortal. 19:33.799 --> 19:36.749 Or the owner could go through several coats; 19:36.750 --> 19:41.570 but still at some point the owner's going to die as well. 19:41.569 --> 19:45.159 The owner is far more immortal, in that sense, 19:45.163 --> 19:47.083 closer to immortality. 19:47.079 --> 19:50.219 And I've gone through many coats in my life, 19:50.224 --> 19:53.374 but for all that, I'm not indestructible. 19:53.369 --> 19:57.389 If all we've got is the mere fact that the soul is "nearly" 19:57.386 --> 20:00.496 indestructible, it takes a whole lot more work 20:00.503 --> 20:03.373 to destroy it, maybe it lasts a whole lot 20:03.371 --> 20:05.781 longer; maybe it goes through a whole 20:05.779 --> 20:08.739 lot of bodies being reincarnated a half-dozen, 20:08.743 --> 20:12.433 or a dozen, or hundred times before it wears out and gets 20:12.432 --> 20:14.432 destroyed. That's not enough to give us 20:14.431 --> 20:15.481 the immortality of the soul. 20:15.480 --> 20:18.670 20:18.670 --> 20:20.750 That's the objection that Cebes raises. 20:20.750 --> 20:26.360 And one of the oddities is that, as far as I can see, 20:26.361 --> 20:31.111 Socrates never responds to that objection. 20:31.109 --> 20:35.279 Raises the objection--that is, Plato raises the objection in 20:35.281 --> 20:38.891 the voice of Cebes--but Socrates, on Plato's behalf, 20:38.887 --> 20:41.147 never answers the objection. 20:41.150 --> 20:43.280 It's hard to say what exactly is going on. 20:43.279 --> 20:46.369 It might be that Plato's worried that he hasn't really 20:46.368 --> 20:48.988 shown that the soul is immortal afterwards. 20:48.990 --> 20:52.300 Maybe this argument from simplicity isn't really as good 20:52.304 --> 20:53.514 as it needs to be. 20:53.509 --> 20:58.199 And maybe that explains why Plato then goes on to offer yet 20:58.195 --> 20:59.725 another argument. 20:59.730 --> 21:02.540 After all, if this argument really did show the immortality 21:02.535 --> 21:04.855 of the soul, why would he need to offer a further 21:04.857 --> 21:07.467 argument?--The argument from essential properties, 21:07.470 --> 21:10.040 which we'll be turning to later. 21:10.039 --> 21:14.929 So maybe Plato just thought there wasn't a good answer to 21:14.930 --> 21:16.590 Cebes' objection. 21:16.589 --> 21:19.819 But I want to say, on Plato's behalf, 21:19.820 --> 21:23.410 or at least on behalf of the argument, 21:23.410 --> 21:28.890 Socrates should never have concluded the argument with this 21:28.890 --> 21:34.180 odd qualifying phrase that the soul is "indestructible or 21:34.182 --> 21:38.742 nearly so." He should've just said the soul 21:38.735 --> 21:41.765 is indestructible, full stop. 21:41.769 --> 21:46.529 After all, if we have premises one, two, and three--only 21:46.526 --> 21:49.636 composite things can be destroyed, 21:49.640 --> 21:53.360 only changing things are composite, invisible things 21:53.358 --> 21:56.418 don't change--if you put those together, 21:56.420 --> 21:59.980 you get four, invisible things can't be 21:59.984 --> 22:03.154 destroyed. You don't get the more modest 22:03.147 --> 22:07.147 conclusion, "invisible things can't be destroyed or it's a 22:07.150 --> 22:09.750 whole lot harder to destroy them." 22:09.750 --> 22:11.970 If we've got one, two and three, 22:11.967 --> 22:15.897 we're entitled to the bold conclusion: "invisible things 22:15.901 --> 22:18.191 can't be destroyed, period." 22:18.190 --> 22:22.310 Full stop. And then if five is true, 22:22.307 --> 22:25.787 if the soul really is invisible, we're entitled to 22:25.792 --> 22:28.192 conclude six, the soul can't be 22:28.192 --> 22:31.382 destroyed--not, the soul can't be destroyed, 22:31.384 --> 22:34.284 or if it can be destroyed it's very, 22:34.279 --> 22:37.609 very hard and takes a very, very long time. 22:37.609 --> 22:41.969 We are, rather, entitled to the bolder 22:41.970 --> 22:47.860 conclusion, the soul can't be destroyed, full stop, 22:47.863 --> 22:51.873 period, end of the discussion. 