シャドーイング練習: The Most Controversial Problem in Philosophy - 動画で英語スピーキングを学ぶ
レッスンを作成中...
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Do not hit the like button or the dislike button, at least not yet.
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I want you to consider a problem that's been one of the most controversial in math
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and philosophy over the past 20 years.
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There is no consensus answer, so I want you to listen to the problem
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and then vote for the answer you prefer using the like and dislike buttons.
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Okay?
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Here is the setup.
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Sleeping Beauty volunteers to be the subject of an experiment.
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And before it starts, she's informed of the procedure.
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On Sunday night, she will be put to sleep.
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And then, a fair coin will be flipped.
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If that coin comes up heads, she'll be awakened on Monday and then put back to sleep.
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If the coin comes up tails, she will also be awakened on Monday and put back to sleep.
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But then she will be awakened on Tuesday as well and then put back to sleep.
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Now, each time she gets put back to sleep, she will forget that she was ever awakened.
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In the brief period, anytime she's awake, she will be told no information.
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But she'll be asked one question.
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What do you believe is the probability that the coin came up heads?
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So how should she answer?
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Feel free to pause the video and answer the question for yourself right now.
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This was my reaction after hearing the problem for the first time.
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I mean, the intuitive answer that pops into my head is clearly one in three.
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It could be the Monday when it came up heads, or it could be the Monday when it came up tails,
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or it could be the Tuesday when it came up tails.
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But you know what's really interesting is you just answered that the probability of a coin coming up heads is 1 third.
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I think a lot of this comes down to what specific question is asked of her.
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What is the probability that a fair coin flipped gives heads?
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That's 50%.
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What is the probability that the coin came up heads?
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I would say the answer is 1 third from her perspective.
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It's remarkably the same question.
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The simple reason why Sleeping Beauty should say the probability of heads is one half is
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because she knows the coin is fair.
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Nothing changes between when the coin is flipped and when she wakes up, and she knew for a fact that she would be woken up, and she receives no new information when that happens.
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Imagine that instead of flipping the coin after she's asleep, the experimenters flip the coin first and ask her immediately.
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what's the probability that the coin came up heads?
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Well, she would certainly say one half.
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So why should anything change after she goes to sleep and wakes up?
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This is known as the halfer position.
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But there is another way to look at it.
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Others would argue that something does change when she's awakened.
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I mean, it seems like she gets no new information, there are no calendars, no one tells her anything, and she knew that she would be woken up.
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But she actually learns something important.
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She learns that she's gone from existing in a reality where there are two possible states,
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the coin came up either heads or tails to existing in a reality where there are three possible states, Monday heads, Monday tails, or Tuesday tails,
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and therefore she should assign equal probability to each of these three outcomes where heads only occurred in one.
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So the probability that the coin came up heads is one third.
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This is known as the third-er position.
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Now I know it seems wrong to suggest that a fair coin should have a one third probability of coming up heads, but that's because the question she's asked is subtly different.
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The implied question is, given you're awake, what's the probability that the coin came up heads?
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And that is one third.
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Now halfers would counter that just because there are three possible outcomes doesn't mean they are each equally likely.
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In the Monty Hall problem, for example, the contestant ultimately has to choose between two doors.
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But it'd be wrong to assign them 50-50 odds, the prize is actually twice as likely to be behind one door than the other.
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In the sleeping beauty problem, we know a heads outcome and a tails outcome are equally likely, so the chance of waking up on Monday with heads is 50%,
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and the chance of waking up on Monday or Tuesday with tails should be 50%.
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Therefore, the tails probability gets split across two days, 25% each.
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But if you repeat the experiment over and over, which you can try for for yourself by repeatedly flipping a coin, you find she wakes up a third of the time Monday heads,
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a third of the time Monday tails, and a third of the time Tuesday tails, not 50, 25, 25, like the previous analysis would suggest.
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So if you were Sleeping Beauty and you were awakened and asked what's the probability the coin came up heads, what would you say?
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If you would say one third, then hit the like button.
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If you would say one half, hit the dislike button.
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The answer may seem obvious to you, but you should know that to other people, the other answer seems equally obvious.
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And that's why hundreds and hundreds of philosophy papers have been published on this problem over the past 22 years.
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There have been many variations of this problem.
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Like what if instead of being woken up twice of the coin lands tails, she's instead woken up a million times?
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If the coin comes up heads, she's still woken only once.
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Doesn't it seem absurd in this case when Sleeping Beauty wakes up to say
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that it was just as likely that the coin landed heads as tails?
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When we know there are a million more wake-ups in the tails case than in the heads case.
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I mean, if you reach into a bag of one white marble and a million black marbles, what are the chances that you pull out that one white marble?
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I was pretty convinced by this, and I considered myself a third-er, but this same argument is used to convince people that we're living in a simulation.
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The thinking goes that our computing technology has improved so dramatically, even over just the last 40 years,
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that we can imagine a time in the not-too-distant future when we can create a completely realistic simulation of our world.
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And once that occurs, it should be trivial to make unlimited copies of that simulation.
