I Instrumentalism and consistency

[mikeyork]

It's $|\psi \rangle \langle \psi|$ that represents the state, not $|\psi \rangle$ itself.

That seems to me to be a distinction without a difference since $|\psi \rangle \langle \psi|$ has menaing only because of $|\psi \rangle$.

Further, whenever you talk about an eigenbasis you have to specify about which linear operator you are talking.

That's what the observer does.

 

[Fra]

I would say that instrumentalism is naive. There is no strict borderline between measurable (observable) things and non measurable things. There are just concepts that taken as real make our reasoning much simpler.

A problem appears when we use terminology that really comes from "human philosophy" rather thab phyics and thus by logical positivism one ofter refers to _human understanding_ and consciuous brains.

The kind of discrimination i make is that both direct and indirect observations are fine as "observable". Indirect observations are i think sometimes called analytical in old philosophy but my point is that for a given observer there are physial limits on the "analytical power" or computational capacity that renders some complex observations non observable _to that observer_ and thus the action of this observer should be invariant with respect to this.

One of the most common fallacy imo is for a human scientist to come up with complex ideas and project that down to a Planck scale observer.

The trick is that that Planck scale physics looks complex only from the low energy limit! But the naked interactions can not be this complex for infromation processing reasons.

/Fredrik

 

[Lord Jestocost]

I would say that instrumentalism is naive. There is no strict borderline between measurable (observable) things and non measurable things. There are just concepts that taken as real make our reasoning much simpler.

Why is instrumentalism naive? And what are “non measurable things“? Can one say any more about the physical world others than about “linkages of pointer readings with pointer readings”? That's the "physical world".

 

[bahamagreen]

Perhaps instrumentalists are being naive and inconsistent to the degree that despite certainly knowing that everything we perceive is an internal phenomenological mental construction, the instrumentalist attaches an external objective naive realism upon his internal mental phenomenological construction of a dial pointer.

 

[Demystifier]

- why is it unnatural? We know that there are the observable events, connected by some objective mathematics (which might well be some unimaginable algorithm of "the Great Transcendent Computer" simulating/generating the whole physical aspect of reality). The best theorists did their best to get the useful ideas about that mathematics; so now it's quite natural - because we've got nothing better - to think in terms of / according to those mathematical ideas until better ideas are discovered.

"... we needn’t take our best theory to be true. It’s simply the best ladder we have to our next theory."
- Donald D. Hoffman

I mean "unnatural" in a different sense.

 

[Fra]

I mean "unnatural" in a different sense.

I think that it is indeeed natural for humans to try to create a mental picture of the "reailty" out there, that exists when we close our eyes. In fact its how we navigate, relying on our map.

I do not see any contradiction between the empirical solipsism and the naturalness for humans to seek realism. On the contrary do i think they are a perfect match because it is the "strive" of all observers to understand the reality in the black box that eventually creates the effective reality. And i think of the reason for this is that is becomea sometimes the "best approximation" given than a simple observer can not endcode a complex map.

If i understand demystifier right i agree that it is unnatural in this sense.

/Fredrik

 

[Demystifier]

Yes, that's what I meant.

 

[Demystifier]

That simply means: Instrumentalists are not so naive to mistake the map for the territory.

That's true, and that's a good thing about instrumentalists. But they are naive in a different sense. They are naive when they think that they never mistake the map for the territory.

Realists, on the other hand, are aware that it can be cognitively useful to think of map as a territory. Therefore they make maps which look more realistic and much better resemble the territory.

 

[zonde]

Perhaps instrumentalists are being naive and inconsistent to the degree that despite certainly knowing that everything we perceive is an internal phenomenological mental construction, the instrumentalist attaches an external objective naive realism upon his internal mental phenomenological construction of a dial pointer.

I would say that the level of certainty with which instrumentalist attaches realism to internal mental construction is naive. As Demystifier said we attach reality to certain mental constructs, but this attachment is not absolute, just useful. Sometimes this attachment is so useful that there is not much point questioning it any more. But anyways this happens over time when we develop more useful models that relay on particular concept.

