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jimrandomh comments on Bayesian Doomsday Argument - Less Wrong Discussion

-5 Post author: DanielLC 17 October 2010 10:14PM

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Comment author: jimrandomh 17 October 2010 11:57:00PM 0 points [-]

First off, you have to assume that, as a prior, you're just as likely to be anyone.

There is a decision-theoretic caveat here. While you may be "just as likely" to be anyone, the amount of influence you have over utility, for most utility functions involving the universe as a whole, varies depending when you were born. People born earlier in the history of humanity have a greater influence, and therefore, you should weight the possibility that you were born early more highly.

Comment author: DanielLC 18 October 2010 01:10:43AM 0 points [-]

You should weigh the importance of your choices more highly.

This doesn't mean future stuff doesn't matter; but it makes it so it's not an obvious choice.

Suppose you do something that has a chance of saving the world. Suppose there have been 100 billion people so far. The expected amount you'd do is ∫k/n dn = ln(n2/n1) If there's less than 200 billion people, that's k ln 2. If it's less than 210^40, that's k ln 210^29. It works out to being about 100 times as important. That seems like a lot, but charity tends to work in orders of magnitude difference.

I'm not sure how good a value 10^40 is, but I think the order of magnitude is within a factor of two, so the predicted value would be within that.