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And then if you were to ask someone if they're living in a simulation, they would have to admit that they probably are, because there are many more instances of that existence than the one true external reality.
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But how do we know that this hasn't happened already, and that we're living inside a simulation?
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I mean, if it can happen, then it probably has happened, and we are living in a simulation.
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This seems like the logical conclusion of the third-er worldview.
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Now I personally don't buy that I'm living in a simulation, and I think most people don't buy it, but maybe that's just a logical bias.
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But there's another thought experiment that makes me seriously reconsider the third or position.
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Let's say there's a soccer game between a really great team like Brazil and a less world-dominating team like Canada.
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So the odds are 80-20 in Brazil's favor.
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Now a researcher is going to put you to sleep before the game starts.
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And if Brazil wins, they'll wake you up one time.
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But if Canada wins, they'll wake you up 30 times in a row.
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And just like Sleeping Beauty, you won't remember if you've been woken before.
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Okay, so the game is about to start.
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You fall asleep.
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And now you're woken up.
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Who do you think won the game?
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The third-er would say Canada.
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But I would almost certainly say Brazil.
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I mean, why should I give any weight to what the researcher would have done if Canada had won
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when I'm fairly confident that they won't?
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To extend this, let's say Brazil plays Canada five times and we do this experiment each time.
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Well then if you say Brazil each time you're woken up, you'll probably be right about four out of five of the games.
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But if you said Canada every time, you would be wrong about those four games, but right 30 times in a row when you're repeatedly asked about Canada's won victory.
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If you stand to win a bet by correctly answering the question, then by all means you should bet on Canada.
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But if you want to correctly pick the winner of more of the games, well then you should say Brazil.
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And this is what's at the heart of the dispute between halfers and thirders in the Sleeping Beauty problem.
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If you want to be right about the outcome of the coin tosses, well, you should say the probability of heads is a half.
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But if you want to answer more questionings correctly, well, then you should say one third.
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I want to leave you with one last thought experiment.
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Imagine that you know for a fact that before our universe began, there was a coin flip, and if it came up heads, only a single universe would be created.
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But if it came up tails, a quasi-infinite multiverse would be created.
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And in each of those multiverse universes, you'd find every possible variation of Earth and the people on it.
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In some versions, there would be no Earth.
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Now, you becoming conscious is just like Sleeping Beauty waking up.
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There's no way to tell if you're in that single universe or in one of the multiverse universes, but you know there are a lot more of them.
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So would you think that you're for sure in the multiverse?
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Or are the chances 50-50?
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The best way to develop intuition about probability is by working through scenarios or running simulations like we did for Sleeping Beauty.
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This video's sponsor, Brilliant, offers probability courses that walk you through lots of situational probability questions.
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Do you want to learn how to build your own simulations?
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Go check out Brilliant.
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You can try it free for 30 days at brilliant.org slash veritasium.
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You know, to me, Brilliant is the best way to learn because it forces you to think critically.
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And it's also a lot of fun.
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I mean, I find learning new things and sharpening my thinking energizing.
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In their lessons, you model the real world with math
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and expand your understanding of cutting edge topics like AI and machine learning, technology that's transforming our world right now.
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Are we actually living in a computer simulation or a multiverse? Who knows?
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But with Brilliant, you might actually get started on your journey to figuring it out.
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They already have thousands of lessons and new ones are added every month.
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So if you wanna get started with Brilliant's annual premium subscription, they're giving 20% off to the first 200 people to sign up via my link, brilliant.org slash Veritasium.
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I will put that down in the description.
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So I wanna thank Brilliant for supporting Veritasium, and I wanna thank you for watching.
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このレッスンの語彙とスピーキングのポイント
このC1レベルのスピーキングレッスンは、動画「The Most Controversial Problem in Philosophy」を教材にしています。 繰り返し出てくる語は次のとおりです：coin, probability, tails, simulation, Monday。 この動画には、シャドーイング用の文が128文、単語が1895語あります。 音声の長さは10:18です。 話す速さは速く、1分あたり約184語です。音のつながりや弱く発音される音が多くなります。 単語の84%は英語の頻出3,000語に含まれます。残りは練習の前に確認しておきましょう。 全128文のうち20文が疑問文なので、疑問文のイントネーションや短い受け答えの練習に向いています。
この動画の重要語彙
動画の中で特に難しい単語15語を、発音と意味つきで紹介します。
| 単語 | 発音 | 意味 |
|---|---|---|
| probability 名詞 | /ˌpɹɑ.bəˈbɪl.ə.ti/ | 確率 |
| simulation 名詞 | /ˌsɪm.jəˈleɪ.ʃn̩/ | 真似, 模擬 |
| awaken 動詞 | /əˈweɪkən/ | 起こす |
| multiverse 名詞 | /ˈmʌltəˌvɝs/ | マルチバス, 多元宇宙 |
| dislike 動詞 | /dɪsˈlaɪk/ | 嫌う, 厭う |
| marble 名詞 | /ˈmɑɹ.bəl/ | 大理石, マーブル |
| assign 動詞 | /əˈsaɪn/ | 割り当てる |
| researcher 名詞 | /ˈɹiˌsɝ.t͡ʃɚ/ | 研究員, 研究者 |
| variation 名詞 | /ˌvɛəɹiˈeɪʃn̩/ | 変動, 変化 |
| compute 動詞 | /kəmˈpjuːt/ | 計算する |
| sharpen 動詞 | /ˈʃɑɹpən/ | 研ぐ, 削る |
| worldview 名詞 | 世界観 | |
| intuition 名詞 | /ˌɪn.tjuːˈɪʃ.ən/ | 直覚, 直感 |
| intuitive 形容詞 | /ɪnˈtjuːɪtɪv/ | 直感的 |
| reconsider 動詞 | /ˈɹiːkənˌsɪdə/ | 再考する |
動画に出てくる句動詞
| 単語 | 発音 | 意味 |
|---|---|---|
| come up 動詞 | 上がる, 登る | |
| wake up 動詞 | /ˌweɪk ˈʌp/ | 目覚める, 目を覚ます |
| check out 動詞 | 試験する, 検査する |
繰り返し練習したい文
動画に出てくる短く完結した文です。日常会話でそのまま使えます。
- Who do you think won the game?
