[HN Gopher] Colorless green DNNs sleep furiously in an unexplain...
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       Colorless green DNNs sleep furiously in an unexplainable fantasy
        
       Author : arthurtakeda
       Score  : 46 points
       Date   : 2024-05-17 12:08 UTC (3 days ago)
        
 (HTM) web link (cacm.acm.org)
 (TXT) w3m dump (cacm.acm.org)
        
       | roywiggins wrote:
       | > To conclude, we can never automate the construction (nor the
       | testing) of computer programs. So says logic and so says the
       | theory of computation.
       | 
       | On the other hand, the strong Church-Turing thesis is that
       | _nothing_ is more powerful than a Turing machine when it comes to
       | solving halting problems, including humans. This is not proven or
       | really provable but it seems more likely than not (humans
       | certainly don 't seem _especially_ good at solving halting
       | problems in general).
       | 
       | If the Church-Turing thesis is true (at least as applied to
       | humans), discovering valid, halting programs by heuristic using a
       | machine isn't barred by the halting problem as far as I can tell.
       | 
       | In other words, _humans_ almost certainly aren 't solving halting
       | problems when they program, why should computers necessarily have
       | to? Humans mess up and produce programs that don't halt or don't
       | produce the output they expect all the time, but we still produce
       | useful programs at least sometimes, even if we can't know for
       | sure which programs are which.
        
         | avsteele wrote:
         | Exactly.
         | 
         | I'm very surprised someone a whole essay like this and have
         | this misconception.
         | 
         | I was half expecting to see "humans building something smarter
         | than human machines violates the laws of thermodynamics" next.
        
           | SamBam wrote:
           | Indeed. It reminds me of Penrose in _The Emperor 's New Mind_
           | (or one of his other books), where a large chunk of his
           | argument that human consciousness and understanding can't be
           | fully explained by computational processes, because humans
           | can understand and see the truth of certain statements that
           | formal systems cannot.
           | 
           | Mathematicians have spilled a bunch of ink explaining why
           | Penrose didn't understand Godel's proof.
        
             | omnicognate wrote:
             | The linked article is ridiculous, but your comment is a
             | misrepresentation of the Penrose debate. The main weak
             | point of Penrose's argument isn't that he "didn't
             | understand Godel's proof". He rightly observed that Godel's
             | incompleteness theorem requires that either human minds are
             | capable of things algorithms are not capable of, or that
             | their perception of mathematical truth is limited in
             | certain ways, an observation that Godel himself made. The
             | main point of disagreement with his critics is not the
             | mechanics of Godel's theorem which, unsurprisingly, this
             | Nobel prize winning mathematician (*) understands perfectly
             | well, but whether human perception of mathematical truth is
             | limited in these ways.
             | 
             | The question of whether human perception of mathematical
             | truth is infallible is open to philosophical debate.
             | Penrose distinguishes between mistakes, which all
             | mathematicians make but which in principle they can later
             | come to recognise as mistakes, and true incorrect
             | perception of mathematical truth, where no amount of
             | checking, re-derivation, etc. could possibly right the
             | incorrect perception. His view is that the latter type of
             | error does not exist, that there is a mathematical ground
             | truth that we can directly perceive and that is infallible,
             | and that the mistakes made by mathematicians are of a
             | different nature to inconsistencies in that perception of
             | mathematical ground truth.
             | 
             | Penrose went too far in presenting this argument as a proof
             | of the impossibility of strong AI based on algorithms. The
             | point about human perception of mathematical truth can very
             | reasonably be disputed, and is part of a much larger debate
             | about the fundamental nature of maths that is far from
             | settled. Personally, though, my intuition is that Penrose
             | is right about the human perception of mathematical truth,
             | and I therefore find the Godel-based argument persuasive.
             | It's not a proof because it rests on an assumption that has
             | not been proven, but I find it convincing to the extent
             | that I tend to think that the assumption is probably true.
             | 
             | So the debate is a philosophical one more than it is a
             | mathematical one, and while Penrose may be guilty of some
             | rather bad PR, accusing him of "not understanding Godel's
             | proof" does him a disservice.
             | 
             | * Yes, there's no Nobel prize in mathematics, but he is a
             | mathematician (as well as a physicist) and he has won a
             | Nobel prize.
        
