# jimrandomh comments on Selecting Rationalist Groups - Less Wrong

35 02 April 2009 04:21PM

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Comment author: 02 April 2009 05:10:47PM *  10 points [-]

I like the concept of the Paranoid Debating game, but would propose one modification. Rather than always having a player assigned to deceive, have one with 50% probability, but don't reveal to anyone (except the deceiver) whether there is a deceiver in the group. To implement this with a group of n players, first choose a spokesman and give him a spade, then deal each other player one card from a deck containing 2n-3 black cards and one red card.

As another possible variant, introduce a small (say, 1/52) chance that everyone except the spokesman is red, and everyone except the spokesman knows it. To implement this, first choose a spokesman at random, then choose a dealer from the remaining players. The dealer looks at one card at random. If it's the ace of diamonds, he prepares a deck containing only diamonds; otherwise, he prepares a deck containing 2n-3 black cards and one heart, shuffles it and then deals from it. Getting a diamond means that everyone else has a diamond; getting a heart means that everyone else has black cards.

Comment author: 02 April 2009 05:28:31PM 9 points [-]

Heh - why should you know whether all the others are evil or not? How interesting would it be, if, by being pulled hard in different directions by liars who didn't know the others were lying, the spokesperson ended up with a more accurate estimate?

Comment author: 02 April 2009 09:57:03PM 3 points [-]

There's endless variety here, since this is essentially a form of Werewolf about real facts. I can't wait to play it.

Comment author: 02 April 2009 05:53:37PM 2 points [-]

Heh - why should you know whether all the others are evil or not?

Logistics. It isn't practical to have someone shuffle a deck if they aren't allowed to see any of the cards they're shuffling, so if you're using playing cards to assign roles, at least the dealer will know whether or not the players are all red.

One possible solution would be to have a PDA or smartphone assign the roles, and pass it around. If you do it this way, you could also have a small chance that one player is given the exact real answer. (But red players could falsely claim that they have it.)

Comment author: 02 April 2009 06:13:15PM 4 points [-]

Our version had one person (Robin Gane-McCalla) as central coordinator. Also, it's quite possible to shuffle small units of cards without seeing their undersides.

Comment author: 03 April 2009 05:26:17AM *  0 points [-]

A simple variant with interesting results would be to deal everyone one card from a full deck. Anyone who is dealt a diamond is a deceiver. The dealer can be the spokesman, so it will rotate each turn. This way there is a 1/4 chance that any given person is a deceiver, and a small (1/(4^n))-ish chance that all n players (including the dealer) are trying to deceive each other.

Trying to reach the best outcome for everyone with an unknown number of deceivers in the mix? Sounds like life.

Comment author: 03 April 2009 05:44:37AM 3 points [-]

But the spokesperson is the only one known to be trustworthy who has to put together the final estimate - if they're a deceiver, they can just say "One googol!" or whatever.