22:51.869 --> 22:55.369 So despite the fact that Socrates draws this weaker 22:55.365 --> 22:59.765 conclusion, it seems to me that the argument he's offered us, 22:59.769 --> 23:05.209 if it works at all, entitles us to draw the bolder 23:05.207 --> 23:07.557 conclusion. Not that the soul is 23:07.559 --> 23:09.739 indestructible or nearly so, but that the soul is 23:09.741 --> 23:10.561 indestructible. 23:10.560 --> 23:13.590 23:13.590 --> 23:18.620 Well, maybe Plato realized that; maybe that's the reason why he 23:18.615 --> 23:21.095 doesn't bother giving an answer to Cebes. 23:21.099 --> 23:27.609 Maybe it's an invitation to the reader to recognize that there's 23:27.612 --> 23:34.232 a better argument here than even the characters in the drama have 23:34.228 --> 23:39.528 noticed--don't know, don't know what Plato had in 23:39.534 --> 23:41.354 mind. But at any rate, 23:41.346 --> 23:45.416 our question shouldn't be, "What was Plato thinking?" 23:45.420 --> 23:50.210 but, "Is the argument any good?" 23:50.210 --> 23:53.570 Do we now have an argument for the immortality of the soul? 23:53.569 --> 23:57.509 After all, if the soul can't be destroyed, it's immortal. 23:57.510 --> 24:02.390 Is it a good argument or not? 24:02.390 --> 24:06.540 Simmias raises a different objection. 24:06.539 --> 24:11.739 Simmias says we can't conclude that the soul is indestructible, 24:11.741 --> 24:14.441 or nearly so, or whatever, 24:14.436 --> 24:20.776 because we should not believe the sub-conclusion four, 24:20.781 --> 24:25.451 invisible things can't be destroyed. 24:25.450 --> 24:33.540 Simmias says invisible things can be destroyed. 24:33.539 --> 24:36.549 And if that's true, then of course we no longer 24:36.549 --> 24:39.759 have an argument for the indestructibility or near 24:39.755 --> 24:41.975 indestructibility of the soul. 24:41.980 --> 24:45.340 Because even if the soul is invisible, five, 24:45.342 --> 24:48.782 if nonetheless, contrary to what Socrates was 24:48.783 --> 24:51.513 claiming, invisible things can be 24:51.514 --> 24:55.694 destroyed, then maybe the invisible soul can be destroyed 24:55.689 --> 24:58.139 as well. Now, Simmias doesn't merely 24:58.140 --> 25:00.430 assert, boldly, invisible things can be 25:00.434 --> 25:05.044 destroyed. He offers an example of an 25:05.042 --> 25:12.102 invisible thing that can be destroyed--harmony. 25:12.099 --> 25:16.089 He starts talking about the harmony that gets produced by a 25:16.094 --> 25:20.294 stringed instrument; let's say a harp. 25:20.289 --> 25:24.299 In fact, he says, this is a very nice example for 25:24.300 --> 25:29.310 us to think about because some people have suggested--Simmias 25:29.312 --> 25:34.912 says--some people have suggested that the mind is like harmony. 25:34.910 --> 25:38.850 It's as though the mind is like harmony of the body. 25:38.849 --> 25:43.359 So to spell out the analogy a bit more fully, 25:43.363 --> 25:49.623 and I'll say a bit more about it later, harmony is to the harp 25:49.620 --> 25:52.800 as the mind is to the body. 25:52.800 --> 25:55.990 All right. He says, there are people who 25:55.986 --> 26:00.906 put forward views like this, and at any rate harmony can 26:00.911 --> 26:03.241 certainly be destroyed. 26:03.240 --> 26:05.130 You don't see harmony, right? 26:05.130 --> 26:08.380 Harmony is invisible. 26:08.380 --> 26:10.530 But for all that, you can destroy harmony. 26:10.529 --> 26:15.279 So there's the harp making its melodious, harmonious sounds, 26:15.280 --> 26:18.340 and then you take an ax to the harp, 26:18.339 --> 26:20.479 bang, bang, bang, chop, chop, chop, 26:20.476 --> 26:24.036 or a hammer or whatever; now the harmony's been 26:24.043 --> 26:28.313 destroyed. So even though it's invisible, 26:28.309 --> 26:33.039 you can destroy it by destroying the musical 26:33.039 --> 26:36.779 instrument on which it depends. 26:36.779 --> 26:38.709 And of course, there's the worry, 26:38.708 --> 26:41.428 right? If the mind is like the harmony 26:41.425 --> 26:45.025 of the body, then maybe you could destroy the mind, 26:45.029 --> 26:49.499 the soul, by destroying the body on which the mind depends. 