What We Can Never, Ever Know: Does Science Have Limits?

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I got two books in the mail that, if they could have, would've poked, scratched and ripped each others' pages out. I don't know if Martin Gardner and Patricia Churchland ever met, but their books show that there are radically, even ferociously, different ways to think about science. Gardner died last year. He was a science writer whose monthly "Mathematical Games" column in Scientific American was wildly popular. Patricia Churchland is a philosopher who teaches at U.C. San Diego.


The issue between them is: How much can we know about the universe?

"I am a mysterian," says Gardner, in his new (posthumously published autobiography) . Mysterians, he writes, believe that some things — how life began, the nature of time, what consciousness is, whether there is free will — are so inherently complex that they will forever elude human understanding. Not only does "no philosopher or scientist living today [have] the foggiest notion" of how mind or time or consciousness work, "we believe" he wrote, "it is the height of hubris" to suppose those things will ever be understood completely.

Forever Unintelligible

Gardner allows that humans have wonderful brains, that we can invent thinking machines, microscopes and any number of intelligence-enhancers, but he says there are still limits, hard limits.

Written By: Robert Krulwich
continue to source article at radiolab.org

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  1. Any concept you name was once “unknowable” if you go back far enough along the line of our ancestors. Yes, there have to be things, today, that are just as unknowable for the same reason, i.e. we don’t have the brain capacity. It is also predictable that if we have a long line of descendants (say thousands of generations) they will be quite different (especially if they go transhuman) and expected to understand things that we simply can’t, today. There is a lot in what you define as “we.” (See: Who will be “we” in 2093?)

    Part of the job of science is to find the limits of science. I suspect there are limits to what can be known about the Universe from looking at it while inside it (both in space and time). We intrinsically cannot know what is going on outside our own light-cone, even though that is not considered “outside” the Universe. We may project what is going to happen trillions of years in the future to the Universe, but we cannot really know for sure because it depends on the assumption of basic observations of the workings of the Universe not changing over time more slowly than we can measure, or something like a collision with something vastly bigger that won’t be seen for, say, another hundred billion years.

    So, there has to be both the unknown and the unknowable, and workers in the sciences are glad about the unknown part, so there are jobs to do, and fun to be had, chipping away at that.

  2. Who cares what you can and can’t do. Saying what you can’t know is even worse than hubris, it’s defeatist and lazy.

    It’s worth trying at least, no point shrugging your shoulders about it. You may learn a few things along the way.

  3. How presumptuous of us, twenty first century apes, to assume that there is a limit to what can be known about the universe. Serious science has only been done for four centuries now, and see what has been achieved in such a short period of time. Our brains are the product of the universe. So why couldn’t it be that this amazing instrument is the ‘gate’ to total knowledge?

    • In reply to #5 by Lonard:

      How presumptuous of us, twenty first century apes, to assume that there is a limit to what can be known about the universe.

      I don’t think its presumptuous to ask the question. The more I learn about how evolution “designed” our brain the more I can understand how there may be inherent limits imposed by the fact that our brains were never designed to understand things like quantum behavior. But I agree with you to assume that because we evolved to be efficient hunter gatherers means we just inherently can’t understand some problems seems totally ass backwards. The goal I would think is to understand how our evolutionary past limits us and biases our understanding so that we can continue to progress beyond those limits and to adjust for those biases. It may turn out at some point that there are just inherent limits we can’t get beyond but to assume such limits exist seems completely counter productive.

      • In reply to #27 by Red Dog:

        I don’t think its presumptuous to ask the question.

        But to believe that one knows the answer to what those limits might be is the height of intellectual arrogance, and also shows that one did not completely understand or fully appreciate the question.

  4. I don’t care either way because there’s only one non-assumptive way to test it: throw your all at the questions, devise new means and new technologies to enhance your ability to tackle them, and never stop looking for a way to solve any problems you encounter. If, after all this, no answer is produced, then maybe you can call it a day, and probably not even then since you can’t be sure you have tried everything.

    I have no problem with the “we don’t know” part, but the assumption that we never will when it comes to inductive research is premature to the point of dismissive. I’m not saying the opposite is true – that we will someday get there – but it would be better policy to act as though it was true and try and answer it rather than act as though it was false and give up when the answer could be within reach.

  5. A dog probably feels it fully understands the universe, well enough for all that matters to a dog. Humans might achieve something similar.
    However, that is not necessarily the level a larger brained animal would desire.

    We humans will likelly achieve beyond our weight using AI. AI will have to tell us baby stories to explain its findings.

  6. My first reading of the title was to the effect that whether science had limits was an example of what could never be known, including by science. But any example of something that could never be known by science would imply science does have limits, so no-one could know that we can never know that science has limits. At any rate, the argument that some things are forever unknowable because of the finite limits of our brains misses the point that we could improve our brains using future technology.

