Edward WittenWe’ll never understand consciousness, says Edward Witten. Ashutosh Jogalekar’s post here features a video of the eminent physicist talking about fundamentals; the bit about consciousness starts around 1:10 if you’re not interested in string theory and cosmology. John Horgan has also weighed in with some comments; Witten’s view is congenial to him because of his belief that science may be approaching an end state in which many big issues are basically settled while others remain permanently mysterious. Witten himself thinks we might possibly get a “final theory” of physics (maybe even a form of string theory), but guesses that it would be of a tricky kind, so that understanding and exploring the theory would itself be an endless project, rather the way number theory, which looks like a simple subject at first glance, proves to be capable of endless further research.

Witten, in response to a slightly weird question from the interviewer, declines to define consciousness, saying he prefers to leave it undefined like one of the undefined terms set out at the beginning of a maths book. He feels confident that the workings of the mind will be greatly clarified by ongoing research so that we will come to understand much better how the mechanisms operate. But why these processes are accompanied by something like consciousness seems likely to remain a mystery; no extension of physics that he can imagine seems likely to do the job, including the kind of new quantum mechanics that Roger Penrose believes is needed.

Witten is merely recording his intuitions, so we shouldn’t try to represent him as committed to any strong theoretical position; but his words clearly suggest that he is an optimist on the so-called Easy Problem and a pessimist on the Hard one. The problem he thinks may be unsolvable is the one about why there is “something it is like” to have experiences; what it is that seeing a red rose has over and above the acquisition of mere data.

If so, I think his incredulity joins a long tradition of those who feel intuitively that that kind of consciousness just is radically different from anything explained or explainable by physics. Horgan mentions the Mysterians, notably Colin McGinn, who holds that our brain just isn’t adapted to understanding how subjective experience and the physical world can be reconciled; but we could also invoke Brentano’s contention that mental intentionality is just utterly unlike any physical phenomenon; and even trace the same intuition back to Leibniz’s famous analogy of the mill; no matter what wheels and levers you put in your machine, there’s never going to be anything that could explain a perception (particularly telling given Leibniz’s enthusiasm for calculating machines and his belief that one day thinkers could use them to resolve complex disputes). Indeed, couldn’t we argue that contemporary consciousness sceptics like Dennett and the Churchlands also see an unbridgeable gap between physics and subjective, qualia-having consciousness? The difference is simply that in their eyes this makes that kind of consciousness nonsense, not a mystery.

We have to be a bit wary of trusting our intuitions. The idea that subjective consciousness arises when we’ve got enough neurons firing may sound like the idea that wine comes about when we’ve added enough water to the jar; but the idea that enough ones and zeroes in data registers could ever give rise to a decent game of chess looks pretty strange too.

As those who’ve read earlier posts may know, I think the missing ingredient is simply reality. The extra thing about consciousness that the theory of physics fails to include is just the reality of the experience, the one thing a theory can never include. Of course, the nature of reality is itself a considerable mystery, it just isn’t the one people have thought they were talking about. If I’m right, then Witten’s doubts are well-founded but less worrying than they may seem. If some future genius succeeds in generating an artificial brain with human-style mental functions, then by looking at its structure we’ll only ever see solutions to the Easy Problem, just as we may do in part when looking at normal biological brains. Once we switch on the artificial brain and it starts doing real things, then experience will happen.

24 Comments

  1. 1. SelfAwarePatterns says:

    Well said. We will likely explain all the components, and maybe eventually use those explanations to build artificial versions, but no understanding will ever add up the experience of actually being the system. In that sense, the Hard Problem will never be solved, at least not to the satisfaction of those troubled by it, but it will also not be an obstacle to progress.

  2. 2. Callan S. says:

    but the idea that enough ones and zeroes in data registers could ever give rise to a decent game of chess looks pretty strange too.

    Nice! I’m going to keep that one to use in future 🙂

    Maybe experience will be mapped more in terms of what it misses. All the things not seen, not smelt, not heard, not touched (certainly human sight only covering a certain amount of the electromagnetic spectrum is already clearly established). So experience might be mapped to a certain stream within a potential range. While a machine might be mapped to an entirely different stream pattern.

    I mean with the what-you-see-is-all-there-is type effect, the thing is experience is compelling in that it presents itself as the entire deal. Probably a lot of the experience of experience is that it denies anything outside of it as possible.