26:49.500 --> 26:54.020 26:54.019 --> 26:58.939 So the crucial point right now is that thinking about harmony 26:58.939 --> 27:03.529 is offered as a counterexample to the generalization that 27:03.530 --> 27:06.810 invisible things can't be destroyed. 27:06.810 --> 27:08.470 Harmony is invisible. 27:08.470 --> 27:10.440 Harmony can be destroyed. 27:10.440 --> 27:13.760 So invisible things can be destroyed. 27:13.759 --> 27:15.569 So you're wrong, Socrates, when you say 27:15.565 --> 27:17.365 invisible things can't be destroyed. 27:17.369 --> 27:19.659 So even if we grant that the soul is invisible as well, 27:19.660 --> 27:21.870 maybe the soul also is an invisible thing that can be 27:21.866 --> 27:22.456 destroyed. 27:22.460 --> 27:25.840 27:25.840 --> 27:28.950 That's a great objection. 27:28.950 --> 27:35.450 It's an objection worth taking very seriously. 27:35.450 --> 27:41.220 And the oddity is, Socrates doesn't respond to it 27:41.222 --> 27:48.802 in the way that he should have, in the way that he needed to. 27:48.799 --> 27:55.779 Socrates instead spends some time worrying about the 27:55.778 --> 28:03.028 question, "Is the soul really like harmony or not?" 28:03.029 --> 28:08.119 Is this metaphor--think about the relationship between the 28:08.116 --> 28:13.736 mind and body as similar to the relationship between harmony and 28:13.738 --> 28:19.358 a harp--Socrates spends some time criticizing that analogy. 28:19.360 --> 28:22.940 28:22.940 --> 28:28.560 Now, in a few minutes I'll turn to the question, 28:28.555 --> 28:34.405 what about Socrates' criticisms of the analogy? 28:34.410 --> 28:36.170 Are they good criticisms or not? 28:36.170 --> 28:40.160 28:40.160 --> 28:44.260 But even if they are good criticisms, I want to say, 28:44.263 --> 28:48.773 that's not good enough to help your argument Socrates. 28:48.769 --> 28:51.889 Even if we were to say, you know what? 28:51.890 --> 28:55.470 The mind isn't very much like harmony at all. 28:55.470 --> 28:59.620 That analogy really stinks. 28:59.620 --> 29:04.140 So what? All that Simmias needs to cause 29:04.141 --> 29:09.491 problems for Socrates' argument is the claim that harmony is 29:09.491 --> 29:13.301 invisible and harmony can be destroyed. 29:13.299 --> 29:18.279 As long as that is true, we can't continue to believe 29:18.281 --> 29:22.401 that invisible things can't be destroyed. 29:22.400 --> 29:27.240 So what Socrates needs to do is to say either harmony can't be 29:27.238 --> 29:30.488 destroyed, but pretty obviously it can, 29:30.490 --> 29:34.740 the melodious sounds coming out of an instrument can be 29:34.736 --> 29:37.896 destroyed. So he would need to argue then, 29:37.901 --> 29:41.271 perhaps, that harmony is not really invisible. 29:41.269 --> 29:43.719 If he could show us, if he could convince us, 29:43.719 --> 29:45.889 that harmony is not really invisible, 29:45.890 --> 29:49.490 then we would no longer have a counterexample to the claim that 29:49.494 --> 29:51.534 the invisible can't be destroyed, 29:51.529 --> 29:56.169 and the argument could still then proceed as it was before. 29:56.170 --> 29:59.170 So that's what Socrates should have done. 29:59.170 --> 30:02.210 He should have said, "You know what? 30:02.210 --> 30:06.090 Harmony is not really invisible," or "It can't be 30:06.089 --> 30:08.989 destroyed." But there's not a whiff of 30:08.989 --> 30:12.259 that, at least in the dialogue as we've got it, 30:12.261 --> 30:15.321 not a whiff of that as far as I can see. 30:15.319 --> 30:17.829 Socrates never says, "Simmias, here is where your 30:17.828 --> 30:19.028 objection goes wrong. 30:19.029 --> 30:21.069 Harmony is not really invisible, can't really be 30:21.072 --> 30:22.292 destroyed, whatever it is. 30:22.289 --> 30:24.609 So we don't really have a counterexample." 30:24.609 --> 30:27.419 Instead, he gets hung up on this question, 30:27.416 --> 30:29.056 "Is it a good analogy? 30:29.059 --> 30:32.489 Is it a good way for thinking about the mind or not?" 30:32.490 --> 30:36.300 But even if it isn't, that wouldn't save the 30:36.304 --> 30:40.504 argument. Now, I am going to take some 30:40.501 --> 30:47.401 time to think about whether or not harmony is a good analogy, 30:47.403 --> 30:53.043 because I actually think it is a good analogy. 