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The trouble is that (assuming sufficient computational power) if we can't simulate it then we don't really understand it. It's one thing to say "that's computat
by Reelin 6y ago
The trouble is that (assuming sufficient computational power) if we can't simulate it then we don't really understand it. It's one thing to say "that's computationally intractable", but entirely another to say "for some reason our computationally tractable model doesn't work, and we don't know why".
Present day ANNs may well be inspired by biological systems but (as you noted) they're not even remotely similar in practice. The reality is that for a biological system the wiring diagram is just the tip of the iceberg - there's lots of other significant chemical things going on under the hood.
I don't mean to detract from the usefulness of present day ML, just to agree with and elaborate on the original point that was raised (ie that "we have a neural wiring diagram" doesn't actually mean that we have a complete schematic).
- staticassertion 6y agoBut we understand tons of things without simulating them.
- Reelin 6y agoIf you think you understand something, write a simulation which you expect to work based on that understanding, and it doesn't work - did you really understand it?
- staticassertion 6y agoOK, what if the simulation works, did you understand it before?
- Reelin 6y agoNot necessarily. A working simulation (for some testable subset of states) doesn't carry any hard and fast logical implications about your understanding. On the other hand, assuming no errors in implementation then a broken simulation which you had expected to work directly implies that your understanding is flawed.
- burnte 6y agoMaybe, maybe your simulation is just buggy. I can write a simulator of how my wife would react to the news I'm cheating on her, and fail miserably, but I'm quite positive I understand how she would actually react.
- Reelin 6y agoYes, you have to debug your code. I suspect that the people who implemented OpenWorm are capable of and have done that.
- gogoincar 6y agoCan you give some examples? I'm guessing there is a different in definition of understanding here. As I interpret GP, the claim is you can't describe something in sufficient detail to simulate it, then you don't actually understand it. You may have a higher-order model that generally holds, or holds given some constraints, but that's more of a "what" understanding rather than the higher-bar of "why".
- staticassertion 6y agoI don't think that's what they're saying. We could have the detail and understanding but lack compute. It seems that they are saying that a simulation is required for proof. We write proofs for things all the time without exhaustively simulating the variants.
- Reelin 6y agoI explicitly called out the case where issues arise solely due to lack of compute in my original comment. I never claimed that a simulation is required for proof, just that an unexpectedly broken (but correctly implemented) simulation demonstrates that the model is flawed.
- staticassertion 6y ago> (but correctly implemented) Do you ensure this by simulating it?
- Reelin 6y agoNo? It honestly seems like you're being intentionally obtuse. The simulation being correctly implemented is an underlying assumption; in the face of failure the implementer is stuck determining the most likely cause. Take for example cryptographic primitives. We often rely on mathematical proofs of their various properties. Obviously there could be an error in those proofs in which case it is understood that the proof would no longer hold. But we double (and triple, and ...) check, and then we go ahead and use them on the assumption that they're correct.
- jimfleming 6y agoI'm aware of that and I've done quite a bit of work on both spiking neural networks and modern deep learning. My point is that those complexities are not required to implement many important functional aspects of the brain: most basically "learning" and more specifically, attention, memory, etc. Consciousness may fall into the list of things we can get functional without all of the incidental complexities that evolution brought along the way. It may also critically depend on complexities like multi-channel chemical receptors but since we don't know we can't say either way. It's a tired analogy but we can understand quite a lot about flight and even build a plane without first birthing a bird.
- kbenson 6y ago> It's a tired analogy but we can understand quite a lot about flight and even build a plane without first birthing a bird. The problem is we don't know if we're attempting to solve something as "simple" as flight with a rudimentary understanding of airflow and lift, or if we're attempting to achieve stable planetary orbit without fully understanding gravity and with a rudimentary understanding of chemistry. I think it's still worth trying stuff because it could be closer to the former, and trying more stuff may help us better understand where it is on that spectrum, and because if it is closer to the the harder end, the stuff we're doing is probably so cheap and easy compared to what needs to be done to get to the end that it's a drop in the bucket compared to the eventual output required, even if it adds nothing.
- echelon 6y ago> we can understand quite a lot about flight and even build a plane without first birthing a bird Or fully understanding fluid dynamics and laminar flow. No doubt that the Wright Brothers didn't fully grok it, at least.
- ramraj07 6y agoYour analogy is actually quite apt here - the wright brothers took inspiration from birds but clearly went with a different model of flight, just like ANN field has. The fundamental concept of the neurons are same, but that doesn't mean the complexity is similar. Minimally, whatever the complexity inside a Biological neuron maybe, one fundamental propery we need to obtain is thr connection strengths for the entire connectome, which we don't have. Without that we actually don't know the full connectome even of the simplest organisms, and no one to my knowledge has hence actually studied the kind of algorithms that are running in these systems. I would love to be corrected here of xourse.