WEBVTT 00:00:00.835 --> 00:00:02.901 I love a great mystery, 00:00:02.901 --> 00:00:07.313 and I'm fascinated by the greatest unsolved mystery in science, 00:00:07.313 --> 00:00:09.271 perhaps because it's personal. 00:00:09.681 --> 00:00:11.539 It's about who we are, 00:00:11.539 --> 00:00:13.656 and I can't help but be curious. NOTE Paragraph 00:00:14.186 --> 00:00:16.275 The mystery is this: 00:00:16.275 --> 00:00:19.710 What is the relationship between your brain 00:00:19.710 --> 00:00:21.221 and your conscious experiences, 00:00:21.221 --> 00:00:23.891 such as your experience of the taste of chocolate 00:00:23.891 --> 00:00:25.665 or the feeling of velvet? NOTE Paragraph 00:00:26.805 --> 00:00:28.389 Now, this mystery is not new. 00:00:28.999 --> 00:00:32.598 In 1868, Thomas Huxley wrote, 00:00:32.598 --> 00:00:37.892 "How it is that anything so remarkable as a state of consciousness comes about 00:00:37.892 --> 00:00:41.259 as the result of irritating nervous tissue 00:00:41.259 --> 00:00:43.325 is just as unaccountable 00:00:43.325 --> 00:00:47.378 as the appearance of the genie when Aladdin rubbed his lamp." 00:00:49.268 --> 00:00:51.545 Now, Huxley knew that brain activity 00:00:51.545 --> 00:00:54.819 and conscious experiences are correlated, 00:00:54.819 --> 00:00:56.978 but he didn't know why. 00:00:56.978 --> 00:01:00.299 To the science of his day, it was a mystery. 00:01:00.299 --> 00:01:02.435 In the years since Huxley, 00:01:02.435 --> 00:01:05.801 science has learned a lot about brain activity, 00:01:05.801 --> 00:01:07.822 but the relationship between brain activity 00:01:07.822 --> 00:01:10.910 and conscious experiences is still a mystery. 00:01:10.910 --> 00:01:14.555 Why? Why have we made so little progress? 00:01:14.555 --> 00:01:19.414 Well, some experts think that we can't solve this problem 00:01:19.414 --> 00:01:23.213 because we lack the necessary concepts and intelligence. 00:01:23.883 --> 00:01:27.952 We don't expect monkeys to solve problems in quantum mechanics, 00:01:27.952 --> 00:01:32.117 and as it happens, we can't expect our species to solve this problem either. 00:01:32.527 --> 00:01:35.661 Well, I disagree. I'm more optimistic. 00:01:35.661 --> 00:01:38.703 I think we've simply made a false assumption. 00:01:38.703 --> 00:01:42.209 Once we fix it, we just might solve this problem. 00:01:42.209 --> 00:01:44.626 Today, I'd like tell you what that assumption is, 00:01:44.626 --> 00:01:47.384 why it's false, and how to fix it. NOTE Paragraph 00:01:47.874 --> 00:01:49.568 Let's begin with a question: 00:01:49.778 --> 00:01:52.866 Do we see reality as it is? 00:01:52.866 --> 00:01:54.561 I open my eyes 00:01:54.561 --> 00:01:59.498 and I have an experience that I describe as a red tomato a meter away. 00:02:00.606 --> 00:02:03.849 As a result, I come to believe that in reality, 00:02:03.849 --> 00:02:06.491 there's a red tomato a meter away. 00:02:06.751 --> 00:02:11.615 I then close my eyes, and my experience changes to a gray field, 00:02:12.425 --> 00:02:17.591 but is it still the case that in reality, there's a red tomato a meter away? 00:02:18.361 --> 00:02:21.913 I think so, but could I be wrong? 00:02:21.913 --> 00:02:26.511 Could I be misinterpreting the nature of my perceptions? NOTE Paragraph 00:02:27.351 --> 00:02:30.551 We have misinterpreted our perceptions before. 00:02:30.551 --> 00:02:34.010 We used to think the Earth is flat, because it looks that way. 00:02:34.707 --> 00:02:37.586 Pythagorus discovered that we were wrong. 