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

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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.

[@avadadah6088]

"There were no reflective surfaces" *shows image of mad dictator with reflective sunglasses*

[@magnusnord8353]

As if he would show himself to the prisoners

[@NetheriteMiner]

@@magnusnord8353 well he had to look at them....

[@tinevodopivec9692]

@@magnusnord8353 also, you can't really see color all that well in sunglasses, unless they're one of those really reflective pairs.

[@MiniMia48]

I'm pretty sure those would change the color in the reflection

[@golddigger1196]

plus its an island which has water around it which is probably reflective.

[@qwerty-ye1hu]

or just be like "lmao why y'all haven't left yet"

[@willhblob1171]

this is the smartest "solution" so far imo lol

[@bonnie4283]

Lol

[@shely_D7vil]

Lol

[@shely_D7vil]

Not a statement tho

[@MrAYAAN2009]

🤣🤣

[@x-tremefactory2542]

Imagine being the only one without green eyes and on the 99th day everyone just leaves 💀

[@MariaAbraham2010]

I imagined the same thing.

[@DavidSharma-ds]

In that case no one will leave the island. So all the prisoners go on the 100th night after confirming each other's eye color. So the confirmation comes from the fact that everyone stayed thinking all others have green eyes and they still stayed because they weren't sure of their eye color but were seeing all green color. Which would indicate that their eye color is also green. It takes 100 days to confirm for 100 green eyes prisoner. So even if 1 person has blue eyes, then none of them would leave.

[@dtseng69]

No, I believe by induction that 99 prisoners would leave on the 99th day. The blue eyed prisoner would be left alone and could not escape. HOWEVER it boggles the mind the level of mental record keeping those 99 prisoners would have to hold in their heads. “Perfect logicians”. Hrumpf! It’d never work in reality.

[@karlcole5617]

@@DavidSharma-ds actually, they would leave on the 99th night, because everyone else would just ignore their existence for the point of reference

[@JESUSISLORD.........]

But the LORD said unto Samuel, Look not on his countenance, or on the height of his stature; because I have refused him: for the LORD seeth not as man seeth; for man looketh on the outward appearance, but the LORD looketh on the heart. 1 Samuel 16:7, now how do we distinguish these people? Matthew 7:19‭-‬20 Jesus says Every tree that bringeth not forth good fruit is hewn down, and cast into the fire. Wherefore by their fruits ye shall know them. God bless.😊😊

[@oatmeallover4302]

My brain understands this for about .2 seconds before getting confused again. It’s like trying to remember a dream

[@gabrielecanali1385]

truee

[@sierrarose1512]

I got the main part but I didn't understand how it would work for four, five, six people etc I had to write down exactly what the narrator said for three people and move all the numbers up one to understand it lol

[@gerieconomides2776]

@@sierrarose1512 Yeah I'm trying to figure that out. The statement was, "At least one of you has green eyes." At least one. That doesn't necessarily imply more than one, so how would Carl know he had green eyes? How would a fourth person know, if in that situation, everyone knew that everyone was seeing at least two pairs of green eyes? Please help!

[@pavanshetty9806]

​@@gerieconomides2776 The process of elemination is happeneing. When there are 3 people: Lets assume Carl's thought process: On Day 1: He can see person A and Person B have green eyes. He also thinks that if he doesnt have green eyes both A and B can see it directly and completely eleminate him from consideration of "atleast 1 lerson has green eyes" Now as per Carl, A is thinking that B has green eyes and since B can see A's eye color. If B sees A's eye color as NOT Green. He would have left immediatelty on Day 1 as he could see both of them non green. Day 2: Since B did not leave, Both A and B would realize that both of them have green . Since no body left out of them 2. So as per Carl on day both should leave. DAY 3: As nobody left, Carl realizes that confusion still exists which can only occour when Carl also has green eyes. All 3 of them will realize the same thing as nobody left and all have same thought process of each other. On Day 4: All leave. Since end status is always nobody leaving. And 3 people logic became 2 people logic because of elemination based on Carls assumption of him jot having green eyes. When 4 people are involved, I believe it will come down to 3 people logic via elemination, then 2 people logic and final realization when no body leaves. I verified 3 people logic while expressing here. I will think about 4 people now :).

[@pavanshetty9806]

Oh yes, its the same process of elemination. If there are 4 people: And Carl assumes that gis eyes are not Green. Day 1: He can see others are green and they can eleminate him from calculation which now turns the group into 3 person logic. So as per Carl on 4th day, 3 people should leave. If they dont leave on 4th day , it means the confusion is because his eyes are also green. So on 5th day all leave realising the confusion is because everyone is green. This is 4 person logic. For 5 person logic: First 5 days will be occoupied by 4, 3,2,person logic. On 6 Day: All leave as the confusion was not cleared until this day. And so on.

[@samwise1530]

Dictator: What is your statement? Me: THE DICTATOR HAS REFLECTIVE SUNGLASSES

[@milo_south3670]

Then run!

[@aquaboi7818]

yeah then run

[@stevencarenduff2623]

XD it’s fair to cause they know he wears them but didn’t try it. Or just plug a sink and fill it look at your eyes

[@kylerivera3470]

@Michael Baron Be Jesus and run on the ocean.

[@lxmber_wxtches5982]

@@milo_south3670 You can’t know the joestar family secret technique!

[@kirbycreep]

"Perfectly logical" Yet no one tries to spill the water somewhere to see their reflection

[@landofboobs8872]

okay dis is underrated

[@xiix-xcvii3421]

it is said that, they don't know what is "green".. so how will they figure it out...

[@roppis9258]

@@xiix-xcvii3421 They know what green is, they just don't know their own eye colour.

[@zahrah8512]

nhil gallanosa It’s not Said that but if they didn’t know why colour green is then all of this is moot

[@Jyuuu3u]

@@landofboobs8872 Remember they were raised here from birth so the might not even know what reflections are as the Dictator may not have taught them about it.

[@nikhilgarg9618]

Adria: Do you have green eyes? Bill: Ozo.

