Humans certainly do not build on massive amounts of symbolic knowledge because we are absolutely terrible at symbolic knowledge. Reliably reasoning through a basic logical argument is a specialist skill. Even reviewing evidence before making decisions is uncommon, most humans operate on a look -> assess -> do model where the tricky bit is well approximated by a neural net. Which is why neural nets seem to be so good at real-world tasks.
It is completely plausible that when neural nets get scaled up to something approaching human-brain numbers of connections they will well approximate a human brain or be a few tweaks away. Obviously it won't be knowable until state of the art gets there, but there is no reason to think human intelligence is going to be complicated. It is one evolutionary step up from some pretty basic animals.
Maybe you’re talking about a different kind of symbolic knowledge than the OP. To give an example humans can instantly tell whether an arbitrary sentence is grammatical or not which is a deep kind of symbolic reasoning that computers absolutely cannot do right now. And humans can also get the semantic meaning.
Then again math is hard for us. So I think there are nuances.
The fact that computers can't do sentence grammar and meaning right now doesn't tell us anything much about similarities or differences between humans and neural nets. It just tells us that training a neural net purely on a big corpus isn't enough to derive semantic meaning and makes it hard to work out grammatical meaning. No human has ever tried to do that either, everyone comes at text with some real-world experience. So we don't know how well they would do at it. Probably terribly.
It is reasonable to believe that written language is easier to train on a neural net that is trained on both images and words so it can form visual links between words. Maybe that takes more computational grunt than we have at the moment. The failure so far proves nothing.
instantly tell whether an arbitrary sentence is grammatical or not
You do realize we can train a neural network to perform this task? It is a binary classification problem. When I look at a grammatically incorrect sentence I don't do much symbolic reasoning - it just feels "wrong" to me. It does not match any patterns I have in my head for grammatically correct sentences. There's a lot of pattern matching in our thinking process.
What's missing in the current generation of neural networks is efficient information storage and ability to recall that information (e.g. lookup) or update it (direct write).
"You do realize we can train a neural network to perform this task"
I'm doing a master's in deep learning for NLP and I'm not sure we can. Language modelling can't do this because grammatical yet semantically implausible combinations of words yield very low perplexity, like the classic being Noam Chomsky's "Colorless green ideas sleep furiously".
What would be a training set for this? I assume we would first try to do parsing to extract the grammatical role of each word. Then what would be the dataset? A massive attempt at generating the set of all possible trees that are grammatical?
I guess we could use massive textual datasets from reputable sources and extract their grammatical role tree, and learn from that. Generating negative examples with sufficient coverage would be very hard. Strict generative modelling without negative examples with good coverage would see the same problem as with language modelling, where acceptable but unlikely examples would have low perplexity despite being good.
It would seem to me that in order to generate negative examples with good coverage, your would need to have a man made program with a definition of what grammaticality means, which would make making a neural network useless to begin with.
Constructing a training dataset is a separate problem. You could potentially crowdsource enough negative examples. Once you have the dataset, a neural network would most likely be able to learn to classify sentences with a reasonably good accuracy.
Unlike current DL models, humans have a world model (common sense) which is formed through an ability to create/update/lookup explicit rules/facts. Once we figure out how to incorporate that into a learning algorithm and/or a model architecture, AI will become a lot smarter.
If we can train a computer to classify sentences as grammatical or not please let me know where. You’ll save the linguistics department a lot of money as they’ll no longer have to contact native speakers for this research.
Humans also require a lot of examples to learn a language - years of everyday practice for a young human. Learning algorithms are not the same, but you still need to train a large neural network - lots of neurons with lots of connections (weights) - whether it's in your head or in a datacenter.
There’s some evidence that humans have a Universal Grammar and learn through deletion. And humans can not learn any old language — only a restricted class — meanwhile there’s no reason to think that an ML model would have that problem.
I’d encourage you to read a little more about the topic with an open mind. You might learn something.
Neural nets fundamentally cannot operate the same way a brain does, because they cannot create an abstract representation of a problem, and then gradually and deliberately manipulate that mental model until they develop a solution. They just don't work that way, with current structures. They basically apply a single pass of a very complex function to the data, and spit out a result.
That isn't a problem of scale, it's a problem of architecture. This is one of the reasons Deepmind decided to tackle Starcraft. It's very difficult to solve Starcraft without your AI having some ability to develop and then manipulate a mental model of the game, because that's what you need to construct and unfold original, non-linear strategies.
It is completely plausible that when neural nets get scaled up to something approaching human-brain numbers of connections they will well approximate a human brain or be a few tweaks away. Obviously it won't be knowable until state of the art gets there, but there is no reason to think human intelligence is going to be complicated. It is one evolutionary step up from some pretty basic animals.