The
theory that we live in a simulated universe continues to attract
attention, and it seems like a month never goes by without a web site
producing a headline such as: Do We Live in a Simulated Universe?
But the argument given for such a possibility is basically the same
old argument that has been circulating since Nick Bostrom advanced it
quite a few years ago.
The
argument goes something like this:
- The universe is billions of years old, and contains billions of galaxies, each containing many millions or billions of stars.
- It is therefore likely that advanced civilizations arose on many planets long ago.
- Such advanced civilizations would have fantastically advanced computing powers, including the ability to create incredibly complicated simulations so realistic they would be indistinguishable from reality.
- Even if only a small fraction of such civilizations created such simulations, the total number of simulations they would create would be incredibly high, probably many times higher than the total number of planets containing civilizations similar to ours.
- We therefore should conclude that we are probably living in such a simulation, rather than living on a real planet in a non-simulated universe.Artistic depiction of a culture living on a moon revolving around an alien planet
There
are a number of problems with such an argument, some of which I
mentioned in a previous post entitled Why You Are Not Living in a Computer Simulation. One of the objections I made in that post is that
it is very doubtful that any extraterrestrial civilization could
produce a simulation matching the reality we observe. Some have
estimated that such a simulation could be produced by creating a
planet-sized computer. I doubt the feasibility of creating a
computer that large. I also think it is very doubtful that even a
computer the size of the sun would be enough to produce a simulation
of what we observe, given the nearly infinite number of combinations
that are possible, assuming that free will is real.
In
this post I will discuss a different objection to such an argument
for a simulated universe, an objection I did not previously make. The
objection I refer to is simply that the basic argument for a
simulated universe is an argument that is self-destroying. This is
because the argument reaches a conclusion that ends up destroying some
of its premises.
To
understand the concept of a self-destroying argument, let us consider
a much simpler example. Consider the following argument:
- John was born in the city of San Ansales in the United States.
- Everyone born in the city of San Ansales looks like a Mexican.
- People who look like Mexicans must have been born in Mexico.
- Therefore John must have been born in Mexico.
This
is a self-destroying argument, because the conclusion ends up
destroying one of the premises used to derive the conclusion. If the
conclusion is correct, and John was born in Mexico, then he cannot
also have been born in the United States; and if he was not born in
the United States, the whole argument falls apart.
The
argument for a simulated universe discussed above is also a
self-destroying argument. The argument reaches a conclusion that we
are probably living in a simulated universe. But if we are living in
such a simulated universe, there is no reason to believe in the first
three premises of the argument. If we are living in a simulated
universe, there is no reason to believe that the universe is billions
of years old, no reason to believe that there are many other planets,
and no reason to believe that there are other civilizations vastly
older than ours.
If
you assume that you are living in a simulated universe, what can you
conclude about the existence of entities other than yourself? Almost
nothing. You cannot conclude that observations of entities outside
our planet correspond to an actual reality, because all such
observations may simply be part of the fictional simulation. You
cannot conclude that there really is a planet Earth, because your
observations of our planet may merely be part of the simulation.
Shockingly,
if you assume that you are living in a simulated universe, you cannot
even assume that the people you observe with your own eyes are real
people who exist, either physically or as people who are experiencing
a simulation that partially matches the simulation you observe. You
may have observations of your mother, but if you assume that you are
living in a simulation you cannot assume that your mother really
exists, and cannot even assume that your mother is at least
experiencing some simulation similar to the simulation you are
experiencing. What you perceive as your mother could be just a part
of the simulation, like a CGI character in a video game or a movie.
Or course, if you are living in a simulation, you also cannot assume
that any of the people you see on the street really exist, either in
a physical form or even in the minimal form of minds that are
actually experiencing consciousness.
There
is no reason to think that simulators creating a simulation would
follow some “rule of simulation” which says that any human
perceived in a simulation must also be experiencing his own
simulation. So if you are in a simulation, there is no particularly
good reason for believing that anyone else is experiencing the
simulation other than yourself.
So
once you have assumed that you are living in a simulated universe,
you are only entitled to assume two things: that you exist at least
as some form of consciousness, and that some unknown external agent
exists that is producing the simulation you are experiencing.
Given
such a radical situation, in which you can't even assume that anyone
else you perceive really exists outside of your mind, it is very
clear indeed that once you assume that you are in a simulation there
is then no reason to believe that there exist other stars, other
planets, and other alien civilizations, nor is there any reason to
believe that the universe is old enough to have produced technically
advanced civilizations on other planets.
This,
then, is why the basic argument for a simulated universe is
self-destroying. It starts out with some fairly plausible premises.
But once it reaches its conclusion, that conclusion destroys the very
premises used to reach that conclusion.
We
can have no basis for assuming that there really are highly advanced
extraterrestrial civilizations capable of simulating our experience
unless we believe that we live in a real, material, non-simulated
universe. But if we believe that, we cannot possibly use the
likelihood of such civilizations as a basis for assuming that we live
in a simulation.
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