Re: Doomsday Example

Robin Hanson (
Mon, 24 Aug 1998 21:48:55 -0700 (PDT)

Nick Bostrom writes:
>> Doomsday argument folks also seem to want talk about the possibility
>> that I might have been some other human at some other place in
>> space-time.
>That is only shorthand. You can replace this phraseology if
>you find it problematic. Instead you can talk about the possibility
>that Robin Hanson, while remaining Robin Hanson, could forget certain
>facts, and about what probabilities RH would then assign to the
>hypothesis that RH is living in such-and-such a place and time.
>That's actually quite simple.

It's not at all simple for me. I could sortof accept the idea that I might have been someone else instead. But I find it very hard to believe that you could make Robin hanson forget not so much that he was no longer Robin Hanson, *and* enough so he couldn't tell he wasn't a Martian living on Hermes in 2200. And even if you could I don't see the relevance of that poor hypothetical creature and what I should infer from what I know. If you're going to rest the DA on this construction, it seems implausible from the get go.

>I don't see why you should would want to stick to that view. You can
>admit that only observers can enter the reference class while still
>holding on to your view that we should accept the SIA and thereby
>cancel the DA.

I'm not sure the SIA is sufficient to deal with all the cases of interest. I'd rather instead accept an approach to defining states and priors.