Blue Eyes: The Hardest Logic Puzzle in the World A group of people with assorted eye colors live on an island. They are all perfect logicians -- if a conclusion can be logically deduced, they will do it instantly. No one knows the color of their eyes. Every night at midnight, a ferry stops at the island. Any islanders who have figured out the color of their own eyes then leave the island, and the rest stay. Everyone can see everyone else at all times and keeps a count of the number of people they see with each eye color (excluding themselves), but they cannot otherwise communicate. Everyone on the island knows all the rules in this paragraph. On this island there are 100 blue-eyed people, 100 brown-eyed people, and the Guru (she happens to have green eyes). So any given blue-eyed person can see 100 people with brown eyes and 99 people with blue eyes (and one with green), but that does not tell him his own eye color; as far as he knows the totals could be 101 brown and 99 blue. Or 100 brown, 99 blue, and he could have red eyes. The Guru is allowed to speak once (let's say at noon), on one day in all their endless years on the island. Standing before the islanders, she says the following: "I can see someone who has blue eyes." Who leaves the island, and on what night? There are no mirrors or reflecting surfaces, nothing dumb. It is not a trick question, and the answer is logical. It doesn't depend on tricky wording or anyone lying or guessing, and it doesn't involve people doing something silly like creating a sign language or doing genetics. The Guru is not making eye contact with anyone in particular; she's simply saying "I count at least one blue-eyed person on this island who isn't me." And lastly, the answer is not "no one leaves." Of the 200 islanders, 100 have blue eyes, and 100 have brown eyes. However, no individual knows what color their own eyes are. There are no reflective surfaces on the island for the inhabitants to see a reflection of their own eyes. They can each see the 199 other islanders and their eye colors, but any given individual does not know if his or her own eyes are brown, blue, or perhaps another color entirely. And remember, they cannot communicate with each other in any way under penalty of death. ADVERTISEMENT - CONTINUE READING BELOW Each night, when the captain of the ship comes, the islanders have a chance to leave the barren and desolate spit of land they have been marooned on. If an islander tells the captain the color of his or her own eyes, they may board the ship and leave. If they get it wrong, they will be shot dead. Now, there is one more person on the island: the guru, who the islanders know to always tell the truth. The guru has green eyes. One day, she stands up before all 200 islanders and says: I see a person with blue eyes. Who leaves the island? And when do they leave?
This riddle is actually kind of bull shit The answer would never actually happen without some type of communication More like planning.
yeh i just read the solution. it is bullshit. It'd actually be more interesting if there was only 2 of each blue and brown eyed people (and the guru). That'd make the logic to arrive at the answer the same, but make it way less convoluted. Spoiler https://xkcd.com/solution.html
Hardest riddle I’ve ever heard is - if you have one banana and you eat half of it, how much is left. that shits fucking bamboozling guys.
Riddle isn't bullshit and the solution makes sense. There was a similar riddle posted on a youtube channel. EDIT: It's definitely not the hardest logic puzzle ever though lmao. I know plenty of people that could have solved this, myself included.
the riddle works on sound logic but it’s just too vague of a problem for anyone to reasonably come to the right answer
Here is a video of the famous logic puzzle. The video does a good job of explaining things, and simplifies the problem by only having 100 people with the same eye color, while this riddle adds in brown eye colored people.
It's the exact same riddle, not a pity puzzle. I posted it because the explanation in the video is explained much better.
What if one of them is a turquoise but mistaken for a blue? What then? What if one of them is a blue but identifies as a brown? What then?
They're perfect logicians. The riddle adds that caveat in the beginning to prevent such silly questions.