30:53.039 --> 30:57.269 I think what's going on in the harmony--the suggestion that we 30:57.274 --> 31:00.264 should think about the mind like harmony, 31:00.259 --> 31:07.029 as though it was the harmony of the body--is an early attempt to 31:07.032 --> 31:10.152 state the physicalist view. 31:10.150 --> 31:14.070 Talk about the mind, says the physicalist, 31:14.072 --> 31:18.092 is just a way of talking about the body. 31:18.089 --> 31:21.999 Or, more carefully, it's a way of talking about 31:21.995 --> 31:27.425 certain things the body can do when it's functioning properly, 31:27.430 --> 31:32.280 when it's well tuned, as we might put it. 31:32.279 --> 31:37.649 Just like, talk about the harmony or the melodious sounds 31:37.654 --> 31:43.104 or what have you of the harp, is a way--these things are a 31:43.103 --> 31:47.523 way of talking about what things the harp can do. 31:47.519 --> 31:51.929 It can produce melodious, harmonious sounds when it's 31:51.931 --> 31:55.751 functioning properly, when it's well tuned. 31:55.750 --> 32:00.810 So the harmony analogy is, I think, an attempt, 32:00.809 --> 32:05.869 and not a bad attempt, at gesturing towards the 32:05.869 --> 32:11.919 question, how do physicalists think about the mind? 32:11.920 --> 32:16.420 Now, when I tried to get you to grasp how physicalists think 32:16.422 --> 32:19.932 about the mind, I used examples about computers 32:19.933 --> 32:22.073 and robots and the like. 32:22.069 --> 32:27.169 Well, it's not remotely surprising that Plato doesn't 32:27.169 --> 32:30.209 use those kinds of analogies. 32:30.210 --> 32:33.180 He doesn't have computers; he doesn't have robots. 32:33.180 --> 32:37.770 Still, he has physical objects that can do things. 32:37.769 --> 32:41.329 And the ability to do things depends on the proper 32:41.331 --> 32:44.021 functioning of the physical object. 32:44.019 --> 32:49.339 And so, I think he can see that there's this alternative to his 32:49.341 --> 32:52.071 dualism. He can see you could be a 32:52.070 --> 32:56.560 physicalist and say that the mind is dependent on the body; 32:56.559 --> 33:00.419 the mind is just a way of talking about what the body can 33:00.416 --> 33:02.616 do when it's working properly. 33:02.619 --> 33:06.069 It's dependent just the same way that, well, 33:06.067 --> 33:09.357 for example, harmony is dependent upon the 33:09.355 --> 33:11.275 physical instrument. 33:11.279 --> 33:16.909 So I think it's a very nice attempt to discuss the 33:16.909 --> 33:22.079 physicalist alternative to Plato's dualism. 33:22.079 --> 33:25.909 And that's why it will be worth taking some time to ask 33:25.914 --> 33:29.114 ourselves, well, what about Plato's objections 33:29.110 --> 33:31.410 then? If he can convince us that the 33:31.406 --> 33:34.716 soul is not like harmony of the body, maybe that will be some 33:34.720 --> 33:36.930 sort of problem for the physicalists. 33:36.930 --> 33:41.310 So I'll come back to that in a few more minutes. 33:41.309 --> 33:45.759 But first, let's worry about the point that I was emphasizing 33:45.756 --> 33:48.936 earlier, namely, even if the soul's not very 33:48.942 --> 33:51.242 much like harmony, so what? 33:51.240 --> 33:54.410 If harmony really is invisible and harmony really can be 33:54.411 --> 33:57.411 destroyed, then invisible things can be destroyed. 33:57.410 --> 34:00.920 34:00.920 --> 34:04.470 Even if the soul's nothing like--that's not a good analogy 34:04.472 --> 34:07.592 for thinking about the physicalist position or what 34:07.588 --> 34:08.958 have you--so what? 34:08.960 --> 34:11.930 If some invisible things can be destroyed and harmony is an 34:11.928 --> 34:13.798 example of that, then, by golly, 34:13.801 --> 34:17.041 it's going to follow that we can't conclude from the 34:17.036 --> 34:20.966 invisibility of the soul that the soul cannot be destroyed. 34:20.969 --> 34:24.399 So even though Socrates doesn't respond to that objection, 34:24.402 --> 34:27.652 we need to ask on Socrates' behalf, is there a possible 34:27.653 --> 34:29.403 answer to this objection? 