    Hope the spam system doesn’t eat this post 🙂

  3. 3. Jayarava says:

    Yet another physicist, steeped in metaphysical reductionism, admits that his worldview cannot explain consciousness, but does not see this as a problem with his worldview.

    Usually in science we allow our theory to make predictions, test them, and then either adjust or abandon our theory in response. Why are so many physicists and neuroscientists so reluctant to apply this procedure to the study of consciousness? By contrast, how many biologists are still metaphysical reductionists? I.e. how many biologists have abandoned observing their living organisms and insist that all that is needed to understand them is dissection and the genome? Probably none I suspect.

    I fully expect that physicists will be the *last* people to understand consciousness and a physicist would be the last person whose opinion on consciousness I would ask for. If anyone, it will be biologists who come to understand consciousness, because they at least allow for structure-antireductionism in their worldview and that will be a minimal requirement for studying something which is irreducible.

  4. 4. Sci says:

    Sorry, what’s strange about 1s and 0s making a chess game?

    We can explain that down to the atoms, maybe even the necessary quantum equations correct? (Well, except for the experiential parts I suppose but that just leads us back to the consciousness question.)

  5. 5. John Davey says:


    “Witten’s view is congenial to him because of his belief that science may be approaching an end state in which many big issues are basically settled while others remain permanently mysterious.”

    I wonder how many times down the centuries people have made this ludicrous assumption. “We know it all now, only a bit left”. You can read it in writings of the 18th century, 19th century, 20th century… no doubt the romans and the greeks said similar things. Utter hubris and unbelievable fixation with current culture : testament to the evergreen capacity of propaganda – it really does work, even in academic circles.

    If you know it all, how would you know you know it all in any case ?


    Witten’s view is congenial to him because of his belief that science may be approaching an end state in which many big issues are basically settled while others remain permanently mysterious.

    That’s a fact, and you don’t need to be a physicist to work that one out. Nonetheless it doesn’t mean science can’t solve the issue. Witten, and old-fashioned reductionist, evidently subscribes to the 0th law of physics, namely “all science” == “physics”

    “but the idea that enough ones and zeroes in data registers could ever give rise to a decent game of chess looks pretty strange too.”

    I have to say that this is just not the same. Zeros and ones can be used to make a turing machine, and a turing machine can hammer any rule-based task like playing chess. It’s not weird.

    “The extra thing about consciousness that the theory of physics fails to include is just the reality of the experience”

    It’s even simpler. Physics has a mathematics-based toolkit. You can’t get semantic from mathematics.

    That is why physics is built on three semantic building blocks : space, time and matter. It has a lot to say about the relationship between all three but nothing to say about each one of them individually. Physics has nothing to say about time(other than it’s relationship to space and energy) , nothing to say about space ( other than it’s relationship to time and energy) and nothing to say about matter ( other than it’s relationship to space and time).

    Space, time and matter are basic, semantic assumptions of physics, upon which the mathematical toolkit can sit. But those assumptions are what make physics a propert science and not just a branch of mathematics. Physics- contrary to the beliefs of many of its proponents – is not abstract but tied implicitly to the very building blocks of human cognition. It is a man-made creation in every sense, and thus limited to human cogntive scope and limits. Physics is not an a priori toolkit but an elaboration on the properties of earth-bound “stuff”. There is NO “information” in the world of physics, and attempts to show this are just plain daft.

    J

  6. 6. John Davey says:

    sorry



    Witten’s view is congenial to him because of his belief that science may be approaching an end state in which many big issues are basically settled while others remain permanently mysterious.

    That’s a fact, and you don’t need to be a physicist to work that one out. Nonetheless it doesn’t mean science can’t solve the issue. Witten, and old-fashioned reductionist, evidently subscribes to the 0th law of physics, namely “all science” == “physics”

    should be

    “But why these processes are accompanied by something like consciousness seems likely to remain a mystery; no extension of physics that he can imagine seems likely to do the job, ”

    That’s a fact, and you don’t need to be a physicist to work that one out. Nonetheless it doesn’t mean science can’t solve the issue. Witten, and old-fashioned reductionist, evidently subscribes to the 0th law of physics, namely “all science” == “physics”

    J

  7. 7. Callan S. says:

    For goodness sake, when the first gramaphones were used people would apparently look behind curtains and furniture for the singer. But zeroes and ones leading to an intellectually stimulating activity, which is to say experientially stimulating activity, has never been weird? The mechanical Turk did not raise even one eyebrow? I don’t think this is really gauging human reaction to these things.

