0:00 Almost every cell in your body is replaced over the course of about seven to ten years.0:06 So the physical stuff that made you up a decade ago is, for the most part, gone.0:13 Right.0:13 And last week, we were wrestling with the edges of reality, asking if the table in front of us is actually real.0:22 It feels like this week we have to turn that question inward.0:27 If my physical body is completely different, am I the same person who was sitting here ten years ago?0:34 Exactly.0:35 The continuity we feel, that sense of being "me" across my whole life...0:41 what is that?0:42 Where does it live if not in my physical parts?0:45 The classic answer, uh, going back to the philosopher John Locke, is memory.0:51 You are you because you remember being you yesterday, and last year, and when you were a kid.0:59 It’s a chain of psychological connection.1:02 Okay, but that feels...1:04 fragile.1:04 What if someone has severe amnesia from an accident?1:08 Are they literally not the same person anymore?1:12 Their family would say they are.1:15 That's the problem, isn't it?1:17 Or what about false memories?1:19 We know our brains invent and distort things all the time.1:24 If my identity is built on a memory that didn't actually happen, what does that say about who I am?1:31 It feels like building a house on, I don't know, a fog bank.1:36 A fog bank, yeah.1:37 So if it's not the body, and it’s not just memory...1:41 what's left?1:42 Is it just...1:43 consciousness?1:45 The feeling of being aware right now?1:47 That’s another candidate.1:49 The continuous stream of experience.1:52 But then, you know, what happens when you go to sleep every night?1:57 Or if someone is in a coma?1:59 Does the self just...2:01 switch off?2:02 Cease to exist and then get rebooted in the morning?2:06 Whoa.2:06 I mean, we don't experience it that way.2:10 It feels like I'm the one who wakes up.2:13 But I can't prove it.2:14 The thought experiments here get really tricky.2:18 There’s one about a teleporter.2:20 Imagine a machine on Earth scans every molecule of your body, destroys it, and then transmits that information to Mars, where a new machine reassembles you perfectly from new atoms.2:35 Okay...2:35 so I arrive on Mars.2:37 Well, a person arrives on Mars.2:39 That person has all your memories, your personality, your consciousness.2:45 They feel exactly like you, and they'd pick up a conversation right where you left off.2:52 Is that person...2:53 you?2:53 My first instinct is to say yes.2:56 If it has my memories and feels like me, it's me.2:59 But what if the machine on Earth malfunctioned?3:03 And it...3:04 uh...3:04 forgot to destroy the original you?3:07 So now there's a you on Earth and a you on Mars.3:11 Which one is the REAL you?3:13 Ohhh.3:13 Okay, no.3:14 Then the one on Mars isn't me.3:16 It's a copy.3:17 A perfect replica, but not me.3:20 Which means...3:21 in the first scenario, I just died.3:23 I stepped into a suicide machine.3:26 And that's the core of it.3:28 We have this deep intuition that our identity is more than just a pattern of information.3:35 There has to be some kind of continuous, unbroken existence.3:40 But we can't find what that existence is tied to.3:43 Not the body, not the memories, not even just consciousness.3:48 So what are we choosing when we say "I am the same person"?3:53 It's not a fact we're stating, is it?3:56 It feels more like...3:57 a decision.3:58 Or a story.3:59 I think that's getting close to where a lot of modern thinking on this lands.4:05 The idea of a "narrative self." Maybe the "I" that persists through time is the protagonist of a story that you're constantly telling yourself, about yourself.4:18 So I'm the main character.4:20 And the continuity comes from the fact that I keep telling the story, incorporating new events, reinterpreting old ones...4:29 Exactly.4:30 The self isn't a thing, it's an activity.4:33 It's a process of weaving all these disparate parts—memories, hopes, physical changes—into a single, coherent narrative thread.4:43 Huh.4:43 So the question isn't "What am I?" but maybe...4:47 "What story am I telling?" And that feels like a question you can actually live with.
