Graduate Consistent Histories solipsism?

[Morbert]

That's very hard to digest, that "reality cannot be completely described with a single logic". Is there some analogy or example unrelated to quantum mechanics?

Nothing immediate springs to mind. In classical physics we can build multiple valid but incompatible logics if we want, but there is always some logic built from a common refinement of the sample spaces associated with these logics. The Spekkens toy theory in a sense artificially restricts this common refinement, but is interpreted as an epistemic limit rather than an ontological one.

 

[EPR]

Decoherence on its own does not provide or guarantee classically consistent past/history where causal relationships with the present are maintained.

Yet - we always find causal connection of the decohered present with the decohered past(be it dinasaur bones or remnants of the second World War)

 

[JamieSalaor]

One subtle point here. Ontological flavours of CH still only posit a singular reality. Gell-Mann and Hartle sometimes call history frameworks "realms" which certainly doesn't help matters, but all history frameworks still describe the same reality. It's just that this reality cannot be completely described with a single logic. This is still a deal breaker for some people, but still worth emphasising that CH is a "one world" interpretation.

Then after all this why was CH accused of being solipsistic?
From the sounds of things it definitely isn't...

 

[PaoloDiM]

Summary:: Consistent Histories interpretation question on relativism / solipsism

I have recently finished reading Fay Dowker and Adrian Kent's 1994 paper On the Consistent Histories Approach to Quantum Mechanics.

As I understand it this interpretation of QM is not very popular, collecting only two votes from the 2016 survey - Surveying the Attitudes of Physicists Concerning Foundational Issues of Quantum Mechanics.

In the paper it appears as if they believe this interpretation implies solipsism (which may be why it is so unpopular).

However, I'm not entirely sure what they mean by this.
There seems to be two definitions of solipsism; epistemological and metaphysical.
With epistemological saying that we cannot be sure about the true nature of reality, but not outright denying other minds, and with metaphysical straight up denying other minds and external reality.

I have noted that in the paper they believe solipsism to be an unreasonable position. Which I too agree with (along with most other philosophers and physicists).

I have had a couple of brief chats with supporters of the Consistent Histories interpretation. They deny this framework entails solipsism.

They instead believe that their framework implies a form of 'relativism'.
For example:
If observer A uses framework S, and observer B uses framework S', then each observer draws his own conclusions on the history of the system (in our example, A will say that at t1 the particle was in the interval [0.1-0.2], and B will insist that the particle at t1 had energy E=13.6), but they can't combine their results into a unique, consistent picture of reality.

However, since these observers with their different frameworks can still communicate their contrasting results and in turn disagree. Surely if observers can disagree then there can be no metaphysical solipsism. Just a lack of real knowledge about the outside world? Therefore, since observers still communicate this cannot imply metaphysical solipsism.
Instead, they have argued it is relative.
I see this as comparable to relativity of simultaneity, how we can disagree on the timing of an event...
Therefore, I can see how this may imply epistemological solipsism, in the sense that through this interpretation we all come out equally clueless about the true nature of reality...
But I don't think it denies other observers...

Does anyone who properly understand the interpretation have anything to say?

Would appreciate any comments

Interesting post, thanks. Would a discussion of language here be too far afield here? For example, how is any disagreement measured, whether between persons or between observations, but through language? Does the same string of words refer to the same mental object (a theory in QM, for example)?
If this is too far afield, pardon the intrusion.

 

[JamieSalaor]

Interesting post, thanks. Would a discussion of language here be too far afield here? For example, how is any disagreement measured, whether between persons or between observations, but through language? Does the same string of words refer to the same mental object (a theory in QM, for example)?
If this is too far afield, pardon the intrusion.

I think yes, this is a one world interpretation so I'd assume when we talk about the same thing, we actually talk about the same thing. We truly communicate.
If that's what you mean
Pardon any misunderstanding

 

[Morbert]

Then after all this why was CH accused of being solipsistic?
From the sounds of things it definitely isn't...

