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Our future, our universe, and other weighty topics


Thursday, April 3, 2014

The Main Argument for a Simulated Universe is Self-Destroying

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:
  1. The universe is billions of years old, and contains billions of galaxies, each containing many millions or billions of stars.
  2. It is therefore likely that advanced civilizations arose on many planets long ago.
  3. 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.
  4. 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.
  5. 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:
  1. John was born in the city of San Ansales in the United States.
  2. Everyone born in the city of San Ansales looks like a Mexican.
  3. People who look like Mexicans must have been born in Mexico.
  4. 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.