[@chaytsai4890]

I was waiting to see a comment like this lmao

[@MaruMaruMaruMaruMaruMaru]

I didn't get it

[@_emmz]

This made me chuckle

[@_emmz]

​@@MaruMaruMaruMaruMaruMaruit's a reference to another of their riddle

[@ahhhhhhhhhhhhsocool]

its amazing how the dictator made 100 perfect logicians without being one

[@Imamotherfreakingavocado]

Imagine Adria didn't have green eyes and Bill just wanted to watch the world burn.

[@marcusscience23]

If I was Bill I would watch the world burn outside of prison.

[@stephydare8324]

Imagine a situation, a guy wait happily with everybody until the 99th morning and find out everyone but him has left yesterday night.

[@deathvideogame]

DEAR GOD

[@kylerivera3470]

@@stephydare8324 Oof, that would hurt.

[@hairpuff]

Let it BURNNNN 🔥

[@asjakresevljakovic7988]

Too much information for my 3 brain cells

[@jazmin-bt4ub]

Too much information for my three brain cells after using them all trying to understand buzzfeed unsolved

[@jazmin-bt4ub]

:/

[@2h4]

Same lol

[@mahez4874]

Everyone can see the reflection from the eyes so everyone can see what colour is the eyes. so everyone should be out less than 90 days

[@mahez4874]

This puzzle isn't too accurate xD

[@erikthehalfabee6234]

The original situation on the island is still weird to me. Every prisoner will see 99 pairs of green eyes at the meeting every day. But he/she might be the only blue-eyed prisoner. Nobody leaves, wouldn't you conclude most likely all 100 are green-eyed?

[@ArthurKhazbs]

"Most likely" is not convincing enough for a perfect logician to risk their life

[@jovanljuna1111]

i agree with you this is best answer

[@pugsnhogz]

If the perfect logicians are utilitarian, then they'll all just leave on the first night since the worst possible outcome is 1 person dies so that 99 can go free

[@JakeLondonRivers]

what I dont understand is how 100 prisoners who cant talk to eachother start this little "experiment", yeah it makes sense with 2 prisoners but how do 2 prisoners rationalize this logic knowing there is 98 other prisoners on the island....

[@captainnomekop5056]

@@JakeLondonRiversThey are all perfect Logicians.

[@puzzLEGO]

For people still confused about how they got new information without you directly telling them new information, it’s because you say it to everyone collectively, effectively meaning everyone knows that everyone else knows that at least one person has green eyes. If you told them each separately without them knowing that everyone else was told the same information, they wouldn’t be able to escape. Once they all collectively know this, they all have that chain of hypothetical scenarios which goes until everyone except one person has red eyes. That one person with green eyes would leave on day one, but they don’t. Now you can see how they are able to communicate by either "leaving" or "not leaving". If we go back to the three-person example, if they knew everyone else's eye colour, but weren't allowed to know how many people were there on the following days, it would actually be impossible for them to all escape on the 4th day. Person A would only get as far as thinking "if I had red eyes they would leave on day 2" without actually being able to tell, because he wouldn’t know if they left or not on day 2.

[@cristian-bull]

what didn´t make sense to me about this riddle was that all of them knew that everyone else had green eyes, so it was literally, no new or useful information. I figured out the inductive process, but still didn't know why they didn´t start this reasoning from the beginning (since they already knew the given information). The real problem, if I get it right, is that they can see the eye color of people next to them AND count the amount of people, but not see the other people´s eye´s color. If that´s the case, I think it should be made clear in the video. I stopped the video, didn´t see the answer last night, and under slept trying to figure it out because of that :´v

[@jort281]

@@cristian-bull So annoying isn't it!? Why not say at least 99 of you have green eyes. That's not new info. If you had blue eyes everyone would leave you asap. They don't immediately so it's solved after that.

[@patrikbede8950]

@@jort281 the new info is that the others also know that 99 have green eyes

[@jensopink7240]

I still didn't get that...

[@testack8806]

@@jensopink7240 imagine we are the only 2 logicians. You knew there was at least one green eye (which is me), but you don't what the world is like in my mind. After the visit, you now know that in my mind, there is at least one pair of green eyes(although you don't know if I can see them), and you can count on me to react upon it. "He now knows there is at least one green eye. If I am not a green eye, he will be able to know he himself is a green eye."

[@justinvanilla9785]

Meh, if I saw 99 other kids with green eyes Id also assume I have green eyes

[@rayflo9441]

id be scared shi*less !!!

[@user-ry1bb7wv8i]

lmao

[@Moosetapheles]

If I've been there since birth, I'd assume all humans have green eyes at that point...

[@theRPGmaster]

The dictator also has green eyes under the sunglasses

[@Tombee2]

so true

[@danielrosenfeld4053]

"you cant tell them new information" me, an intellectual: you all are allowed to approach the guard at night and ask to leave

[@safe4547]

but there's no certainty in you information. They wouldn't dare.

[@Halo-lg7rq]

“You should slap everyone with green eyes”

[@SPxxxxx]

@@Halo-lg7rq thats new information

[@Halo-lg7rq]

SPx you’re right “you can* slap anyone with green eyes”

[@yelllowjacket1756]

@VestedLove But that's the bullsh#t part. You can easily communicate using anything including your eyes or breathing, face mimicing.... If they are allowed to stare into each others eyes then you can easily tell to that person that he has a green eye.

[@john_duncan]

you could also say "everyone you see has green eyes." Then everyone would know that they themselves have green eyes. Even if the mad dictator gets mad, you would not have broken his rules.

[@electrolitdecharmander3555]

Well, actually yes, they don’t know what the color green is, and when telling that to everyone, you would tell them something they didn’t knew.

[@j4nn4h4sh]

@@electrolitdecharmander3555 y would the madman remove all mirrors if they didn’t know what green was in the first place?

[@electrolitdecharmander3555]

@@j4nn4h4sh Maybe they know the green color exists, but do they know how is it? When saying “everyone you see has green eyes” they would know that the eyes’ color they’re looking at is green.

