I guess the question boils down to the choice of reference classes, so what makes the reference class "early 21st century humans" so special?
One very speculative reason why it might be worth modeling 21st century humanity is that this century could be a pivotal period in civilizational development. This might be useful because it provides insight into what sort of value systems end up getting "locked in" after this stage of our development concludes.
Roughly speaking, given that the future civilization could determine the distribution of value systems that are eventually optimized by civilizations at our stage of development, they could use this information to predict what type of stuff is being optimized throughout the multiverse. This is helpful because it allows the future civilization to cooperate with other civilizations in the multiverse, which is probably useful if the civilization cares about more than just astronomical waste.
Furthermore, if you're convinced by the simulation argument, why not believe that you're a Boltzmann brain instead using the same line of argument?
Why not both?
Confession: my entire metaphysical worldview has been strongly shaped by reading Greg Egan's Permutation City, so I kind of subscribe to something like the Dust Theory/Max Tegmark's Mathematical Multiverse.
To return to your question: if your mind can be construed as existing within many different contexts, be they simulations, Boltzmann Brains, or boring old meatsacks in cosmoses... does it make any sense to say 'I am in _this_ one'? You're in all of them, so long as those contexts can be said to 'exist'. And what is stopping them from 'existing'?
The problem with Dust theory is that it assumes that conscious states supervene on brain states instantaneously. There is no evidence for that. We should not be fooled by the "specious present". We seem to be conscious moment-by-moment, but the "moments" in question are rather coarse-grained, corresponding to the specious present of 0.025-0.25 second or so. It's quite compatible with the phenomenology that it requires thousands or millions of neural events or processing steps to achieve a subjective "instant" of consciousness. Which would mean you can't salami-slice someone's stream-of-consciousness too much without it vanishing, and also mean that spontaneously occurring Boltzman-consciousnesses are incredibly unlikely (because you would need a string of states to arise that are "as if" causally connected). Additionally, the idea of computational supervening on instantaneous snapshots of physical activity, irrespective of causal connection and temporal sequence, doesn't make much sense as a theory of computation. What is the difference between a computational state and any old state, if not the fact that is part of a computation, that is, a sequence of states.
I don't believe that that is a necessary assumption at all; the conscious state is still an abstractable representation, and if it maps to a dynamic process that itself can map to a temporally-connected collection of brain-states, then that is just more layers of abstraction.
The Boltzmann Brain could easily be not a brain-state representation, but a conscious-state representation.
That then runs into Bible Code problems: anything maps to anything under a sufficent complex and arbitrary interpretation. But who's doing the interpretation?
It's only a problem if you want it to be a problem.
There doesn't *need* to be anyone doing the interpreting, because all possible representations (and the interpreters/ees within) exist for free. I'm comfortable with that. There's no need to invoke special privilege to make reality more complicated, just because you want it to be. Fundamental reality *should* be simple, on some level, don't you think? The complexity is all internal.
It’s only a problem if you want it to be a problem.
Quodlibet, being able to prove anything, is widely seen as a problem.
There doesn’t need to be anyone doing the interpreting, because all possible representations (and the interpreters/ees within) exist for free.
Is that a fact?
Boltzman brains would certainly follow from that bold conjecture. However, something similar would follow from simpler assumptions.
You seen to be saying:
There are certain configurations of matter that could be conscious minds under a certain interpretation.
The required interpretations exists, since all interpretations exist in some immaterial way, for some unspecified reason.
Therefore accidental conscious minds, Boltzman brains, exist.
Which has the simpler equivalent:-
(Alternatively you might be saying that Boltzman interpreters exist, that there are some configurations of matter which are performing computations equivalent to interpretation. However, that would be based on the implicit assumption that being an interpreter is not itself a matter of interpretation. But it if there are interpretation-free facts about which computation maps onto which physical process, then why should there not be such facts about the the computations corresponding to consciousness -- again, the detour into interpretation is unnecessary. And the original applies: accidental computations are of any sort are going to be rare, because a computation is a coherent sequence).
Just read up on the Dust Theory, and I think you can take it a notch further: no need for a vast universe, a rock is sufficient to represent any mind since there exists some mapping between the interactions of its constituent atoms to the brain activity of anyone. In fact, why not discard physical reality entirely and rest in the thought of everything existing in abstract math space?
does it make any sense to say 'I am in _this_ one'? You're in all of them, so long as those contexts can be said to 'exist'. And what is stopping them from 'existing'?
Well, why not jump from a bridge for fun then? You will continue to exist no matter what you do. Not saying that you won't, but it seems once one gets to this point anthropics stops having any implications for actions in the real world and is forever relegated to the realm of abstract philosophical thought experiments.
Why not both?
My thought was that Boltzmann was proposed as a counter-argument to the idea of the Big Bang as the result of quantum fluctuations of an eternal universe. Since Boltzmann brains are much less massive than the whole observable universe, it is vastly more likely that the observer is just a random-fluctuation-generated Boltzmann brain hallucinating its observations than an observer (simulated or not) in an actual Big-Bang universe.
In fact, why not discard physical reality entirely and rest in the thought of everything existing in abstract math space?
Well, yes, that's kind of the implication here. The minimum reality required to contain everything is, basically, nothing. Any more is entirely superfluous and reducible back to that bedrock.
Well, why not jump from a bridge for fun then? You will continue to exist no matter what you do.
You're talking about quantum immortality/suicide, and it's another corollary. Whether you find it ridiculous or not, I find the idea of an arbitrary 'physical' reality far more absurd.
Quantum immortality can be easily adapted to the Tegmark multiverse idea. Turchin wrote an article naming the idea 'Multiverse immortality'. His formulation is that : for every sequence with n observer movements, there shall be an observe moment n+1.
Maybe the answer is:
This is the latest era that there were sufficient humans with survival traits related to treating people decently.
The simulator will hold onto the biologically friendly humans, since beyond a certain point, if certain circumstances generate people with no ingrained feelings of necessary coordination and interpreservational behaviors, then it reverts and restores that state.
This is a point of confusion I still have with the simulation argument: Upon learning that we are in an ancestor simulation, should we be any less surprised? It would be odd for a future civilization to dedicate a large fraction of their computational resources towards simulating early 21st century humans instead of happy transhuman living in base reality; shouldn't we therefore be equally perplexed that we aren't transhumans?
I guess the question boils down to the choice of reference classes, so what makes the reference class "early 21st century humans" so special? Why not widen the reference class to include all conscious minds, or narrow it down to the exact quantum state of a brain?
Furthermore, if you're convinced by the simulation argument, why not believe that you're a Boltzmann brain instead using the same line of argument?