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ChrisHallquist comments on Bayesianism for Humans - Less Wrong

52 Post author: ChrisHallquist 29 October 2013 11:54PM

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Comment author: ChrisHallquist 29 October 2013 05:00:10PM 0 points [-]

There's a sense in which what I said is true (see ygert's comment), but I agree it's confusing. Suggested re-word? Or maybe I should just cut that point.

Comment author: Lumifer 29 October 2013 05:25:18PM *  2 points [-]

I think that problem is in the sentence

You should expect that, on average, a test will leave your beliefs unchanged.

That happens to be not true. A test which ouputs useful information WILL change your beliefs. Especially given point 2, one can say "Any informative test will always change your beliefs".

What's tricky here is expectation. You expect your beliefs to change but you don't know in which direction. So your expectation is for zero change even though you know that you'll get some non-zero change.

This looks paradoxical, but is the entirely standard way in which statistics (in particular random variables) operate. Consider a toss of a fair coin. The expectation is half heads half tails which is guaranteed not to happen. You know you'll get either heads or tail but not which one of those two. The expectation will not match the outcome -- all it can do is be equidistant (appropriately weighted) from all possible outcomes.

Comment author: Vaniver 29 October 2013 07:40:07PM 1 point [-]

I might go with:

Your expectation of the possible beliefs you could have after seeing the test results should match your current belief.

Another option is to try to illustrate both CoEE and Beliefs Pay Rent in Anticipated Experiences at the same time, since I think failing BPRiAE demonstrates an easy way to fail CoEE.