I think what I'll do is reread Dowker and Kent's paper and specifically address their charge of solipsism.

 

[JamieSalaor]

I think what I'll do is reread Dowker and Kent's paper and specifically address their charge of solipsism.

That would be amazing thank you!
The thing is its a very old paper. So I imagine their opinions must have changed since then.
Furthermore they specify that they think solipsism is daft..
I would love hear your opinions on it all.
Again thank you for everything!

 

[Anixx]

Well. First of all, besides solipsism, there is another, less radical possibility: an ego-asymmetric theory.
In solipsism the objective reality does not exist. In ego-asymmetric theory the objective reality exists, but one observer is distinguished and follows different physical laws than the rest.

One can notice that even the Anthropic principle somehow implies ego-asymmetry.
There is also a big problem of self-reference. Thomas Breuer in his papers showed that from the point of view of any observer, a system in which he is properly included follows different physical laws compared to an external system, due to self-reference. And his proof is purely mathematical. Particularly, such system is less predictable (has indistinguishable states or uncertain probabilities).

 

[JamieSalaor]

Well. First of all, besides solipsism, there is another, less radical possibility: an ego-asymmetric theory.
In solipsism the objective reality does not exist. In ego-asymmetric theory the objective reality exists, but one observer is distinguished and follows different physical laws than the rest.

One can notice that even the Anthropic principle somehow implies ego-asymmetry.
There is also a big problem of self-reference. Thomas Breuer in his papers showed that from the point of view of any observer, a system in which he is properly included follows different physical laws compared to an external system, due to self-reference. And his proof is purely mathematical. Particularly, such system is less predictable (has indistinguishable states or uncertain probabilities).

Why would one observer be distinguished?
I had a little look and found very little information in this idea.
Just saw a few threads on forums..

 

[JamieSalaor]

Well. First of all, besides solipsism, there is another, less radical possibility: an ego-asymmetric theory.
In solipsism the objective reality does not exist. In ego-asymmetric theory the objective reality exists, but one observer is distinguished and follows different physical laws than the rest.

One can notice that even the Anthropic principle somehow implies ego-asymmetry.
There is also a big problem of self-reference. Thomas Breuer in his papers showed that from the point of view of any observer, a system in which he is properly included follows different physical laws compared to an external system, due to self-reference. And his proof is purely mathematical. Particularly, such system is less predictable (has indistinguishable states or uncertain probabilities).

From what I have read this idea posits that consciousness is important in QM?
Is that correct?

 

[Anixx]

this idea posits that consciousness is important in QM?

No. It does not imply consciousness at all. The theorem is similar the the Goedel's incompleteness theorem or Cantor's diagonalization argument. Put is simply, a computer, however powerful it is, cannot predict its own future state (or have a model of itself). Since the usual physical laws allow to predict a future state of any closed system, the conclusion is, from the point of view of the computer it does not follow the usual (bayesian) physical laws. In other words, you cannot predict a system from within that system, only from the outside of it.
So, there are true statements about physical reality that do not follow from any physical laws (compare Goedel here). Or unpredictable events.
The relevant papers by Breuer:
https://homepages.fhv.at/tb/tb/cms/index.html?download=tbDISS.pdf
https://homepages.fhv.at/tb/tb/cms/index.html?download=tbPHILSC.pdf
https://homepages.fhv.at/tb/tb/cms/index.html?download=QuantumTuring-v2b.pdf

 

[Anixx]

This leads to one of the following conclusions:
* The most complete physical description of reality is non-Bayesian. It includes uncertain probabilities (such as Knightian uncertainty).
or
* The universe constantly experiences influence from the outside of physical (measurable) world (God's intervention, free will, input ports etc)
or
* The universe includes an oracle or a hyper-turing computing device (hypercomputer)
or
* The universe has infinitely many in principle immesurable initial conditions that yet did not affect any events in the past but will affect events in the future, however distant that future is.

