Why should ideal Bayesian rationalists alter their estimates to something that is not more likely to be true according to the available evidence? The theorem states that they reach agreement because it is the most likely way to be correct.
The parties do update according to their available evidence. However, neither has access to all the evidence. Also, evidence can be misleading - and subsets of the evidence are more likely to mislead.
Parties can become less accurate after updating, I think.
For example, consider A in this example.
For another example, say A privately sees 5 heads, and A's identical twin, B privately sees 7 tails - and then they Auman agree on the issue of whether the coin is fair. A will come out with more confidence in thinking that the coin is biased. If the coin is act...
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