 

[Lord Jestocost]

That's true, and that's a good thing about instrumentalists. But they are naive in a different sense. They are naive when they think that they never mistake the map for the territory.

Realists, on the other hand, are aware that it can be cognitively useful to think of map as a territory. Therefore they make maps which look more realistic and much better resemble the territory.

Instrumentalism is a non-realist approach to quantum mechanics:
“From the early days of quantum mechanics, there has been a strain of thought that holds that the proper attitude to take towards quantum mechanics is an instrumentalist or pragmatic one. On such a view, quantum mechanics is a tool for coordinating our experience and for forming expectations about the outcomes of experiments.“ (from https://plato.stanford.edu/entries/qt-issues/)

Why should an instrumentalist ever mistake the map for the territory? What territory?

 

[Demystifier]

Why should an instrumentalist ever mistake the map for the territory? What territory?

Ideal persistent and consistent instrumentalist would never make such a mistake. But such an ideal instrumentalist does not exist in human species. Perhaps you could program an ideal computer instrumentalist, but there is no ideal human instrumentalist.

 

[Demystifier]

Let me use a simple analogy. Suppose that you watch your computer screen on which two windows are open, window 1 and window 2. And suppose that you see only window 1. Why don't you see window 2? A natural intuitive explanation is that window 2 must be behind window 1. And really, when you move window 1, you start to see window 2. There is nothing more intuitive for a human than to think that window 2 was there, behind window 1, even before you moved window 1. On the other hand, if you know something about how computer and monitor really work, you know that it isn't true. In reality, window 2 was "made" on the monitor at the moment when you moved window 1, it was not there before. And yet, even if you are a computer expert, even if you programed the computer that way yourself, you will still find cognitively natural and useful to think that window 2 was there all the time.

That's a hidden variable, or realist, interpretation. Even though there is no window 2 before you see it, you interpret that it is there even when you don't see it. And even though this interpretation is wrong, it is a very useful interpretation for a human.

In the same sense, a hidden variable interpretation of QM, such as Bohmian mechanics, can be useful as a thinking tool, even if Bohmian trajectories don't exist in reality. The point of Bohmian mechanics is not to restore determinism. Its point is to restore realism, that is the view that things are there even when we don't observe them.

 

[vanhees71]

Well, Window 2 "was there" in some sense already. Although not shown on the screen, the information provided by it was stored in "bits and bytes" in the Computer's memory (no matter, how this works in all technical detail). So in a sense the picture in Window 2 has been there. Of course, it's built up on the screen only at the moment you shift away Window 1, but in the sense of information it has been there before in the computer's memory.

I think this metaphor elucidates very well, the meaning of quantum states as providing (probabilistic) information about a system due to preparation, but that's again interpretation, and maybe provokes heated debates about "epistemic vs. ontic" interpretations.

 

[Fra]

(Apologies in advance for not linking to demystifiers papers.. typing this in from the phone and physicsforums app)

if you programed the computer that way yourself, you will still find cognitively natural and useful to think that window 2 was there all the time.
...
That's a hidden variable, or realist, interpretation. Even though there is no window 2 before you see it, you interpret that it is there even when you don't see it. And even though this interpretation is wrong, it is a very useful interpretation for a human.
...
Its point is to restore realism, that is the view that things are there even when we don't observe them.

I can't avoid observing that there is an abstraction here that makes realism as per Demystfier suspiciously alike what i call "rationality". Rationality that can be furher used in the inferential picture to explain the expected evolution.

This connection is even more interesting if you think of future possible ways to distinguish demystifiers solipsist hidden variables from regular QM.

The conceptual argument is that an observer (which we should think of as a PLAYER in an enviromment that offers both opportunities and dangers) that is behaving rationally will places his bets - according to his map - anything else is simply irrational, EVEN if the map is wrong as per another perspective. And in the exampl above we can argue that the best guess is indeed that the other window is below.