 

[Anixx]

Yes, in quantum mechanics one should sacrifice some basic philosophical principles that otherwise are looking obvious. In some interpretations you sacrifice equivalence of all observers, in others you sacrifice indivisibility of mind, etc.

 

[JamieSalaor]

Idk what to make of all that (I'm not a physicist, but a philosopher)
But talk of God and free will or the oracle idea throws me off...

Maybe I am getting the wrong idea.. But I couldn't find anyone else talking about these ideas except you on forums.
Please correct me if I'm confused..

 

[EPR]

Objections to a purported theory of everything are mainstream science. From Goedels theorem to emergent properties.

 

[JamieSalaor]

Objections to a purported theory of everything are mainstream science. From Goedels theorem to emergent properties.

Yes I thought that was broadly the case. Theories of everything tend to be extremely problematic and controversial to say the least.
Though I'm by no means against them

 

[Anixx]

Look, there are some mathematical theories that generalize the probability theory. Such as Generalized Information Theory or Dempster-Shafer theory, and others.
The main point of these theories is that they deal with uncertain probabilities.

In other words, if bayesian (usual) probabilistic theory has less predictive power than a deterministic theory, a non-bayesian theory (for instance, possibilistic) has even less predictive power than a probability theory.

Standard quantum mechanics is bayesian: given the state of a system at one point, one can predict (probabilistically) the state of the system at another point.

Breuer, however, showed that this is only true if the system to predict does not include the observer themself.
An universally-valid bayesian theory is impossible.

One can put it in other words: the observer's own wavefunction is uncertain (in a more fundamental way than the wave function of any other system, external to the observer).

Thus, a system that includes the observer either has undistinguishable states or somehow "channels" information from the outside of the physical world. In other words, it includes variables which are neither deterministic, not probabilistic in nature, but affect the future of the system. It can be from-the-outside intervention or "free will" or initial conditions of the universe (as in Bohmian mechanics).

One can think of it as of a computer game where no in-game computer can predict the future behavior of a player-controlled character, whose behavior from the in-game point of view is neither deterministic, not probabilistic.

 

[Anixx]

In short, one can summarize it this way: "There are unpredictable (probabilistically) events." Or events with no physical cause.

 

[Halc]

In the paper it appears as if they believe this interpretation implies solipsism (which may be why it is so unpopular).

However, I'm not entirely sure what they mean by this.
There seems to be two definitions of solipsism; epistemological and metaphysical.
With epistemological saying that we cannot be sure about the true nature of reality, but not outright denying other minds, and with metaphysical straight up denying other minds and external reality.

I am no expert on CH, but that interpretation, like almost all (*) the others, does not acknowledge the existence of an entity of 'mind', nor even mention any arrangement of quantum particles (life forms say) that has quantum properties absent in other arrangements.
In other words, the positing of the special status of 'mind' goes against the principle methodological naturalism. That principle is what got science out of the dark ages.

* The only exception is the Wigner interpretation which suggests such a special status, thus being in violation of said principle methodological naturalism. Wigner himself withdrew support of it since it was logically driven to philosophical solipsism. No other interpretation implies it.
No, there is no way to actually falsify such solipsism.

 

[Morbert]

Then after all this why was CH accused of being solipsistic?
From the sounds of things it definitely isn't...

Dowker and Kent bring up solipsism in a few contexts. I'll start with the first:

In section 5.1 they discuss the notion of an "actual history", the history containing all actual facts. They remark that the notion of an actual history is ambiguous and we could define the actual history in various solipsistic ways. E.g. "Solipsism of the moment" would only ascribe factive status to propositions about the present. Darwin's records are factive. Dinosaurs are not.

Codifying the "actual history" is an interesting challenge, but CH is an interpretation of the language of quantum theories, not a theory in itself. It offers us an interpretation of operators, state spaces and subspaces, projectors, decompositions etc. What is and is not a fact would depend on the theory we subscribe to. If we want to postulate the factive existence of dinosaurs to explain the observed fossil record, CH will let us employ a logic to evaluate this theory, but CH itself is neutral about what the correct theory for explaining the fossil record is.

