1 00:00:06,437 --> 00:00:10,926 What is reality, knowledge, the meaning of life? 2 00:00:10,926 --> 00:00:13,251 Big topics you might tackle figuratively 3 00:00:13,251 --> 00:00:18,196 explaining existence as a journey down a road or across an ocean, 4 00:00:18,196 --> 00:00:25,194 a climb, a war, a book, a thread, a game, a window of opportunity, 5 00:00:25,338 --> 00:00:28,986 or an all-too-short-lived flicker of flame. 6 00:00:29,011 --> 00:00:30,800 2,400 years ago, 7 00:00:30,849 --> 00:00:36,240 one of history's famous thinkers said life is like being chained up in a cave, 8 00:00:36,265 --> 00:00:39,722 forced to watch shadows flitting across a stone wall. 9 00:00:39,722 --> 00:00:41,358 Pretty cheery, right? 10 00:00:41,358 --> 00:00:45,503 That's actually what Plato suggested in his Allegory of the Cave, 11 00:00:45,503 --> 00:00:47,916 found in Book VII of "The Republic," 12 00:00:47,916 --> 00:00:51,521 in which the Greek philosopher envisioned the ideal society 13 00:00:51,521 --> 00:00:56,124 by examining concepts like justice, truth and beauty. 14 00:00:56,149 --> 00:01:01,032 In the allegory, a group of prisoners have been confined in a cavern since birth, 15 00:01:01,032 --> 00:01:03,582 with no knowledge of the outside world. 16 00:01:03,607 --> 00:01:07,346 They are chained, facing a wall, unable to turn their heads, 17 00:01:07,371 --> 00:01:10,390 while a fire behind them gives off a faint light. 18 00:01:10,415 --> 00:01:13,230 Occasionally, people pass by the fire, 19 00:01:13,255 --> 00:01:18,485 carrying figures of animals and other objects that cast shadows on the wall. 20 00:01:18,485 --> 00:01:21,445 The prisoners name and classify these illusions, 21 00:01:21,470 --> 00:01:23,899 believing they're perceiving actual entities. 22 00:01:23,899 --> 00:01:28,978 Suddenly, one prisoner is freed and brought outside for the first time. 23 00:01:29,003 --> 00:01:33,507 The sunlight hurts his eyes and he finds the new environment disorienting. 24 00:01:33,532 --> 00:01:35,872 When told that the things around him are real,` 25 00:01:35,933 --> 00:01:39,902 while the shadows were mere reflections, he cannot believe it. 26 00:01:39,902 --> 00:01:42,445 The shadows appeared much clearer to him. 27 00:01:42,445 --> 00:01:45,193 But gradually, his eyes adjust 28 00:01:45,218 --> 00:01:47,676 until he can look at reflections in the water, 29 00:01:47,701 --> 00:01:49,380 at objects directly, 30 00:01:49,405 --> 00:01:51,643 and finally at the Sun, 31 00:01:51,668 --> 00:01:55,548 whose light is the ultimate source of everything he has seen. 32 00:01:55,573 --> 00:01:59,228 The prisoner returns to the cave to share his discovery, 33 00:01:59,279 --> 00:02:01,628 but he is no longer used to the darkness, 34 00:02:01,628 --> 00:02:05,804 and has a hard time seeing the shadows on the wall. 35 00:02:05,804 --> 00:02:09,878 The other prisoners think the journey has made him stupid and blind, 36 00:02:09,910 --> 00:02:13,576 and violently resist any attempts to free them. 37 00:02:13,876 --> 00:02:16,833 Plato introduces this passage as an analogy 38 00:02:16,833 --> 00:02:21,269 of what it's like to be a philosopher trying to educate the public. 39 00:02:21,269 --> 00:02:24,473 Most people are not just comfortable in their ignorance 40 00:02:24,498 --> 00:02:28,174 but hostile to anyone who points it out. 41 00:02:28,199 --> 00:02:32,028 In fact, the real life Socrates was sentenced to death 42 00:02:32,028 --> 00:02:35,272 by the Athenian government for disrupting the social order, 43 00:02:35,297 --> 00:02:38,339 and his student Plato spends much of "The Republic" 44 00:02:38,364 --> 00:02:40,802 disparaging Athenian democracy, 45 00:02:40,802 --> 00:02:44,201 while promoting rule by philosopher kings. 46 00:02:44,226 --> 00:02:45,873 With the cave parable, 47 00:02:45,873 --> 00:02:50,113 Plato may be arguing that the masses are too stubborn and ignorant 48 00:02:50,113 --> 00:02:52,025 to govern themselves. 49 00:02:52,050 --> 00:02:56,223 But the allegory has captured imaginations for 2,400 years 50 00:02:56,223 --> 00:02:59,279 because it can be read in far more ways. 51 00:02:59,304 --> 00:03:03,187 Importantly, the allegory is connected to the theory of forms, 52 00:03:03,212 --> 00:03:05,524 developed in Plato's other dialogues, 53 00:03:05,549 --> 00:03:07,951 which holds that like the shadows on the wall, 54 00:03:07,976 --> 00:03:12,834 things in the physical world are flawed reflections of ideal forms, 55 00:03:12,859 --> 00:03:16,028 such as roundness, or beauty. 56 00:03:16,053 --> 00:03:19,692 In this way, the cave leads to many fundamental questions, 57 00:03:19,717 --> 00:03:21,786 including the origin of knowledge, 58 00:03:21,811 --> 00:03:23,931 the problem of representation, 59 00:03:23,956 --> 00:03:27,138 and the nature of reality itself. 60 00:03:27,163 --> 00:03:31,950 For theologians, the ideal forms exist in the mind of a creator. 61 00:03:31,975 --> 00:03:35,995 For philosophers of language viewing the forms as linguistic concepts, 62 00:03:36,020 --> 00:03:39,580 the theory illustrates the problem of grouping concrete things 63 00:03:39,605 --> 00:03:41,815 under abstract terms. 64 00:03:41,840 --> 00:03:44,546 And others still wonder whether we can really know 65 00:03:44,546 --> 00:03:49,110 that the things outside the cave are any more real than the shadows. 66 00:03:49,135 --> 00:03:50,491 As we go about our lives, 67 00:03:50,516 --> 00:03:53,452 can we be confident in what we think we know? 68 00:03:53,452 --> 00:03:54,638 Perhaps one day, 69 00:03:54,663 --> 00:03:58,810 a glimmer of light may punch a hole in your most basic assumptions. 70 00:03:58,835 --> 00:04:01,207 Will you break free to struggle towards the light, 71 00:04:01,232 --> 00:04:03,904 even if it costs you your friends and family, 72 00:04:03,929 --> 00:04:07,353 or stick with comfortable and familiar illusions? 73 00:04:07,378 --> 00:04:10,751 Truth or habit? Light or shadow? 74 00:04:10,776 --> 00:04:14,824 Hard choices, but if it's any consolation, you're not alone. 75 00:04:14,824 --> 00:04:17,363 There are lots of us down here.