[@j4nn4h4sh]

@@electrolitdecharmander3555 exactly. In that logic u wouldn’t need to remove the mirrors bcs they wouldn’t know if their eyes r green if they don’t know how green looks like, even if they can see their green eyes.

[@j4nn4h4sh]

@@electrolitdecharmander3555 so they most likely already know what green looks like otherwise the madman wouldn’t remove reflective surfaces, which means it wouldn’t be new information to say everyone around them has green eyes

[@Urmom-yx3ld]

Has anybody realized at 3:28, there are 101 people if you’d count up everybody shown on the screen?

[@shikhagupta877]

GET A HOBBY

[@17thstellation]

@@shikhagupta877 it doesn't take that long to count 101 things dude it's like a minute

[@cathylin6140]

@@17thstellation ratio

[@blackicynoob6119]

@@cathylin6140 indeed, it is 101:1. for every 101 counted there is 1 minute.

[@juliadubaj6558]

Similarly at 1:55 there are only 89 people if you count everyone on the screen

[@ariella118]

Honestly, if everyone around me had green eyes I wouldn't even think of the fact that another eye color could exist. Edit: I'm going to stop responding to comments now, you all bring up valid points, but this wasn't meant to be a super well thought out comment lol

[@paulmahoney7619]

You aren’t a perfect logician though.

[@ariella118]

​@@paulmahoney7619 That I most certainly am not, but do I need to be a perfect logician to make a KZbin comment?

[@pushpakesarwani4361]

But the dictator has red eyes which means you would know that people can have red eyes and think you also have them

[@Tin_-lp8qm]

You can see the dictator's red eyes and think ur eyes are red too

[@markernestdelacruz4895]

@@Tin_-lp8qm FATHE- I MEANT DICTATOR SIR, I DO NOT HAVE RED EYES DO I? I SURELY HAVEN'T INHERITED MY RED EYES FROM YOU

[@the7thapocalypse948]

And then there would be that one idiot who wouldn't understand the logic

[@thetoontastictoon1720]

it would be me prolly because I didn't understand any of this-

[@xwearenumber1x]

All are perfect logicians.

[@thegiovannimauro]

I know this is true, but if they are truly perfect why did it take them so long to find out they all had green eyes

[@pokesurvivor3271]

orig12.deviantart.net/6f13/f/2014/061/5/d/gumshoe_s_logic_by_1230james-d78nbq1.png

[@LiLScunt]

The 7th Apocalypse yep

[@a_disgruntled_snail]

These logic puzzles are always so ridiculously contrived.

[@Kur404]

This my friends is where the “green eyes” meme was born

[@scytri4882]

imagine being a perfect logician while not realizing that 100 people can take 1 person easily

[@freds233]

I imagine a dictator would have at least a few guns and guards (hence the guard tower)

[@buck7268]

Hey, if Reznov and I could do it at Vorkuta....

[@casperfiol69]

The guy has the power to make you live without ever talking or seeing your own reflection, I'm pretty sure you're outclassed.

[@MarioGarcia-io9gj]

How did they become logicians without communication and grown up there from birth

[@erusthaliel1568]

@@freds233 Someone should do a Lord Farquaad "Some of you may die, but its a sacrifice I'm willing to make"

[@silverfish2315]

The Dictator's glasses = reflective surface

[@limecyanizer4394]

No they aren't, he can't see, not sure of your eye color, let you leave.

[@kaytk1762]

Ocean= reflective surface

[@sauceaddict9569]

Lol

[@mlrd6622]

They were opaque, so no.

[@mesmart8771]

what I was gonna say!

[@nerox953]

0:42 "There are no reflective surfaces" The toilet in the back: Am i a joke to you

[@abstract_guy1052]

This gave me nightmares as a kid

[@wacka.]

I would have said "If I were you, I would leave tonight"

[@baertomeneguzzi9181]

+wacka That would actually work. because Your not telling them to leave, your just giving an opinion that could go either way. But Opinions aren't always right, and the prisoners could of all realized that and not leaved.

[@zoushuu]

+Baerto Meneguzzi But your opinion is the same as new information, they didn't know it before.

[@magnuslindgren5640]

+Яг вет интe Well, by that logic you can't even show your self infront of them (non the less speak), because then the new information is "I now know that you are standing there"

[@zoushuu]

Slap Happy Well well, but getting to stand in front of the children and speak to them had already been guaranteed by the dictator. This is about fooling the dictator with what you have. Would he really allow you to say "If I were you, I would leave tonight."? Stating opinions would be very risky I'd say. An opinion like the one previously mentioned strongly implies facts unknown to the children, that they all can leave without problem. Also, phrasing it like an opinion would make the kids uncertain whethet it is true or not, which could go both ways.

[@magnuslindgren5640]

Яг вет интe Ok, I get what you mean, and you're right about that. But if you ASK them "all the people with green eyes are allowed to go (they already know this) so why aren't you ALL just leaving?". Would it be legit or have you given them the information that you are wondering about this?

[@morganthe2998]

Green eyed people: *exist* Mad dictator: *and I took that personally*

[@dimondeater5416]

And I took that person*

[@guywhochangeshisprofilealo7163]

@@dimondeater5416 take my goddamn like or I swear I’ll actually take that person

[@cplmoai]

You misspelled "person"

[@avarubi]

@@dimondeater5416She/He didn’t mean person they meant personally. “I take it personally that there are green eyed people living on this world.”, if you put it in a full sentence. Personally means he was offended by it, so she/he didn’t misspell anything and they didn’t use the wrong word.

[@avarubi]

@@cplmoai They didn’t misspell anything, they meant to use personally, as in “I take it personally that green eyed people are here.” Personally means they felt offended by something, and what he/she meant was the dictator was offended by green eyed people existing, therefore, he/she didn’t misspell anything.

[@ChrisAsHell]

they could have reached the same conclusion without anyone having to tell them that at least one of the had green eyes. They already knew that and knew that everyone knew

[@robertcane7432]

i don't think the solution is actually correct.

