We Are Not a Sim

Michael Egnor argues that computers simply compute, they do computations in which keystroke inputs are mapped to outputs expressed on the screen.

The computer, however, has no understanding of what it's doing and therein lies his argument against the possibility that our world, and we ourselves, are actually a computer simulation designed by some super-smart programmer in some other universe in the multiverse:

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.

Egnor goes on to explain that human thoughts are always about something. They have what philosophers call intentionality, that is, they're directed at something - either a conceptual or a physical object. Another way of saying this is that our thoughts have meaning.

Egnor then concludes by arguing that this quality of minds precludes our living in a sim:

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

Those who argue that the universe is a simulation must make the assumption that human consciousness, the ability to have sensory experiences like pain, color and sound, as well as the ability to abstract and to have ideas, is something that can somehow be programmed into a simulation. Yet, as far as I know, no one has the foggiest idea how this could be done.

For that matter, we don't even have the foggiest idea what consciousness actually is let alone how it could be simulated by a computer.