RE: New website: The Simulation Argument

From: Emlyn O'regan (
Date: Sun Dec 02 2001 - 20:50:40 MST

Nick Bostrom replied:
> Emlyn wrote:
> >I don't quite understand Nick's disproof of this
> transhumanist idea. I
> >thought that I understood the paper, but I don't understand Nick's
> >conclusion as stated in the paper and below.
> >
> >Could someone please explain it, preferably in monosylables?
> And type slow.
> Ok, I'll try to explain the conclusion (but not the argument):
> Do you think you are currently living in a computer
> simulation (like the
> Matrix)? No? Thought so. But then, because of the argument
> that this paper
> presents, you must believe that EITHER our species is
> overwhelmingly likely
> never ever to reach the posthuman level (really bad -ugh!), OR it is
> extremely unlikely for any posthuman civilization that it
> should contain
> individuals that run ancestor-simulations (not so bad - there
> are many
> versions of this possibility that would be very good). (Or both the
> preceding are true.)
> So what we should hope for is that we are either in a
> simulation, or else
> that a strong convergence thesis is true, such that any posthuman
> civilization will almost certainly develop in a direction
> that precludes it
> from running ancestor-simulations.

I think I see my mistake...

Where you say this:

"We can, however, conclude that one na´ve transhumanist dogma is false.: The
probability that you or your descendants will ever run an
ancestor-simulation is negligible, unless you are now living in such a

I took it to mean that the statement

"The probability that you or your descendants will ever run an
ancestor-simulation is negligible, unless you are now living in such a

was concluded by you to be false.

Obviously this seemed strange, seeing that you had gone to some pains to
show it to be true.

I imagine that you mean the following:

We can, however, conclude that one na´ve transhumanist dogma (that humanity
will achieve a post-human status and run ancestor simulations) is false,
unless we are now living in such a simulation.

Does that make sense?


Oh, and by the way, no I didn't think I was running in a sim, until recently
maybe. I came across this argument about nested simulations recently (or
fully digested it, anyway), and it's intrigued me, I must admit... possibly
the best argument for the existence of "god" (in the broadest possible
sense) that I've ever come across. That's not fun given that I am an atheist

One piece of the argument which troubles me is this:

"Since the experiences that an observer has if she is living in a simulation
are indistinguishable from those she has if she is living in unmediated
physical reality, it follows from a very weak form of the principle of
indifference that the probability of her living in a simulation equals the
fraction of observers that live in simulations[5]. "

This seems to take it for granted that an entity living in the "real world"
(at the root) and an entity living inside any level of sim are equivalent in
terms of what I might call "being", for wont of a better term. ie: there is
no significant difference between a simulated being and an actual being.

While this may be the case, it does assume a strong materialist view of
consciousness. This must be the case for the principle of indifference to
apply. That's probably ok, but maybe it needs to be stated explicitly? (Note
that I'm not trying to get into a consciousness debate here.)

A couple of other points:

"Reality may thus contain many levels. Even if it is necessary for the
hierarchy to bottom out at some stage - the metaphysical status of this
claim is somewhat obscure - there may be room for a large number of levels
of reality, and the number could be increasing over time. "

Speaking about change over time in the overall hierarchy of simulations is a
bit dangerous. While it might be true that there is a loose "arrow of time"
across the whole set of simulations/universes (simuverses?), with the
hierarchy defining dependencies, it is still the case that time, as part of
the notion of space/time, is local to each given simulation... if it is
sensibly defined in all. To give a very basic example, it is entirely
possible that a given sim might be run backwards, if the universes' creators
had reversed the physical laws, such that the local experience of time in
the inner sim was reversed when compared to the outer sim.

I would have thought that, if you are arguing that the probability that we
are in a sim approximates 1, you are likewise arguing that the number of
sims approximates infinity (or some slightly more sensible statement), and
does so right now (in whatever reference you draw "now" from).

"(One consideration that counts against the multi-level hypothesis is that
the computational costs for the basement-level simulators would be very
great. Simulating even a single posthuman civilization might be too
expensive. If so, then we should expect our simulation to be terminated when
we are about to reach the posthuman stage.)"

This makes major assumptions about the physics of computation outside of our
universe, which are entirely ungrounded in my opinion. It may be that it is
more common for infinite computing capacity to be possible in sims than not.
Alternatively, it does not take into account the possibility that the sim
would be rigged to slow down, relative to the outer sim, to make up for lack
of concurrent execution resources. As the relative time frames became
infinitely divergent (the inner sim approaching stasis with respect to the
outer sim), the inner sim would approach infinite computational ability
*with respect to its own time frame".


Thanks for a thought provoking paper, Nick.


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