[@getthedunkon9347]

On a large scale yes, it's hard to tell what changed. The new information doesn't come from the statement, it comes from the other's reaction to the statement.

[@TheEnderLeader1]

The inductive part of the logic works without it, but the statement is required for the base case. It may seem like the case where there's only 1 green-eyed prisoner never has to be considered, but think of it this way: For simplicity, there are 4 prisoners, A B C and D. All have green eyes. A sees 3 green-eyed people and thinks "if I had red eyes, then B would see 2 green-eyed people and think "if I had red eyes, then C would see 1 green-eyed person and think "if I had red eyes, then D would see no green-eyed people and think "oh, I have green eyes." ... And then the logic carries itself back out. The important thing is that D's reasoning, even though it's in a hypothetical within a hypothetical within a hypothetical, is crucial to the real reasoning of A, and wouldn't work without the statement being made.

[@pavanshetty9806]

It was necessary to start the clock from which they all will start their calculation in silence. Repetation of this info acted like a start of a clock.

[@pavanshetty9806]

​@@getthedunkon9347not reaction but lack of action (of not leaving after certain days)

[@Jmaniac9204]

I would’ve told them: “you’ve never seen anyone without green eyes”

[@theyormlad]

That is extremely conspicuous

[@charliedegiulio9951]

The dictator has red eyes.

[@TheEnderLeader1]

assuming we reword this to "You can see 99 green-eyed prisoners", there are still problems with this, and they're quite interesting! The main problem is in the word "you". Logically, you're making a different statement (asserting a different truth about the world) to each prisoner, which breaks the dictator's first rule. Even though each statement doesn't tell the listener anything new, it's still made up of multiple statements. There are two things we can do to try and fix it. First we remove the subjectivity, and just express the totality of what we're stating (you may already see the problem with this, but hear me out). "Each of you sees 99 green-eyed prisoners." Unfortunately, this adds information to every prisoner who hears it - it directly tells them that they have green eyes. So we need to weaken the statement somehow. Well, the strongest thing we can state without explicitly telling anyone they have green eyes is that "Each of you sees at least 98 green-eyed prisoners." This is like saying "there are at least 99 green-eyed prisoners". But this is not that different from saying "there is at least 1 green-eyed prisoner"! The prisoners will go through the same reasoning, although they'll leave after waiting only a single day.

[@edgyraag3643]

Ahhh.. So this is where every "green eye" meme started! The origin 😂

[@nadian848]

yep, this is where it was born. and it’ll literally never get old.

[@_z-tl5un]

what green eye meme

[@someonesomeone8295]

isn't it from the Disney main character thing...

[@jessicav931]

@@_z-tl5un if you keep following the riddle videos of this channel you will see it in the comments. Not matter the challenge the people say something like "ok, is obvious: first confirm you have green eyes..."

[@royhutauruk2432]

@@someonesomeone8295 wat

[@thegayestgaythatevergayed5449]

Why’d he raise them all to be perfect logicians...

[@paulmahoney7619]

He’s a mad man

[@quitequeerquesadilla]

cause he's maaaad

[@stevencarenduff2623]

Idk

[@tuononnovainbici]

@@paulmahoney7619 What a madlad

[@seraphim9219]

to feed them to the demons, of course

[@No-ic6ru]

The girl: at least one of you has green eyes. Me: sees everybody with green eyes. Me: *starts doubting my color recognition capabilities*

[@ilikepie4685]

This is where it all begins. The green damn eyes.

[@winnersduplicate554]

Step 1: Confirm you have green eyes Step 2: Realize this is the green-eyes riddle

[@ngeechend4483]

or you could just leave since you already confirmed if you have green eyes or not lmao

[@MrJORFUS]

Step 3: Ask Ted ed if you can leave

[@hamzamemon3081]

The answer is Ozo

[@grambo1690]

Nice you got a cuddly

[@franchesca2418]

i love this reply section

[@mariakhan6090]

I'd tell them, "don't worry, the volcano is a paid actor"

[@akisa7865]

The dictator is bluffing about the eye search

[@valentina5885]

that would be new information, though

[@tuki897]

That's new info

[@blauwbeer556]

@@valentina5885 that new information has killed 15000000 braincells in every prisoner's brain, i think that is a fair price.

[@valentina5885]

@@blauwbeer556 your joke just killed 15000000 of my braincells

[@genericname155]

This was such a good riddle

[@photon220]

So nobody tried pointing at their eyes, then the grass? Or something green at least.

[@hekr0029]

if you were the only one with different colored eyes, wouldnt people look at you like you are some kind of freak?

[@Mizraab2912]

Haha

[@jofx4051]

Nah, yeah that way they can actually do it in faster days

[@zeniashanze1882]

No....they don't know what color thier eyes are....actually they must think they're probably not green considering they're not tryna get out...

[@davidbasa9985]

“They’re not one of us”

[@LamanKnight]

Heh. I find this funny, because in real life I do have green eyes. There was a time in my life when I lived among mainly Latino people, who almost exclusively have brown eyes. And, yes. When we made eye contact, sometimes I could see that people thought I looked like a freak. They were usually polite about it, though.

[@mrmurpleqwerty4838]

I'm just imagining a group of 100 people simultaneously asking a guard to leave the island and then all 100 packing themselves into 1 helicopter.

[@xndybxyo]

clown car? more like clown helicopter

[@hithere9106]

this made me laugh so much😭🤣

[@andreinivchik5247]

Afghanistan today

[@xndybxyo]

@@andreinivchik5247 :((

[@pineapplejuice6954]

@@andreinivchik5247 r/cursedcomments Also I don’t have reddit

[@bagybachi]

Love these. But you should wait between announcing the riddle and starting to provide a tip.

[@SerendipitousProvidence]

They should've made a rule of 'No creating new opaque surfaces like spilling water or urine to name but a few so people in the comment section can shut up.

[@TheRandomizerYT]

0:43 Ted-Ed: *""...All water is in opaque surfaces...""* Me, an intellectual: *_Proceeds to pour the water on the floor and use it as a reflective surface_* You guys sure are intellectuals too...