00:02:37.586 --> 00:02:41.598 Then we thought that the Earth is the unmoving center of the Universe, 00:02:41.603 --> 00:02:43.506 again because it looks that way. 00:02:44.406 --> 00:02:49.312 Copernicus and Galileo discovered, again, that we were wrong. NOTE Paragraph 00:02:49.312 --> 00:02:53.400 Galileo then wondered if we might be misinterpreting our experiences 00:02:53.400 --> 00:02:54.908 in other ways. 00:02:54.908 --> 00:02:59.917 He wrote: "I think that tastes, odors, colors, and so on 00:02:59.917 --> 00:03:01.921 reside in consciousness. 00:03:02.291 --> 00:03:08.043 Hence if the living creature were removed, all these qualities would be annihilated." NOTE Paragraph 00:03:08.955 --> 00:03:10.794 Now, that's a stunning claim. 00:03:11.184 --> 00:03:12.995 Could Galileo be right? 00:03:12.995 --> 00:03:17.593 Could we really be misinterpreting our experiences that badly? 00:03:17.593 --> 00:03:20.154 What does modern science have to say about this? NOTE Paragraph 00:03:20.704 --> 00:03:25.928 Well, neuroscientists tell us that about a third of the brain's cortex 00:03:25.928 --> 00:03:27.786 is engaged in vision. 00:03:27.786 --> 00:03:31.292 When you simply open your eyes and look about this room, 00:03:31.292 --> 00:03:35.564 billions of neurons and trillions of synapses are engaged. NOTE Paragraph 00:03:35.564 --> 00:03:37.172 Now, this is a bit surprising, 00:03:37.172 --> 00:03:39.813 because to the extent that we think about vision at all, 00:03:39.813 --> 00:03:42.650 we think of it as like a camera. 00:03:42.650 --> 00:03:46.590 It just takes a picture of objective reality as it is. 00:03:46.590 --> 00:03:50.290 Now, there is a part of vision that's like a camera: 00:03:50.290 --> 00:03:54.929 the eye has a lens that focuses an image on the back of the eye 00:03:54.929 --> 00:03:58.319 where there are 130 million photoreceptors, 00:03:58.319 --> 00:04:02.219 so the eye is like a 130-megapixel camera. 00:04:02.219 --> 00:04:05.702 But that doesn't explain the billions of neurons 00:04:05.702 --> 00:04:09.324 and trillions of synapses that are engaged in vision. 00:04:09.324 --> 00:04:11.623 What are these neurons up to? NOTE Paragraph 00:04:11.623 --> 00:04:15.830 Well, neuroscientists tell us that they are creating, in real time, 00:04:15.830 --> 00:04:20.160 all the shapes, objects, colors, and motions that we see. 00:04:20.160 --> 00:04:23.651 It feels like we're just taking a snapshot of this room the way it is, 00:04:23.651 --> 00:04:27.226 but in fact, we're constructing everything that we see. 00:04:27.226 --> 00:04:30.407 We don't construct the whole world at once. 00:04:30.407 --> 00:04:33.172 We construct what we need in the moment. NOTE Paragraph 00:04:33.542 --> 00:04:36.909 Now, there are many demonstrations that are quite compelling 00:04:36.909 --> 00:04:38.720 that we construct what we see. 00:04:38.720 --> 00:04:40.763 I'll just show you two. 00:04:40.763 --> 00:04:46.529 In this example, you see some red discs with bits cut out of them, 00:04:46.529 --> 00:04:49.470 but if I just rotate the disks a little bit, 00:04:49.470 --> 00:04:54.207 suddenly, you see a 3D cube pop out of the screen. 00:04:54.207 --> 00:04:57.040 Now, the screen of course is flat, 00:04:57.040 --> 00:04:59.640 so the three-dimensional cube that you're experiencing 00:04:59.640 --> 00:05:02.617 must be your construction. NOTE Paragraph 00:05:03.397 --> 00:05:05.310 In this next example, 00:05:05.310 --> 00:05:09.534 you see glowing blue bars with pretty sharp edges 00:05:09.534 --> 00:05:12.718 moving across a field of dots. 00:05:13.708 --> 00:05:16.845 In fact, no dots move. 00:05:16.845 --> 00:05:21.466 All I'm doing from frame to frame is changing the colors of dots 00:05:21.466 --> 00:05:23.927 from blue to black or black to blue. 00:05:23.927 --> 00:05:25.761 But when I do this quickly, 00:05:25.761 --> 00:05:29.476 your visual system creates the glowing blue bars 00:05:29.476 --> 00:05:32.147 with the sharp edges and the motion. 