Re: practical reasoning and strong SSA

From: Wei Dai <>
Date: Tue, 8 Jun 1999 15:23:16 -0700

On Mon, Jun 07, 1999 at 11:15:52PM -0700, wrote:
> 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?

That seems to contradict what you said earlier:

> They would reason something like:
> P (I observe "N[Pi]=3.14159" | PI == 3.14159 AND I am here/now, doing
> this) is very high.
> P (I observe "N[Pi]=3.14159" | PI != 3.14159 AND I am here/now, doing
> this) is very low.

If the reference class only consist of people who observe "N[Pi]=3.14159"
then both probabilities would be one and you wouldn't be able to make any
conclusions. Also I don't understand what you mean by "in other worlds it
[Pi] has a different value". Pi always has the same value since it is a
mathematical constant not a physical constant.

> 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
> implications in your mathematica example?

My example works ok with both. However I think there are reasons to prefer
the extra strong SSA over the strong SSA. I gave these reasons earlier.
Received on Tue Jun 08 1999 - 15:24:28 PDT

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