- Do you want to learn how to build your own simulations?
- Are we actually living in a computer simulation or a multiverse?
この動画の文法
話し手がよく使っている文型を、動画の実際の表現とともに紹介します。
| 文型 | 動画での表現 |
|---|---|
| 条件文 if + 節, will/would + 動詞 — 条件とその結果 | If that coin comes up heads, she'll be · if Brazil wins, they'll wake · if Canada wins, they'll wake |
| 受動態 be + 過去分詞 — 誰がするかより、何が起きるかに焦点を当てる | will be put · will be flipped · be awakened |
| 現在完了形 have/has + 過去分詞 — 過去の出来事が今も関係している | have been published · have been · has improved |
注意したい発音
話し手はyou're, wanna, doesn'tなど、短縮形や弱形を30回使っています。聞こえたとおりの短い形で発音しましょう。
- 「sh」と「zh」の音: simulation /ˌsɪm.jəˈleɪ.ʃn̩/, variation /ˌvɛəɹiˈeɪʃn̩/, sharpen /ˈʃɑɹpən/, situational /sɪtjuːˈeɪʃənəl/, intuition /ˌɪn.tjuːˈɪʃ.ən/
- 長い単語（アクセントの位置に注意）: probability /ˌpɹɑ.bəˈbɪl.ə.ti/, experimenter /ɪkˈspɛɹ.ɪ.mɛn.tə/, situational /sɪtjuːˈeɪʃənəl/, intuition /ˌɪn.tjuːˈɪʃ.ən/, intuitive /ɪnˈtjuːɪtɪv/
日本語話者が苦手な音：
- /r/ と /l/ の区別 — /l/ は舌先を歯茎につけ、/r/ はどこにもつけない: probability /ˌpɹɑ.bəˈbɪl.ə.ti/, marble /ˈmɑɹ.bəl/, trivial /ˈtɹɪv.i.əl/, remarkably /ɹɪˈmɑɹkəbli/, critically /ˈkɹɪt.ɪ.kə.li/
- /v/ — /b/ にならないように、上の歯を下唇に当てる: multiverse /ˈmʌltəˌvɝs/, variation /ˌvɛəɹiˈeɪʃn̩/, intuitive /ɪnˈtjuːɪtɪv/, trivial /ˈtɹɪv.i.əl/
- 子音の連続 — 間に母音を入れない: probability /ˌpɹɑ.bəˈbɪl.ə.ti/, compute /kəmˈpjuːt/, contestant /kənˈtɛstənt/, experimenter /ɪkˈspɛɹ.ɪ.mɛn.tə/, intuition /ˌɪn.tjuːˈɪʃ.ən/
この動画での練習方法
- まず声を出さずに動画を最後まで聞き、知らない単語をメモします。
- まず0.75倍速で一文ずつシャドーイングし、慣れてきたら通常の速度に戻します。
- 自分の声を録音して元の音声と比べます。probability, simulation, awakenなどの単語に特に注意しましょう。
シャドーイングとは？英語上達に効果的な理由
シャドーイング（Shadowing）は、もともとプロの通訳者養成プログラムで開発された言語学習法で、多言語習得者として知られるDr. Alexander Arguelles によって広く普及されました。方法はシンプルですが非常に効果的：ネイティブスピーカーの英語を聞きながら、1〜2秒の遅延で声に出してすぐに繰り返す——まるで「影（shadow）」のように話者を追いかけます。文法ドリルや受動的なリスニングと異なり、シャドーイングは脳と口の筋肉が同時にリアルタイムで英語を処理・再現することを強制します。研究により、発音精度、抑揚、リズム、連音、リスニング力、そして会話の流暢さが大幅に向上することが確認されています。IELTSスピーキング対策や自然な英語コミュニケーションを目指す方に特におすすめです。