00:05:32.147 --> 00:05:34.817 There are many more examples, but these are just two 00:05:34.817 --> 00:05:37.580 that you construct what you see. NOTE Paragraph 00:05:37.580 --> 00:05:39.955 But neuroscientists go further. 00:05:41.395 --> 00:05:46.496 They say that we reconstruct reality. 00:05:46.496 --> 00:05:50.722 So, when I have an experience that I describe as a red tomato, 00:05:50.722 --> 00:05:54.855 that experience is actually an accurate reconstruction 00:05:54.855 --> 00:05:56.970 of the properties of a real red tomato 00:05:56.970 --> 00:06:00.265 that would exist even if I weren't looking. NOTE Paragraph 00:06:01.595 --> 00:06:04.816 Now, why would neuroscientists say that we don't just construct, 00:06:04.816 --> 00:06:06.696 we reconstruct? 00:06:06.696 --> 00:06:09.227 Well, the standard argument given 00:06:09.227 --> 00:06:11.781 is usually an evolutionary one. 00:06:12.941 --> 00:06:15.380 Those of our ancestors who saw more accurately 00:06:15.380 --> 00:06:20.233 had a competitive advantage compared to those who saw less accurately, 00:06:20.233 --> 00:06:22.989 and therefore they were more likely to pass on their genes. 00:06:22.989 --> 00:06:26.380 We are the offspring of those who saw more accurately, 00:06:26.380 --> 00:06:29.149 and so we can be confident that, in the normal case, 00:06:29.149 --> 00:06:31.680 our perceptions are accurate. 00:06:31.680 --> 00:06:35.375 You see this in the standard textbooks. 00:06:35.375 --> 00:06:37.369 One textbook says, for example, 00:06:37.369 --> 00:06:39.340 "Evolutionarily speaking, 00:06:39.340 --> 00:06:43.383 vision is useful precisely because it is so accurate." 00:06:43.383 --> 00:06:48.181 So the idea is that accurate perceptions are fitter perceptions. 00:06:48.181 --> 00:06:50.325 They give you a survival advantage. NOTE Paragraph 00:06:50.325 --> 00:06:52.240 Now, is this correct? 00:06:52.240 --> 00:06:54.899 Is this the right interpretation of evolutionary theory? 00:06:54.899 --> 00:06:58.280 Well, let's first look at a couple of examples in nature. NOTE Paragraph 00:06:58.800 --> 00:07:01.238 The Australian jewel beetle 00:07:01.238 --> 00:07:04.349 is dimpled, glossy and brown. 00:07:04.349 --> 00:07:06.694 The female is flightless. 00:07:06.694 --> 00:07:10.711 The male flies, looking, of course, for a hot female. 00:07:10.711 --> 00:07:14.659 When he finds one, he alights and mates. 00:07:14.659 --> 00:07:17.130 There's another species in the outback, 00:07:17.130 --> 00:07:18.464 Homo sapiens. 00:07:18.464 --> 00:07:21.531 The male of this species has a massive brain 00:07:21.531 --> 00:07:25.479 that he uses to hunt for cold beer. 00:07:25.889 --> 00:07:27.168 (Laughter) 00:07:27.168 --> 00:07:29.542 And when he finds one, he drains it, 00:07:29.542 --> 00:07:32.932 and sometimes throws the bottle into the outback. 00:07:32.932 --> 00:07:37.180 Now, as it happens, these bottles are dimpled, glossy, 00:07:37.180 --> 00:07:41.320 and just the right shade of brown to tickle the fancy of these beetles. 00:07:42.772 --> 00:07:46.235 The males swarm all over the bottles trying to mate. 00:07:47.582 --> 00:07:50.369 They lose all interest in the real females. 00:07:50.369 --> 00:07:54.572 Classic case of the male leaving the female for the bottle. 00:07:54.572 --> 00:07:57.519 (Laughter) (Applause) 00:07:59.402 --> 00:08:01.773 The species almost went extinct. 00:08:02.443 --> 00:08:06.752 Australia had to change its bottles to save its beetles. 00:08:06.752 --> 00:08:09.752 (Laughter) 00:08:09.752 --> 00:08:13.960 Now, the males had successfully found females for thousands, 00:08:13.960 --> 00:08:16.398 perhaps millions of years. 