# Re: practical reasoning and strong SSA

From: <hal.domain.name.hidden>
Date: Mon, 7 Jun 1999 23:15:52 -0700

Wei Dai, <weidai.domain.name.hidden>, writes:
> On Fri, Jun 04, 1999 at 12:30:52PM -0700, hal.domain.name.hidden wrote:
> > The way I have seen this calculation justified is to consider that you
> > are randomly chosen from among all possible observers who are consistent
> > with what you are experiencing here/now. This is more limited than
> > the SSA because the reference set is just those observers who share
> > identical mental states. Each person does his probability calculations
> > with regard to that reference set. From his perspective, he is in one
> > of many possible universes, constrained by what he observes and knows.
> > But there is no chance that he is a tentacled alien on alpha centauri.
>
> This is what I meant by forgetting the old way of thinking. The above
> paragraph probably would have made sense before I learned about the SSA,
> but now it doesn't. If the reference set is just those observers who share
> identical mental states, then everyone in the reference set must be having
> identical observations, right? Or are you saying the reference set is just
> those observers who are in a similar mental state as my own (e.g. everyone
> who have the same memories as me and are reading a Mathematica output but
> not necessarily "N[Pi]=3.14159")? This has many problems, but let me make
> sure I understand you first.

Yes, I think it is the former. The reference set is those observers who
are having identical observations to me. We all see the same display.
In some worlds Pi actually has that value, and in other worlds it has a
different value, but all see the same mathematica display. What is the
problem with this line of reasoning?

> The strong SSA (without the SIA) and the extra strong SSA do not have
> identical implications for conscious beings, however. The extra strong SSA
> allows one to draw conclusions from the fact that one is conscious,
> whereas the strong SSA does not. For example, if we can show that the
> truth of a certain mathematical statement implies that the universe
> contains more conscious beings (for whatever definition of "conscious"
> that includes me), then under the extra strong SSA the fact that I am
> conscious is evidence for that statement being true.
>
> Interestingly, the extra strong SSA and the strong SSA with the SIA do
> produce identical conclusions for conscious beings. The DA (Doomsday
> Argument), for example, is neutralized by the extra strong SSA as well as
> by the SIA. I think the SIA should really be seen as an implication of the
> extra strong SSA rather than as a fundamental axiom of reasoning.

Nick Bostrom and Robin Hanson had a debate on extropians, which I was
not able to follow very well. One of the issues seemed to be whether
the reference set should include rocks. That is interesting that the
SIA can be seen to follow from the assumption that the reference set
should be expanded like this.

So does your Bayesian reasoning example work OK with either the strong
SSA and the "extra strong" SSA? Or are you saying now that the latter
is the only consistent position to allow you to derive the kinds of