 

[JamieSalaor]

Dowker and Kent bring up solipsism in a few contexts. I'll start with the first:

In section 5.1 they discuss the notion of an "actual history", the history containing all actual facts. They remark that the notion of an actual history is ambiguous and we could define the actual history in various solipsistic ways. E.g. "Solipsism of the moment" would only ascribe factive status to propositions about the present. Darwin's records are factive. Dinosaurs are not.

Codifying the "actual history" is an interesting challenge, but CH is an interpretation of the language of quantum theories, not a theory in itself. It offers us an interpretation of operators, state spaces and subspaces, projectors, decompositions etc. What is and is not a fact would depend on the theory we subscribe to. If we want to postulate the factive existence of dinosaurs to explain the observed fossil record, CH will let us employ a logic to evaluate this theory, but CH itself is neutral about what the correct theory for explaining the fossil record is.

So, would solipsism of the moment be if we ascribe the only reality to be now? As in presentism. So the solipsism here refers to time? Only one time exists at once.

As you say CH is neutral. It doesn't at all imply solipsism. But if you were to say solipsism was true you could produce a framework that correlated with that?

So, obviously no body is a solipsist (as they say in the paper its unreasonable and has no scientific reasoning behind it).
So though you can construct such a framework if you desire, but it's realistically wrong.

Surely we could construct another where just me and you exist and nobody else?

Am I getting the right idea?

 

[Morbert]

So, would solipsism of the moment be if we ascribe the only reality to be now? As in presentism. So the solipsism here refers to time? Only one time exists at once.

As you say CH is neutral. It doesn't at all imply solipsism. But if you were to say solipsism was true you could produce a framework that correlated with that?

So, obviously no body is a solipsist (as they say in the paper its unreasonable and has no scientific reasoning behind it).
So though you can construct such a framework if you desire, but it's realistically wrong.

Surely we could construct another where just me and you exist and nobody else?

Am I getting the right idea?

You could be a presentist while still believing that at some stage dinosaurs existed in the past even if they don't exist now. A solipsist of the moment would deny even this and deny any inference about what might have been the case in the past based on what is now. Kind of like someone who believe we all came into existence today, with preformed fictitious memories. If an interpretation entails solipsism of the moment it is a mark against it.

 

[JamieSalaor]

Right I see...
So, what Dowker and Kent are saying that if an interpretation starts to imply solipsism then there's something wrong with the interpretation?
They aren't saying quantum mechanics implies solipsism. They are saying that some interpretations can imply solipsism and that they should be discredited.
CH is a tool that can be used by solipsist interpretations.
But CH is not solipsistic?

 

[Morbert]

They ultimately go on to argue that CH implies solipsism an I will get to that but I have so far only addressed their first charge, which is that since CH does not sharply define the notion of an "actual history" it accommodates all sorts of notions of an actual history, including solipsism of the moment. They see this as a negative point.

 

[JamieSalaor]

As a supporter of CH do you think implies solipsism of the moment?

 

[Morbert]

As a supporter of CH do you think implies solipsism of the moment?

definitely not

 

[JamieSalaor]

Do you think that, since 25 years has passed since the publishing of this paper. The CH interpretation has changed a lot?
Dowker and Kent's opinions are obviously very old now...

 

[Morbert]

Do you think that, since 25 years has passed since the publishing of this paper. The CH interpretation has changed a lot?
Dowker and Kent's opinions are obviously very old now...

It has not changed dramatically. Details have been filled in, and Omnes's notion of truth across multiple history sets has been refuted, but the broad structure is the same.

 

[JamieSalaor]

Have these details been vital in showing that CH is not solipsistic?

 

[Morbert]

Have these details been vital in showing that CH is not solipsistic?

Not vital, but probably helpful in clarifying.