[@dearaili]

Genius

[@TheRandomizerYT]

@@dearaili IKR

[@kennyferds]

Thought of this too :)

[@TheRandomizerYT]

@@kennyferds Yup, there are many intellectuals in this world

[@skinnyjasper3097]

The leader is wearing reflective sun glasses also eyes are reflective

[@relic4948]

Just take one for the team *”ALL OF YOU HAVE GREEN EYES”* then book it

[@thepurified8386]

in the case you did this, the dictator would change the rules and not let anybody out you still die

[@bdbailey]

That would be new information though

[@edstevens2772]

@@bdbailey surely 'at least one of you has green eyes' is also new information?

[@bdbailey]

@@edstevens2772 No, because they all know that someone else has green eyes, they can see them

[@jackbagbaga6965]

@@bdbailey therefore they don't even need that statement, they should be able to figure it out on their own. they are perfect logicians

[@Shibru1612]

it's like induction axiom. if a statement holds true for P(n) then it should hold true for P(n+1) aswell

[@karenfan6231]

you didn't give them new information,but you did give them something to think and focus on.

[@TheEnderLeader1]

In the hypothetical case where there is only 1 green-eyed prisoner, it actually does add information. It's subtle, but the prisoners figure it out by considering that situation.

[@mao-janlin6751]

Imagine a situation, a guy wait happily with everybody until the 99th morning and find out everyone but him has left yesterday night.

[@medexamtoolsdotcom]

That would be a devious thing for the dictator to do, he could simply move everyone into isolated soundproofed rooms so they all think everyone else left even though they're all still there.

[@hiimjustin8826]

Terrible English

[@hiimjustin8826]

@@sawsawsuka yep. not that impressive. and knowing if how well you're doing in your second language is useful. how many languages have you learned?

[@mao-janlin6751]

@@sawsawsuka Thanks for your understanding that English is not our native language. Though language ability can definitely affect our expression, I believe the ideas behind any language are more important.

[@lockkeythetrickstar5359]

@@hiimjustin8826 eleh kau mcm la reti bahasa org lain puihhh

[@AbleRaxskall]

Props to the dictator for making 100 perfect logicians. He might be insane but hes a good teacher

[@quinnmaster504]

Also somehow genetically breeding each of them to have green eyes specifically

[@amberwerwolfschool8927]

​@quinnmaster504 nope, the none green eyed babies got tossed into the volcano lmao

[@ellotheearthling]

@amberwerwolfschool8927 That’s also artificial selection in a way

[@fatemehshojaei9983]

That was really exciting for me👌🌹 thanks

[@thedummyaccount]

I love riddles like this

[@noahclark7603]

I love how logical these videos are and how unintelligent the comments are. “Just crush him with the helicopter lmao”

[@maidenofthemist9423]

Saying "Just Leave." or "You all have green eyes, you can leave." would've worked too, the fact that all the prisoners have green eyes could be discovered by themselves without communication so it's not new info. The helicopter comments are smart too.

[@wewewewewewewewwewe]

LMAO AT THIS COMMENT

[@thedinopug]

Maiden of the Mist (for the second one) Except that’s not how that works. They don’t know they have green eyes, therefor telling them everyone has green eyes breaks the second condition, “you cannot tell them any NEW information”. Just because they could theoretically learn it doesn’t mean it isn’t new at the time

[@quackatitty7430]

Noah Clark that one comment is above u for me lmao

[@Bob-aaaaa]

Right below this comment

[@SchokoFondu]

you could have just told them "as you all already know, every prisoner you have ever met had green eyes."

[@GucciStinkbug]

Except they're not allowed to communicate, so they've never actually "met" eachother 👀

[@robertwalsh1401]

@@GucciStinkbug met, seen, samw thing. if they cant even look at eachother then no solution will work

[@londonmason6129]

That would make the guy 😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡😡

[@kuro2899]

that is giving them new information

[@yeahkeen2905]

Albernas no it’s not. They’ve seen everyone else and knows everyone else has green eyes. So as they already know, everyone they’ve met has green eyes.

[@letsdoodlesomethinghome3404]

Can’t they just dump water onto the ground to see their reflection?! Or what if it rains? 😂

[@abdelmouladhia8560]

Wow this is amazing at so many levels my mind has been stuck for 30 mn. I don't think I ever utilized my brain more

[@peternebesny9712]

Dictator: "All water is in opaque containers." Me: "This is an island..."

[@Dramilos]

The island is in an opaque container

[@absdee91]

Do you find seawater to be very reflective?

[@Bxll_Bxll]

@@absdee91 Well ya

[@Selfg12]

@@Bxll_Bxll Never been to an ocean huh? lol

[@TSH425]

Just throw out the water out of the container and look at urself like It ain't hard by the time night falls ur would have already left or when u bath or brush ur teeth

[@oryxthetakenking8275]

I would have said, "you can slap people you see with green eyes" Everyone will receive a slap and then be free in less than 90 days Edit: to those who really nitpicking and pointing out the flaws, realize that this is a joke.

[@goldgamez8843]

Pharaoh Hamza Naqvi XXVII toche My eyes are brown with green specks lel

[@frenzied3478]

Oryx, The Taken King XD perfect!

[@tanmoybhattacharjee2439]

Damn that's a lotta slaps.....99 for each person.....that's gotta hurt

[@grrr1351]

Oryx, The Taken King is that an information? Can we tell them one thing other than information?

[@adventurecraft_6_yt817]

hahahahhahahahahahhahahahahahhahahahahahhahahahahahahahhaha

[@Kertyna1]

I just had a funny realisation. If you would do the exact same scenario with the exact same rules and the same statement given, but add one rule from the dictator. If a prisoner doesn't want to go to the headcount they can decide to stay home and this will reward them with an extra piece of bread or something. Then what you would see is that no prisoner would ever go to the headcount until after night 99 when suddenly everyone would show up for the headcount. Then they realise everyone else is still there and they all leave on night 100.

