rhollerith_dot_com comments on Open Thread, August 2010 - Less Wrong

4 Post author: NancyLebovitz 01 August 2010 01:27PM

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Comment author: rhollerith_dot_com 03 September 2010 08:14:44PM *  0 points [-]

Can I get a yes or no on my question of whether you take the existence of human civilization to be just as strong evidence for the probabilities we have been discussing as you would have taken it to be if you were a non-human observing human civilization from a position of invulnerability?

Actually, "invulnerability" is not the right word: what I mean is, "if you were a non-human whose coming into existence was never in doubt and whose ability to observe the non-appearance of human civilization was never in doubt."

Comment author: Stuart_Armstrong 06 September 2010 02:58:53PM *  1 point [-]

Can I get a yes or no on my question of whether you take the existence of human civilization to be just as strong evidence for the probabilities we have been discussing as you would have taken it to be if you were a non-human observing human civilization from a position of invulnerability?

If the existence of the "invulnerable non-human" (INH) is completely independent from the existence of human-like civilizations, then:

  • If the INH gets the information "there are human-like civilizations in your universe" then this changes his prior for "lots of human-like civilizations" much less that we get from noticing that we exist.
  • If the INH gets the information "there are human-like civilizations in your immediate neighbourhood", then his prior is updated pretty similarly to ours.
Comment author: rhollerith_dot_com 10 September 2010 03:58:38PM *  1 point [-]

Thanks for answering my question. I repeat that you and I are in disagreement about this particular application of observational selection effects, a.k.a., the anthropic principle and would probably also disagree about their application to an existential risk.

I notice that last month saw the publication of a new paper, "Anthropic Shadow: Observation Selection Effects and Human Extinction Risk" by Bostrum, Sandberg and my favorite astronomy professor, Milan M Circovic.

As an aid to navigation, let me link to the ancestor to this comment at which the conversation turned to observation selection effects.

Comment author: gwern 10 September 2010 04:28:28PM 1 point [-]

I have been meaning to write a post summarizing "Anthropic Shadow"; would anyone besides you and me be interested in it?

Comment author: rhollerith_dot_com 10 September 2010 05:47:14PM *  1 point [-]

I think you should write that post because thoughtful respected participants on LW use the anthropic principle incorrectly, IMHO. The gentleman who wrote great grandparent for example is respected enough to have been invited to attend SIAI's workshop on decision theory earlier this year. And thoughtful respected participant Cousin It probably misapplied the anthropic principle in the first paragraph of this comment. I say "probably" because the context has to do with "modal realism" and other wooly thinking that I cannot digest, but I have not been able to think of any context in which Cousin It's "every passing day without incident should weaken your faith in the anthropic explanation" is a sound argument.

(Many less thoughtful or less respected participants here have misapplied or failed to take into account the anthropic principle, too.)

Comment author: gwern 10 September 2010 09:32:05PM 1 point [-]

And thoughtful respected participant Cousin It probably misapplied the anthropic principle in the first paragraph of this comment.

It has been a while since I skimmed "Anthropic Shadow", but IIRC a key point or assumption in their formula was that the more recent a risk would have occurred or not, the less likely 'we' are to have observed the risk occurring, because more recently = less time for observers to recover from the existential risk or fresh observers to have evolved. This suggests a weak version: the longer we exist, the fewer risks' absence we need to appeal to an observer-based principle.

(But thinking about it, maybe the right version is the exact opposite. It's hard to think about this sort of thing.)

Comment author: gwern 13 October 2010 07:25:51PM 0 points [-]

I've read "Anthropic Shadow" a few times now. I don't think I will write a post on it. It does a pretty good job of explaining itself, and I couldn't think of any uses for it.

The Shadow only biases estimates when some narrow conditions are met:

  1. your estimate has to be based strictly on your past
  2. of a random event
  3. the events have to be very destructive to observers like yourself
  4. and also rare to begin with

So it basically only applies to global existential risks, and there aren't that many of them. Nor can we apply it to interesting examples like the Singularity, because that's not a random event but dependent on our development.

Comment author: Stuart_Armstrong 13 September 2010 01:15:54PM 0 points [-]

Thanks for answering my question. I repeat that you and I are in disagreement about this particular application of observational selection effects, a.k.a., the anthropic principle and would probably also disagree about their application to an existential risk.

Indeed. I, for one, do not worry about the standard doomesday argument, and such. I would argue that SIA is the only consistent anthropic principle, but that's a long argument, and a long post to write one day.

Fortunately, the Anthropic shadow argument can be accepted whatever type of anthropic reasoning you use.

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