00:08:16.398 --> 00:08:20.832 It looked like they saw reality as it is, but apparently not. 00:08:20.832 --> 00:08:23.689 Evolution had given them a hack. 00:08:23.689 --> 00:08:28.425 A female is anything dimpled, glossy and brown, 00:08:28.425 --> 00:08:30.701 the bigger the better. 00:08:30.701 --> 00:08:32.535 (Laughter) 00:08:32.535 --> 00:08:37.375 Even when crawling all over the bottle, the male couldn't discover his mistake. NOTE Paragraph 00:08:37.945 --> 00:08:41.590 Now, you might say, beetles, sure, they're very simple creatures, 00:08:41.590 --> 00:08:43.448 but surely not mammals. 00:08:43.448 --> 00:08:46.165 Mammals don't rely on tricks. 00:08:46.165 --> 00:08:52.178 Well, I won't dwell on this, but you get the idea. (Laughter) NOTE Paragraph 00:08:52.178 --> 00:08:55.336 So this raises an important technical question: 00:08:55.336 --> 00:09:01.327 Does natural selection really favor seeing reality as it is? 00:09:01.877 --> 00:09:05.413 Fortunately, we don't have to wave our hands and guess; 00:09:05.413 --> 00:09:08.594 evolution is a mathematically precise theory. 00:09:08.594 --> 00:09:12.147 We can use the equations of evolution to check this out. 00:09:12.147 --> 00:09:16.300 We can have various organisms in artificial worlds compete 00:09:16.300 --> 00:09:18.253 and see which survive and which thrive, 00:09:18.253 --> 00:09:21.806 which sensory systems are more fit. NOTE Paragraph 00:09:21.806 --> 00:09:25.891 A key notion in those equations is fitness. 00:09:25.891 --> 00:09:28.586 Consider this steak: 00:09:29.956 --> 00:09:32.918 What does this steak do for the fitness of an animal? 00:09:33.438 --> 00:09:39.454 Well, for a hungry lion looking to eat, it enhances fitness. 00:09:40.179 --> 00:09:44.773 For a well-fed lion looking to mate, it doesn't enhance fitness. 00:09:46.053 --> 00:09:49.924 And for a rabbit in any state, it doesn't enhance fitness, 00:09:49.924 --> 00:09:54.048 so fitness does depend on reality as it is, yes, 00:09:54.048 --> 00:09:58.236 but also on the organism, its state and its action. 00:09:58.236 --> 00:10:01.789 Fitness is not the same thing as reality as it is, 00:10:01.789 --> 00:10:05.272 and it's fitness, and not reality as it is, 00:10:05.272 --> 00:10:09.451 that figures centrally in the equations of evolution. NOTE Paragraph 00:10:09.451 --> 00:10:12.642 So, in my lab, 00:10:12.642 --> 00:10:16.417 we have run hundreds of thousands of evolutionary game simulations 00:10:16.417 --> 00:10:19.482 with lots of different randomly chosen worlds 00:10:19.482 --> 00:10:23.661 and organisms that compete for resources in those worlds. 00:10:23.661 --> 00:10:27.980 Some of the organisms see all of the reality, 00:10:27.980 --> 00:10:29.869 others see just part of the reality, 00:10:29.869 --> 00:10:31.974 and some see none of the reality, 00:10:31.974 --> 00:10:33.740 only fitness. 00:10:34.240 --> 00:10:35.820 Who wins? NOTE Paragraph 00:10:36.290 --> 00:10:42.255 Well, I hate to break it to you, but perception of reality goes extinct. 00:10:42.255 --> 00:10:44.164 In almost every simulation, 00:10:44.164 --> 00:10:46.346 organisms that see none of reality 00:10:46.346 --> 00:10:48.436 but are just tuned to fitness 00:10:48.436 --> 00:10:53.660 drive to extinction all the organisms that perceive reality as it is. 00:10:53.660 --> 00:10:58.250 So the bottom line is, evolution does not favor veridical, 00:10:58.250 --> 00:10:59.906 or accurate perceptions. 00:10:59.906 --> 00:11:03.668 Those perceptions of reality go extinct. NOTE Paragraph 00:11:03.668 --> 00:11:05.688 Now, this is a bit stunning. 00:11:05.688 --> 00:11:09.370 How can it be that not seeing the world accurately 00:11:09.370 --> 00:11:11.190 gives us a survival advantage? 00:11:11.190 --> 00:11:13.303 That is a bit counterintuitive. 