Edge detection doesn’t explain line drawing

I don't think so. I do understand this lineage of thought, and I agree with you that they are somewhat similar. But I must insist in saying that what I'm talking about is different.

The trickster demon metaphor talks about a being (you) whose senses are replaced by the demon. But that means there is a you outside of the demon/computer simulation.

I believe if this universe is a simulation, then I am part of that simulation. My mind is not an external observer hooked up to the simulation, but just matter simulated by the simulation according to the rules of the simulation. The thing Descartes was talking about is a Matrix situation. (Or rather to say the creators of Matrix were paraphrasing Descartes) Neo thinks he is living his life, but in truth his body is laying in a pod in the goo. I don't believe in that. I don't think that is likely true. If this is a simulation then me (and you, and this computer, and all of the people, and the butterflies and the stars) are in the simulation. And not the way how Neo is in there, but the way a cubic meter of minecraft sand is inside a minecraft world. Inside the minecraft world it is a cubic meter of sand, outside of it is just a few bytes in the memory of some program.

Let me illustrate what I mean when I say that I don't speak about the universe being a computer simulation as a metaphor. Imagine that it is a simulation. What does this computer simulation have to do? Well, it seems that there are particles, and there are forces between them (gravity, electric, weak/strong nuclear force) In every iteration of this simulation it would seem that you need to calculate which particles are close to others so you can update the forces on them, so you can calculate their new state.

To do this you need to inspect the distance between every two particle. That scales with ordo N^2 with the number of particles N. If the universe is a computer simulation it probably runs on a computer of immense power. But even then N^2 scaling is not good news in a hot path. Funny thing is that if the universe you want to simulate is relatively sparse (as is ours), and has an absolute speed limit (as ours seems to have), then you can shard your workload into parallel processes. And then you can run the separate shards relatively independently, and you only need to pass information from one shard to an other periodically.

Now if our universe is a simulation, and it is sharded this way, then you would expect anomalies to crop up on the shard boundaries. Where the simulated mater is moved from one executor "node" to an other. We could construct small spacecraft and send them far away (perhaps other solar systems?). We would furnish these small automated spacecraft with sensitive experiments. Microscopic versions of a Newton's cradle, or some sort of subatomic oscillator, or a very precisely measured interferometric experiment. And the craft would autonomously check constantly that the laws of physics are unchanged, and work without glitches.

If we don't see any glitches, then we shrug. Either we don't live in a computer simulation, or the computer simulation is not sharded this way, or the edge cases are very well handled, or the instruments were not sensitive enough, or the shards are even bigger (perhaps we should have sent the same experiments to a different galaxy?) If we see glitching, then we should try to map out exactly where they happen, and how they happen, and that would be very interesting. And if we see glitching of this kind that would increase my confidence in us living in a computer simulation.

Does this make sense? You cannot design an experiment to test a metaphor. It doesn't even make sense. But I think of this as a possible literal truth, in which case you can formulate hypothesises based on it and you can check those with experiments.

> so it’s safe to say their believers took them a bit more literally

I believe you. Did anyone ever propose to solve a famine by sending a hunting party to cut a chunk of the turtle's flesh? Or to send gatherer's to collect the dung of the turtle to fertilise the land? Or to send holly people to the edge of the world, to peer down at the turtle to predict earthquakes? If the turtles are meant to be literal turtles these are all straightforward consequences. If nobody ever proposed anything like these, then perhaps the turtles were more of a metaphor?

The other information isn't necessarily discarded. It's just used to identify that this is a line drawing and not the real thing. It's still remarkable that just the lines themselves (I make no claim as to whether it really is edge detection or something else) are still enough information to be able to identify the representation, but it doesn't mean the brain is discarding the other information.

Precisely. Deep CNNs were directly inspired by studying the structure and behavior of visual cortical tissue.

The algorithm is just recursive feature detection, where the visual elements are transformed into abstractions, based on both sensory input and projected expectations. If anything, that's the real exciting part of the visual system, why do illusions occur, how does expectation affect perception, etc. Not "how do line drawings evoke similar concepts to images". That's just bypassing the first few layers of filters. Basic ass tiny MNIST nets can do this.