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Comment by plaid_hatter | Hacker News Reader

The information that is added is that the knowledge is made common or infinite degree (ie. everyone knows that everyone knows that everyone knows......that there is someone with blue eyes)

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The time which everyone made an accurate count was the new common knowledge. I believe the traveler's words added no new information, or even his presence (other than bringing everyone together). It was the gathering together, where everyone could see everyone else, and know that counts were synchronized.

I think if there were an earlier all-hands-meeting without the traveler, the counts would have been synchronized then.

So, the faux pas had no effect, but he still "caused" it by accident. So, to combine the two arguments from the main link:

The foreigner's words have no effect, because his comments do not tell the tribe anything that they do not already know. On the 100th day, the blue eyed people commit suicide, unless they die/leave/disappear first.

You are wrong. The traveler's words are necessary, and you can easily see that by considering the case where the blue-eyed group consists of one person. Even when the entire island population is collected into a meeting, there is no reason for the unique blue-eyed person to suddenly intuit that he has blue eyes.

Not sure what you're refering to by "count" here. There's nothing to count. What matters is everybody coming into the knowledge that everybody knows at least one person has blue eyes. This takes a prompt about that, which is the foreigner's speech. If the foreigner doesn't cause them to start sorting themselves into blue eyes/not blue eyes groups, there's no basis for them to start deducing anything.

Counting is how they measure the days passed versus how many blue-eyed people they see. I'm sure you're right, but I have to check the assumption that seeing everyone is the same as hearing a fact about everyone.

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