garethrees comments on Updating, part 1: When can you change your mind? The binary model - Less Wrong

11 Post author: PhilGoetz 13 May 2010 05:55PM

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Comment author: garethrees 17 May 2010 07:22:26PM 1 point [-]

The Wikipedia page explains how a frequentist can get the answer ⅓, but it doesn't explain how a Bayesian can get that answer. That's what's missing.

I'm still hoping for a reference for "the Bayesian rules of forgetting". If these rules exist, then we can check to see if they give the answer ⅓ in the Sleeping Beauty case. That would go a long way to convincing a naive Bayesian.

Comment author: timtyler 17 May 2010 10:07:37PM *  0 points [-]

I do not think it is missing - since a Bayesian can ask themselves at what odds they would accept a bet on the coin coming up heads - just as easily as any other agent can.

What is missing is an account involving Bayesian forgetting. It's missing because that is a way of solving the problem which makes little practical sense.

Now, it might be an interesting exercise to explore the rules of Bayesian forgetting - but I don't think it can be claimed that that is needed to solve this problem - even from a Bayesian perspective. Bayesians have more tools available to them than just Bayes' Law.

FWIW, Bayesian forgetting looks somewhat managable. Bayes' Law is a reversible calculation - so you can just un-apply it.