guess 2/3 of the average

How I got here

Started with

If everyone picks a number and the winner is closest to 2/3 of the average, what should you pick?

Ended at

Common knowledge (logic)

The Trail

1. “guess two thirds of the average game answer” (google.com)
2. Guess 2/3 of the average (en.wikipedia.org)

   the right answer depends entirely on who you're playing with

3. Keynesian beauty contest (en.wikipedia.org)

   from chapter 12 of the General Theory, 1936

4. Nash equilibrium (en.wikipedia.org)
5. Common knowledge (logic) (en.wikipedia.org)

What I came away with

In theory everyone should reason all the way down to 0. With real people the winning number is usually well above zero, because most people only think a step or two ahead. Winning means guessing how deep everyone else goes, which was Keynes's point about markets.

Keep going

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