[chubot]

From the Church-Turing Thesis, we know there’s nothing special going on! We know humans can’t do anything more than a computer can.

I see people making such claims about human cognition all the time, and I have no idea how it follows. (note the author is paraphrasing "people" here)

The Church-Turing Thesis says nothing about human cognition.

It is perfectly plausible that a human can do things a computer can't. (Scott Aaronson has a paper "Why Philosophers Should Care About Computational Complexity" which sheds some light on why that might be, but it's far from the only possible reason.)

The burden of proof is on people who claim that human cognition can be simulated by computer, not the other way around. To me, it seems far more likely that it can't.

Human cognition can obviously be simulated by "the laws of physics", since brains are material, but it seems very likely that computers are less powerful than that.

That's my refutation of the (silly IMO) "simulation argument". I'd argue it's simply not possible to simulate another universe. You can simulate something like SimCity or whatever, but not a real universe. The people who make that argument always seem to leave out the possibility that it's physically impossible.

In fact I would actually take the simulation argument ("we are almost certainly living in a simulation") as proof by contradiction that simulation is impossible.

[throwamon]

> That's my refutation of the (silly IMO) "simulation argument"

I'm not one of these people, but your rebuttal wouldn't convince me if I were. Maybe we are the SimCity of a much more complex universe.

[chubot]

OK, but I'm saying the burden of proof is on who think that simulation is possible. It's not at all obvious that it is.

As far as I can tell, the idea was basically made popular by movies [1], and there is no science behind it. All the science I know of points the other way -- simulating anything is incredibly hard and slow. It requires approximations and shortcuts to make it work for specific cases, and it doesn't work in the general case.

(Maybe some alternative model like quantum computation will be different, but we're MUCH much further there. I think "adding two small numbers" is still an issue for state of the art quantum computers.)

-----

Here's a nice example from a few days ago, trying to represent even a tiny part of the human brain in a computer:

https://news.ycombinator.com/item?id=27362883

[1] I think this is more literally true than you might expect; IIRC the published papers in philosophy liberally reference The Matrix, maybe because it attracts readers.

[PaulDavisThe1st]

There's an important misconception here.

The part you're right about is that simulating what we understand about our own reality on some subset of that reality (e.g. some kind of computer) is really, really hard, possibly verging on impossible.

But that's not really the simulation hypothesis at all.

It's relatively easy to build a simulation of a simplified or (and this is important) a different reality in some subset of our own. Trivial examples like Conway's Game of Life come to mind, but also (somewhat obviously) SimCity.

The simulation hypothesis is that our reality is a simulation running in some subset of a different reality. Given what we know about building simulations in our own reality, the hypothesis implicitly recognizes that the meta-reality in which which our reality is a simulation is necessarily different (and likely more complex) than our own.

There's an even deeper notion to the simulation hypothesis. If our reality is a "simulation", given the richness that we see around us, what is the difference between a "simulation" and something that isn't a simulation? Based on what I said above, the different "levels" would necessarily need to differ in terms of their own complexity. But is a reality in which our own could be simulated really any "better" than our own?

[ema]

> given the richness that we see around us, what is the difference between a "simulation" and something that isn't a simulation?

One thought that stayed with me for a while is, my entire experience could, theoretically, be encoded in (a rather large) integer and in the same way that the number 2 exists in many contexts maybe I exist simultaneously in reality and multiple simulations as well.

[pontifier]

This all assumes that the limitations of our universe are the same as the limitations on the hardware outside the simulation.

We can run Conway's game, but a being inside that simulation, contemplating it's existence, would have no way to even begin to think about quantum computing.

The rules are just too different.

That being said, I almost look at the finite speed of light, and quantum effects as shortcuts to simulation.

The light speed limit allows greater parallelization by reducing the number of particles inside the local light cone. Likewise, quantum effects seem like a compiler optimization where a calculation isn't performed until the result is needed.

It's fun to think about, but I doubt we will ever know for sure either way.

[zeroonetwothree]

It seems to be purely an issue of computing power, not feasibility. That’s why it’s conceivable that future advances would make it feasible.

Like if in 1950 you looked at a computer and thought “there’s no way to make realistic 3D graphics”.

[CRConrad]

OK, somewhat stale already... But WTH, there are still "Reply" links, so AFAICS replying is acceptable. And the "reverse-perspective" rebuttal I'm about to propose hasn't been proposed so far.

> OK, but I'm saying the burden of proof is on who think that simulation is possible. It's not at all obvious that it is.

You seem to be arguing about whether it's possible to simulate this reality, the one we're in, within itself. That's like saying Sim City is impossible, because you can't build the computer Sim City is running on in Sim City; you can't have your Sims build a PC and then run that same copy of the Sim City game on that simulated PC.

If we and the universe we live in are all part of a simulation, that simulation can be running on something that cannot be built in our universe -- within that simulation itself -- without, AFAICS, that constituting any logical contradiction.

Or, IOW: Ants can build anthills, but we can build ant farms. If an ant claims "I can't be living in an ant farm; there can be no such thing, because we ants don't know how to make one!"... Then it is wrong.

In the simulation hypothesis, it is not necessary for humans to know how to build the simulation environment, because in that hypothesis we aren't the simulation builders. We're just the Sims (or ants).

[mannykannot]

If we go around demanding proof of every hypothesis before considering its implications, we will find that we have very little to think about. Not even mathematics and philosophy are conducted at this level of rigor.

The burden of proof is a double-edged sword: it can be used to rein in tendentiousness, but also to avoid discussing an issue.

[zeroonetwothree]

> The burden of proof is on people who claim that human cognition can be simulated by computer, not the other way around. To me, it seems far more likely that it can't.

C-T makes a claim about computable functions on natural numbers. It seems strange to argue that humans can perform such computations on a fundamental level better than a computer, thus we might assume the same is true of more complex computations. So while I suppose you could take the position that the burden of proof is to show every individual method of computation is equivalent, since there are infinitely many methods this seems a bit unfair.

[mannykannot]

I don't think anyone is claiming that humans can compute computable functions in some way better than a computer, the claim is that minds can do things that are not reducible to computing computable functions. See, for example, the Lucas-Penrose argument:

https://en.wikipedia.org/wiki/Penrose%E2%80%93Lucas_argument

Note that I am not suggesting that I concur with it.