    Is there a real argument for a limit on what is knowable? There’s Bremermann’s limit, for one. But I bet the questions philosophers trot out as unanswerable aren’t anywhere near hard enough to hit said limit.

    • In reply to #8 by Jos Gibbons:

      Is there a real argument for a limit on what is knowable? There’s Bremermann’s limit, for one. But I bet the questions philosophers trot out as unanswerable aren’t anywhere near hard enough to hit said limit.

      I just had to look that up…

      Bremermann’s Limit, named after Hans-Joachim Bremermann, is the maximum computational speed of a self-contained system in the material universe. It is derived from Einstein’s mass-energy equivalency and the Heisenberg uncertainty principle, and is c2/h ≈ 1.36 × 1050 bits per second per kilogram. [1][2] This value is important when designing cryptographic algorithms, as it can be used to determine the minimum size of encryption keys or hash values required to create an algorithm that could never be cracked by a brute-force search.

      I gotta hand it to you, it’s worth coming to this site just to find stuff like this. Thanks for posting!

      • In reply to #9 by Zeuglodon:

        In reply to #8 by Jos Gibbons:
        Bremermann’s Limit

        Cracking encryption presumes the current algorithm is the best algorithm. There are hints quantum computers may soon crack encryption.

        At that point will have to revert to one time pad. I have written an reasonably idiot proof one, but under contract I can’t release the source until 2014-02

        • In reply to #17 by Roedy:

          Cracking encryption presumes the current algorithm is the best algorithm. There are hints quantum computers may soon crack encryption.

          I read somewhere that combining digital computers with the old analogue systems achieves a similar effect.

    • In reply to #8 by Jos Gibbons: + Zeuglodon

      Bremermann’s Limit, named after Hans-Joachim Bremermann, is the maximum computational speed of a self-contained system in the material universe.

      I have two questions regarding this:-

      • Can a present/future human population be considered a self contained system?

      • How would the limit apply to specific targeted local areas of knowledge, rather than the whole? In other words, while we may not be able to investigate all of a system, does that exclude partial investigation of any selected areas, while accepting a lack of capability to cover the whole?

    • In reply to #8 by Jos Gibbons:

      Hi Jos,

      I liked your comment, and I had this additional thought:

      Not only could future humanity invent new technologies, microscope, radio telescope, particle collider, etc., it could also learn to better harness group dynamics to magnify intelligence (fireside, writing, alphabets, printing, Net … [etc.?]) and what’s to stop humanity evolving a greater ability in each biological individual? There appear to be selection pressures – are those unable to use their cognitive abilities to ensure their offspring live to adulthood, by immunizing them, more likely to see their genetic contribution to shrink in the overall population?

      Evolution works very slowly, but some of these people are being very specific:

      … We Can Never, Ever Know …

      Never … that’s a very long time.

      Peace.

  7. “I am a mysterian,” says Gardner, in his new (posthumously published autobiography) . Mysterians, he writes, believe that some things — how life began, the nature of time, what consciousness is, whether there is free will — are so inherently complex that they will forever elude human understanding. Not only does “no philosopher or scientist living today [have] the foggiest notion” of how mind or time or consciousness work, “we believe” he wrote, “it is the height of hubris” to suppose those things will ever be understood completely.

    This is just personal incredulity and ignorance. As Patricia Churchland points out, the developments in the last 200 years should spell out the giant strides which can be made in a few generations.

    Spaceflight and railways would be good examples: (1725 railway:-)

    When a friend of hers, another philosophy professor, jumped out of his seat at a conference and yelled, “I hate the brain, I hate the brain!” because all this attention to brain science was taking attention away from philosophical pursuits, she smelled his fear. “Does he worry that neuro-knowledge is forbidden fruit, a Promethean fire, a Pandora’s box, … an evil genie released from a rightly sealed bottle?”

    Neuroscience is certainly making rapid progress in demystifying conscious and unconscious thought processes.

    Fumbling philosophers and theologians, are right to fear it will lead to their unemployment, as science takes over from quackery and mythology.

    His views on this subject, casually mentioned at the end of a chapter, are my own. He wrote that he finds his life, his being here, deeply mystifying. He loses friends to diseases and doesn’t know why. He loves deeply, but doesn’t know how. “Can there be any possibility of completely understanding who we are and why we’re here and where we’re going? These are questions that can never be answered completely,” Kunitz says, contradicting Patricia.

    Oh dear! The author identifies as a fudgist and makes a fool of himself citing “WHY?” questions as science which cannot be answered!
    “WHY?” questions, either have “HOW?” answers, lead to the presently unknown, or are simply incoherent and unfalsifiable!