[@maxmini8506]

i did it as 1 of the prisnoners get a leaf and waved it to another prisnor and makeing a hole with his/her hand and covering his/her hand telling his/her that his/her have green eyes and repeat

[@keanureeveslusciousweave]

mad dictator: makes sure there are no reflective surfaces and you can't talk to each other me, an intellectual: *removes an eyeball to check if it's green or not* edit: I understand that heterochromia exists, no need to repeat yourselves lmao

[@vabbysch]

This is the best comment.

[@jenjung577]

That... will hurt. a lot. And you'll be half blind... so it's not the best way...

[@keanureeveslusciousweave]

@@jenjung577 I didn't say it was the best way, I just said it so you know your options

[@porque6835]

You , an intelectual, has heterochromia and is thrown to a volcano

[@keanureeveslusciousweave]

@@porque6835 woo fun

[@Kronman590]

Ah, finally found the riddle everyone's referencing

[@etoilefilante2110]

Tell me please where do I stop the video in order not to see the answer Thanks!

[@alliumiao]

@@etoilefilante2110 1:53 I guess

[@etoilefilante2110]

@@alliumiao thanks a lot

[@lounajushpe4906]

More like 2:03 so you get a hint

[@etoilefilante2110]

@@lounajushpe4906 thank you but I deduced this hint myself and it didn't help much , this riddle is getting me

[@YamenNazer]

Wooooow this is very good when you understand it😅 Thank you TED-Ed❤

[@skeetorretard]

they can't talk but they could write things out, draw pictures, have a "green eye" sign in the courtyard and just start moving people to it. but that would involve trusting the others i suppose.

[@callmegary2622]

If I've been there since birth, I'd assume all humans have green eyes at that point...

[@LePoseidon]

Don't forget the dictator's eyes are red :) So are the sharks' lol

[@ilmarivienamo2987]

+Tùng Lê Sơn But they haven't seen dictators eyes and he said humans... It really should be told that they can understand what green is

[@lpstolate1341]

+Stupid Kid I subscribed to you so please subscribe to me 😄😋

[@CerealGirl]

true

[@BigMikeNetwork]

Cereal For Me Games

[@harsinsinquin4032]

“At least ten of you have green eyes” is equally as non suspicious but saves a ton of time.

[@Kirbyoh]

@Frances Hogg are you familiar with logical induction? They cannot use that information to determine their own eye color before being explicitly told, because they dont have a base case. When you tell them all at the same time that at least one has green eyes, it synchronizes their knowledge in time and induction is only then valid. It is a classic paradox that catches a lot of people.

[@salbrismind]

@Frances Hogg I thought the same thing and they also already know that everyone at least sees 98 people with green eyes. The problem is that you can't be certain that everyone sees 99 until the 99th day after the outside person talks to them. Because after 99 days from when they were left there (but not told anything) each person must assume that even if they have brown eyes no one would leave on the 99th night because they are not certain everyone else is thinking about when they could leave. Think about 3 people. Why wouldn't they simply all leave the 3rd night they are there? Because each of them thinks "I might have brown or green". But they don't know if the others see one or two green eyes. At best all they know is that the others see at least 1. But that's not enough information to act on. You have to be certain that if they didn't leave the 2nd night it's because you have green eyes and not because they themselves aren't certain. By being told at least one has green eyes then they can all freely make the assumption that leaving the second night was due to one other having brown eyes.

[@mattkim96]

@Luis Hernandez this will only save ten days out of 100.

[@InezAllen]

@Frances Hogg the outsider gives them a day to start counting from. they couldn't do this before because not everyone would necessarily count from the same day, or even count at all, because they can't communicate with each other

[@bigchungus9740]

I said everyone adjacent to you has green eyes and that would get you all out on the first day

[@YouOfficialOfficialAngle]

Its Hard , Fun And You Have Right !

[@lambadajewo.4143]

i realized that riddle is much more understandable once you realize that no prisoner is 100% sure the others realize how do the rules work. so essentially, we’re just making every individual person know that everyone else knows the rules

[@Kendall2727]

I would be the one prisoner that didn't think this through like everyone else did

[@oksananakonechna128]

same

[@RKD1010]

300th like. Hahahaha, so many people would do the same.

[@potatogames5410]

Same

[@kjl3080]

Then you would be dooming the other 99 lol

[@victoriah4278]

Kyle Lee no.... he'd just be stuck alone with the dictator

[@jackclements5026]

or you take one for the team and shout "you all have green eyes,"

[@linky6452]

Meh, YOLO.

[@cyberauxi9375]

Remove the comma and put either a full stop or a exclamation mark

[@Foxzor1337]

an exclamation mark*

[@cesarflores1224]

or the dictator never said u cant bring weapons and kill the dictator and leave or stay cuz the island is dope now

[@Bobbiejoe]

But how would you know what the color green looks like

[@user-kf9rz9sx4m]

Imagine all going good for 50 days then one person gets mad and leaves the place to leave others in confusion

[@merubindono]

Damn it Carl why you gotta be the third wheel

[@philscott1445]

Carl is me in a nutshell :”>

[@eddie246]

Why you gotta assume? It could've been Adria for all we know

[@Kevy707]

@@eddie246 OwO

[@mayaalvarez205]

Adria's the third wheel

[@PinkENBlue]

Wha- u want the 3rd wheel to be a girl or what?

[@mortmort97]

I would've said everyone you look at has green eyes. The only rule is that you can't tell people something they don't already know, and everyone knows that everyone they see has green eyes. They wouldve realized that they must have green eyes because someone has looked at them. A lot simpler IMO But aside from that, if they're on an island, why didn't they just look at their reflection in the water?

[@tchudson75]

Nice!!

[@nnzfmly]

+Mariah W You just gave new information. Any individual (who thought they might have non-green eyes themselves) did NOT know that everyone they see has green eyes. Now that individual knows that everyone else sees everyone has green eyes.

