# Of Course You Aren’t Living in a Computer Simulation. Here’s Why.

Atheist astrophysicist Neil deGrasse Tyson takes the idea seriously.

[Tyson] put the odds at 50-50 that our entire existence is a program on someone else’s hard drive. “I think the likelihood may be very high,” he said. He noted the gap between human and chimpanzee intelligence, despite the fact that we share more than 98 percent of our DNA. Somewhere out there could be a being whose intelligence is that much greater than our own. “We would be drooling, blithering idiots in their presence,” he said. “If that’s the case, it is easy for me to imagine that everything in our lives is just a creation of some other entity for their entertainment.”

Scientific American editor Clara Moskowitz explains the roots of the idea:

A popular argument for the simulation hypothesis came from University of Oxford philosopher Nick Bostrum in 2003, when he suggested that members of an advanced civilization with enormous computing power might decide to run simulations of their ancestors.  They would probably have the ability to run many, many such simulations, to the point where the vast majority of minds would actually be artificial ones within such simulations, rather than the original ancestral minds. So simple statistics suggest it is much more likely that we are among the simulated minds.

And there are other reasons to think we might be virtual. For instance, the more we learn about the universe, the more it appears to be based on mathematical laws. Perhaps that is not a given, but a function of the nature of the universe we are living in. “If I were a character in a computer game, I would also discover eventually that the rules seemed completely rigid and mathematical,” said Max Tegmark, a cosmologist at the Massachusetts Institute of Technology (MIT). “That just reflects the computer code in which it was written.”

But of course you aren’t living in a computer simulation. Here’s why.

We begin with this question: What is computation? Computation is a mapping of an input to an output according to a set of rules (an algorithm). The output is a function of the input, calculated for each independent variable in the input. For example, as I type this post, the electrical signal evoked by each keystroke is mapped to a pattern of electrons on my computer screen, according to the rules of the algorithm in my Microsoft Word program.

Note that the mapping is independent of the meaning of the input and the output signals. Microsoft Word pays no heed to the meanings conveyed by my keystrokes. The program doesn’t “care” whether I am typing an essay or a poem or a novel. It doesn’t even really care that I am typing anything at all. It merely maps the electrical signal generated by my keystrokes to electrical signals on my computer screen. It is an electro-mechanical process, not any kind of comprehension.  Computation is mapping of signals, and pays no heed to the meaning of the signals it maps. Computation pays no heed to the meaning of anything.

Now, the next question. What is the mind? What is the human ability by which we ask the question “Am I living in a computer simulation?” What is it about a thought that distinguishes a thought from other things, like physical objects? Nineteenth-century German philosopher Franz Brentano gave an answer that seems decisive: Thoughts are always about something, whereas physical objects are never (intrinsically) about anything. He called this aboutness of thoughts “intentionality,” using a word derived from the scholastic philosophers’ theory of mind that dates back to Aristotle.

Thoughts are intentional, in the sense that they always point to something — to a concept, to an object, to a person, etc. Our thoughts always have an object (conceptual or physical) to which they are intrinsically directed. Our thoughts always mean something.

So are we living in a computer simulation? As I noted above, meaning is precisely what computation lacks. The most fundamental human power — the power of thought to have meaning — is just what a computer simulation cannot do.

Computation is syntax, whereas thought is semantics. If we were living in a computer simulation, and our mind were computation, the one thing we couldn’t do is think.

We couldn’t ask the question “Are we living in a computer simulation?” if we were living in a computer simulation. The irony here is that, of all the possible fundamental truths of reality, the notion that we are living in such a simulation is the one we can rule out simply because it’s self-refuting.

If we are living in a computer simulation, we couldn’t think to ask the question.

Photo credit: blickpixel, via Pixabay.