Can you solve the famously difficult green-eyed logic puzzle? - Alex Gendler

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  • Опубликовано: 16 июн 2015
  • View full lesson: ed.ted.com/lessons/the-famously-difficult-green-eyed-logic-puzzle-alex-gendler
    One hundred green-eyed logicians have been imprisoned on an island by a mad dictator. Their only hope for freedom lies in the answer to one famously difficult logic puzzle. Can you solve it? Alex Gendler walks us through this green-eyed riddle.
    Lesson by Alex Gendler, animation by Artrake Studio.

Комментарии • 8 300

  • Jacob Wagers
    Jacob Wagers 3 часа назад

    I have green eyes XD

  • pikminman13
    pikminman13 5 часов назад

    Unless everyone on the island is extremely selfish all they had to do was point at the eyes of any given person and give some form of positive message, unless they are unable to/dont know what a thumbs up, smile, vertical nod, point to the exit, or anything similar is.

  • Nothing
    Nothing 5 часов назад

    Just say everyone should leave.

  • Miku01
    Miku01 8 часов назад

    Couldn’t they see themselves in other people’s eyes? Like use the eyes as a mirror?

  • Pifflepoff
    Pifflepoff 10 часов назад

    It might also work to say you don't know you all have green eyes

  • Jack Jaeger
    Jack Jaeger 12 часов назад

    Or just say evryone next to you has green eyes, it is not new info

  • Árgyelán Ádám
    Árgyelán Ádám 14 часов назад

    I would just say that all the prisoners you've met by now has green eyes. It is not new info, they saw it themselves.

  • EpicGamer425
    EpicGamer425 15 часов назад

    Then they all fail in modern society because they were raised on an island and probably have no math, language, or social skills.

  • Gopher
    Gopher День назад

    I wasn't paying attention, give me a summary

  • CharChar Binks
    CharChar Binks День назад

    Couldn’t you say that the person next to u has green eyes

  • Bomb Comics
    Bomb Comics День назад

    Couldn't she just say that at least 99 of them have green eyes? Since every prisoner sees the other 99 prisoners and sees they have green eyes, then wouldn't they all just wait one day and leave the next night?

  • Kaileb McDonald
    Kaileb McDonald День назад

    Or maybe they see 99 other green eyed people so they just assume hmm maybe there's a trend

  • Kaileb McDonald
    Kaileb McDonald День назад

    This is a huge logic leap I mean the first thing I think isn't woah I got green eyes it's oh maybe he wants to stay with the only people he's known for idk his whole life or maybe the green eyed guy already left oh well back to my regular day.

  • Cindy Ngooo
    Cindy Ngooo День назад

    Honestly I would just wing it

  • Joshsicle
    Joshsicle День назад

    did the dictator teach them to be logicians?

  • plush n puppet shenanigans
    plush n puppet shenanigans 2 дня назад

    I would say you all have green eyes

    • Nolan Chojnacki
      Nolan Chojnacki 2 дня назад

      plush n puppet shenanigans. Thats new info

  • sofia_ leavemealone
    sofia_ leavemealone 2 дня назад

    As a person with green eyes, I feel kinda relieved

  • Seline B
    Seline B 2 дня назад

    I thought they even don't know what green is

  • Shreya Monga
    Shreya Monga 3 дня назад

    This mad dictator is Kim Jong Un!😅😇😀😃😂😄🤣😋😛😝😜🤪 By the way, good riddles!

  • Iris Ariola
    Iris Ariola 3 дня назад

    Solution: Throw the dictator into the volcano.

  • Cory Whitten
    Cory Whitten 4 дня назад

    with the two people example if sh

  • Frans Erasmus
    Frans Erasmus 4 дня назад

    I don't get this.
    I would like if they explained with 4 people.
    2 people is easy.
    And I understand with 3, if you have non-green eyes, then the other two can use the 2 person logic to leave and the next day they are gone, since they did not leave, you know you have green eyes as well and everyone leaves that night.
    *But can someone explain with 4?* The only way that someone will leave before anyone else is if they see no green eyes, but you know they all see at least 2 green eyes (you see 3, but since you don't know your color and the other person cant see their own), so you know they will stay for that reason and not because of your color.