So what if what demystifyers "useful" interpretation" is simply a "rational expectation"?

Of course tere needs to be a formalism behind this, but i see a hope in the future discrimination D mentions in his solipsist paper. Namely that if we take this seriously (ie that alice actions depends only on her HV (to stick to D's terminology) and Bobs only on his. Then consider Observer3 that is bigger atr more domimant... observing/interacting with the "alice and bob interacting"-system... now in this pictute i see the chance for these ideas to distinguish themselves from just an interpretation by requiring that in O3's observers "rational expectaion" of composite Alice-Bob system the "internal interactions" between alice and bobs reflects this logic.

Thus this impacts unification! We are no longer "only" making reinterpretations.

Q. Demystifier, does this realism ~ rationality analogy make sense in conjuction with your journey?

(Hope this gets readable. Typing a lot on the phone is not ideal)

/Fredrik

 

[Demystifier]

I think this metaphor elucidates very well, the meaning of quantum states as providing (probabilistic) information about a system due to preparation, but that's again interpretation, and maybe provokes heated debates about "epistemic vs. ontic" interpretations.

The debates are heated when people discuss which interpretation is "right". What I propose here is that emphasis should not be on which interpretation is right, but on how various interpretations are useful as thinking tools. You often complain that you don't see how Bohmian view is useful (let alone true), and the analogy above should explain that. And just because Bohmian view is useful (at least for some users) doesn't mean that some more standard view is less useful.

 

[Demystifier]

Q. Demystifier, does this realism ~ rationality analogy make sense in conjuction with your journey?

I guess it does.

 

[vanhees71]

The debates are heated when people discuss which interpretation is "right". What I propose here is that emphasis should not be on which interpretation is right, but on how various interpretations are useful as thinking tools. You often complain that you don't see how Bohmian view is useful (let alone true), and the analogy above should explain that. And just because Bohmian view is useful (at least for some users) doesn't mean that some more standard view is less useful.

BM is ok for non-relativistic QT. It's at least not contradicting any fundamental laws. I personally consider it useless, because it doesn't provide any further insight compared to minimally interpreted standard QT. It's also hard to say, which interpretation is "right". It's, however, easy to say, which interpretational pieces are definitely wrong, among them the assumption of an instantaneous collapse in relativistic QFT. Then there is the category of interpretational items that are simply not testable within the realm of natural sciences as the assumption of a classical-quantum cut. At least so far there's no evidence for such a thing.

 

[Lord Jestocost]

Ideal persistent and consistent instrumentalist would never make such a mistake. But such an ideal instrumentalist does not exist in human species. Perhaps you could program an ideal computer instrumentalist, but there is no ideal human instrumentalist.

If I understand you correctly: Of course, even an instrumentalist has – as a human being – the feeling that there is “some reality” or “some territory”. But the feeling that there is “some reality (territory)” emerges merely from the usefulness of our “mental concepts (map)”; the usefulness for finding our ways, for our thinking and for our communicating with others. The more useful the map the stronger is the feeling that we are really wandering through “some territory”. To my mind, however, the map isn’t able to tell us finally what the “TERRITORY” is: There are mental images, which are in our minds and not in the external world, and there is some kind of “counterpart” in the external world which is of inscrutable nature.

 

[Demystifier]

If I understand you correctly: Of course, even an instrumentalist has – as a human being – the feeling that there is “some reality” or “some territory”. But the feeling that there is “some reality (territory)” emerges merely from the usefulness of our “mental concepts (map)”; the usefulness for finding our ways, for our thinking and for our communicating with others. The more useful the map the stronger is the feeling that we are really wandering through “some territory”. To my mind, however, the map isn’t able to tell us finally what the “TERRITORY” is: There are mental images, which are in our minds and not in the external world, and there is some kind of “counterpart” in the external world which is of inscrutable nature.

Yes, you explained it very well!

