Is Bohmian Mechanics incompatible with free will/choice?

[bohm2]

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:

A prominent example is the de Broglie-Bohm model which recreates quantum correlations, providing higher explanation in the form of hidden particle positions. These can be thought of as parameters of a higher theory that would allow perfect predictions of the outcomes. However, introducing these parameters comes at a price: it is incompatible with the freedom of choice assumption of our theorems.

The completeness of quantum theory for predicting measurement outcomes
http://arxiv.org/pdf/1208.4123.pdf

Is a system's wave function in one-to-one correspondence with its elements of reality?
http://arxiv.org/pdf/1111.6597v2.pdf

No extension of quantum theory can have improved predictive power
http://arxiv.org/pdf/1005.5173v3.pdf

A short note on the concept of free choice
http://arxiv.org/pdf/1302.4446.pdf

2. Bohmian mechanics is compatible with free will/choice:

Here we prove that the argument is basically flawed by an inappropriate use of the assumption of free will. In particular, among other implications, the claim, if correct, would imply that Bohmian Mechanics is incompatible with free will. This statement, appearing in the paper, derives from the unjustified identification of free will with the no-signaling constraint and of a purely formal and not physical use of such a constraint.

About possible extensions of quantum theory
http://lanl.arxiv.org/pdf/1301.5040v1.pdf

Comment on "Is a system's wave function in one-to-one correspondence with its elements of reality?"
http://arxiv.org/pdf/1301.5040v1.pdf

On the completeness of quantum mechanics and the interpretation of the state vector
http://lanl.arxiv.org/pdf/1302.6278.pdf

 

[Demystifier]

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.

 

[bohm2]

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:

A first argument arguing that ψ-epistemic models necessarily contrast with quantum mechanics was developed in (Pusey et al.), but its conclusions are severely limited by the assumption that factorized quantum states correspond to factorized states of the underlying theory. In fact, an explicit ψ-epistemic model has been built by relaxing this assumption (Lewis et al.).

Ghirardi writes the same thing in another one of his papers:

Therefore, violation of FR (freedom of choice of measurement settings) does not necessarily imply lack of free will as long as ST or NS are violated. This means that ψ-epistemic models fully consistent with quantum mechanics, with the free will assumption and without superluminal communication are indeed possible, as long as the supplementary information on the ontic state is not static P_C|ABXY = P_C. For instance, they can be easily built by following the lines described in (Lewis et al.)

Comment on “Is a Systems Wave Function in One-to-One Correspondence with Its Elements of Reality?
http://lanl.arxiv.org/pdf/1302.1635.pdf

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:

Let me briefly explain the interesting science that lies at the heart of the “key assumption” the editor is alluding to in the above. I will call this assumption preparation independence. Suppose an experiment at one lab reproduces the results of an earlier experiment at another. This would righty be called an “independent” verification of the first lab’s results. No scientist would attempt to refute this by appealing to correlations between random events at the two labs, there being no realistic mechanism for such to be established. Even in a single lab, repeated runs of an experiment must be assumed independent in order to estimate probabilities based on the results. Preparation independence is simply the assumption that we have the ability to build independent, uncorrelated experimental apparatuses to act as preparation devices of microscopic systems, and that any deeper theory of nature than quantum theory will not overthrow this principle by virtue of “hidden super-correlations” where to date scientists have always successfully assumed there are none.

The theorem we prove – that quantum states cannot be understood as merely lack of knowledge of an underlying deeper reality described by some as yet undiscovered deeper theory – assumes preparation independence. It is an important insight that this assumption is necessary for the theorem, and the point of our second paper was to show this explicitly. That second paper is, however, simply making a mathematical/logical point – it is not a serious proposal for how the physical world operates..

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:

We further assume that a complete description can be obtained by confining our attention to a specific set of physical systems, the rest of the universe not contributing at all, as appropriately required by Shimony, Horne and Clauser...Accordingly, we do not consider superdeterministic models in our analysis.

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?

Or

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?

 

[1977ub]

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.

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...

 

[bohm2]

Anyhow, I'm a bit surprised that free will is of serious concern in physics...

Some physicists do believe it is important for the following reasons:

Bell comments:

There is a way to escape the inference of superluminal speeds and spooky action at a distance. But it involves absolute determinism in the universe, the complete absence of free will. Suppose the world is super-deterministic, with not just inanimate nature running on behind-the-scenes clockwork, but with our behavior, including our belief that we are free to choose to do one experiment rather than another, absolutely predetermined, including the "decision" by the experimenter to carry out one set of measurements rather than another, the difficulty disappears. There is no need for a faster than light signal to tell particle A what measurement has been carried out on particle B, because the universe, including particle A, already "knows" what that measurement, and its outcome, will be.

