The doomsday argument, the self-sampling assumption (SSA), and the self-indication assumption (SIA)
The interview contained an interesting discussion of those ideas. I was surprised to find that, during that discussion, I felt like I actually understood what the ideas of SSA and SIA were, and why that mattered. (Whereas thereāve been a few previous times when I tried to learn about those things, but always ended up mostly still feeling confused. That said, itās very possible I currently just have an illusion of understanding.)
While listening, I felt like maybe that section of the interview could be summarised as follows (though note that I may be misunderstanding things, such that this summary might be misleading):
āWe seem to exist āearlyā in the sequence of possible humans. Weāre more likely to observe that if the sequence of possible humans will actually be cut off relatively early than if more of the sequence will occur. This should update us towards thinking the sequence will be cut off relatively earlyāi.e., towards thinking there will be relatively few future generations. This is how the SSA leads to the doomsday argument.
But, we also just seem to exist at all. And weāre more likely to observe that (rather than observing nothing at all) the more people will exist in totalāi.e., the more of the sequence of possible humans will occur. This should update us towards thinking the sequence wonāt be cut off relatively early. This is how the SIA pushes against the doomsday argument.
Those two updates might roughly cancel out [Iām not actually sure if theyāre meant to exactly, roughly, or only very roughly cancel out]. Thus, these very abstract considerations have relatively little bearing on how large we should estimate the future will be.ā
(Iād be interested in peopleās thoughts on whether my attempted summary seems accurate, as well as on whether it seems relatively clear and easy to follow.)
One other thing on this section of the interview: Ajeya and Rob both say that the way the SSA leads to the doomsday argument seems sort-of āsuspiciousā. Ajeya then says that, on the other hand, the way the SIA causes an opposing update also seems suspicious.
But I think all of her illustrations of how updates based on the SIA can seem suspicious involved infinities. And we already know that loads of things involving infinities can seem counterintuitive or suspicious. So it seems to me like this isnāt much reason to feel that SIA in particular can cause suspicious updates. In other words, it seems like maybe the āactive ingredientā causing the suspiciousness in the examples she gives is infinity, not SIA. Whereas the way the SSA leads to the doomsday argument doesnāt have to involve infinity, so there it seems like SSA is itself suspicious.
Iām not sure whether this is a valid or important point, but maybe it is? (I obviously donāt think we should necessarily dismiss things just because they feel āsuspiciousā, but it could make sense to update a bit away from them for that reason, and, to the extent that thatās true, a difference in the suspiciousness of SSA vs SIA could matter.)
The doomsday argument, the self-sampling assumption (SSA), and the self-indication assumption (SIA)
The interview contained an interesting discussion of those ideas. I was surprised to find that, during that discussion, I felt like I actually understood what the ideas of SSA and SIA were, and why that mattered. (Whereas thereāve been a few previous times when I tried to learn about those things, but always ended up mostly still feeling confused. That said, itās very possible I currently just have an illusion of understanding.)
While listening, I felt like maybe that section of the interview could be summarised as follows (though note that I may be misunderstanding things, such that this summary might be misleading):
āWe seem to exist āearlyā in the sequence of possible humans. Weāre more likely to observe that if the sequence of possible humans will actually be cut off relatively early than if more of the sequence will occur. This should update us towards thinking the sequence will be cut off relatively earlyāi.e., towards thinking there will be relatively few future generations. This is how the SSA leads to the doomsday argument.
But, we also just seem to exist at all. And weāre more likely to observe that (rather than observing nothing at all) the more people will exist in totalāi.e., the more of the sequence of possible humans will occur. This should update us towards thinking the sequence wonāt be cut off relatively early. This is how the SIA pushes against the doomsday argument.
Those two updates might roughly cancel out [Iām not actually sure if theyāre meant to exactly, roughly, or only very roughly cancel out]. Thus, these very abstract considerations have relatively little bearing on how large we should estimate the future will be.ā
(Iād be interested in peopleās thoughts on whether my attempted summary seems accurate, as well as on whether it seems relatively clear and easy to follow.)
One other thing on this section of the interview: Ajeya and Rob both say that the way the SSA leads to the doomsday argument seems sort-of āsuspiciousā. Ajeya then says that, on the other hand, the way the SIA causes an opposing update also seems suspicious.
But I think all of her illustrations of how updates based on the SIA can seem suspicious involved infinities. And we already know that loads of things involving infinities can seem counterintuitive or suspicious. So it seems to me like this isnāt much reason to feel that SIA in particular can cause suspicious updates. In other words, it seems like maybe the āactive ingredientā causing the suspiciousness in the examples she gives is infinity, not SIA. Whereas the way the SSA leads to the doomsday argument doesnāt have to involve infinity, so there it seems like SSA is itself suspicious.
Iām not sure whether this is a valid or important point, but maybe it is? (I obviously donāt think we should necessarily dismiss things just because they feel āsuspiciousā, but it could make sense to update a bit away from them for that reason, and, to the extent that thatās true, a difference in the suspiciousness of SSA vs SIA could matter.)