00:11:13.303 --> 00:11:15.138 But remember the jewel beetle. 00:11:15.138 --> 00:11:18.899 The jewel beetle survived for thousands, perhaps millions of years, 00:11:18.899 --> 00:11:21.593 using simple tricks and hacks. 00:11:21.593 --> 00:11:24.770 What the equations of evolution are telling us 00:11:24.770 --> 00:11:30.413 is that all organisms, including us, are in the same boat as the jewel beetle. 00:11:30.413 --> 00:11:32.343 We do not see reality as it is. 00:11:32.343 --> 00:11:36.615 We're shaped with tricks and hacks that keep us alive. NOTE Paragraph 00:11:36.615 --> 00:11:38.635 Still, 00:11:38.635 --> 00:11:40.702 we need some help with our intuitions. 00:11:40.702 --> 00:11:45.485 How can not perceiving reality as it is be useful? 00:11:45.485 --> 00:11:49.154 Well, fortunately, we have a very helpful metaphor: 00:11:49.154 --> 00:11:51.986 the desktop interface on your computer. 00:11:51.986 --> 00:11:56.119 Consider that blue icon for a TED Talk that you're writing. 00:11:56.119 --> 00:12:00.123 Now, the icon is blue and rectangular 00:12:00.123 --> 00:12:02.504 and in the lower right corner of the desktop. 00:12:03.324 --> 00:12:07.510 Does that mean that the text file itself in the computer is blue, 00:12:08.200 --> 00:12:11.955 rectangular, and in the lower right-hand corner of the computer? 00:12:11.955 --> 00:12:13.278 Of course not. 00:12:13.278 --> 00:12:17.987 Anyone who thought that misinterprets the purpose of the interface. 00:12:17.987 --> 00:12:20.755 It's not there to show you the reality of the computer. 00:12:20.755 --> 00:12:23.680 In fact, it's there to hide that reality. 00:12:23.680 --> 00:12:25.555 You don't want to know about the diodes 00:12:25.555 --> 00:12:27.805 and resistors and all the megabytes of software. 00:12:27.805 --> 00:12:30.936 If you had to deal with that, you could never write your text file 00:12:30.936 --> 00:12:32.411 or edit your photo. 00:12:32.411 --> 00:12:37.128 So the idea is that evolution has given us an interface 00:12:37.128 --> 00:12:41.443 that hides reality and guides adaptive behavior. 00:12:41.443 --> 00:12:44.461 Space and time, as you perceive them right now, 00:12:44.461 --> 00:12:46.635 are your desktop. 00:12:46.635 --> 00:12:51.372 Physical objects are simply icons in that desktop. NOTE Paragraph 00:12:52.192 --> 00:12:54.413 There's an obvious objection. 00:12:54.413 --> 00:12:58.361 Hoffman, if you think that train coming down the track at 200 MPH 00:12:58.361 --> 00:13:00.822 is just an icon of your desktop, 00:13:00.822 --> 00:13:02.947 why don't you step in front of it? 00:13:02.947 --> 00:13:05.240 And after you're gone, and your theory with you, 00:13:05.240 --> 00:13:08.554 we'll know that there's more to that train than just an icon. 00:13:08.554 --> 00:13:10.597 Well, I wouldn't step in front of that train 00:13:10.597 --> 00:13:12.153 for the same reason 00:13:12.153 --> 00:13:16.448 that I wouldn't carelessly drag that icon to the trash can: 00:13:16.448 --> 00:13:19.629 not because I take the icon literally -- 00:13:19.629 --> 00:13:22.634 the file is not literally blue or rectangular -- 00:13:22.934 --> 00:13:25.260 but I do take it seriously. 00:13:25.260 --> 00:13:27.291 I could lose weeks of work. 00:13:27.291 --> 00:13:29.845 Similarly, evolution has shaped us 00:13:29.845 --> 00:13:34.281 with perceptual symbols that are designed to keep us alive. 00:13:34.811 --> 00:13:37.276 We'd better take them seriously. 00:13:37.276 --> 00:13:39.481 If you see a snake, don't pick it up. 00:13:40.391 --> 00:13:43.150 If you see a cliff, don't jump off. 00:13:43.150 --> 00:13:46.726 They're designed to keep us safe, and we should take them seriously. 00:13:46.726 --> 00:13:49.417 That does not mean that we should take them literally. 