[plokiju]

So it sounds like we both agree the brain is at least a physical object that performs computations. I'm surprised you don't see similarities with other physical systems that perform computations, but sounds like a terminology difference

[aristofun]

Here is the heart of our disagreement:

> perform computations

Brain doesn’t perform computations in any CS accepted sense (neither it is a turing machine nor it has any encoded program to execute any defined algorithm).

It processes information, yes. But anything more specific than that is full of unknowns, unconfirmed hypothesis and speculations.

Would you call an ants colony a computer? A tree? A government? But they all obviously processes information and seemingly perform computations, don’t they?

[plokiju]

> Brain doesn’t perform computations in any CS accepted sense (neither it is a turing machine nor it has any encoded program to execute any defined algorithm).

That's a big statement. Anything that can be effectively described with math, can be described using Turing machines and algorithms. Any Turing-complete system is equivalent. As far as we know, all of physics can be described by equations, therefore is (theoretically) computable. What makes you think brains are special? Are there any other physical systems that you think are uncomputable?

The only arguments I've found for why the brain can't be described by algorithms go into unconvincing pseudo-scientific arguments about the magic of quantum mechanics, which I find very unconvincing (quantum algorithms are still algorithms, and describable through math after all). Do you have a better one?

> Would you call an ants colony a computer? A tree? A government? But they all obviously processes information and seemingly perform computations, don’t they?

Yes, absolutely. You can use ant colonies or slime molds as biological computers to solve real-world finding problems: https://www.youtube.com/watch?v=BZUQQmcR5-g&t=1s

Some of your other examples are more complicated, but all of them can be described through the computational lens, and modeled as Turing machines. you will find many scientific papers filled with equations trying to describe the algorithms behind each of them

[aristofun]

okay, we came to conclusion that almost any living organism can be called a computer

then what's the point in using this term if it doesn't differentiate anything?

it becomes meaningless, therefore there is no value in calling the brain a computer - it gives zero information about how brain actually works

case closed )

[plokiju]

Because calling it a computer means you can apply computer science concepts to it. That's the interesting part. You can talk about the classes of algorithms the brain uses to solve difficult problems, the ways it tries to conserve energy, the architecture trade offs, how to model it with math, etc. That stuff is non-obvious if you treat it like a magic black box. It's not a meaningless insight

Can the brain solve NP problems in polynomial time? The brain itself is a mystery, but we know some things about computation, so it's pretty safe to say no, it cannot.

Maybe on HN it's consensus that all living things are computers in this way, but plenty of people think the brain is literally supernatural. By saying "the brain nothing in common with a computer. We don't know what it's doing", those people will be nodding their heads. But we do know some things about computation, so we can apply those insights to the brain

[aristofun]

> You can talk about the classes of algorithms the brain uses to solve difficult problems

> But we do know some things about computation, so we can apply those insights to the brain

You can.

But it is a snake oil, it doesn't give you any actual insight on how brain really works.

To be able to model something with computer doesn't mean it is like a computer.

But at the same time such thinking can really confuse unprepared mind that brain is really modeled by nature as some sort of sophisticated turing machine.

This is misleading.

[plokiju]

At the same time, pretending that brains don't obey the laws of computation has its own implications, which can confuse unprepared minds into thinking:

1) That brains are something supernatural, instead of physical information processing systems that can be analyzed and understood as such.

2) That digital turing-complete computers are limited and can't possibly do the kinds of complex processing that biological computers can do

Which is also misleading

A brain is not a Turing machine, but a Turing machine can be a brain. Biological brains are just a subset in the space of all possible computers

But I don't think either of us is confused, so this is just a conversation about the semantics, which I'm not very interested in