The only thing I would add is this. Since those mental images can be very useful, science should not strive to avoid them. Just the opposite, in addition to making testable predictions (which is what pure instrumentalists tend to do), theoretical science should also strive to develop good mental images. To answer whether some mental image is "true" or not, it can be left to philosophers. But the construction of useful mental images is too important to be left to philosophers.

 

[akvadrako]

To answer whether some mental image is "true" or not, it can be left to philosophers. But the construction of useful mental images is too important to be left to philosophers.

I would like to add that I see something in between philosophically true and useful. Newtonian gravity and GR are both useful and perhaps Newtonian is even more so, depending on the use case. But I would say the question of which is more true also lies within science, not just philosophy.

I'm not sure of the precise criteria, but I can see some trends. When theory B is strictly a limiting case of theory A, we should say A is more true. Or when A has strictly less assumptions than B. Or when A is applicable in more general cases. I suppose finding exactly what criteria to use is part of the philosophy of science, because science can't be self-defining. But I don't think the search for truth can be left to philosophy.

 

[DrChinese]

Newtonian gravity and GR are both useful and perhaps Newtonian is even more so, depending on the use case...

I'm not sure of the precise criteria, but I can see some trends. When theory B is strictly a limiting case of theory A, we should say A is more true. Or when A has strictly less assumptions than B...

Your gravity example is good. I wouldn't use the word/attribute "TRUE" to compare theories though; because no model (theory) can be considered objectively "true". Models can be compared on the basis of utility, which ties back to your example.

 

[akvadrako]

Models can be compared on the basis of utility, which ties back to your example.

My point is that utility and usefulness are not the most important basis for comparison in the pursuit of scientific knowledge. At least I would not be very satisfied with a model which allowed me to manipulate nature quite well, yet didn't have a good mapping to reality.

 

[Lord Jestocost]

Since those mental images can be very useful, science should not strive to avoid them. Just the opposite, in addition to making testable predictions (which is what pure instrumentalists tend to do), theoretical science should also strive to develop good mental images. To answer whether some mental image is "true" or not, it can be left to philosophers. But the construction of useful mental images is too important to be left to philosophers.

But that's the point! Physics isn’t able to construct useful mental images when addressing the quantum world. No resoned mental images exist for generic quantum objects which behave in their peculiar quantum manner. Is there a comprehensible idea of what is "out there"? Therefore, the instrumentalist’s approach:

„In science we study the linkage of pointer readings with pointer readings.“ (Arthur Stanley Eddington)

 

[vanhees71]

Physics provides utmost useful mental images of the quantum world. It's called quantum theory! Given that there's not a single example of any phenomeno where QT was wrong, I'd say it's among the most successful mental image of nature mankind has ever found.

 

[Demystifier]

Physics isn’t able to construct useful mental images when addressing the quantum world.

Maybe physics isn't, but physicists are. Bohm, for instance, constructed a mental image which is very useful (at least for me).

 

[Fra]

I think we talk three types of "mental images" here.

Two of them are

- the humans theory of our environment

- a human "mechanical" pictue of our world in terms of bullets flying around in a 3d space

I think vanesh talks about the first kind, but sometimes realists talk about the second kind.

/Fredrik

 

[Fra]

The third type of "mental image" I was metaphorically talking about is earlier in the thread.

- the physical observers theory/map of its physical environment

physical observer = is simply a ANY physical system, a quark, an atom, a single cell, or a human.
and this theory/map is IMPLICIT in the internal structure of the observer.
Example. the internal structure of a proton, reveals it "mental map" of its environment.

Let me explain why i repeat this:

To reconnect to the OT, that while Quantum Mechanics and QFT are no doubt are great achivements of science and an impressive "mental image" of the first kind, it is not satisfactory and lacks a coherent inferential line of reasoning.

But this is NOT just because it can not be explained in terms of chaotical dynamical classical mechanics, its because quantum mechanics presents a new inferential perspective to science, that i think is a GOOD thing (imo outperforming classical thinking in intellectual standards). It anchors the concept of measurements into the very laws of physics. BUT while doing so i find that it is not following consistent reasoning and it has bugged me badly since my mechanistic deterministic worldview was popped during my first QM course.