34:29.400 --> 34:32.520 34:32.519 --> 34:34.689 And I think there are at least the beginnings of one. 34:34.690 --> 34:39.340 34:39.340 --> 34:42.660 We have to ask: when we say, 34:42.661 --> 34:49.671 "invisible things can't be destroyed," what did we mean by 34:49.672 --> 34:55.052 "invisible?" And I want to distinguish three 34:55.046 --> 34:58.776 different possible interpretations, 34:58.782 --> 35:01.642 three different claims. 35:01.639 --> 35:14.579 So invisible means, one, there's one possibility, 35:14.577 --> 35:25.147 can't be seen. Two, different possibility, 35:25.146 --> 35:29.546 can't be observed. 35:29.550 --> 35:38.790 I've got in mind the broader notion of all five senses. 35:38.789 --> 35:42.789 Three, different possible interpretation of invisible, 35:42.790 --> 35:44.300 can't be detected. 35:44.300 --> 35:53.750 35:53.750 --> 35:55.930 What we have to ask ourselves is, when Socrates puts his 35:55.929 --> 35:57.749 argument forward, which of these did he have in 35:57.753 --> 36:00.313 mind? First, let's be clear on how 36:00.309 --> 36:02.509 these things are different. 36:02.510 --> 36:11.820 Some things can't be seen but can be sensed some other way. 36:11.820 --> 36:16.650 So colors can be seen; smells cannot be seen, 36:16.649 --> 36:20.509 but of course smells--the smell of coffee--can be sensed through 36:20.514 --> 36:21.684 the five senses. 36:21.680 --> 36:25.200 36:25.199 --> 36:28.799 Sounds can't be seen, they're not visible, 36:28.801 --> 36:32.141 but for all that they can be sensed. 36:32.139 --> 36:35.919 You can hear them through your ears. 36:35.920 --> 36:40.600 So, without getting hung up on what does the English word 36:40.600 --> 36:44.530 "invisible" mean, let's just notice that there's 36:44.529 --> 36:49.709 a difference between saying "it can't be seen through the eyes" 36:49.711 --> 36:54.811 and "can't be observed through one sense or the other." 36:54.809 --> 36:58.989 And then three is a different notion altogether, 36:58.991 --> 37:01.751 a stronger notion altogether. 37:01.750 --> 37:05.610 There might be things that can't even be detected through 37:05.614 --> 37:07.344 any of the five senses. 37:07.340 --> 37:10.640 The number three--not only can't I see it, 37:10.644 --> 37:13.304 I can't taste it, I can't hear it, 37:13.303 --> 37:15.883 I can't smell it, can't touch it, 37:15.882 --> 37:19.732 right? The number three is invisible 37:19.728 --> 37:22.208 in this much bolder way. 37:22.210 --> 37:28.740 It can't be detected at all by the five senses--can't be 37:28.737 --> 37:35.377 detected in terms of its--it doesn't leave traces behind, 37:35.383 --> 37:37.773 right? I don't see dinosaurs, 37:37.769 --> 37:40.549 but of course they leave traces behind in fossils. 37:40.550 --> 37:43.880 There's a way in which you can talk about it being detected by 37:43.884 --> 37:46.374 its effects. All right. 37:46.369 --> 37:48.889 So again, don't get hung up on what does the English word 37:48.886 --> 37:51.796 invisible mean. Let's just ask ourselves, 37:51.798 --> 37:57.208 what notion of invisibility--if we'll use the word between these 37:57.214 --> 38:02.204 three ways--what notion did Socrates' argument turn on? 38:02.199 --> 38:06.449 Well, the most natural way to start by interpreting him is 38:06.448 --> 38:08.908 with number one. When he says, 38:08.912 --> 38:13.142 "Invisible things don't change," what he means is, 38:13.143 --> 38:16.773 things that you can't see don't change, 38:16.769 --> 38:21.069 and so--continue to interpret invisible in number four the 38:21.074 --> 38:24.704 same way--invisible things can't be destroyed. 38:24.699 --> 38:28.639 On the first interpretation what he'd be saying is, 38:28.637 --> 38:33.517 "If you can't see it with your eyes, it can't be destroyed." 38:33.519 --> 38:38.969 Now, the trouble is, harmony shows that that's not 38:38.973 --> 38:41.493 so. Harmony is indeed invisible in 38:41.492 --> 38:42.672 sense number one. 38:42.670 --> 38:44.510 You cannot see it with your eyes. 38:44.510 --> 38:49.300 But for all that, it can be destroyed. 