  8. 8. VicP says:

    Is it any different Peter if I said I can track all of the movements of the planets and simulate all of the calculations in a computer program?

    Well tracking the movements is no different than saying I have all of the timing correct. But timing has little to do with the ‘feel’ of the forces of nature like gravity.

    A computer is just a fancy clock that recreates timing or behavior so it is limited to one dimension of nature. Biological cells have more dimensions so they exhibit mysterious effects like qualia, sentience etc.

  9. 9. Sci says:

    @ Callan: Those are just situations in historical context. I don’t really see that as “strange” in the same sense that consciousness is strange. Quantum weirdness would be more in the ball park, or that the laws of physics & universal constants are held fixed.

    Really computationalism seems to require laying a veil of mystique over what’s a completely understood process to make it a contender for sufficiently explaining consciousness. But pull the veil off and I see no more reason to believe in Turing Machine consciousness than car-engine consciousness.

  10. 10. John Davey says:

    Callan

    No. I don’t think using a rule based calculation system to play a rule based game is weird. If non-technical people marvel at automated chess – certainly an achievement in its day – Im not sure “weird” is the appropriate adjective – “marvellous” perhaps, or “amazing” but weird ?
    Certainly doesn’t really qualify as “weird”as consciousness arising from blobs of protein, which is “weird” even if you’re not a reductionist.

    J

  11. 11. John Davey says:

    Jayarava

    Agree, 100%

    Jbd

  12. 12. VicP says:

    Just like the geek who knows a lot about the computer including all of the various models and functions but do not have the slightest idea how to read the specs, circuit schematics and model diagrams. Similarly the physicist has knowledge of the basic components of nature but no idea how they structure up to a higher level. The philosopher like the geek is very adept at the language and concepts, able to communicate with others. I call it the MRI Approach or Mutually Reinforced Ignorance.

  13. 13. Sergio Graziosi says:

    When I first read this post I was anticipating the evil pleasure I’ll get from bashing another physicist. Now that I see how many have indulged already, I’m almost tempted to swing the other way.
    Almost! After all, the original temptation is still stronger. Against the current consensus I will only ask one question, which is mostly coming from my idiosyncratic kind of ignorance:

    Jayarava (#3), what exactly do you mean with “metaphysical reductionism”?
    My limited mind can understand “reductionism” as a method of enquiry, and even in this confined sense, I can find multiple interpretations which may all be equally valid (in their own context/scope/aim). Add “metaphysical” to it and the possible ways to interpret the definition explode beyond my abilities to cope. One possibility is that you are simply referring to monism, which would nicely explain the whole comment. I don’t want to reach this conclusion because I feel monism is the most sensible/defensible starting point, but otherwise I’d tend to agree with your comment (if I don’t dig too much, that is). So I’m conflicted!

    Back to the original plan, the one thing that I like about John’s comments is that he constantly makes Peter’s point, but in provocative terms. My take is that science, all science(!) relies on measurements and/or detection. Measuring/detecting requires the measured to have some effect on something else (the measuring/detecting device or the measurer/detector). Thus, all that science can do is investigate causal relations (Jochen: that’s why epiphenomena don’t mix well with science, which does not preclude the possibility of producing additional, purely theoretical & unverifiable offshoots). As both John and Peter keep reminding us in their own way, what makes reality real is not something that is accessible to science, and by extension, it is not the kind of knowledge that is accessible to us (or anyone). Fullstop. I enjoy bashing physicists because of their (well documented) tendency of forgetting this basic fact, justified by the fantastic success science has in mapping causal relations. Witten doesn’t seem to be the worse offender, but he’s getting

    Overall, Peter’s closure is a little gem, I think: it points to the mismatch between the limits of scientific enquiry (no, biology won’t produce a new, magically different solution to the Hard problem) and our different, opposing expectations: some presume that the hard problem really needs to be Hard with the capital H (i.e. unsolvable by definition), others retort that it must not be a problem at all. Both forget the hard limits of science/knowledge, and hence both starting points look hopeless to me…

  14. 14. VicP says:

    Sergio,

    True biology “as we know it” but the bridge between biology and physics is chemistry or its more complex child biochemistry. The “hard science” methodology of measurement/detection accounts for limited data in terms of all of the forces of nature present in chemical reactions and biochemical reactions at the highest levels of cell metabolic processes. How do we know these processes cannot “escape” the cells and form metaphysically “larger cells” or supercells?