00:13:49.417 --> 00:13:51.671 That's a logical error. NOTE Paragraph 00:13:51.671 --> 00:13:54.876 Another objection: There's nothing really new here. 00:13:54.876 --> 00:13:58.800 Physicists have told us for a long time that the metal of that train looks solid 00:13:58.800 --> 00:14:03.188 but really it's mostly empty space with microscopic particles zipping around. 00:14:03.188 --> 00:14:04.676 There's nothing new here. 00:14:04.676 --> 00:14:06.880 Well, not exactly. 00:14:06.880 --> 00:14:10.920 It's like saying, I know that that blue icon on the desktop 00:14:10.920 --> 00:14:13.219 is not the reality of the computer, 00:14:13.219 --> 00:14:16.678 but if I pull out my trusty magnifying glass and look really closely, 00:14:16.678 --> 00:14:18.489 I see little pixels, 00:14:18.489 --> 00:14:20.950 and that's the reality of the computer. 00:14:20.950 --> 00:14:24.758 Well, not really -- you're still on the desktop, and that's the point. 00:14:24.758 --> 00:14:27.754 Those microscopic particles are still in space and time: 00:14:27.754 --> 00:14:30.145 they're still in the user interface. 00:14:30.145 --> 00:14:33.907 So I'm saying something far more radical than those physicists. NOTE Paragraph 00:14:34.727 --> 00:14:36.200 Finally, you might object, 00:14:36.200 --> 00:14:38.759 look, we all see the train, 00:14:38.759 --> 00:14:41.801 therefore none of us constructs the train. 00:14:41.801 --> 00:14:43.891 But remember this example. 00:14:43.891 --> 00:14:46.607 In this example, we all see a cube, 00:14:47.597 --> 00:14:49.690 but the screen is flat, 00:14:49.690 --> 00:14:52.427 so the cube that you see is the cube that you construct. 00:14:53.736 --> 00:14:55.779 We all see a cube 00:14:55.779 --> 00:15:00.638 because we all, each one of us, constructs the cube that we see. 00:15:00.638 --> 00:15:02.698 The same is true of the train. 00:15:02.698 --> 00:15:07.180 We all see a train because we each see the train that we construct, 00:15:07.180 --> 00:15:10.733 and the same is true of all physical objects. NOTE Paragraph 00:15:12.343 --> 00:15:17.396 We're inclined to think that perception is like a window on reality as it is. 00:15:17.396 --> 00:15:22.400 The theory of evolution is telling us that this is an incorrect interpretation 00:15:22.400 --> 00:15:23.865 of our perceptions. 00:15:25.095 --> 00:15:28.639 Instead, reality is more like a 3D desktop 00:15:28.639 --> 00:15:31.936 that's designed to hide the complexity of the real world 00:15:31.936 --> 00:15:33.802 and guide adaptive behavior. 00:15:34.282 --> 00:15:37.210 Space as you perceive it is your desktop. 00:15:37.210 --> 00:15:40.236 Physical objects are just the icons in that desktop. NOTE Paragraph 00:15:41.456 --> 00:15:45.126 We used to think that the Earth is flat because it looks that way. 00:15:45.520 --> 00:15:48.654 Then we thought that the Earth is the unmoving center of reality 00:15:48.654 --> 00:15:50.378 because it looks that way. 00:15:50.378 --> 00:15:51.520 We were wrong. 00:15:51.520 --> 00:15:54.190 We had misinterpreted our perceptions. 00:15:54.910 --> 00:15:58.319 Now we believe that spacetime and objects 00:15:58.319 --> 00:16:00.933 are the nature of reality as it is. 00:16:01.453 --> 00:16:05.377 The theory of evolution is telling us that once again, we're wrong. 00:16:05.377 --> 00:16:10.416 We're misinterpreting the content of our perceptual experiences. 00:16:10.416 --> 00:16:12.947 There's something that exists when you don't look, 00:16:12.947 --> 00:16:16.350 but it's not spacetime and physical objects. 00:16:16.350 --> 00:16:19.378 It's as hard for us to let go of spacetime and objects 00:16:19.378 --> 00:16:22.861 as it is for the jewel beetle to let go of its bottle. 