38:49.300 --> 38:53.540 So if what Socrates means by invisibility is the first 38:53.535 --> 38:58.165 notion, can't been seen with your eyes, then the argument's 38:58.171 --> 39:02.411 not any good. Harmony is a pretty compelling 39:02.406 --> 39:05.686 counterexample. But maybe that's not what 39:05.694 --> 39:07.734 Socrates means by invisible. 39:07.730 --> 39:10.740 Maybe instead of one, he means two. 39:10.739 --> 39:14.189 When he talks about the soul being invisible and invisible 39:14.192 --> 39:17.772 things being indestructible, maybe he means things that 39:17.769 --> 39:21.219 can't be observed through any of your five senses. 39:21.220 --> 39:25.430 39:25.429 --> 39:32.559 Now, in point of fact, I think that is what he meant. 39:32.560 --> 39:37.440 Let me just give a quick quote. 39:37.440 --> 39:43.320 In our edition, this is page 29. 39:43.320 --> 39:45.880 Some of you may have noticed that there are little 39:45.878 --> 39:48.488 standardized paginations in our edition as well. 39:48.489 --> 39:53.409 So it's in the academy paginations, number 79; 39:53.409 --> 39:56.339 he's talking about the difference between the visible 39:56.335 --> 39:59.255 and the invisible things, chairs versus the forms. 39:59.260 --> 40:01.820 And he says, "These latter, 40:01.819 --> 40:06.249 chairs, trees, stones, you could touch and see 40:06.250 --> 40:10.090 and perceive with the other senses. 40:10.090 --> 40:13.570 But those that always remain the same, the forms, 40:13.573 --> 40:17.713 can only be grasped by the reasoning power of the mind. 40:17.710 --> 40:22.650 They are not seen but are invisible." 40:22.650 --> 40:25.270 So I think it's pretty clear that when Socrates starts 40:25.270 --> 40:27.500 talking about what's visible versus invisible, 40:27.495 --> 40:29.815 he doesn't mean to limit himself to vision; 40:29.820 --> 40:34.690 he means to be talking about all of the five senses. 40:34.690 --> 40:39.450 So when we say--when he says--"Invisible things can't be 40:39.454 --> 40:44.744 destroyed," he means the things that you can't see or touch or 40:44.738 --> 40:48.028 hear or feel--whatever it is--see, 40:48.030 --> 40:49.700 touch, smell, taste. 40:49.700 --> 40:51.030 Those things can't be destroyed. 40:51.030 --> 40:57.430 40:57.429 --> 41:01.639 Now, notice that if that's the way we interpret his argument, 41:01.635 --> 41:04.855 harmony no longer works as a counterexample. 41:04.860 --> 41:09.990 Harmony was invisible when we meant definition number one, 41:09.989 --> 41:14.269 can't be seen. But it's not invisible if we 41:14.266 --> 41:18.616 mean definition number two, can't be sensed, 41:18.622 --> 41:20.752 can't be observed. 41:20.750 --> 41:28.180 Harmony can be sensed through the ears, in which case it's not 41:28.184 --> 41:30.504 a counterexample. 41:30.500 --> 41:34.320 It's not a counterexample to four. 41:34.320 --> 41:37.340 Four says, "Invisible things can't be destroyed." 41:37.340 --> 41:42.890 And what Socrates should have said is, harmony is not 41:42.886 --> 41:47.576 invisible in the relevant sense of invisible, 41:47.579 --> 41:50.459 since it can be sensed. 41:50.460 --> 41:54.860 But--and this would be the crucial point--notice, 41:54.861 --> 42:00.361 Socrates should've continued, the soul is invisible in 42:00.364 --> 42:03.344 that sense. You don't see the soul; 42:03.340 --> 42:06.700 you don't taste the soul; you don't touch the soul; 42:06.700 --> 42:10.540 you don't hear the soul. 42:10.539 --> 42:14.519 So if we understand the argument in terms of the second 42:14.518 --> 42:18.868 interpretation of invisible, it looks as though the argument 42:18.865 --> 42:20.555 still goes through. 42:20.560 --> 42:24.740 Simmias' counterexample fails. 42:24.739 --> 42:26.809 Harmony is not invisible in the relevant sense, 42:26.811 --> 42:29.291 so it could still be true that invisible things can't be 42:29.289 --> 42:32.299 destroyed. Since the soul is invisible in 42:32.303 --> 42:37.233 that sense, it would follow that the soul can't be destroyed. 