It is vacuously true that a Turing machine can implement human intelligence: simply solve the Schrödinger equation for every atom in the human body and local environment. Obviously this is cost-prohibitive and we don’t have even 0.1% of the data required to make the simulation. Maybe we could simulate every single neuron instead, but again it’ll take many decades to gather the data in living human brains, and it would still be extremely expensive computationally since we would need to simulate every protein and mRNA molecule across billions of neurons and glial cells.

So the question is whether human intelligence has higher-level primitives that can be implemented more efficiently - sort of akin to solving differential equations, is there a “symbolic solution” or are we forced to go “numerically” no matter how clever we are?

▲

walleeee 3 days ago | parent | next [-]

> It is vacuously true that a Turing machine can implement human intelligence

The case of simulating all known physics is stronger so I'll consider that.

But still it tells us nothing, as the Turing machine can't be built. It is a kind of tautology wherein computation is taken to "run" the universe via the formalism of quantum mechanics, which is taken to be a complete description of reality, permitting the assumption that brains do intelligence by way of unknown combinations of known factors.

For what it's worth, I think the last point might be right, but the argument is circular.

Here is a better one. We can/do design narrow boundary intelligence into machines. We can see that we are ourselves assemblies of a huge number of tiny machines which we only partially understand. Therefore it seems plausible that computation might be sufficient for biology. But until we better understand life we'll not know.

Whether we can engineer it or whether it must grow, and on what substrates, are also relevant questions.

If it appears we are forced to "go numerically", as you say, it may just indicate that we don't know how to put the pieces together yet. It might mean that a human zygote and its immediate environment is the only thing that can put the pieces together properly given energetic and material constraints. It might also mean we're missing physics, or maybe even philosophy: fundamental notions of what it means to have/be biological intelligence. Intelligence human or otherwise isn't well defined.

▲

Davidzheng 3 days ago | parent [-]

QM is a testable hypothesis, so I don't think it's necessarily like an axiomatic assumption here. I'm not sure what you mean by "it tells us nothing, as ... can't be built". It tells us there's no theoretical constraint and only an engineering constraint to doing simulating the human brain (and all the tasks)

	▲	walleeee 3 days ago \| parent [-]
		Sure, you can simulate a brain. If and when the simulation starts to talk you can even claim you understand how to build human intelligence in a limited sense. You don't know if it's a complete model of the organism until you understand the organism. Maybe you made a p zombie. Maybe it's conscious but lacks one very particular faculty that human beings have by way of some subtle phenomena you don't know about. There is no way to distinguish between a faithfully reimplemented human being and a partial hackjob that happens to line up with your blind spots without ontological omniscience. Failing that, you just get to choose what you think is important and hope it's everything relevant to behaviors you care about.

▲

tshaddox 3 days ago | parent | prev | next [-]

> It is vacuously true that a Turing machine can implement human intelligence: simply solve the Schrödinger equation for every atom in the human body and local environment.

Yes, that is the bluntest, lowest level version of what I mean. To discover that this wouldn’t work in principle would be to discover that quantum mechanics is false.

Which, hey, quantum mechanics probably is false! But discovering the theory which both replaces quantum mechanics and shows that AGI in an electronic computer is physically impossible is definitely a tall order.

▲

card_zero 3 days ago | parent [-]

There's that aphorism that goes: people who thought the epitome of technology was a steam engine pictured the brain as pipes and connecting rods, people who thought the epitome of technology was a telephone exchange pictured the brain as wires and relays... and now we have computers, and the fact that they can in principle simulate anything at all is a red herring, because we can't actually make them simulate things we don't understand, and we can't always make them simulate things we do understand, either, when it comes down to it. We still need to know what the thing is that the brain does, it's still a hard question, and maybe it would even be a kind of revolution in physics, just not in fundamental physics.

▲

thfuran 3 days ago | parent [-]

>We still need to know what the thing is that the brain does

Yes, but not necessarily at the level where the interesting bits happen. It’s entirely possible to simulate poorly understood emergent behavior by simulating the underlying effects that give rise to it.

	▲	card_zero 3 days ago \| parent [-]
		Can I paraphrase that as make an imitation and hack it around until it thinks, or did I miss the point?

▲

b_e_n_t_o_n 3 days ago | parent | prev | next [-]

It's not even known if we can observe everything required to replicate consciousness.

▲

Davidzheng 3 days ago | parent | prev | next [-]

i'd argue LLMs and deep learning are much more on the intelligence from complexity side than the nice symbolic solution side of things. Probably the human neuron, though intrinsically very complex, has nice low loss abstractions to small circuits. But on the higher levels, we don't build artificial neural networks by writing the programs ourselves.

▲

missingrib 3 days ago | parent | prev [-]

That is only true if consciousness is physical and the result of some physics going on in the human brain. We have no idea if that's true.

	▲	Timwi 2 days ago \| parent \| next [-]
		Whatever it is that gives rise to consciousness is, by definition, physics. It might not be known physics, but even if it isn't known yet, it's within the purview of physics to find out. If you're going to claim that it could be something that fundamentally can't be found out, then you're admitting to thinking in terms of magic/superstition.
	▲	amanaplanacanal 2 days ago \| parent \| prev [-]
		You got downvoted so I gave you an upvote to compensate. We seem to all be working with conflicting ideas. If we are strict materialists, and everything is physical, then in reality we don't have free will and this whole discussion is just the universe running on automatic. That may indeed be true, but we are all pretending that it isn't. Some big cognitive dissidence happening here.