00:16:22.861 --> 00:16:27.279 Why? Because we're blind to our own blindnesses. 00:16:28.409 --> 00:16:30.756 But we have an advantage over the jewel beetle: 00:16:30.756 --> 00:16:32.544 our science and technology. 00:16:32.544 --> 00:16:34.935 By peering through the lens of a telescope 00:16:34.935 --> 00:16:39.571 we discovered that the Earth is not the unmoving center of reality, 00:16:39.571 --> 00:16:42.449 and by peering through the lens of the theory of evolution 00:16:42.449 --> 00:16:44.771 we discovered that spacetime and objects 00:16:44.771 --> 00:16:47.139 are not the nature of reality. 00:16:47.139 --> 00:16:51.424 When I have a perceptual experience that I describe as a red tomato, 00:16:51.424 --> 00:16:54.361 I am interacting with reality, 00:16:54.361 --> 00:16:59.571 but that reality is not a red tomato and is nothing like a red tomato. 00:16:59.571 --> 00:17:04.972 Similarly, when I have an experience that I describe as a lion or a steak, 00:17:04.972 --> 00:17:06.820 I'm interacting with reality, 00:17:06.820 --> 00:17:09.978 but that reality is not a lion or a steak. 00:17:09.978 --> 00:17:11.998 And here's the kicker: 00:17:11.998 --> 00:17:16.688 When I have a perceptual experience that I describe as a brain, or neurons, 00:17:16.688 --> 00:17:18.778 I am interacting with reality, 00:17:18.778 --> 00:17:22.307 but that reality is not a brain or neurons 00:17:22.307 --> 00:17:25.805 and is nothing like a brain or neurons. 00:17:25.805 --> 00:17:30.584 And that reality, whatever it is, 00:17:30.584 --> 00:17:34.195 is the real source of cause and effect 00:17:34.195 --> 00:17:38.227 in the world -- not brains, not neurons. 00:17:38.227 --> 00:17:40.827 Brains and neurons have no causal powers. 00:17:40.827 --> 00:17:43.428 They cause none of our perceptual experiences, 00:17:43.428 --> 00:17:45.216 and none of our behavior. 00:17:45.216 --> 00:17:50.592 Brains and neurons are a species-specific set of symbols, a hack. NOTE Paragraph 00:17:50.592 --> 00:17:53.273 What does this mean for the mystery of consciousness? 00:17:53.923 --> 00:17:57.916 Well, it opens up new possibilities. 00:17:57.916 --> 00:17:59.611 For instance, 00:17:59.611 --> 00:18:06.590 perhaps reality is some vast machine that causes our conscious experiences. 00:18:06.590 --> 00:18:10.260 I doubt this, but it's worth exploring. 00:18:10.260 --> 00:18:15.609 Perhaps reality is some vast, interacting network of conscious agents, 00:18:15.609 --> 00:18:21.182 simple and complex, that cause each other's conscious experiences. 00:18:21.182 --> 00:18:24.432 Actually, this isn't as crazy an idea as it seems, 00:18:24.432 --> 00:18:26.052 and I'm currently exploring it. NOTE Paragraph 00:18:26.592 --> 00:18:28.658 But here's the point: 00:18:28.658 --> 00:18:31.979 Once we let go of our massively intuitive 00:18:31.979 --> 00:18:35.903 but massively false assumption about the nature of reality, 00:18:35.903 --> 00:18:40.291 it opens up new ways to think about life's greatest mystery. 00:18:41.251 --> 00:18:45.860 I bet that reality will end up turning out to be more fascinating 00:18:45.860 --> 00:18:49.834 and unexpected than we've ever imagined. NOTE Paragraph 00:18:49.834 --> 00:18:54.222 The theory of evolution presents us with the ultimate dare: 00:18:54.222 --> 00:18:59.364 Dare to recognize that perception is not about seeing truth, 00:18:59.364 --> 00:19:03.460 it's about having kids. 00:19:03.460 --> 00:19:08.200 And by the way, even this TED is just in your head. NOTE Paragraph 00:19:08.200 --> 00:19:10.244 Thank you very much. NOTE Paragraph 00:19:10.244 --> 00:19:13.632 (Applause) NOTE Paragraph 00:19:20.786 --> 00:19:24.221 Chris Anderson: If that's really you there, thank you. 00:19:24.221 --> 00:19:27.152 So there's so much