42:37.230 --> 42:42.940 However, even if Simmias' objection, his particular 42:42.940 --> 42:45.910 counterexample, harmony, 42:45.909 --> 42:51.329 fails, that doesn't mean that we should still accept the 42:51.334 --> 42:57.354 argument because there might be a different counterexample. 42:57.350 --> 42:58.420 So here's my proposal. 42:58.420 --> 43:05.220 Suppose we think not about harmony but radio waves. 43:05.220 --> 43:08.860 Radio waves are not sensible. 43:08.860 --> 43:12.360 They are not observable. 43:12.360 --> 43:15.750 You don't see a radio wave. 43:15.750 --> 43:20.330 You can't touch a radio wave; you can't smell a radio wave, 43:20.329 --> 43:24.219 and interestingly enough, you can't hear radio waves. 43:24.220 --> 43:27.860 43:27.860 --> 43:29.080 But of course, for all that, 43:29.077 --> 43:30.157 they can be destroyed. 43:30.160 --> 43:34.340 43:34.340 --> 43:39.310 So even if we grant that what Socrates meant by invisible was 43:39.313 --> 43:42.823 "cannot be observed," we still have to say, 43:42.823 --> 43:45.883 with Simmias, "You know, four is just not 43:45.878 --> 43:48.858 true. Some invisible things can be 43:48.856 --> 43:51.866 destroyed." Radio waves can be destroyed 43:51.871 --> 43:55.661 even though they're invisible in the relevant sense. 43:55.660 --> 43:59.880 Yeah? Question? Student: 43:59.884 --> 44:08.324 [inaudible] Professor Shelly Kagan: 44:08.315 --> 44:11.675 Okay. So the suggestion was, 44:11.679 --> 44:14.649 radio waves are a bit like the forms. 44:14.650 --> 44:15.300 Student: [inaudible] 44:15.304 --> 44:16.514 Professor Shelly Kagan: They're not forms, 44:16.513 --> 44:17.423 but they're perfect in that way. 44:17.420 --> 44:19.550 Was that the thought? 44:19.550 --> 44:20.850 Student: [inaudible] 44:20.849 --> 44:22.649 Professor Shelly Kagan: Ah! 44:22.650 --> 44:23.660 Okay, I misunderstood. 44:23.659 --> 44:27.329 So the question is rather, "Look, radio waves are not like 44:27.332 --> 44:30.812 forms," to which the answer is "Yes, that's exactly the 44:30.812 --> 44:33.702 problem." They are invisible, 44:33.696 --> 44:38.326 like the forms, but unlike the forms they're 44:38.326 --> 44:42.726 destructible. And that's precisely why we've 44:42.734 --> 44:45.334 got to worry about the soul. 44:45.329 --> 44:48.899 Is the soul invisible in the way the forms are, 44:48.900 --> 44:52.780 being indestructible, or is it invisible in the way 44:52.782 --> 44:55.812 that radio waves are, destructible? 44:55.809 --> 44:58.589 Now again, my point here is not to say, "Oh, you idiot, 44:58.588 --> 45:01.448 Plato! Why didn't you think of radio 45:01.445 --> 45:03.395 waves?" Our question is not, 45:03.395 --> 45:07.025 was Plato overlooking something he should've thought of? 45:07.030 --> 45:09.970 It's, does his argument work or not? 45:09.969 --> 45:14.549 Is it true that the invisible things can't be destroyed? 45:14.550 --> 45:17.990 And it seems to me that some things that are invisible in the 45:17.992 --> 45:20.632 relevant sense, radio waves being an example of 45:20.631 --> 45:22.181 that, can be destroyed. 45:22.179 --> 45:26.529 So even though the soul is also invisible in the relevant sense, 45:26.526 --> 45:29.006 maybe it can be destroyed as well. 45:29.010 --> 45:30.780 Now, the answer, it seems to me, 45:30.784 --> 45:34.284 the only answer I can imagine Socrates or Plato giving at this 45:34.277 --> 45:35.987 point, is to say, "Look, 45:35.989 --> 45:38.939 I need a different definition of invisible. 45:38.940 --> 45:43.130 Not two, but three. 45:43.130 --> 45:45.850 Don't talk about what we can sense; 45:45.850 --> 45:48.190 talk about what we can detect." 45:48.190 --> 45:51.500 45:51.500 --> 45:56.280 Radio waves can be detected, right? 45:56.280 --> 45:59.670 After all, radios do that. 45:59.670 --> 46:02.350 You turn on your radio, the radio wave's passing by, 46:02.346 --> 46:04.336 boom--properly tuned, you detect it. 46:04.340 --> 46:08.380 It turns it into these sounds that we can hear. 46:08.380 --> 46:13.300 We can detect radio waves on the basis of their effects on 46:13.297 --> 46:15.797 radios, among other things. 