    What would be the effect of a supercell? Well if starting with particles and working up to biological particles and theoretical supercells, the event horizon may be the emergent property or a form of time evolves within a nervous structure of activated neural networks.

    What is the anatomical equivalent for this evolution? Well muscle cells also have a short event horizon which evolve into muscles with very long event horizons. Nervous systems evolve for bodily movement.

    The spooky pansychism is no worse than saying a single H2O molecule is also a drop of water.

    John said: “…..physics is built on three semantic building blocks : space, time and matter.” Consciousness in our brain and mental experience is built on space, time and detection of objects. The brain is physically built around the somesthetic and somatosensory cortices that match right through the spinal chord that also moves the complex skeleton-muscle system which is also our philosophical body in the brain-body problem.

    An engineering approach is missing from the approach to the problem. Engineering expertise is required to analyze the system from the component level up to the system level. The people who write about this problem do not have this expertise.

  15. 15. John Davey says:

    Sergio

    IMHO it’s important to realise the “Hard” problem isn’t the problem it’s made out to be, and that is because of triumphalist physicists. So Witten says “physics can’t do this (now) so it’s just not possible to do it” . Indefinite mystery. Thus is outrageous physics-centrism, and an outrageously narrow contemporary bias, precluding the possibility of change in physics.

    The only other alternative for physics fundamentalists/axiom jihadis is the Dennett camp of pretending consciousness does not exist. Now that’s the dead end to out-dead all dead ends.

    The other alternative is to just do science without the religious physics fundamentalism. Brain matter produces consciousness : odd but evidently no more than that. The universe doesnt have to comply with a conception of physics. All over the earth (and probably elsewhere) it’s happening all the time : brains generating sadness, happiness, sexual excitement, all in peaceful ignorance of the fact it makes no sense to some physicists. Well, tough. The brain does it anyway.

    There is no hard problem and never has been : only a physics problem.

  16. 16. Michael Murden says:

    “…the idea that enough ones and zeroes in data registers could ever give rise to a decent game of chess looks pretty strange too.”

    It looks strange because at one time people though chess was an art, and therefore a uniquely human kind of activity. We have since learned otherwise. Why do some people think that we know enough about human brains to determine the nature of the relationship between brains and consciousness?

    One thing we should all be pretty sure about is that no consciousness has ever been observed independent of a brain. Another thing we should all be pretty sure about is that the destruction of the brain always destroys the consciousness associated with it. Given those two things, it seems reasonable to assume that the activity of brains makes consciousness possible. When surgeons cut the top of a person’s skull off to perform neurosurgery they see neurons, glial cells etc. They see a mere biological organ. If the activity of that merely biological organ makes consciousness possible why do we think that elucidating the process whereby it does so is any more impossible than elucidating the processes by which other organs, or systems of organs acting in concert, make other human phenomena possible? To put it another way, why do we think consciousness is something other than a biological process?

    The several thousand years of failure humans have experienced so far in trying to understand consciousness might be because philosophy does not possess the right tools for the job. I’d suggest letting science have at least as much time to work on the problem as philosophy has had before concluding that science can’t solve the problem. If we’re still as stuck 2500 years from now as we are now then I’ll concede that the hard problem is really hard.

  17. 17. Sci says:

    “One thing we should all be pretty sure about is that no consciousness has ever been observed independent of a brain.”

    What about microscopic organisms that don’t have brains?

  18. 18. Sergio Graziosi says:

    VicP,
    you lost me almost immediately: event horizon of cells, of supercells and muscles? I have no idea!
    I can sort-of make contact again with the latter paragraphs, for example, I can parse this:

    Consciousness in our brain and mental experience is built on space, time and detection of objects.

    Just to add more gibberish to the mix, here is a thought of mine: what we perceive as “time”, is a function of how our genes replicate, not the other way round. I’ll leave it like this, as in this thread we all seem happy to talk in riddles ;-).

    An engineering approach is missing from the approach to the problem. Engineering expertise is required to analyze the system from the component level up to the system level. The people who write about this problem do not have this expertise.