         | mlyle wrote:
         | Came here to write this, was glad to see it's already here.
         | 
         | All the limits that exist for computing machines almost
         | certainly exist for us too; we don't need to solve the halting
         | problem; we don't solve large NP-hard problems; etc.
         | 
         | Of course, if one believes there's something mystical about
         | brains -- whether a soul or access to quantum computing --
         | perhaps one would disagree.
        
           | soist wrote:
           | The brain is not a computer. Computation is an abstraction of
           | thinking but it does not coincide with it.
        
             | aSanchezStern wrote:
             | This is a particular philosophical conjecture, not a proven
             | scientific fact. We don't understand enough about the human
             | brain to prove whether it is fundamentally different from a
             | very complex computer.
        
               | roywiggins wrote:
               | My intuition is that we _probably_ should assume they 're
               | different until proven otherwise, but also that brains
               | are probably not Turing oracles either.
        
             | roywiggins wrote:
             | I think this is quite possible, but it doesn't imply that
             | the strong Church-Turing thesis isn't true: brains could
             | still be Turing equivalent to computers, in that neither
             | would be able to solve the halting problem for the other
             | (at least insofar as humans have a "halting problem", which
             | maybe we don't, but you could formulate other things like
             | predicting behavior, which in standard computation is also
             | Turing complete usually)
             | 
             | Since humans don't seem to be particularly good at solving
             | the halting problem even for very small TMs, it doesn't
             | seem that likely to me that we are categorically stronger
             | at it than computers, whether our cognition is truly
             | "computation" or not.
        
         | viccis wrote:
         | I got a flashback to Zed Shaw's infamous Turing completeness
         | quip about Python 3, except that at least his was really just a
         | stupid joke. Here, the author is using a motte-and-bailey
         | fallacy in which he attacks a more complex and open ended
         | statement ("AI will Soon Replace Programmers") by instead
         | retreating to a more straightforward and falsifiable statement
         | (the ability to write any computer program).
        
         | mmoskal wrote:
         | I guess the short way to say it is that "undecidable" doesn't
         | mean "it can't ever be decided", just not always.
         | 
         | And of course all programs of practical significance are finite
         | state machines (since there is only a finite number of atoms in
         | the universe).
        
           | XorNot wrote:
           | Isn't the point closer to, humans simply go "hey that seems
           | to be taking a little long?" when a program doesn't halt, so
           | why couldn't a machine? Basically a fairly obvious constraint
           | on the solution space is "completes in less then N wall-clock
           | time".
        
             | roywiggins wrote:
             | You can definitely detect a portion of halting machines
             | this way, but it's probably a relatively small portion
             | because the Busy Beaver numbers grow _inconceivably_
             | quickly: the longest-running machines that halt can go
             | practically forever, you 'd need more time than the
             | universe has negentropy left to detect them.
        
         | zer00eyz wrote:
         | >> but any talk of fully automating human intuition (Turing's
         | Oracle!) in coming up with novel solutions to complex problems
         | is fantasy and the computer science police department (CSPD)
         | should issue a citation for any such talk.
         | 
         | You and I both intuit that there are conjectures that, likely,
         | do not have a solution. The author is proposing (and maybe
         | rightly) that an AI as a Turing machine with this intuition
         | would inherently (have to) be a Turing Oracle...
         | 
         | It's an interesting take that has some implications...
        
           | aSanchezStern wrote:
           | Err, only if humans have to be turing oracles to have that
           | intuition, right? Plus, the halting problem only says that
           | you can't have a procedure which will be 100% right on 100%
           | of programs about whether or not they halt. Relax either of
           | those 100%s, and it becomes possible again, just like how
           | human intuition can be right about things 90% of the time,
           | even if those things can't possibly be predicted 100% of the
           | time.
        
