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Comment by NhanH | Hacker News Reader

The new piece of information is that you also know everyone in the tribe know about that information. That was not a given before the statement.

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In the original, you know the other islanders can see a minimum of 98 BP (blue eyed people). And you know that they know that you know that they can see at least 97 BP.

Given that, the statement that there is at least 1 blue eyed person doesn't provide new info. The argument that this "synchronizes" them is a little strange. For all we knew, they were in the middle of counting to 100 days prior to this statement due to the aforementioned common knowledge that everyone already knew there were blue eyed people.

They wouldn't be counting to 100 days, because there's no point where everyone would start counting together (no one is allowed to reveal anything about eye color).

So you know there's no reason for all the blue eyed people to commit suicide together, so you can't reason anything out about the total number of blue eyed people.

As per a comment in the original article, they could choose to "sync" when one of their children is first told the rules about not knowing your own eye color. This changes the way that person would behave, and is a completely reasonable time for each islander to reevaluate the logical cascade.

> they could choose to "sync"

They can't discuss it. That would be a difficult social experiment, that would risk your life.

Close, but not quite. As others have pointed out, that's not new information either. The information given is the knowledge that everyone knows that everyone knows...that at least one person has blue eyes, to infinite depth. The key is that this knowledge was one level short of allowing the chain reaction to start prior to the announcement.

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