So you're working backwards from the claim that reality is a computer to defining computer.

Yes, by the time you enumerate all the properties of reality, and call them a "computer", you'll find that this is not a computer in the sense of computer science.

That's a bit like determining a ship can only be made of wood, isn't it? A ship needs to float, it needs to be made of buoyant material and it needs to have a sail. If a "sailor" is adjusting the power to a propellor that's turned by an electric motor that's running off a turbine driven by steam from a magical rock, it's not what we define as naval science, is it?

The thing missing here is that it's only a ship for humans. Ships are cultural artifacts. If we said the universe was a ship that was sailing itself, that would be misapplying something we make for nature itself. Independent of human culture, ships are just arrangements of matter. We make particular arrangements meaningful.

Same thing applies to computers and computation. It's only meaningful to use those words for matter we arrange to do certain stuff for us.

> It's only meaningful to use those words for matter we arrange to do certain stuff for us.

But not, say, an octopus?

> Your brain is a computer and we still don’t have much of a clue how it works.

Notwithstanding the fact that Daniel Dennet thinks of the brain as a virtual machine on which memes execute and evolve via cultural evolution, the common understanding of a computer does not include gray matter.

> What would happen if our concepts were entirely different?

That’s why we use different words to denote different concepts.

Predictability of output is very much a computing thing. If I try to compute the 11 trillionth digit of Pi in base-7, I should get the same answer every time. If I do not get the same answer, then the device is either malfunctioning (often) or just not a computer at all.

It it sort of assumed our brains are computers, but no one has ever demonstrated this to be the case to any degree. Human brains seem to, at least partially, operate on different principles.

I think a device which outputs a distribution of answers is still a computer. The information is an answer and needs to be computed. Determinism and repeatability isn't a requirement for defining computation.

Something can be predictable in some ways and not in others. If you build AI that is capable of giving you answers to complex world issues, the intermediary steps might not be predictable, and perhaps neigher the final answer, but you might just need it to be correct, because it will be an answer dependent on the external world, which is itself not very predictable.