Rationality Quotes: November 2010

A monthly thread for posting rationality-related quotes you've seen recently (or had stored in your quotesfile for ages).

Please post all quotes separately, so that they can be voted up/down separately. (If they are strongly related, reply to your own comments. If strongly ordered, then go ahead and post them together.)
Do not quote yourself.
Do not quote comments/posts on LW/OB.
No more than 5 quotes per person per monthly thread, please.

A monthly thread for posting rationality-related quotes you've seen recently (or had stored in your quotesfile for ages).

Please post all quotes separately, so that they can be voted up/down separately. (If they are strongly related, reply to your own comments. If strongly ordered, then go ahead and post them together.)
Do not quote yourself.
Do not quote comments/posts on LW/OB.
No more than 5 quotes per person per monthly thread, please.

Two questions:

Why do you believe the TDT agents would find the correlated equilibrium? Your previous statement and Eliezer quote suggested that a pair of TDT agents would always play symmetrically in a symmetric game. No "spontaneous symmetry breaking".
Even without a shared random source, there is a Nash mixed equilibrium that is also better than symmetric cooperation. Do you believe TDT would play that if there were no shared random input?

In a symmetric game, TDT agents choose symmetric strategies. Without a source of randomness, this entails playing symmetrically as well.
I'm not sure why you're talking about shared random input. If both agents get the same input, they can both be expected to treat it in the same way and make the same decision, regardless of the input's source. Each agent needs an independent source of randomness in order to play the mixed equilibrium; if my strategy is to play C 30% of the time, I need to know whether this iteration is part of that 30%, which I can't do deterministically because my opponent is simulating me.

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