Anton Zeilinger similarily writes:

[W]e always implicitly assume the freedom of the experimentalist... This fundamental assumption is essential to doing science. If this were not true, then, I suggest, it would make no sense at all to ask nature questions in an experiment, since then nature could determine what our questions are, and that could guide our questions such that we arrive at a false picture of nature.

 

[1977ub]

Some physicists do believe it is important for the following reasons...

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...

 

[bahamagreen]

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?

 

[Demystifier]

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.

 

[bohm2]

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.

I think this sounds a bit like the following:

While some argue that unpredictable (or random) choice does not qualify for their definition of free will, it is precisely the freedom from the chains of causality that most scholars see as a crucial prerequisite for free will. Importantly, this freedom is a necessary but not a sufficient component of free will. In order for this freedom to have any bearing on moral responsibility and culpability in humans, more than mere randomness is required. Surely, no one would hold a person responsible for any harm done by the random convulsions during an epileptic seizure. Probably because of such considerations, two-stage models of free will have been proposed already many decades ago...one stage generates behavioural options and the other one decides which of those actions will be initiated. Put simply, the first stage is ‘free’ and the second stage is ‘willed’. This implies that not all chance events in the brain must manifest themselves immediately in behaviour. Some may be eliminated by deterministic 'selection' processes before they can exert any effects. Analogous to mutation and selection in evolution, the biological process underlying free will can be conceptualized as a creative, spontaneous, indeterministic process followed by an adequately determined process, selecting from the options generated by the first process. Freedom arises from the creative and indeterministic generation of alternative possibilities, which present themselves to the will for evaluation and selection. The will is adequately determined by our reasons, desires and motives—by our character—but it is not pre-determined.

Towards a scientific concept of free will as a biological trait: spontaneous actions and decision-making in invertebrates
http://rspb.royalsocietypublishing.org/content/278/1707/930.full.pdf

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.

 

[Quantumental]

bohm2: the brain obeys classical mechanics, so QM doesn't matter, you still don't get free will.

 

[bohm2]

bohm2: the brain obeys classical mechanics, so QM doesn't matter, you still don't get free will.

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.

 

[Nugatory]

bohm2: the brain obeys classical mechanics, so QM doesn't matter, you still don't get free will.

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.

 

[Quantumental]

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.

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.

 

[SuccessTheory]

bohm2, regarding what you said earlier about Bell's comments on free will, will these experiments (1, http://discovermagazine.com/2010/apr/01-back-from-the-future#.URdziWc4D0c) on future decisions affecting past outcomes solidify the possibility that:

There is no need for a faster than light signal to tell particle A what measurement has been carried out on particle B, because the universe, including particle A, already "knows" what that measurement, and its outcome, will be.

 

[bohm2]

bohm2, regarding what you said earlier about Bell's comments on free will, will these experiments (1, http://discovermagazine.com/2010/apr/01-back-from-the-future#.URdziWc4D0c) on future decisions affecting past outcomes solidify the possibility that:

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:

The only reasonable resolution seems to be that of the Two-State-Vector Formalism, namely that the weak measurement's outcomes anticipate the experimenter’s future choice, even before the experimenter themselves knows what their choice is going to be. Causal loops are avoided by this anticipation remaining encrypted until the final outcomes enable to decipher it...Ergo, the weak measurements’ agreement with the strong measurements could have been obtained only by the former anticipating the spin orientation to be chosen for the latter. This result indicates the existence of a hidden variable of a very subtle type, namely the future state-vector...Therefore, when a weak measurement precedes a strong one, the only possible direction for the causal effect is from future to past.

Finally, this experiment sheds a new light on the age-old question of free will. Apparently, a measurement's anticipation of a human choice made much later renders the choice fully deterministic, bound by earlier causes. One profound result, however, shows that this is not the case. The choice anticipated by the weak outcomes can become known only after that choice is actually made. This inaccessibility, which prevents all causal paradoxes like “killing one's grandfather,” secures human choice full freedom from both past and future constraints.

Can a Future Choice Affect a Past Measurement's Outcome?
http://arxiv.org/ftp/arxiv/papers/1206/1206.6224.pdf

 

[1977ub]

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.

 

[bohm2]

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.

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.

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 (!)

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?

 

[1977ub]

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?

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.

 

[bohm2]

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.

Without sentience, you don't have empirical evidence as argued in this famous quote:

Wretched mind, from us you are taking the evidence by which you would overthrow us? Your victory is your own fall.

 

[1977ub]

Without sentience, you don't have empirical evidence as argued in this famous quote:

Without *my* sentience, *I* don't have empirical evidence. This empirical evidence *I* have can never include *your* sentience.

 

[ParticleGrl]

Without *my* sentience, *I* don't have empirical evidence. This empirical evidence *I* have can never include *your* sentience.

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.

 

[1977ub]

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.

