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Comment by jedberg | Hacker News Reader

I've been studying how the brain works since college, which is now 20+ years. One thing a professor said back then really sticks out -- "we always assume that the brain works the same way as the most advanced computing of the time". In the 50s we assumed the brain worked like a telephone switching system. In the 80s we assumed the brain worked like a bunch of transistors.

In the 90s we finally switched it up, and developed computing paradigms based on human biology, and came up with applying neural nets to brain science. Then someone had the idea to create a Bayesian NN.

Each iteration we get closer to explaining how the brain works, but showing that each iteration is closer to workable based on our knowledge of the biology of the brain.

But we still have no idea how we get from brain biology to rational (and irrational) thought. I'd be excited if we solved this within my lifetime.

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I don't think it will be, unfortunately. I think it's important to distinguish between explaining "how the brain works" and "understanding the brain, the mind, and their relationship". There are hundreds of studies every year elucidating correlations between certain kinds of brain activity and certain states of conscious experience. There are also many valiant attempts at modeling various aspects of human cognition and brain function. Unfortunately, none of this research says anything at all about the nature of the actual feelings and experiences we have.

People are taught in school that a sufficient response to the question "how do we hear things?" is to talk about sound waves, the shape of the outer ear, the tympanic membrane, malleus, incus, stapes, cochlea, etc. At some point you arrive at: "and then the brain processes the signal in the auditory cortex and stuff." We have become accustomed to this sort of answer, but it really doesn't even begin to answer the real (and interesting) question: why does all that processing result in the felt experience of hearing, rather than the nervous system just bubbling up and causing a behavior with no feelings? Why does it "feel" that way and not some other way? Is there a different kind of hearing that "feels" fundamentally different from our experience?

My point is that, we are closer to explaining some functional aspects of the brain, but when it comes to explaining the nature and character of our qualitative experience, we are at the same place as the ancient Eastern philosophers - we've really gotten nowhere.

Musicologists have been asking this question from a phenomenological angle for some time. It's quite interesting how listening and perception in the English language have almost no distinction from each other. Our ears listen always, but our brain perceives is about as far as we get. In French musicology and music psychology, there is much more desperation between modes of listening and they all have their own definitions.

> why does all that processing result in the felt experience of hearing

Fortunately, it is a question, which can stay unanswered with no practical consequences. It is a subjective counterpart of "Why is there something rather than nothing?", and we aren't answering either anytime soon.

> Is there a different kind of hearing that "feels" fundamentally different from our experience?

Even if there is, we will need different brain hardware to experience it first-hand, otherwise we'd have to do with analogies or, for more precision, with functional descriptions of perceptual processing.

Utterly absurd and completely false. An explanation for the question of why pain feels the why it does, for example, has enormous practical implications and consequences. The current neurological and medical approaches to pain management are poorly understood and often dangerous in extreme cases. We literally don't know why or how Tylenol works. That is a huge problem. The current best-case scenario, absent an explanation of the nature of the character of pain experiences, is that we find some neural activities that we can alter with advanced medical techniques which reliably suppress pain experiences. But it's not clear that 1) we will ever find such techniques, 2) that such techniques would exhaustively alter all the kinds of physical pain a human might experience, 3) that such techniques wouldn't negatively alter other aspects of a person's mind. If we had a fuller explanation of the nature of the character of the experience itself (rather than just treating consciousness like a black box), we might be able to alter the experiences more precisely and appropriately.

For all those ends you'll need observables: patient reports, behaviors associated with pain and so on. You probably have in mind the question "why this pain processing results in the observed effects?"

I was talking about the question "why does all that processing result in the felt experience [...]?"

No, I have in mind the exact question I outlined at the beginning of my response.

Then I don't understand you. What is important to address the problems you outlined is the question of "How brain activity corresponds to the felt experiences (as reported by subjects)?", not "Why there are felt experiences corresponding to brain activity?"