    • In reply to #10 by Alan4discussion:

      “I am a mysterian,” says Gardner, in his new (posthumously published autobiography) . Mysterians, he writes, believe that some things — how life began, the nature of time, what consciousness is, whether there is free will — are so inherently complex that they will forever elude human understanding. Not only does “no philosopher or scientist living today [have] the foggiest notion” of how mind or time or consciousness work, “we believe” he wrote, “it is the height of hubris” to suppose those things will ever be understood completely.

      This is just personal incredulity and ignorance. As Patricia Churchland points out, the developments in the last 200 years should spell out the giant strides which can be made in a few generations.

      This must be some of the richest irony I’ve encountered lately (and that’s saying a lot considering all the reading on religion we are treated to here on this site). The sin Churchland accuses Gardner of is almost exactly what she herself engages in vis-à-vis Sam Harris’ The Moral Landscape and against Harris personally with a pathetic ad hominem attack:

      “Sam Harris has this vision that once neuroscience is much more developed then neuroscientists will be able to tell us what things are right or wrong, or at least what things are conducive to well-being and not. But even if you cast it in that way, that’s pretty optimistic – or pessimistic, depending on your point of view. Different people even within a culture, even within a family, have different views about what constitutes their own well-being. Some people like to live out in the bush like hermits and dig in the ground and shoot deer for resources, and other people can’t countenance a life that isn’t in the city, in the mix of cultural wonderfulness. So people have fundamentally different ideas about what constitutes well-being.

      “I think Sam is just a child when it comes addressing morality. I think he hasn’t got a clue. And I think part of the reason that he kind of ran amuck on all this is that, as you and I well know, trashing religion is like shooting fish in a barrel. If Chris Hitchens can just sort of slap it off in an afternoon then any moderately sensible person can do the same. He wrote that book in a very clear way although there were lots of very disturbing things in it. I think he thought that, heck, it’s not that hard to i gure these things out. Morality: how hard can that be? Religion was dead easy. And it’s just many orders of magnitude more difficult.”

      • In reply to #15 by godsbuster:

        This must be some of the richest irony I’ve encountered lately (and that’s saying a lot considering all the reading on religion we are treated to here on this site). The sin Churchland accuses Gardner of is almost exactly what she herself engages in vis-à-vis Sam Harris’ The Moral Landscape and against Harris personally with a pathetic ad hominem attack:

        The quote you give does seem to support that view of her in facing in opposite directions on different occasions.

  8. We discuss this topic poorly in my view. Does “knowing” encompass “mastery” and/or “understanding”. Newton mastered gravity within the limits of his ability to observe, but couldn’t claim he understood it. His mastery nevertheless got us to the moon.

    By “understanding” I mean the emotional state of satisfaction we get when we are happy enough with our mastery of an aspect of the universe. This inevitably is the result of there existing some element of analogy with another area of the universe and our experience of it that has achieved exactly this level of satisfied mastery for us. (Here I count mathematics as analogy also, which is more or less satisfying, but never ultimately so.)

    But this satisfaction at some point will start to evaporate away, if not for us, for our kids with their infinite regress of “but why’s”.

    I see no necessary exclusion of the vision that some future (collective?) we might achieve complete mastery of everything we can detect, making reliable predictions of outcomes in every case. But the sense of satisfaction of “understanding” may be forever denied by the absence of a separate extra-universal analogue.

  9. It’s one thing to suggest that the mistakes of the past, things that we know now were once claimed to be unknowable, are the same mistakes being made now. But this is in itself a limited and simplistic view. To say “there are no limits” is a limited view, it’s an absolute derived from very little data.

    Yes, our understanding has expanded on the understanding of our ancestors, and our descendants will expand on ours in turn. However one of those things of which our knowledge of has expanded, is the subject of our own ability to understand things.
    Sure, in the ages past it was onced claimed that we could never go into space, or view the image of an atom, that we could never reach the speed of sound, or travel over 30 miles per hour, or reach the top of mount Everest or the bottom of the ocean or build higher than 20 stories.
    Since breaking all of these misconceptions we have learned more about our own ability to understand than in all the centuries before. We have also learned to be wary of maming such limited misconceptions.

    So what does this tell us.
    We avoid placing such limits of predictions of future advancements, and we have a greater understanding today of our own ability to understand the universe than ever before, and yet we are now coming to conclusions about the limit of our understanding.

    I think we’re approaching a time in which we will know enough about the functions of our minds and the limits of our technology to reliably place limits on the future of scientific discoveries that we can’t currently make.
    We are after all mortal, biological entities living in this middle world, we do have limits. But even if we can’t break those limits we can at least accurately predict where they are. Simply because previous generations failed to do so doesn’t mean we will as well.