[@mortmort97]

Pete Nunez that would be something they figure out from what I said. I would say that everyone THEY (referring to each of them individually) see has green eyes. they would use logic to figue out that it applies to everyone else, just like they did in the answer the video gave

[@cameronmacdonald8394]

+Mariah W You are giving them new knowledge. They already know that everyone they see has eyes of the same color. By telling them what that color is, you have given them all the knowledge of what green eyes look like, thus giving them new information. They would not have to use logic to figure out that it applies to everyone else because you've told them that it applies to everyone else.

[@AsianNinjaGod]

+Cameron MacDonald The prisoners already know what the color "green" is and what green eyes look like. That's not new information.

[@MA-vx2lg]

“It is so lovely here! The trees are green all year here”

[@Stellarainn]

0:12 yes its called Cuba

[@osheridan]

Shout out to the 100 Cubans out there! Can't believe all 100 are perfect logicians

[@headcanon6408]

Step 1. Confirm your eyes are green Ste-Wait a minute…

[@Tippex_Official]

This is so underrated

[@andreailas3906]

Underrated.

[@thesaroscycle_archive]

Renee Park Perfectly balanced, as all things should be

[@tronalddump6768]

@@thesaroscycle_archive this does put a smile on my face

[@thecount_zen]

Can someone explain

[@hourofberries]

I love how everyone’s turned this riddle into a huge meme and every time there’s another riddle there’s always someone who comments something related to green eyes

[@northfox5368]

Gggggggrrrrrrrreeeeeeeeennnnnnn eeeeeeeeeyyyyyyyyyeeeeeeeesssss

[@cubefromblender]

They are meming it because everyone thinks they have green eyes

[@DeathnoteBB]

Same with a few other riddles too

[@SacsachCCABP]

“Can you rearrange the cube so that it can make the full journey?” “Well, we can rearrange the cube so that it lands on planet 3, catching the criminals on our 2nd trip!” “Yes, and I’ve also figured out how we can use the dark matter fuel most effectively.” “We can also have other pilots to go a quarter of the way and refuel our ship mid-flight!” “Though, do we press buttons A, B, C, D or E? The fuel gauge is spinning!” “I don’t know, but I’ve got 6 crystals to time travel back in time in case it fails.” “I assume you got those from our secret agent spying on the rival restaurants.” “Yes, we had to infiltrate on the sixth floor as we figured the control room was there.” “I also got the water levels to safe areas so the AI wouldn’t attack us.” “Our other team of secret agents are currently removing Schrödinger’s cats so they don’t terrorize our space plans.” “Ooh! While this probe is in orbit, we can laser-cut the purple blob so it only has acute sides!” “We can also cut B-E, D-G, F-A, and H-C to cure the werewolf!” “Well, if we’re going on the ship, we’ll need our instruments for the journey! Everyone, check the box with your own instrument!” “Remember, just because the package has a red top doesn’t mean we need to check if an even number is on the bottom.” “Uh oh… I pushed the button with a skull on it just to see what it did - everyone get out of the lab! The zombies are coming! We must get everyone across the bridge!” “The passcode out is 2, 2, 9!” “Send 2 groups of 3 that way, and a pair that way. I’ll go this way. Meet back here later, two of us are cursed to occasionally lie! Understand? “Ozo!?” “Well, at least one of us has green eyes. We can all cross the bridge if we have green eyes!” “Now we need to get the lions and wildebeests across using the raft!”

[@Orange_Pear]

Ozo

[@Al_Guzman21]

I see a connection with the frog puzzle, the more infromation the less(in this case more) probabilities

[@Scapestoat]

You know a riddle is forced when neither the ocean, some water in your hands and even other peoples eye-balls lack reflection.

[@finfon2287]

Pupils are reflective, so if you stare really hard into someone’s face you could see your eye color.

[@summerjohnson2177]

But I feel like there would be the uncertainty if the green was from your eyes, or from theirs.

[@4c00h]

They've been there all their life, they don't have a concept of what green looks like in the first place

[@klowee5240]

Yeah i can see myself in my dog's eyes lol

[@jagadambika1590]

Exactly what I thought 😂

[@jagadambika1590]

Exactly what I thought 😂

[@kenana5941]

Ted: there is no reflective surfaces *Everyone on an island surrounded by water*

[@alx2900]

That's what I thought!!!

[@Noz_h]

Their trapped inside a prison and maybe cant get out duh.

[@kenana5941]

Lucid Dr3amer what? They are all outside headass

[@Noz_h]

@@kenana5941oh, maybe i forogt whats 'walls'

[@jf2801]

@@Noz_h you're right, judging from the outside view of the island. But, no need to be smug and rude about it. 😂

[@theoh.5734]

I had the statement "All the person you can see have green eyes", I'm not sure if that's "new information" or just using the fact that I'm not telling them every of them have green eyes

[@thatcringeyone9558]

i’d just say the person next to you has green eyes

[@ornela7019]

"I see the freedom in your eyes"- would make it easier, right?

[@cerealbeforemilk8976]

that's so true! Lol

[@g0dly1]

But thats new info

[@g0dly1]

If ur wondering how Green eye : freedom See. Freedom. In your eyes = seeing green in ur eyes

[@ameliamarshall5377]

Omg yasss

[@crystalxxx_xplays28blogs98]

YOO THAT MAKES SENSE

[@jullitaczajkowska4200]

The result: They escaped because they have green eyes But you have pink eyes so you cant leave

[@cy.7493]

pinkeye means you have mould in your eye

[@jullitaczajkowska4200]

Well yea

[@cy.7493]

@Hellbanisher Rockz I know

[@cathylin6140]

@@cy.7493 bruh

[@soupdujour4994]

I did and did not understand this, but I like it

[@phoenix799]

All I would have said was, "You can all ask to leave tonight."

[@angelaphsiao]

Imagine being the one brown-eyed person on that island

[@hpr2986]

Angela Hsiao sad

[@alexsabau5942]

Or blue...