  • [CG] SNIPER
    [CG] SNIPER 6 дней назад

    After 30 minutes I completely understand and have a headache

  • Amir LEVY
    Amir LEVY 6 дней назад +1

    I would say: "Trust me, the outside world is terrible. It isn't worth the trouble of trying to escape"

  • Sam Gardner
    Sam Gardner 7 дней назад

    "At least 99 of you have green eyes" Now they can all leave the second night.

  • Jade333j
    Jade333j 7 дней назад

    i solved it at first

  • ProoGenji
    ProoGenji 8 дней назад

    Wow this girl just saved 100 Nobel prizes

  • Mallory Stiles
    Mallory Stiles 9 дней назад

    or, the dictator could have taught all of the prisoners that “green” was a different color, so for example they would have learned that the word “green” was associated with the color “red”.

  • Mallory Stiles
    Mallory Stiles 9 дней назад

    Lol. i would have said “You’ll all be fine if you ask to leave.”

  • jaspermulder1999
    jaspermulder1999 9 дней назад

    It's more efficiënt to say: the majority of the group has green eyes. Thereby the group split in half, so the same concept of the video applies. However it's easier to track for bigger (even) groups.

  • Raj Hariya
    Raj Hariya 9 дней назад

    This riddle is wrong! This method only works for 2 people not more.think about it logically. doesn't make sense more more amount of people.

  • Gachasodes/alexi cedo
    Gachasodes/alexi cedo 10 дней назад

    How did I get this correct

  • Carolyn D
    Carolyn D 10 дней назад

    poopity scoop

  • Nothing Channel
    Nothing Channel 10 дней назад

    I have olive green eyes..does that count?

  • SD SsnoopyDog
    SD SsnoopyDog 11 дней назад

    YOU SAID THAT NOBODY WAS LEFT AFTER tomorrow WHICH MEANS THEY ALL LEFT IN ONE DAY BUT CLEARLY IT TAKE MORE AS THREE PEOPLE TAKES 3 DAYS

  • SD SsnoopyDog
    SD SsnoopyDog 11 дней назад

    WRONG

  • kookiekream
    kookiekream 13 дней назад

    It's impossible to grow up to be a logician in those kinda living conditions...

  • Peter minator
    Peter minator 13 дней назад

    Here's my solution since these prisoners are perfect logicians:
    Every prisoners look only at green eyed prisoners , and they will realize that they all look at each other so, they will all escape the island the next day.

  • Exterel YT
    Exterel YT 14 дней назад +2

    When the narrator said “At least ninety-nine of you have green eyes” you could tell he was at he brink of laughing.

  • soham trivedi
    soham trivedi 14 дней назад

    badria
    the ship has sailed

  • corgi_ lover64
    corgi_ lover64 14 дней назад

    I have brown eyes so I hope I don’t go there

  • Scott Hurst
    Scott Hurst 14 дней назад

    They could have just thought (when there are 3 or more) "hey everyone else has the same colour eyes that means I have the green eyes

  • 05candyman
    05candyman 15 дней назад

    I get it.
    If I have non-green eyes, then they'd both see I have non-green eyes, and each would look at the other and see that the other has green eyes and each will think to themselves "well, he has non-green eyes, so if I too have non-green eyes, then this third guy will leave", so then they'd wait to see which will leave on the first night. When neither one leaves on the first night, they'd realize that they both of green eyes, and that I'm the only one with non-green eyes, and leave on the second night. But because they did not leave on the second night, then each of the two did not conclude that they must have green eyes (applying the original logic), and that would only be the case if I too had green eyes.
    The key is to imagine a scenario where you have brown eyes, and that's it. It's really that simple lol. A high school maths teacher of mine used to say about maths "if it wasn't easy, humans couldn't do/think it".

