Re: Request for a glossary of acronyms

From: Hal Finney <>
Date: Wed, 5 Nov 2003 14:40:26 -0800

Jesse Mazer writes:
> In your definition of the ASSA, why do you define it in terms of your next
> observer moment?

The ASSA and the RSSA were historically defined as competing views.
I am not 100% sure that I have the ASSA right, in that it doesn't seem
too different from the SSSA. (BTW I have kept the definitions at the end
of this email.) (BTW, BTW means By The Way.) But I am pretty sure about
the RSSA being in terms of the "next" moment, so I defined the ASSA the
same way, to better illustrate its complementary relationship to the RSSA.

The real difference between these views was not addressed in my
glossary, which is that the RSSA is supposed to justify the QTI, the
quantum theory of immortality, while the ASSA is supposed to refute it.
That is, if you only experience universes where your identity continues,
as the RSSA implies, then it would seem that you will never die. But if
your life-moments are ruled by statistics based on physical law as the
ASSA says, then the chance that you will ever experience being extremely
old is infinitesimal.

Personally I think the ASSA as I have it is somewhat incoherent, speaking
of a "next" observer moment in a framework where there really isn't any
such notion. But as I said it has been considered as the alternative
to the RSSA. I invite suggestions for improved wording.

> Wouldn't it be possible to have a version of the SSA where
> you consider your *current* observer moment to be randomly sampled from the
> set of all observer-moments, but you use something like the RSSA to guess
> what your next observer moment is likely to be like?

That seems contradictory. You have one distribution for the current
observer-moment (sampled from all of them), and another distribution for
the next observer-moment (sampled from those that are continuous with
the same identity). But the current observer-moment is also a "next"
observer-moment (relative to the previous observer-moment). So you can't
use the ASSA for current OM's and the RSSA for next OM's, because every
next is a current, and vice versa. (By OM I mean observer-moment.)

> Also, what about a weighted version of the ASSA? I believe other animals are
> conscious and thus would qualify as observers/observer-moments, which would
> suggest I am extraordinarily lucky to find myself as an observer-moment of
> what seems like the most intelligent species on the planet...but could there
> be an element of the anthropic principle here? Perhaps some kind of theory
> of consciousness would assign something like a "mental complexity" to
> different observer-moments, and the self-sampling assumption could be biased
> in favor of more complex minds.

Yes, I think the possibility of weighting OM's is implicit in these
definitions. We often use the term "measure" to indicate that some
OM's carry more weight and more probability than others. For example,
one theory is that OM's which take a larger program to output would
have lower measure than ones which are described by a short program.
By this definition we might think that less complex minds would have
more measure, the opposite of your idea.

I haven't heard of anyone suggesting that complex minds would inherently
have higher measure. Instead, it seems that most people use a somewhat
arbitrary cutoff for complexity which is necessary to qualify as an
observer. In the anthropic literature this general issue is discussed
as the problem of the reference class. I'm not that familiar with all
the ideas which have been proposed.

Your idea, and my alternative about less complex minds having more
measure, have the problem that it seems that much more and less complex
minds should exist in the multiverse, and as you note we obviously have
evidence of less-complex minds existing in abundance right here on Earth.
So if more complexity is better, why aren't we super-intelligent aliens?

> Likewise, one might use a graded version of the RSSA to deal with "degrees
> of similarity", instead of having it be a simple either-or whether a future
> observer-moment "belongs to the same observer" or not as you suggest in your
> definition. There could be some small probability that my next
> observer-moment will be of a completely different person, but in most cases
> it would be more likely that my next observer-moment would be basically
> similar to my current one. But one might also have to take into account the
> absolute measure on all-observer moments that I suggest above, so that if
> there is a very low absolute probability of a brain that can suggest a
> future observer-moment which is very similar to my current one (because,
> say, I am standing at ground zero of a nuclear explosion) then the relative
> probability of my next observer-moment being completely different would be
> higher. Again, one would need something like a theory of consciousness to
> quantify stuff like "degrees of similarity" and the details of how the
> tradeoff between relative probability and absolute probability would work.

This seems hard to motivate because it fails to satisfy the desire of
RSSA proponents to get quantum immortality, while still introducing
the problematic notions of identity which the ASSA was supposed to free
us from. Also, you would need to come up with some rules for how big the
threshold has to be in order to kick you out of your current identity-line
and into someone else's. It looks problematic to me.


: SSA - The Self-Sampling Assumption, which says that you should consider
: yourself as a randomly sampled observer from among all observers in the
: multiverse.
: SSSA - The Strong Self-Sampling Assumption, which says that you should
: consider this particular observer-moment you are experiencing as being
: randomly sampled from among all observer-moments in the universe.
: ASSA - The Absolute Self-Sampling Assumption, which says that you should
: consider your next observer-moment to be randomly sampled from among all
: observer-moments in the universe.
: RSSA - The Relative Self-Sampling Assumption, which says that you should
: consider your next observer-moment to be randomly sampled from among all
: observer-moments which come immediately after your current observer-moment
: and belong to the same observer.
Received on Wed Nov 05 2003 - 18:11:34 PST

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