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Is Bohmian Mechanics incompatible with free will/choice?

  1. Feb 26, 2013 #1
    There has been some back and forth debate between Colbeck et al. vs. Ghirardi et al. on whether a recent no-go theorem by Colbeck and Renner would imply that Bohmian Mechanics is incompatible with free will/choice. I don't fully understand all the arguments but I thought I'd post them here in case someone who understands or read the papers might comment:

    1. Bohmian mechanics is incompatible with free will/choice:
    The completeness of quantum theory for predicting measurement outcomes

    Is a system's wave function in one-to-one correspondence with its elements of reality?

    No extension of quantum theory can have improved predictive power

    A short note on the concept of free choice

    2. Bohmian mechanics is compatible with free will/choice:
    About possible extensions of quantum theory

    Comment on "Is a system's wave function in one-to-one correspondence with its elements of reality?"

    On the completeness of quantum mechanics and the interpretation of the state vector
    Last edited: Feb 27, 2013
  2. jcsd
  3. Feb 27, 2013 #2


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    The answer to the question whether Bohmian Mechanics is compatible with free will/choice crucially depends on the precise definition of the free will/choice itself. It seems that different authors use different definitions and cannot agree which definition is most suitable.
  4. Mar 3, 2013 #3
    The thing that confuses me is that both authors (Ghirardi and Colbeck et al.) appear to appeal to one of the free will/choice assumptions used in the PBR theorem but interpret that assumption differently. For instance, Ghirardi writes:
    Ghirardi writes the same thing in another one of his papers:
    Comment on “Is a Systems Wave Function in One-to-One Correspondence with Its Elements of Reality?

    Note, however, that with respect to the Lewis et al. paper that Ghirardi is talking about, one of the authors of both those papers (Terry Rudolph) writes that the key assumption is, in fact, preparation independence (no conspiracy/superdeterminism) just like in Bell's theorem:
    So basically Terry Rudolph is arguing that PBR relies on the same free will/choice assumption (preparation independence) as Bell's theorem so neither theorem is able to rule out superdeterminism. But then Ghirardi in that same paper appears to argue the following:
    Maybe I'm messing up something here but does this mean that:

    1. if Ghirardi is correct, the key assumptions used in both PBR and Colbeck's et al. no-go theorems are not really denying superdeterminism but something far weaker?


    2. If they are, in fact, denying free choice (no superdeterminism), does that mean deBroglie-Bohm models that tries to extend quantum theory via hidden variables can only do so by violating that free choice/will assumption as Colbeck et al. seem to be arguing?
    Last edited: Mar 3, 2013
  5. Mar 4, 2013 #4
    Empirical experiments aside, free will/choice seems to fall apart under nearly any close examination... your actions have effects, but also must be nested in chains of cause-and-effect, thus must have causes. If one does not prefer a material deterministic reason against free will, there is always something more abstract or fundamental. Does a person choose something they don't prefer (for some reason)? Sounds absurd. No, they choose something which is in accord with their own concerns, preferences, desires. Do they choose *what* they prefer - do they choose their own process/system of concerns, preferences, desires? If one answered yes, one would have to ask "on what basis did one choose one's own process/system of preferences?" a meta-process/meta-system of meta-preferences? Infinite regress. Anyhow, I'm a bit surprised that free will is of serious concern in physics...
  6. Mar 4, 2013 #5
    Some physicists do believe it is important for the following reasons:

    Bell comments:
    Anton Zeilinger similarily writes:
  7. Mar 4, 2013 #6
    Yes I saw that on the wiki page. I understand about the freedom of the experimentalist... But when I hear people opposed in general to the very idea of determinism, it makes me wonder if they're trying their hardest to find a deterministic theory...
  8. Mar 5, 2013 #7
    I would think that any method incorporating foundational probability implicitly makes assumptions about determinism.

    Unitarity seems to be maintained from the future to the past by shifting from a sum of probabilities of all possible outcomes to a single outcome... a non time-symmetric operation?
  9. Mar 5, 2013 #8


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    Free will and determinism can be thought of as compatible with each other in the following sense:

    A man can do whatever he decides to do.
    However, he cannot decide whatever he wishes.
  10. Mar 5, 2013 #9
    I think this sounds a bit like the following:
    Towards a scientific concept of free will as a biological trait: spontaneous actions and decision-making in invertebrates

    I'm not sure but I always thought that the Pilot wave offered the greatest hope for free will because of the absence of a classical reaction (e.g. the wave function acts upon the positions of the particles but, evolving as it does autonomously via Schrödinger's equation, the wave function is not acted upon by the particles). But it might be wishful thinking? Regardless, I'm pretty confused.
  11. Mar 5, 2013 #10
    bohm2: the brain obeys classical mechanics, so QM doesn't matter, you still don't get free will.
  12. Mar 5, 2013 #11
    There's a mind also. We haven't solved the "hard" problem, yet. So it's not a given that QM (or whatever theory supercedes it in the future) doesn't matter, at least at some level, and I'm aware of Tegmark's arguments, to the contrary.
    Last edited: Mar 5, 2013
  13. Mar 5, 2013 #12


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    You will find "The emperor's new mind" by Roger Penrose to be a fascinating argument to the contrary.

    I personally agree with the reviewer who described it as "profoundly unconvincing", but in metaphysics there's a big difference between being unconvincing and being wrong.
  14. Mar 6, 2013 #13

    I don't see the "hard problem", at all, mind is what the brain does.
    Sure I accept that qualia etc. is hard to explain, but for the most part I am quite content with the "standard" redutionist-functionalist view of mind.
    Also decision is clearly not affected by the hard problem, we can put people in scanners today and read their decisions seconds before they execute them.