             | zer00eyz wrote:
             | Are people Turing machines is a question...
             | 
             | > Plus, the halting problem only says that you can't have a
             | procedure which will be 100% right on 100% of programs
             | about whether or not they halt.
             | 
             | Your missing it still...
             | 
             | "Given a computer program and an input, will the program
             | terminate or will it run forever?"
             | 
             | We both know that the collatz conjecture likely wont ever
             | halt. We understand that. WE are reasonable oracles. Now
             | write me an oracle that can detect this. Dont feed a list
             | of problems to avoid, write a program that detects these
             | types problems and skips them... Hint, you likley cant. You
             | could simulate one, but that would be cheating...
             | 
             | A real AI needs this, or needs to be able to do it, or it
             | risks working on the collatz conjecture till the heat death
             | of the universe, or till it consumes the universe in a
             | paperclip style problem...
             | 
             | The implication is that real ai might not come out of a
             | Turing machine ever...
        
               | roywiggins wrote:
               | The implication of the article isn't that you can't
               | produce a Turing oracle, it's that it's mathematically
               | impossible to ever replace programmers with computers at
               | all.
               | 
               | The latter claim doesn't follow: programmers aren't
               | Turing oracles either. A programming machine that can
               | emulate whatever humans are doing when they program,
               | would be able to program too.
        
               | oasisaimlessly wrote:
               | > We both know that the collatz conjecture likely wont
               | ever halt.
               | 
               | Speak for yourself. I know that the Collatz Conjecture is
               | an unsolved problem and so wouldn't make any strong
               | statements about it.
        
               | af3d wrote:
               | FWIW the Collatz conjecture actually asserts the exact
               | opposite, that the sequence _always_ terminates.
        
         | Kinrany wrote:
         | There's only one halting problem.
        
       | crockeo wrote:
       | The section "Forget the Theory of Computation, AI will Soon
       | Replace Programmers" feels as if it's missing a practical slant
       | that explains this trend. I think approaching it from a purely
       | theoretical perspective misses the relationship between real
       | software and real problems.
       | 
       | First: most practical problems are computable, and most practical
       | programs do not run forever. Even if an agent had to run a
       | program to termination, it could still use the feedback gathered
       | from running it to make modifications.
       | 
       | Second: an agent with a sufficiently good intermediate
       | representation _which is computable_ doesn't need to actually
       | execute a program to model its behavior. Humans do this all the
       | time--we can read code and understand its approximate function as
       | a means to edit it. I don't want to claim that LLMs have a
       | concept of "understanding," but they definitely build an
       | intermediate representation which, when combined with external
       | input (e.g. having to kill a program, because it exceeded a
       | timeout), can be used to modify the program.
       | 
       | Now with all of that said: I don't feel confident about whether
       | or not AI is actually serious risk to programmers, I just don't
       | feel as if this argument is sufficiently compelling.
        
         | robomc wrote:
         | It's a ridiculous argument that seems to imply that humans
         | can't code either.
        
       | Retr0id wrote:
       | > Let us suppose some AI came up with an algorithm A to solve a
       | specific problem P. To ensure that A solves P, the AI has to
       | execute A to test its functionality.
       | 
       | Not necessarily. It could (in theory) prove through formal
       | methods that A solves P.
        
         | PartiallyTyped wrote:
         | Taking this a step further, if the AI could write Daphne, it
         | could rely on invariants and pre and post conditions for this
         | proof, no?
        
       | piannucci wrote:
       | I don't see how the author's arguments about impossibility
       | results pertaining to "distributed sub-symbolic architectures"
       | apply any more strongly to LLMs or DNNs than they do to human
       | brains. Human programmers aren't magically capable of solving the
       | halting problem either, but we muddle through somehow.
        
         | EnigmaFlare wrote:
         | Yea. Most of what we do isn't that rigorous and it's fine. When
         | we do need rigor, we use external tools, like classical
         | computer programs or writing math down on paper. LLMs can use
         | external tools too. We're also hopeless at explainability -
         | people usually have no idea why they make most of the decisions
         | they do. If we have to, we try to rationalize but it's not
         | really correct because it doesn't reproduce all the intuition
         | that went into it. Yet somehow we can still write software!
        