  • Ahmed El-Rayes
    Ahmed El-Rayes 15 дней назад

    0:33 not 100 people only 66

  • Ignore the cringy Username hi
    Ignore the cringy Username hi 15 дней назад

    Or say "you all have the same eye colour"

    • Nolan Chojnacki
      Nolan Chojnacki 2 дня назад

      Ignore the cringy Username hi. New info

  • Daniel Dizon
    Daniel Dizon 15 дней назад

    *THEN JUST STOP IMAGINING. **_BOOM RIDDLE SOLVED_*

  • Indigo
    Indigo 17 дней назад

    L O G I C I A N S

  • jaygeebear 101
    jaygeebear 101 18 дней назад

    bardadoo

  • Dan Brew
    Dan Brew 18 дней назад

    I'd ask to be thrown in the volcano.

  • JJ Sevins
    JJ Sevins 18 дней назад

    So this island is surrounded by... non-reflective water?!

  • baaard303
    baaard303 19 дней назад

    "The person next to you has green eyes" there, done

  • xxmaster27xx
    xxmaster27xx 23 дня назад

    Maybe I'm A Tad Michiavellian but I have the quickest option allowing this riddle to be solved without even breaking the self sufficiency of the island by introducing more humans. I'm Assuming This Ethno-Prison dosent abide by formal morality based on the premise.
    Once realizing noone would willingly bet their lives on their search for knowledge; You Coerce, Convince, And Cajole another prisoner into testing their eye color. I'd rather take a wild guess than pick 100% first degree murder victim, its the logical choice here aswell. Assuming everyone there logically (again satisfying their inherent "logical" characteristic) infers that they are too genetically specific to have any major biologically differences presented through say recessive traits.
    Once the first person satisfies the requirements everyone will quickly get the idea, even if speech itself would result in death and all they could do is try and leave. These posers are literally one pull off a revolver trigger away from freedom; picking quite an insane solution for a 'Logic Spartans'.
    TLDR: {Set Value_Humanity=0} and suddenly all the ironically nonsensical logic bending becomes pointless

    • xxmaster27xx
      xxmaster27xx 23 дня назад

      For anyone needing the child friendly version: Threaten to cut your bffs Cherry Syrup 'Supply' until He gives in and goes to ask if his eyes on fleek#HazelOrDirtNap

  • Pine Drop Pye AJ
    Pine Drop Pye AJ 25 дней назад

    Logically, in what world is there an island with 100 people with green eyes. I’m pretty sure green eyed people are rare.

  • Vany Susanto
    Vany Susanto 25 дней назад

    I’m lost.

  • alan quah
    alan quah 26 дней назад

    :o

  • Idyllic.Skies
    Idyllic.Skies 26 дней назад

    Couldn't they just grab a stick and write on the ground asking if they have green eyes??

  • Mohammad Baqir Hussain
    Mohammad Baqir Hussain 26 дней назад

    you could just say everyone around you has green eyes

  • jarji de
    jarji de 27 дней назад

    If you tell them that at least one of you have a green eyes then you tell them new information. Before your speech they think there are [0;100] person who has green eyes. After your speech they think there are [1;100] person who has green eyes.

    • Nolan Chojnacki
      Nolan Chojnacki 2 дня назад

      jarji de. No, every day they see 99 others with green eyes, so saying at least one of you has green eyes is not new info

  • KitKat Kate
    KitKat Kate 28 дней назад

    If I were in the hundred people with green eyes, I would just assume I also would have green eyes because why would there only be one person with another eye color?

  • The girls
    The girls 28 дней назад

    you dont know you have green eyes... thats not new information that they didnt know

    • Nolan Chojnacki
      Nolan Chojnacki 2 дня назад

      That statement tells them that they have green eyes

  • Christian Noronha Picoli
    Christian Noronha Picoli Месяц назад

    I hate this intro

  • JustRandomDerp :D
    JustRandomDerp :D Месяц назад

    I would say, ALL OF U HAVE GREEN EYES
    Than I would just run for my life

    • JustRandomDerp :D
      JustRandomDerp :D День назад

      Lisa Busch I would try to out run the guards and the Guy, I’d probably die, but hey at least it’s was a good sacrifice

    • Lisa Busch
      Lisa Busch 2 дня назад

      You can't run away when your on an island

  • Tuanan Pham
    Tuanan Pham Месяц назад

    Wait can't one person realize that they are the green eye if you say that there is only one green eye and everyone else has the same colored eyes so they'd think that they are the green eye and so on.