Even if we had the answer for the second question (say, "There is immaterial soul which is responsible for our felt experiences and that's why we feel"), it will not help with pain treatment.

Neeral-based computing paradigms go as far back as the 1950s.

https://en.wikipedia.org/wiki/Perceptron

Leslie Valiant proposed a mathematical model for human learning (and mostly applied to machine learning theory) in the 1980s, and it's been been refined to more explicftly Bayesian models recently:

https://en.wikipedia.org/wiki/Probably_approximately_correct...

http://web.mit.edu/6.435/www/Valiant84.pdf

Anyway, these aren't intended to be faithful models of hmuan brains, but more loosely inspired by functions observed in human brains. There's on good reasoning that an naturally evolved human brain would operate under one simple, sound, fundamental computing principle. It's far more likely to be a mishmash of unsound models, like all evolved physical characteristics of animals.

>There's no good reasoning that an naturally evolved human brain would operate under one simple, sound, fundamental computing principle. It's far more likely to be a mishmash of unsound models, like all evolved physical characteristics of animals.

Quite the opposite, actually. Anything essential to survival and reproduction is optimized for its design constraints quite heavily, resulting in many attributes of observed organisms being physiologically optimal.

You should look into the "rational analysis" paradigm in cognitive science.

I'm not sure I agree with that professor's claim - who was this, what kind of professor? Look at the claim itself. For instance, who is this "we" that is "always assuming"? Is it biologists at large? Because they do not tend towards unified, reductionist explanations of neuroscience based on computer science.

Theories of mind have been going back thousands of years from before the time computers were dreamed of. This idea of a technological paradigm of neuroscience falls apart quite easily when you consider the far longer exploration into human consciousness and neurophysiological function, both fields of inquiry are far older than computer science.

Never mind the fact, those that study neuroscience, they speak of neurochemical signaling pathways, of pre- and post-synapatic chemical reaction, or of the functional imaging of the brain's different regions. There is a great deal of genetic analysis, of pharmaceutical interest, and of genuine biological mysteries. I'm sorry but I just don't agree that neuroscientists are couching their field in terms of computers.

Computer science: https://www2.eecs.berkeley.edu/Faculty/Homepages/feldman.htm...

The we refers to computer scientists.

And even before computers, we still had technology. But we didn't really have an understanding of brain physiology thousands of years ago, so the statement really only applies to theories on how we get from brain physiology to computing, not theory of mind.

>The we refers to computer scientists.

Well of course computer scientists compare the brain to whatever the most advanced AI is. That's how they pitch grant applications!

Hell, I'm doing it right now in this application I've got on Overleaf in another tab, though I guess in reverse: I describe what we know functionally about the brain, then propose to build computational models to study it.

>But we still have no idea how we get from brain biology to rational (and irrational) thought. I'd be excited if we solved this within my lifetime.

The problem there is that "rational" has dual meanings:

* The a priori kind of "rational", as in "optimal according to some equation", where that equation is often Bayesian or RL-related

* The a posteriori kind of "rational", where we decide that science and math are better than intuition and so on.

I pretty much support the Bayesian brain assumption, and the labs I work with follow it in a few different forms, but I suspect that the cognitive science of rationality will some day be a pretty fruitful field. That is, I suspect that a posteriori rationality can't be neatly reduced to a priori optimality[1].

[1] -- http://www.saet.illinois.edu/papers_and_talks/event-07/nolea...

Your point about irrational thought brought to mind this Turing quote I really like: "If we want a machine to be intelligent, it can't also be infallible."

source: Lecture to the London Mathematical Society on 20 February 1947, pdf: http://www.vordenker.de/downloads/turing-vorlesung.pdf, also see this Quora answer for details: https://www.quora.com/What-did-Alan-Turing-mean-by-his-state...). Actually his exact phrasing is the reverse (on pg 13): "... if a machine is expected to be infallible, it cannot also be intelligent. "

By Goedel's incompleteness theorem.

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