As a student of theoretical physics I'm well acquainted with the multitude of crackpot ideas attempting to circumvent Bell's theorem regarding local hidden variable theories in quantum physics.

Recently, however, I've been working on my master's thesis regarding Bayesian probability, and I came across a very interesting paper by Jaynes on precisely the subject of Bell's theorem (E.T. Jaynes, Clearing Up Mysteries - The Original Goal, In: Proceedings, Maximum Entropy and Bayesian Method, 1989).

Jaynes writes about what he calls the Mind Projection Fallacy and its prevalence in quantum mechanics. He claims the fallacy is a result of failing to appreciate probabilities as representations of states of knowledge (epistemological), as opposed to as fundamental properties of nature (ontological); clearly, Jaynes advocates the Bayesian perspective on probability.

Using his 'Bayesian inference as extended logic' approach, Jaynes derives a number of - to me - impressive results in this paper and others. More to the point, on pages 7-16 he explains two objections to Bell's results:

  1. Bell didn't appreciate the difference between the epistemological nature of probability in making predictions and the ontological nature of causality. This lead him to propose the wrong probability distribution for his class of hidden variable theories; one which is indeed (trivially) violated by quantum mechanics.

  2. Bell did not include all local hidden variable theories. For instance, his choice excludes those where the hidden variables are time-dependent.

These objections don't read crackpot in my opinion, and as demonstrated in the linked papers there is a slight historic tendency for the Bayesian perspective to make one see old results in a new light, particularly in other fields of physics.

I've heard that Jaynes is adept at making himself seem obviously right and others obviously wrong - so I may have fallen for that trap - but this argument struck me as something that should've gotten a lot more attention than I'm aware it has. That is, I was still taught the Copenhagen interpretation complete with Bell's theorem ruling out local determinism, which seems to imply that this argument has either not gotten mainstream attention or has been thoroughly debunked.

Are there any obvious counters to Jaynes' viewpoint that I'm not aware of?

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    $\begingroup$ This blog post comes from a similar position as you and provides references to work that (nominally) answers your question. $\endgroup$ – Derek Elkins left SE Feb 2 '16 at 0:07
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    $\begingroup$ But then Jaynes did not give an example of a locally deterministic theory where Bell's theorem is actually violated. $\endgroup$ – Count Iblis Feb 2 '16 at 0:08
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    $\begingroup$ Great question! +1 $\endgroup$ – Thriveth Feb 2 '16 at 0:42
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    $\begingroup$ @DerekElkins: I'm still rather confused on one issue. Jaynes claims that Bell's assumptions are wrong, and the paper by Colbeck and Renner mentions similarly that the assumptions are too strong, in a way that is reminiscent of Jaynes' logical vs physical causality argument. On the other hand, they explain their assumptions are weaker because they want to exclude more theories, not because Bell is wrong. Jaynes is wrong about a more informative theory existing (either classical or quantum), but his argument regarding Bell's assumptions still seems compelling. I don't know what to make of this. $\endgroup$ – Timsey Feb 2 '16 at 18:40
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    $\begingroup$ Yes, e.g. 't Hooft has been working on locally deterministic models, he claims that the superdeterminism loophole is going to make his effort not futile. But what ultimately matters is whether or not his proposed models will end up working or not. $\endgroup$ – Count Iblis Feb 2 '16 at 19:29

Bell's argument actually fails in a deterministic universe. The argument's fundamental assumption is that the outcome of a measurement on one particle can't depend on the measurement basis chosen by the other experimenter for the other particle at a spacelike separated location. This is usually described as a locality assumption, but there's more to it than that. If the experimenter's choice is actually an inevitable consequence of the state of the universe at earlier times, then it's possible that it's an inevitable consequence of the state at the place and time that the entangled pair of particles was created. If so, the particles could decide then and there how to respond to the measurements that inevitably will happen later, reproducing the prediction of quantum mechanics without any spooky long-distance communication.

It's hard to imagine how elementary particles could know in advance the result of a physical process as complicated as the choice of a measurement basis by an experimenter, nor how that choice could be predictable solely from information localized in a small part of its past light cone, and as far as I know no one has actually proposed a local hidden variable theory in which this happens. But Bell didn't prove it impossible.

So if Jaynes is taking the hardline position that the universe is deterministic and all probabilities are inherently about our lack of knowledge of its state, I think he's at least morally correct, and he may be literally correct in his entire argument. He's right that Bell's argument assumes a Y-causes-X relationship in the probabilities P(X|Y), and he's right that there is no such relationship in subjective probabilities. You need some kind of objective unpredictability in the world for Bell's argument to go through – not quantum unpredictability, but some sort of free choice or true classical randomness at the spacelike separated locations of the measurements.

To the extent that Jaynes acts like the mystery of Bell's theorem is totally resolved just because he can model the quantum prediction in his classical probabilistic logic, I think he's wrong. A deterministic model where particles know the future is not logically impossible, but it would be really frickin' weird, and I don't expect any such model to appear. (Although, quantum mechanics is also weird, and I never would have predicted it, so I suppose I should expect to be surprised.)

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This sounds more like a mild crackpot, the further I read. He accuses Bohr of assuming that all instruments are subject to the uncertainty principle (fourth paragraph, page 8). This, however, was an experimental observation, not an assumption. Page 9, end of paragraph 2, he accuses Bohr of confusing limitations on QM theory with limitations on the validity of lab measurements. This is a rather dubious point, as theory is needed to interpret experimental results. Further on page 9, 5th paragraph, he essentially refutes the orthodox QM view by defining it as incorrect, stating that it violates his "necesarry division of labor" in theoretical physics.

At the top of page 13, the author makes a distinction between a physical influence faster than light and a logical inference, which is charactaristic of the intangibility of the "spooky action at a distance". It does not, however, change the result of the reasoning of the EPR experiment.

The last part, where it looks like he's getting into a possible loophole, he mentions time-varying hidden variables, but really doesn't say clearly how this would work. His closing statement sums his views up well.

It is very common for crackpots to object to relativity or quantum mechanics on "philosophical" grounds, (which I put in quotes to avoid insulting philosophers) and treat their own philosophy as axiomatic. This seems to be what he's doing.

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    $\begingroup$ Jaynes possessed hallmarks of a crackpot - a prolific writer who expressed himself in acerbic, polemical language, proselytized about his ideas, and had a somewhat conspiratorial view of science and mistrust of authorities. But unlike a crackpot, Jaynes made significant, strikingly original contributions in several fields in physics and remains greatly respected in fields he influenced. $\endgroup$ – innisfree Sep 24 '16 at 6:00

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