  • Pokemonfan mario
    Pokemonfan mario Месяц назад

    Wouldn't a country or a large group of them like the EU annex the Island for denying basic human rights to its population?

    If not, just tell the USA the island is in possession of a vast quantity of oil and then sit back and enjoy.

  • xxhalogamer22xx
    xxhalogamer22xx Месяц назад

    JUST SPILL THE WATER AND LOOK AT YOUR REFLECTION OR NOD TO EACH OTHER WHILE POINTING AT THEIR EYES

    • Nolan Chojnacki
      Nolan Chojnacki 2 дня назад

      They cant communicate, and you arent able to change that in the riddle, you can only make a statement with no new info

    • Lisa Busch
      Lisa Busch 2 дня назад

      How would they know what the other one meant. Also they didn't have access to reflections.

  • JJSharkWolf2
    JJSharkWolf2 Месяц назад

    Why not say at least 99 of you have green eyes and save all the complexity

  • Ethan Mathers
    Ethan Mathers Месяц назад

    i would say to all of them everyone you have seen the eye colour of in this prison was green which would make them realise that everyone had seen their green eyes and they would all leave on the first night BEAT THAT

  • 雨宮寧音
    雨宮寧音 Месяц назад

    Honestly if I’m one of the prisoners and see all the other people having green eyes, I’ll just take the risk to ask to leave lol.

  • XxStrategos22xX
    XxStrategos22xX Месяц назад

    How do they know what green is?

  • Viktorija Vaicek
    Viktorija Vaicek Месяц назад +1

    What if they like my friends blue AND green eyes

  • Abulkashem Kabir
    Abulkashem Kabir Месяц назад

    Smart me, i saved one hundred prisioners with one statement

  • malcolm ibrahim
    malcolm ibrahim Месяц назад

    this only applies because all of them are logicians, if they had been niggers then they would never leave the island.

  • oreore
    oreore Месяц назад

    They can all take 1 eye ball out and check for themselves.

  • Derail Booksale
    Derail Booksale Месяц назад

    I pulled out my eye

  • Bri likes art YT
    Bri likes art YT Месяц назад

    I would have said
    "At least 5 of you have green eyes"

  • Jenina Huang
    Jenina Huang Месяц назад

    Just break the rules and tell everyone they have green eyes if u were a prisoner

  • Kenneth Cho
    Kenneth Cho Месяц назад

    How do the prisoners know what green is if they have never been exposed to it.

  • Cypress Lee
    Cypress Lee Месяц назад

    Couldn’t you say that the person beside you has green eyes. Then everyone would have greens eyes?

  • Lisa Busch
    Lisa Busch Месяц назад

    The solution presented is correct...
    But no matter how many people you had wouldn't it always take three days?
    Everyone is thinking, "If I have brown eyes everyone else might be thinking we both have brown eyes" Everyone knows that so of course if anyone saw two brown eyed people they would have left. The next day when everybody is still there they realise there can't be more than one person with brown eyes so if anyone sees someone with brown eyes they would leave. On the third day when they see nobody has left they realise they all have green eyes so they leave. The reason this is true is any two people know that there are at least 98 green eyed people. Nobody could be seeing 97 or less people because everyone knows there are at least 98.