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:

The philosopher Georges Rey once told me that he has no sentient experiences. He lost them after a bicycle accident when he was fifteen. Since then, he insists, he has been a zombie. I assume he is speaking tongue-in-cheek, but of course I have no way of knowing, and that is his point ... At least for now, we have no scientific purchase on the special extra ingredient that gives rise to sentience. As far as scientific explanation goes, it might as well not exist. It's not just that claims about sentience are perversely untestable; it's that testing them would make no difference to anything anyway.

- Steven Pinker, How The Mind Works

 

[James MC]

It would be worth distinguishing two notions of free will (e.g. using subscripts).

I have free will_C 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 will_I 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 will_C 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 will_I. But just because consciousness is a mystery doesn't mean that there is reason to believe in free will_I.

 

[bohm2]

Why limit it to people. Why not rocks and planets? Should humans have a "special vantage point?"

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 most popular attitude to the Hard Problem among neuroscientists is that it remains unsolved for now but will eventually succumb to research that chips away at the Easy Problem. Others are skeptical about this cheery optimism because none of the inroads into the Easy Problem brings a solution to the Hard Problem even a bit closer. Identifying awareness with brain physiology, they say, is a kind of "meat chauvinism" that would dogmatically deny consciousness to Lieut. Commander Data just because he doesn't have the soft tissue of a human brain. Identifying it with information processing would go too far in the other direction and grant a simple consciousness to thermostats and calculators--a leap that most people find hard to stomach. Some mavericks, like the mathematician Roger Penrose, suggest the answer might someday be found in quantum mechanics. But to my ear, this amounts to the feeling that quantum mechanics sure is weird, and consciousness sure is weird, so maybe quantum mechanics can explain consciousness.

And then there is the theory put forward by philosopher Colin McGinn that our vertigo when pondering the Hard Problem is itself a quirk of our brains. The brain is a product of evolution, and just as animal brains have their limitations, we have ours. Our brains can't hold a hundred numbers in memory, can't visualize seven-dimensional space and perhaps can't intuitively grasp why neural information processing observed from the outside should give rise to subjective experience on the inside. This is where I place my bet, though I admit that the theory could be demolished when an unborn genius--a Darwin or Einstein of consciousness--comes up with a flabbergasting new idea that suddenly makes it all clear to us.

Whatever the solutions to the Easy and Hard problems turn out to be, few scientists doubt that they will locate consciousness in the activity of the brain. For many nonscientists, this is a terrifying prospect. Not only does it strangle the hope that we might survive the death of our bodies, but it also seems to undermine the notion that we are free agents responsible for our choices--not just in this lifetime but also in a life to come. In his millennial essay "Sorry, but Your Soul Just Died," Tom Wolfe worried that when science has killed the soul, "the lurid carnival that will ensue may make the phrase 'the total eclipse of all values' seem tame."

The Brain: The Mystery of Consciousness
http://www.time.com/time/printout/0,8816,1580394,00.html

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.

So are you saying that the "physical" (now or in the future) can never accommodate the mental because we can never measure it directly?

 

[1977ub]

So are you saying that the "physical" (now or in the future) can never accommodate the mental because we can never measure it directly?

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.

 

[bohm2]

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.

How about with respect to the quantum states? The quantum state cannot be observed directly either as it can only be reconstructed indirectly by lengthy state estimation procedures. What about dark matter? I just think that defining what's "physical" seems like a difficult task because it changes as our physics changes. I thought this was an interesting comment on this issue:

There is one final issue that deserves a word of comment. I have been using mentalistic terminology quite freely, but entirely without prejudice as to the question of what may be the physical realisation of the abstract mechanisms postulated to account for the phenomena of behaviour or the acquisition of knowledge. We are not constrained, as was Descartes, to postulate a second substance when we deal with phenomena that are not expressible in terms of matter in motion, in his sense. Nor is there much point in pursuing the question of psychophysical parallelism, in this connection. It is an interesting question whether the functioning and evolution of human mentality can be accommodated within the framework of physical explanation, as presently conceived, or whether there are new principles, now unknown, that must be invoked, perhaps principles that emerge only at higher levels of organisation than can now be submitted to physical investigation. We can, however, be fairly sure that there will be a physical explanation for the phenomena in question, if they can be explained at all, for an uninteresting terminological reason, namely that the concept of “physical explanation” will no doubt be extended to incorporate whatever is discovered in this domain, exactly as it was extended to accommodate gravitational and electromagnetic force, massless particles, and numerous other entities and processes that would have offended the common sense of earlier generations. But it seems clear that this issue need not delay the study of the topics that are now open to investigation, and it seems futile to speculate about matters so remote from present understanding.

Langauge and Mind
http://books.google.ca/books/about/Language_and_Mind.html?id=HMtLMhwCXDoC&redir_esc=y