Toby Ord and I wrote a paper that describes how “expanding cosmological civilizations” (my less-snappy but more descriptive term for “grabby civilizations”) update our estimates of any late filters you might want to consider—assuming SIA as anthropic school: https://arxiv.org/abs/2106.13348
Basically, suppose you have some prior pdf P(q) on the probability “q” that we pass any late filter. Then, considering expanding civilizations will tell you to update it to P(q) --> P(q)/q. And this isn’t good, since it upweights low values of “q” (i.e. lower survival probability).
A general argument analogous to this was actually advanced by Katja Grace, long before we started studying expanding cosmological civilizations—just in the context of regular galactic SETI. But the geometry of ECC’s gives it a surprisingly simple, quantifiable form.
So if I am understanding correctly, SIA puts more weight on universes with many civilizations, which lowers our estimate of survival probability q. This is true regardless of how many expanding civs. we actually observe.
The latter point was surprising to me, but on reflection, perhaps each observation of an expanding civ also increases the estimated number of civilizations. That would mean that there are two effects of observing an expanding civ: 1) Increased the feasibility of passing a late filter 2) increasing the expected number of civilizations that didn’t pass the filter. These effects might cancel out leaving one with no net update.
So I was wrong in saying that Grabby Aliens should reduce our x-risk estimates. This is interesting because in a simple discounting model, higher baseline risk lowers the value of trying to mitigate existential risks:
This implies that a person hoping to encourage work on existential risks may want to convince others that it’s feasible to expand into space.
I wonder about different approaches to SIA. For example, could a different version of SIA be used to argue that we are likely the ancestors of a large civilization? Would this up-weight the chances of cosmic expansion?
Toby Ord and I wrote a paper that describes how “expanding cosmological civilizations” (my less-snappy but more descriptive term for “grabby civilizations”) update our estimates of any late filters you might want to consider—assuming SIA as anthropic school: https://arxiv.org/abs/2106.13348
Basically, suppose you have some prior pdf P(q) on the probability “q” that we pass any late filter. Then, considering expanding civilizations will tell you to update it to P(q) --> P(q)/q. And this isn’t good, since it upweights low values of “q” (i.e. lower survival probability).
A general argument analogous to this was actually advanced by Katja Grace, long before we started studying expanding cosmological civilizations—just in the context of regular galactic SETI. But the geometry of ECC’s gives it a surprisingly simple, quantifiable form.
Interesting!
So if I am understanding correctly, SIA puts more weight on universes with many civilizations, which lowers our estimate of survival probability q. This is true regardless of how many expanding civs. we actually observe.
The latter point was surprising to me, but on reflection, perhaps each observation of an expanding civ also increases the estimated number of civilizations. That would mean that there are two effects of observing an expanding civ: 1) Increased the feasibility of passing a late filter 2) increasing the expected number of civilizations that didn’t pass the filter. These effects might cancel out leaving one with no net update.
So I was wrong in saying that Grabby Aliens should reduce our x-risk estimates. This is interesting because in a simple discounting model, higher baseline risk lowers the value of trying to mitigate existential risks:
https://www.lesswrong.com/posts/JWMR7yg7fg3abpz6k/a-formula-for-the-value-of-existential-risk-reduction-1
This implies that a person hoping to encourage work on existential risks may want to convince others that it’s feasible to expand into space.
I wonder about different approaches to SIA. For example, could a different version of SIA be used to argue that we are likely the ancestors of a large civilization? Would this up-weight the chances of cosmic expansion?