46:15.800 --> 46:19.270 46:19.269 --> 46:22.619 So maybe by invisible he should've moved to this 46:22.617 --> 46:25.677 stronger, bolder definition of invisible. 46:25.679 --> 46:29.659 Let's call something invisible not only if it can't seen, 46:29.661 --> 46:33.291 not only if it can't be observed, but if it can't be 46:33.287 --> 46:35.497 detected at all. Look, the forms, 46:35.496 --> 46:36.966 after all, can't be detected. 46:36.969 --> 46:42.089 There's no radio for the number three that will tell--There's no 46:42.087 --> 46:46.547 Geiger counter to tell you the number three is nearby or 46:46.554 --> 46:48.264 something, right? 46:48.260 --> 46:52.750 So Plato could still insist things that are invisible, 46:52.749 --> 46:57.069 in the sense of undetectable, can't be destroyed. 46:57.070 --> 47:00.190 But radio waves, they're detectable. 47:00.190 --> 47:02.260 So they're not a counterexample, 47:02.261 --> 47:06.001 now that we interpret the relevant notion of invisibility 47:06.003 --> 47:07.543 as undetectability. 47:07.539 --> 47:12.929 So couldn't Plato continue to claim, things that are fully 47:12.927 --> 47:17.937 invisible, meaning undetectable, those things can't be 47:17.936 --> 47:20.536 destroyed. Radio waves aren't a 47:20.537 --> 47:22.067 counterexample to that. 47:22.070 --> 47:24.090 I think maybe Plato could say that. 47:24.090 --> 47:29.340 But, if we give him four, where we read invisible as 47:29.340 --> 47:35.310 meaning utterly undetectable, it's no longer so clear to me 47:35.311 --> 47:38.401 that we can give him five. 47:38.400 --> 47:40.550 Is the soul invisible? 47:40.550 --> 47:44.760 Well, it was, when by invisibility we meant 47:44.764 --> 47:49.564 can't be seen; it was, when by invisibility we 47:49.561 --> 47:55.121 meant can't be tasted or touched or heard or smelled. 47:55.119 --> 48:01.409 But is it still invisible if by invisibility we mean can't be 48:01.407 --> 48:06.507 detected? Is it true that the soul can't 48:06.508 --> 48:09.158 be detected? I've got to say, 48:09.155 --> 48:10.905 I think it's no longer right. 48:10.909 --> 48:14.539 Once we interpret invisibility that way, the soul is detectable 48:14.538 --> 48:17.228 in just the way--not literally just the way, 48:17.230 --> 48:20.470 but in something similar to the way--that radio waves are 48:20.468 --> 48:23.198 detectable. If you hook a radio wave up 48:23.199 --> 48:25.769 with a radio, you can tell the radio 48:25.766 --> 48:29.576 is--radio wave--was there because of what the radio's 48:29.579 --> 48:32.219 doing, giving off these sounds. 48:32.219 --> 48:38.309 If you hook a soul up to a body, you can tell the soul is 48:38.306 --> 48:45.476 there by what the body is doing, discussing philosophy with you. 48:45.480 --> 48:50.530 You detect the presence of your friend's soul through its 48:50.532 --> 48:53.422 effects on your friend's body. 48:53.420 --> 48:57.120 48:57.119 --> 49:00.929 But that means the soul isn't really undetectable. 49:00.929 --> 49:03.339 But if the soul's not really undetectable, 49:03.340 --> 49:06.280 it's not really invisible in the relevant sense. 49:06.280 --> 49:09.460 And if it's not really invisible, then even if there is 49:09.457 --> 49:12.827 a notion of invisible, such that things that are 49:12.828 --> 49:17.288 invisible in that sense can't be destroyed, the soul's not 49:17.294 --> 49:19.414 invisible in that sense. 49:19.409 --> 49:23.569 I've gone over this argument at such length because--I hope it's 49:23.573 --> 49:27.013 clear--I think it's a pretty interesting argument. 49:27.010 --> 49:31.700 The argument from simplicity is quite fascinating. 49:31.699 --> 49:35.399 The idea that you couldn't break the soul if it didn't have 49:35.395 --> 49:39.405 parts, and the way to tell that it doesn't have parts is because 49:39.409 --> 49:42.129 it's invisible, because invisible things can't 49:42.130 --> 49:45.100 have parts, that's a quite difficult argument to pin down, 49:45.099 --> 49:47.009 does it work or does it not work. 49:47.010 --> 49:49.870 But I think, as we think it all through, 49:49.871 --> 49:52.661 we have to conclude it doesn't work. 49:52.660 --> 49:54.000 Okay.