    Tegmark does indeed raise very good arguments as to why QM cannot affect decision making.
    However I think it's even easier to just think about it this way:

    If there was any part of the brain that somehow magically went outside the causal domino brick view then your decisions would be completely separate from your identity (which is ruled by the causal domino bricks) and your actions would ultimately just be irreducible random. Not *your will* and certainly not *free will*, but random will.

    I understand that some people find this philosophically weird because they automatically assume that it renders every action they make completely pointless and that they suddenly have become robots. But that's so wrong.
    Your decisions are still your decisions, you are after all your brain, sure from a birds POV you couldn't have chosen differently, but so what? That is what makes you, you, the choice you make.
  15. Mar 6, 2013 #14
    bohm2, regarding what you said earlier about Bell's comments on free will, will these experiments (1, 2) on future decisions affecting past outcomes solidify the possibility that:

  16. Mar 6, 2013 #15
    I posted some of the research of Aharonov's stuff that your links refer to previously. I did not understand the implications. Is it consistent with superdeterminism, Transactional interpretation or what? Do those experiments shed any light whatsoever on the question of free will/choice? I didn't understand it. Maybe someone can decipher the meaning of these quotes from the authors of that research:
    Can a Future Choice Affect a Past Measurement's Outcome?
  17. Mar 6, 2013 #16
    Not to stray too far off into the aether, but the "hard problem" refers to sentience aka first person subjective experience, of which it is not often enough said that there is no empirical evidence (!) For me, perhaps, your mind is what your brain does, but then I can't extrapolate to confidently characterizing you as having a subjective experience. I may as well describe a rock's mind as what a rock does.
  18. Mar 6, 2013 #17
    But that's the whole point. The standard reductionist-functionalist can't explain/deal with qualia. That doesn't mean anything mystical. It may mean that either the reduction "base" (physics) is not yet completed to allow us to see how neural stuff spits out mental stuff (unification problem) or humans are not smart enought to figure it out.
    Maybe I'm misunderstanding you (?) but I'm far more confident in my sentience/existence than I am about any scientific theory. Or is that what you're saying?
    Last edited: Mar 6, 2013
  19. Mar 6, 2013 #18
    What about your neighbor's sentience? You don't have empirical evidence for it. You don't have "empirical evidence" of your own! You can say your knowledge of your own sentience transcends empirical endeavor if you like. But it's impossible to "fit" sentience into empirical science.
  20. Mar 6, 2013 #19
    Without sentience, you don't have empirical evidence as argued in this famous quote:
  21. Mar 6, 2013 #20
    Without *my* sentience, *I* don't have empirical evidence. This empirical evidence *I* have can never include *your* sentience.
  22. Mar 6, 2013 #21
    One of the fundamental assumptions of science is that you (or I) don't occupy a special vantage point. Lots of principles would assert that if I have evidence of my sentience, I extend the concept to you as well, unless I have a specific reason not to.

    Sure, I could be the only sentient person, and also God could have created the Earth 6k years ago and put older dinosaur bones in it just to trick and test us.
  23. Mar 6, 2013 #22
    Why limit it to people. Why not rocks and planets? Should humans have a "special vantage point?"

    Either I believe my neighbor is conscious due to something I can measure (physical science*) or for some other reason (inertia? sentiment? a sense of fairness, not wishing to place myself in a "special vantage point?" )

    *this turns out to be a dead end, in the case of sentience.

    I've seldom seen it put as well as Pinker did:

    - Steven Pinker, How The Mind Works
  24. Mar 6, 2013 #23
    It would be worth distinguishing two notions of free will (e.g. using subscripts).

    I have free willC provided that my actions are caused internally, by my beliefs and desires, as opposed to externally, e.g. by someone else forcing me to do things. Here, 'C', refers to "compatibilism", or the compatibility of free will with determinism (or quantum indeterminism, for that matter).

    I have free willI provided that my actions are caused by my own conscious deliberations, and my conscious deliberations are the first cause of those actions (e.g., my own conscious deliberations are not the causal result of the big bang). Here, "I' refers to "incompatibilism" or the incompatibility of free will with determinism (or quantum indeterminism, for that matter). Sometimes incompatibilism is referred to as "liberterianism".

    The mainstream view amongst philosophers is that free willC is the correct analysis of free will. On this view, the physicists you are referencing are speaking nonsense.

    Still, you rightly note that due to the hard problem, there is no physical explanation of consciousness, which may leave open the possibility that there really does exist free willI. But just because consciousness is a mystery doesn't mean that there is reason to believe in free willI.
  25. Mar 7, 2013 #24
    Because most prefer 'emergence', even if it is the 'brute' type over panpsychism/panprotopsychism. With respect to Pinker's view on consciousness he supports McGinn's mysterianism view; consciousness is a natural/real phenomena but we may not be up to the task of figuring out how nature performs the trick:
    The Brain: The Mystery of Consciousness
    So are you saying that the "physical" (now or in the future) can never accomodate the mental because we can never measure it directly?
  26. Mar 7, 2013 #25
    Simply, one's belief in "other minds" - the consciousness of one's neighbor - is unfalsifiable. Does it belong in science? That's a hurdle to get over before all of the sentences & philosophies which take the consciousness of everybody else for granted. If one person tells you that your neighbor is a conscious entity (as you probably believe) and another person tells you that your neighbor is a zombie / automaton, you don't have - and let's be honest you can in principle never have - a rigorous empirical way of deciding.
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