[@teenyfroog6851]

Then they all leave on night 98 without you 💀 imagine counting for that long only to realize that tou actually were the odd one out

[@Yao_Guai]

@@teenyfroog6851sounds like a movie plot

[@lxxy05]

and then I'll be the one person who is still at the island because I'm stupid

[@professorphoenixia1245]

Lxxy C same

[@janetchen9410]

😂

[@shivanshaggarwal2964]

Np in the beginning he said all people are logicians

[@TheMajedtion]

ههههههه

[@zachb2838]

Same tho

[@harsinsinquin4032]

What if you say “there are an odd number of green eyed people.” ? They would all see an odd number and would expect everyone other than themselves to leave that night. Since everyone would assume that, no one would leave. They’d all see each other the next day making it clear that the statement was false and would all leave that night. That’s what I think.

[@ozanswain2704]

This Statement is better than the one shown in the video because the logicians do not know whether your statement is true or not.

[@RH-nk7eo]

That's new information.

[@zile8869]

Damn, this was tough to follow at the start, but i managed to make sense of it.

[@yveskummer6343]

I would just look in the sunglasses of the mad dictator, and see my reflection

[@zakdunbar2726]

Yves Kummer That’s what I was thinking😂😂

[@want-diversecontent3887]

Yves Kummer I would just spill out my water, and see my reflection.

[@nightshade570]

Everything is opaque, but I have another solution.

[@kaytk1762]

@@yesno1498 but you can see at day, then wait for night.

[@MyshaM.]

That would show you, who - a visitor - what the colour of your own eyes is. That doesn't help the people on the island, though.

[@allisontaylor7287]

What if they were color blind

[@norahneo9770]

HAHAGAHAHAGA

[@charlesbrownjr5618]

Well if they were color blind then if they were raised and taught their colors, then wutever green looks like to them should still register as green

[@Duck-wu3xy]

@@charlesbrownjr5618 this comment is incorrect on every level. Google what colour blindness is.

[@francisdimaano2350]

Charles Brown, Jr but red green colourblindness or whatever its called, both colours are gray

[@thaochu6955]

then they will think they are the only one have green eyes, maybe

[@bhaveerathod2373]

Every couple years I come back to this to see if my brain has grown enough to understand it

[@jesuscardenas9277]

I would've said"You can all go and ask the chief to leave" This would work because you wouldn't tell the anything new as they already know they can do it but they would realise that they can do it as can has two meanings-hope that makes sense

[@deirochimaru25]

I would have said "I wish you all the very best luck in escaping this island." But putting major emphasis on the "all"

[@chupacabra9357]

Interesting idea, but some people wouldn't catch on. Also a more subtle point, is how would you be able to accurately see everyone's eye color? There are 100 people, and if the animation is "canon," so to speak, then you'd be on some announcement tower high above everyone else. Anyways, very interesting proposition.

[@chupacabra9357]

Btw, technically there are no loopholes in yours, it's pure sneakiness

[@jozef97]

Is that not new information?

[@anna-kt3zw]

+Jozef B it's not new information at all, it's just words of encouragement

[@lei916]

deirochimaru25 I wish you *AAAAAALLLLLLLL* the very best luck in escaping

[@jesuspereztorres1942]

"Kill those ones who don't have green eyes". Best case scenario: Nobody does it, everybody leaves. Worst case scenario: They kill me and the dictator for not having green eyes.

[@psi4262]

Thats new information 😂

[@deankaraniya7422]

That's an instruction, not a statement.

[@jesuspereztorres1942]

@@deankaraniya7422 but if nobody does anything, doesn't count as an order... I guess.

[@stevencarenduff2623]

Uhhhhhh I have slight heterocromea so one of my eyes has a tint of green so idk if I count

[@trickytreyperfected1482]

@@jesuspereztorres1942 it's still a command even if no one follows it.

[@iamphayvoured]

How about just saying “your neighbor has green eyes”?

[@apokalypthoapokalypsys9573]

How about this statement: "You can ask the guard to leave." There is no new info here, since a person CAN indeed ask the guard to leave, just keep in mind it may fail. However, hidden in that statement is the implication that doing so is safe, so all prisoners would leave (if they trusted us, and the riddle assumes they do). Then again, I wouldn't get the head start and the dictator would probably catch me.

[@andreivoinea7343]

Or you could've just spill water on the floor ond Look at yourself.

[@pangarcher3554]

Lol

[@ravenwingthewarrior3859]

yes!!!!!!!!!!!!!!! so smaaaaaaaaaaaarrrrt!!!!!!!!!!!!!!!!!!

[@guilhermerafaelzimermann4196]

+Jkaybro Kattencrack flip container onto floor

[@guilhermerafaelzimermann4196]

Jkaybro Kattencrack good point, but they probably don't have sand in their rooms

[@NBACoDGaming]

+Jkaybro Kattencrack Thr containers don't matter, just spit it out on the floor

[@carleigh.charlton]

if they have been on the island since birth and they can't ever talk to anyone how would they have ever learn English or any language for that matter. how would they understand the sentence you told them.

[@nutzworth9094]

Carleigh Charlton I agree. Though, if the dictator schooled them, they'd know, but couldn't tell anyone that they did.

[@leolaserbolt]

Carleigh Charlton shush you plot holing commenter.

[@fizzii5072]

Carleigh Charlton they are perfect logicians.

[@pebritryastuti7481]

Carleigh Charlton thats exactly what i thought! if they cant talk to each other how do they learn the color at all!

[@crazy4bricksthebrickbrothe722]

There is clearly some education in the prison if they are expert logicians.

[@therealveridicalyt497]

I can say "You all can ask to leave". We aren't telling them anything new, but they'll realise what I mean

[@yasarkayraozhan7196]

My statement would be “You can see your eye through others.”

[@ZetaCheese]

Why was this video entirely just the answer? There’s no moment to “pause to solve”

[@thalespro9995]

Nobody pauses anywya

[@FzeroVaporeon]

this was not a ted ed riddle it was more of a logic thingie and yes

[@vondralbra5147]

@@thalespro9995 I would, this is the only reason to watch these videos. Just how boring is it to watch the answer directly.

[@harveysantiago8872]

Well if you really could came out with good statement I guess

[@zahrah8512]

Tacoman17 What