SOME things are subject to measurements, and SOME things(LAWS of physics for example) are subject to classical style realism and are timeless. Also, it is clear how measurements are attached to a classical observer frame, like a laboratory. When you think about this, and also think about cosmological theories, and ask yourself what is the difference between a quark looking out into the environment of a lab, and a human looking out into cosmological scales. Sure we have different complexity scales, but should the "laws of physics" be the same? This doesn't do it for me, as it is too obvious that something is missing. But let's not confuse this with the ideas of Einstein that QM was "incomplete" that was a totally different kind of missing thing.

Thus the third mental image, that would suggest the following radical views to the below questions.

I'm not sure of the precise criteria, but I can see some trends.

Your gravity example is good. I wouldn't use the word/attribute "TRUE" to compare theories though; because no model (theory) can be considered objectively "true". Models can be compared on the basis of utility, which ties back to your example.

In the view i hold, the whole notion of true and false in the objective sense are illdefined simply because there exists not external logical system to judge this. There are ONLY inside views.

Instead there are only degrees of belief, and each observer has its own RIGHT system. A kind of corollary of this, is that the "mental image" of the laws of physics MUST be fundamentally observer dependent. I know this sounds sick, and it is. And the question is how to make sense out this. But if this seems to be the logical conslusion? so what do we do? WE can not reject to answer the right question just because its too hard.

Anyway, this is IMO an alternative solution to the metalaw dilemma raise by Lee Smolin in his ides of evolution of law. Smolin envisions the laws to mutate at the big bang, but i rather thinkg that _in principle_ the evolve all the time, but that for all practical purposes the "evolution of laws" last no more than fractions of a second after big bang. His ideas are in various places. His most recent book is https://en.wikipedia.org/wiki/Time_Reborn.

To make an analogy here if you still don't get the idea. What i am suggesting is that to ask which theory is right is just about as
meaningful as to ask which of the speices in the eco system that has implemented the RIGHT survival strategy? The obvious answer is : all of them! It is the idea that there necessarily exists and observer independent truth that is the deeply confused.

/Fredrik

 

[AlexCaledin]

. . . the idea that there necessarily exists an observer independent truth is deeply confused.

- but apparently some superior observers are able to fake it for us (remember Feynman's "chess")

 

[Fra]

- but apparently some superior observers are able to fake it for us (remember Feynman's "chess")

I don´t understand your association. You mean feymanns chess computer, evaluating all options??

What i suggested does not contradict the "naturalness" of trying to create an understanding of what is "out there" that was discussed earlier in the thread.
Neither does it imply total chaos.

Instead that tendency for an all observers to create a stable internal map of its environment, together with that fundamental lack of objective interaction rules, is they key to understand the emergence of effective "observer independent truth" by means of a kind of negotiation. A lame example of how you can create something from just expectations just look at the stock market. Collective expectations alone can create stable values. At a certain point it really doesn't matter was is "really real" anymore, the collectively harmonized expectations are as good as the real thing. However it is not possible to understand this emergence if you consider an isolated observer in a non-responsive enviroment. They key is that the environment is similary fellow observers (metaphorically speaking).

/Fredrik

 

[bohm2]

Physics isn’t able to construct useful mental images when addressing the quantum world. No resoned mental images exist for generic quantum objects which behave in their peculiar quantum manner. Is there a comprehensible idea of what is "out there"? Therefore, the instrumentalist’s approach:

What is the reason for there being no reasoned mental images for the quantum world? Is it because of us or because of what's "out there"? Could one not argue that the deeper we probe nature, the stranger it looks not because of us; instead, it's because we are straying further away from our common sense ideas of macroscopic objects (and human psychology) that were sculpted into our mind-brain by evolution, etc. So in some sense, the fact that we are unable to easily construct mental images, may actually be telling something very deep about what's "out" there.