Nate_Gabriel comments on Anthropics doesn't explain why the Cold War stayed Cold - Less Wrong

6 Post author: KnaveOfAllTrades 20 August 2014 07:23PM

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Comment author: Nate_Gabriel 22 August 2014 04:04:52AM 4 points [-]

I still don't think George VI having more siblings is an observer-killing event.

Since we now know that George VI didn’t have more siblings, we obtain

Probability(You exist [and know that George VI had exactly five siblings] | George VI had more than five siblings) = 0

I assume you mean "know" the usual way. Not hundred percent certainty, just that I saw it on Wikipedia and now it's a fact I'm aware of. Then P(I exist with this mind state | George VI had more than five siblings) isn't zero, it's some number based on my prior for Wikipedia being wrong.

So my mind state is more likely in a five-sibling world than a six-sibling one, but using it as anthropic evidence would just be double-counting whatever evidence left me with that mind state in the first place.

Comment author: KnaveOfAllTrades 22 August 2014 07:43:54AM 2 points [-]

So my mind state is more likely in a five-sibling world than a six-sibling one, but using it as anthropic evidence would just be double-counting whatever evidence left me with that mind state in the first place.

Yep; in which case the anthropic evidence isn't doing any useful explanatory work, and the thesis 'Anthropics doesn't explain X' holds.

Comment author: Nate_Gabriel 23 August 2014 06:33:55PM 2 points [-]

Anthropics fails to explain King George because it's double-counting the evidence. The same does not apply to any extinction event, where you have not already conditioned on "I wouldn't exist otherwise."

If it's a non-extinction nuclear exchange, where population would be significantly smaller but nonzero, I'm not confident enough in my understanding of anthropics to have an opinion.