  10. There are obvious things you can’t know because they are too detailed. They would overamp your brain or recording device, e.g. the positions and velocities of particles to max accuracy in the solar system.

    You can’t know how to do X if X is impossible.

  11. Mysterians, he writes, believe that some things — how life began, the nature of time, what consciousness is, whether there is free will — are so inherently complex that they will forever elude human understanding.

    Maybe if you learn to ask better questions. “Free will” is nonsense, consciousness is subjective, time is relative and life began with chemistry.

  12. The accumulation of knowledge (past and present) leads to further knowledge in the future. As long as humanity exists this process will go on forever; unless a huge natural disaster, like those that already happened in the past, put an end to our civilization, or human society itself embraces retrograde ideologies. The latter phenomenon is starting to happen among some religious communities that claim that science is going too far or is affecting humanity negatively. If the process of accumulation of knowledge goes on and on in the future more knowledge will be discovered, as long as knowledge is illimited. The question is if the future humans carrying out the quest for knowledge will belong to our own species.

  13. Gardner’s position, that “it is the height of hubris to suppose those things will ever be understood completely,” is not really the position of a mysterian. It is simple common sense, and the only coherent position one can take. Complete knowledge of anything real is not something science can deliver, as everybody knows well.

    The position of the mysterian would rather seem to be something like “there are some things we can never learn more about through science.” This position, I contend is false (if a fact about the real world is true, then that fact has consequences for the appearance of the real world, and scientific analysis of that appearance can always update our confidence in those facts) and the conflation of this position with Gardner’s perfectly reasonable statement (even, it seems, by Gardner himself) is one of the greatest recurring errors about science and philosophy.

    • In reply to #24 by tom campbell-ricketts:

      Complete knowledge of anything real is not something science can deliver, as everybody knows well.

      This is something science has not yet delivered, though it might one day. Don’t see any reason in principle why science couldn’t. In practice it might take a very long time though.

      Otherwise I agree, this supposed mysterian is simply confused, but I guess that’s a given.

      • In reply to #25 by Peter Grant:

        This is something science has not yet delivered, though it might one day. Don’t see any reason in principle why science couldn’t.

        Imagine I am an omniscient being. This implies that I know I am omniscient. But how could I know this? How can I be absolutely certain that this is a true belief, and not just a mistaken perception of true belief? Reductio ad absurdum: the omniscient deity disappears up its own backside in a puff of logical incoherence. No amount of science (or anything) can give justified complete confidence in statements about the real world, as to have justified complete confidence requires justified complete confidence in the procedure that delivered it, which just goes on forever.

        Technically, this is equivalent to the limitation of probability theory, that no probability assignment is independent of the probability model within which it is calculated – I can make my probability model as complicated as I wish, but if I want my calculation to terminate, then sooner or later, I will need to come to rest upon some assumptions that are not justified by any formal procedure.

        • In reply to #31 by tom campbell-ricketts:

          Imagine I am an omniscient being.

          Sorry, I can’t.

          No amount of science (or anything) can give justified complete confidence in statements about the real world, as to have justified complete confidence requires justified complete confidence in the procedure that delivered it, which just goes on forever.

          Yeah, but it could get so good that you wouldn’t be able tell the difference. Science tends towards perfection.

          Technically, this is equivalent to the limitation of probability theory, that no probability assignment is independent of the probability model within which it is calculated – I can make my probability model as complicated as I wish, but if I want my calculation to terminate, then sooner or later, I will need to come to rest upon some assumptions that are not justified by any formal procedure.

          Whatever works, science will adjust its views based on what’s observed.

        • In reply to #31 by tom campbell-ricketts:

          No amount of science (or anything) can give justified complete confidence in statements about the real world,

          It depends on how you round the figures on well tested scientific laws! (Complete confidence is a red-herring)

          You can back 99.999% probability and the tables of calculations, or back the 0.001% doubt. (approx)

          This is the usual god-slot-gapologists, “science cannot know with complete confidence”, argument!

  14. Seems Martin Gardner was a New Mysterian. Qualia again. Look the hard problem of consciousness cannot be resolved by humans because it’s not a real problem, OK! It’s a pseudo problem like “free will”. Consciousness is subjective, but we can still study it objectively. And there is no need to try to objectify consciousness to do so!

  15. We’ve learned so much in the last few hundred years and the pace of discovery is quickening…but there are millions of things in the universe and we don’t know millions of things, which is good as our kids will have something to strive towards….it would be sad to know ‘everything’ – Humans would be lost without something still to discover….anyway the universe is expanding therefore the limits of knowledge will always be beyond our reach… in theory if we cant know something we always try to rationally explain it anyway…

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