       | Havoc wrote:
       | > Automatically discovering formal (i.e., unambiguous) solutions
       | to novel problems can never be automated.
       | 
       | Things like alphafold would suggest to me that this doesn't
       | always hold true.
       | 
       | Perhaps a matter of definition but to me there does seem to be
       | "some" problem solving ability. And once you've got even a little
       | of that then it's a scaling question and not really compatible
       | with " can never be automated."
        
         | soist wrote:
         | Do you know about the manifold hypothesis and why that's the
         | inductive bias in current neural networks?
        
       | hcarvalhoalves wrote:
       | I'm not sure the Halting Problem is a compelling argument
       | theoretical reason why AI can't program.
       | 
       | I do see a compelling argument on the limits of LLMs being
       | probabilistic (rather than logic/symbolic), as I've seen on
       | GPT/Pilot coming up with code that looks syntactically valid but
       | calls completely made-up APIs.
        
       | xvilka wrote:
       | People in the comments started to attack the author's argument
       | about halting problem, which I agree isn't the best one, but what
       | about other arguments? They are not less damning for the current
       | technology.
        
         | aSanchezStern wrote:
         | The claim that "there can be no explainability of such models"
         | is also completely unsupported. We know that some simple
         | networks can be explained, and explanation is a human notion,
         | not a formal one, so we can't know how much explainability is
         | possible. There's active research in explainability of neural
         | networks and progress is being made. I don't know how far it'll
         | go, but it hasn't hit any sort of theoretical boundary yet. I
         | think the author is making a similar sort of mistake that they
         | do in invoking the halting problem here, confusing a "not
         | forall" for a "forall not". There are certainly neural network
         | models that can't be explained ("not every model can be
         | explained" is true), but that doesn't mean that there aren't
         | ones that can ("every model can not be explained" is not true).
         | 
         | As part of the argument on explainability, the author says "we
         | have known for some time these models cannot represent or model
         | symbolic structures". There might be some particular weird way
         | of defining things where this is true, but it's certainly not
         | true in the most basic reading. In fact, we have very strong
         | theoretical results that a sufficiently wide neural network can
         | compute any function, including those that are "symbolic".
         | Whether they can be trained using gradient optimization to
         | compute every function is an open problem, but the idea that
         | there are functions they can't represent is provably false.
         | 
         | The third point, that LLM's aren't as step towards AGI. They
         | again make the claim that there are functions a DNN can't
         | compute (or approximate arbitrarily well) (see
         | https://en.wikipedia.org/wiki/Universal_approximation_theore...
         | for the theorem that this isn't true).
         | 
         | The rest of this point, and the fourth point, are basically
         | just about how current LLM's are actually pretty dumb in a lot
         | of situations. This is the only argument that's actually
         | compelling to me; there's a lot of hype around LLMs and their
         | abilities, but a lot of that might have to do with our brains
         | being happy to paper over flaws to anthropomorphize things. And
         | the fact that we haven't yet learned what to look for in
         | artificial output, like we spent decades doing for other
         | machine outputs before LLMs. Recall that when dumb pattern
         | matching conversation bots were invented in the 60s
         | (https://en.wikipedia.org/wiki/ELIZA), people thought they
         | couldn't possibly be artificial and must really be human, even
         | though they are obviously artificial by todays standards.
         | 
         | So, I agree that we don't know if LLM's are the first step
         | towards AGI, and they probably aren't in a sense more than the
         | fact that inventions tend to build on each other. But we don't
         | have enough information to say _definitively_ that they aren 't
         | that first step.
        
       | jdkee wrote:
       | Did Gary Marcus write this?
        
       | alkonaut wrote:
       | How does AI programming relate to computability and halting? I
       | can't determine whether a program will halt either. But I can
       | kill it if it doesn't halt and just try another program, because
       | I can operate a stopwatch. Where does this recursive argument
       | form? We can already see LLMs solving simple programmer tasks:
       | creating software from an informal description.
        
         | jpasmore wrote:
         | i stopped reading the article at this point...
        
       | hoseja wrote:
       | >"AI is useless"
       | 
       | >Lists a bunch of totally human failings
       | 
       | Great argument.
        
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