    Well, most philosophers know little about biology as well. Then you have neuroscientists/psychologists like Graziano, he openly espouses the “engineering” approach, but perhaps has less time for purely philosophical conundrums. It’s worth noting that some philosophers (or some people in general!) will not, and never will be convinced by an engineering success, the works of “some future genius” from the OP: if we merely deploy an engineering approaches, anyone will be able to just play the zombie card and keep philosophising between themselves. The world would leave these people behind, eventually, but that’s not a good thing, because the implications of such an engineering success are wide, profound an potentially catastrophic. If it will indeed happen, we’ll need people able to think about consequences and possible scenarios, in other words, we’ll need good philosophising.
    (One reason why I love this place).

    John: I don’t know! I’m bad with labels, and struggle already to keep science nicely wrapped. Within science, I see only convenient subdivisions based on tools/expertise. I don’t see a sharp separation between biology and physics, they can be bridged across via chemistry, as VicP pointed out [notably, when I started my very brief experience in postgrad research, I was “officially” doing biophysics; by the time I’ve finished I was doing neurobiology. The labels changed for administrative reasons, what I was doing didn’t!]. So if a problem exists because of how we do physics, it won’t be solved via biology, because it ipso-facto applies to biology as well. It may be solved by developing new epistemological way to create knowledge, but these would apply to all of science broadly construed, if they will ever happen. That’s why I was asking what Jayarava means with “metaphysical reductionism”: perhaps I’m missing something and he (or you) see a sharp epistemological divide between physics and biology, while I see none.

    Sci,

    What about microscopic organisms that don’t have brains?

    Well, I don’t think there is anything like being a single cell (whether it’s a single independent cell or one in an organism: does it really matter? If it does, why?). As you know, I have a convenient theory to explain why, isn’t that handy?

  19. 19. VicP says:

    Sergio,
    I won’t get deeper into the event horizon for now, but perhaps see if others can weigh in and see if they understand me or not.

    Engineering is not just stark formulas and calculations but dealing with real forces like gravity when designing a building or dissipating generated heat when you design faster computer hardware.

    Engineering also deals with having a basic design for a system. Classic example is Hacker in the posted video above where he explains you can express the experience of falling in love or seeing a performance of Hamlet as wonderful; but conversely cannot express the experience of seeing the third lamppost on a street. Well true the first two involve emotion and new experience which are emotionally based vs the lamppost which is based in our visual system. The error he is making is not knowing that the limbic system and emotions is very separate from pure visual experiences.

    I like Graziano’s engineering approach because he is an academic psychologist who has a firmer handle on nervous system structure.

  20. 20. Michael Murden says:

    To Sci:

    This is a difficult conversation to have without a rigorous definition of consciousness, but I’ll ask anyway. Are you saying you have observed the sort of consciousness Professor Witten is calling inexplicable, the sort of consciousness we talk about when we use terms like qualia and hard problem in a microscopic organism?

  21. 21. Sci says:

    @ Michael Murden: Well the only consciousness I’ve ever observed is my own. And I can ascribe intentional stances to other biological systems.

    I guess it’s not clear to me how one goes about excluding the possibility of microbe consciousness while keeping non-human mammalian consciousness?

  22. 22. Michael Murden says:

    To Sci:

    Are microbes among the biological systems to which/whom you ascribe intentional stances? It would be interesting if you did, because there is much less room in a microbe than in a human for any sort of non-biological consciousness or soul or intentionality to hide. I don’t find the idea of consciousness or intentionality or qualia unbelievable but I don’t see how anyone can have concluded these sorts of things are nonbiological except on religious grounds.

    To pose a related question, are these sorts of inscrutable algorithms conscious? Is there something it is like to be this machine?

    http://www.slate.com/articles/technology/bitwise/2015/01/black_box_society_by_frank_pasquale_a_chilling_vision_of_how_big_data_has.html

  23. 23. Sci says:

    @ Michael:

    Not sure why we’re talking about non-biological consciousness/soul?

    I actually agree that it’s a leap of faith to think of consciousness as non-biological, why I reject the computationalist faith.

  24. 24. Phil Lectrip says:

    If the Hard problem is solvable, that means that if I had enough monkeys typing 0’s and 1’s for long enough, I would eventually end up with a working (Digital) copy of my own consciousness. Does that seem right?

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