  • Jack Lewis
    Jack Lewis Месяц назад

    wait couldn't you pour the water on the ground

  • Nebula
    Nebula Месяц назад

    What if one is color blind

  • AustrianFanof TheKedosZone
    AustrianFanof TheKedosZone Месяц назад

    Not 99 but you should have said "At least 98 of you have green eyes." Each sees 98 green eyes, so it wouldn't be a new information :) So you wouldn't have to worry about the dictator 😄

  • cuscus06
    cuscus06 Месяц назад

    So they dont have toilets

  • Chewy Suarez
    Chewy Suarez Месяц назад

    Wait.
    The dictator said they can’t tell them any new information.
    Then the person said at least one of them has green eyes.
    Also how did the prisoners know they’re aloud to leave?

  • Mateusz
    Mateusz Месяц назад

    "you can all leave this island" that's not new information as they all know that any green-eyed person can leave the island. I stated this rule only, however underneath there is the info that ALL of them have green eyes. But that's secondary meaning only so I should be fine

    • Nolan Chojnacki
      Nolan Chojnacki 2 дня назад

      They do not know that they are all able to leave the island as they do not knoe they all have green eyes,

  • Ten Ducks
    Ten Ducks Месяц назад

    If I knew all of them have green eyes but they haven’t tried to leave, I already left the prison before the foreigner come. Because even if they have green eyes, they don’t try to leave as I don’t. And I would realize We all have green eyes.

  • markjvp
    markjvp Месяц назад

    This is actually impossible unless the people can somehow talk to each other or they just ask if they could leave

    • Nolan Chojnacki
      Nolan Chojnacki 7 часов назад

      They explained how in the vid

    • markjvp
      markjvp 9 часов назад

      oh yea and if everyone you saw had green eyes how would you know i reapeat how would YOU know if you had green eye and you dont want to die right or do you

    • markjvp
      markjvp 9 часов назад

      i know but how would you escape with 99 others at the 100th night or more because if no one new that they have green eyes why would you leave

    • Nolan Chojnacki
      Nolan Chojnacki 2 дня назад

      markjvp. Yes, except youre allowed to make a statement without new info

  • ventnor
    ventnor Месяц назад

    Pretty big assumption to think 99 others will think the exact same way. In any group of 100 people, about a quarter will be dim-witted morons. Unless one were confident in the intelligence of the other 99 in the group, one would still be putting one's life at risk.

  • Andrew Baumunk
    Andrew Baumunk Месяц назад

    You would need to have a very smart group of 100 people for this to happen, but maybe that is why they are contained in this camp with the one crazy rule, to see how smart they really are.

  • MistyCloud The Adorable Kitten
    MistyCloud The Adorable Kitten Месяц назад

    You could’ve just said we all have green eyes

  • Savanna Nash
    Savanna Nash Месяц назад

    hold up... why is the guard letting the prisoners out in the first place? they’re obviously in there for a reason. why is he just letting them out by solving a riddle?

  • Lia Cohen-Odiaga
    Lia Cohen-Odiaga Месяц назад

    I would say "You are not alone."

  • Miles Grande
    Miles Grande Месяц назад

    Interesting way to explain common knowledge but... You see 99 people with green eyes, you aren't allowed to talk to others or see your reflection... If the imprisoned are logicians they should've figured it out tbh...

  • Brain Stuff ASMR
    Brain Stuff ASMR Месяц назад

    "Imagine an island with 100 people..."
    Welcome to fortnite

  • TheWh1te V1per
    TheWh1te V1per Месяц назад

    wtf. When the leader leaves the island just whisper to a dude 'I saw 99 green eyes overall, did u saw too?'. Or do body movement, no one will suspect unless there are 100 guards watching each day and night

  • Tyler Stacherski
    Tyler Stacherski 2 месяца назад

    At 0:46 it looks like tape is on their chin and not mouth

  • • ÌñfìņťęČøđęYT -
    • ÌñfìņťęČøđęYT - 2 месяца назад

    That's complicated you know

  • BluesCluesSeason8
    BluesCluesSeason8 2 месяца назад

    My answer was telling them all to blink twice T each other if the other has green eyes

  • Mining Kitten01
    Mining Kitten01 2 месяца назад

    Point at your eyes and give a thumbs up at the other person.

  • xXJazzy JayXx
    xXJazzy JayXx 2 месяца назад

    "You all see me with the same eyes"