from this. 00:19:27.152 --> 00:19:30.421 I mean, first of all, some people may just be profoundly depressed 00:19:30.421 --> 00:19:35.970 at the thought that, if evolution does not favor reality, 00:19:35.970 --> 00:19:39.300 I mean, doesn't that to some extent undermine all our endeavors here, 00:19:39.300 --> 00:19:41.984 all our ability to think that we can think the truth, 00:19:41.984 --> 00:19:45.490 possibly even including your own theory, if you go there? NOTE Paragraph 00:19:45.490 --> 00:19:49.944 Donald Hoffman: Well, this does not stop us from a successful science. 00:19:49.944 --> 00:19:52.756 What we have is one theory that turned out to be false, 00:19:52.756 --> 00:19:57.215 that perception is like reality and reality is like our perceptions. 00:19:57.215 --> 00:19:58.900 That theory turns out to be false. 00:19:58.900 --> 00:20:00.318 Okay, throw that theory away. 00:20:00.318 --> 00:20:03.572 That doesn't stop us from now postulating all sorts of other theories 00:20:03.572 --> 00:20:04.930 about the nature of reality, 00:20:04.930 --> 00:20:08.535 so it's actually progress to recognize that one of our theories was false. 00:20:08.535 --> 00:20:11.193 So science continues as normal. There's no problem here. NOTE Paragraph 00:20:11.193 --> 00:20:13.794 CA: So you think it's possible -- (Laughter) -- 00:20:13.794 --> 00:20:17.904 This is cool, but what you're saying I think is it's possible that evolution 00:20:17.904 --> 00:20:20.551 can still get you to reason. NOTE Paragraph 00:20:20.551 --> 00:20:22.864 DH: Yes. Now that's a very, very good point. 00:20:22.864 --> 00:20:27.391 The evolutionary game simulations that I showed were specifically about perception, 00:20:27.391 --> 00:20:29.969 and they do show that our perceptions have been shaped 00:20:29.969 --> 00:20:31.849 not to show us reality as it is, 00:20:31.849 --> 00:20:36.122 but that does not mean the same thing about our logic or mathematics. 00:20:36.122 --> 00:20:39.744 We haven't done these simulations, but my bet is that we'll find 00:20:39.744 --> 00:20:43.366 that there are some selection pressures for our logic and our mathematics 00:20:43.366 --> 00:20:45.572 to be at least in the direction of truth. 00:20:45.572 --> 00:20:48.219 I mean, if you're like me, math and logic is not easy. 00:20:48.219 --> 00:20:51.570 We don't get it all right, but at least the selection pressures are not 00:20:51.570 --> 00:20:53.908 uniformly away from true math and logic. 00:20:53.908 --> 00:20:57.228 So I think that we'll find that we have to look at each cognitive faculty 00:20:57.228 --> 00:20:59.852 one at a time and see what evolution does to it. 00:20:59.852 --> 00:21:03.613 What's true about perception may not be true about math and logic. NOTE Paragraph 00:21:03.613 --> 00:21:07.607 CA: I mean, really what you're proposing is a kind of modern-day Bishop Berkeley 00:21:07.607 --> 00:21:09.998 interpretation of the world: 00:21:09.998 --> 00:21:12.947 consciousness causes matter, not the other way around. NOTE Paragraph 00:21:12.947 --> 00:21:15.339 DH: Well, it's slightly different than Berkeley. 00:21:15.339 --> 00:21:18.701 Berkeley thought that, he was a deist, and he thought that the ultimate 00:21:18.701 --> 00:21:20.740 nature of reality is God and so forth, 00:21:20.740 --> 00:21:23.850 and I don't need to go where Berkeley's going, 00:21:23.850 --> 00:21:26.545 so it's quite a bit different from Berkeley. 00:21:27.725 --> 00:21:31.235 I call this conscious realism. It's actually a very different approach. NOTE Paragraph 00:21:31.235 --> 00:21:34.825 CA: Don, I could literally talk with you for hours, and I hope to do that. NOTE Paragraph 00:21:34.825 --> 00:21:37.298 Thanks so much for that. DH: Thank you. (Applause)