On the relation between physics and philosophy

  • #1
A. Neumaier
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Summary:

Pointer to a paper by Carlos Rovelli

Main Question or Discussion Point

I'd like to point to the following paper:
From the abstract:
Carlos Rovelli said:
Contrary to claims about the irrelevance of philosophy for science, I argue that philosophy has had, and still has, far more influence on physics than is commonly assumed. I maintain that the current anti-philosophical ideology has had damaging effects on the fertility of science.
 

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  • #2
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According to Niels Bohr, science is to be fertilized by proper complementarity of philosophical variants, right?
 
  • #3
hilbert2
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I'd say that the question of "What counts as well-established enough to be called truth?" is partly philosophical and partly technical, even though there are some simple commonly accepted guidelines like the five-sigma statistical significance when finding new particles in scattering experiments.
 
  • #4
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Rovelli wrote: "I suspect that part of the problem is precisely that the dominant ideas of Popper and Kuhn have misled current theoretical investigations."

Kuhn is essentially not even a philosopher, but a historian of science. I cannot see anything misleading in Popper, but beyond a caricature version of falsification, Popper is widely ignored by the physics community. So, for the actual problems physicists have to blame themselves. First of all, the primitive positivist rejection of philosophy and interpretations in general.

But Rovelli is correct if he emphasizes that there is also such a thing as credibility of theories, and one would better have to take into account the Bayesian interpretation of probability. The rejection of Bayesian probability was certainly a point where Popper failed.

Whatever, the key point of Rovelli is worth to be repeated:

But because philosophers have conceptual tools for addressing the issues raised by this continuous conceptual shift. The scientists that deny the role of philosophy in the advancement of science are those who think they have already found the final methodology, that is, that they have already exhausted and answered all methodological questions. They are consequently less open to the conceptual flexibility needed to go ahead. They are the ones trapped in the ideology of their time.
 
  • #5
vanhees71
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I think, if you are thinking about quantum gravity you must come to the conclusion that you need to rely on philosophy out of desperation, because there are no empirical facts you can rely on. I'm pretty sure that's the reason, why so far there's no success in finding a satisfactory theory, because from pure philosophy/scholastics we can't find the right natural laws, let alone a consistent mathematical theory. For the same reason, because there haven't been any "dark-matter particles" been found, we don't have any hint about which "physics beyond the standard model" might work. On the other hand, without guidance from theoretical models it's hard to find the right observables for such physics beyond the standard model. It's a classical dilemma. The only thing I'm pretty sure about is that philosophy can help. Philosophy is very good in analyzing the methodology and the meaning for scientific discoveries for the wider field of human experience a posteriori. I've not a single example, where philosophy lead to some new scientific discovery though. Maybe philosophy can be a motivation for thinking in other directions though: E.g., what was thought to be a paradox in the infamous EPR paper triggered a vigorous research effort to clarify the foundations of QT (with the known result that QT is correct but philsophical prejudices wrong) leading to an entirely new branch of physics, which we nowadays call quantum information, leading right now to new engineering with applications in quantum cryptography and quantum computing.
 
  • #6
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i. I've not a single example, where philosophy lead to some new scientific discovery though.
I think the Einstein's original formulations of special and general relativity were philosophy, to mention only two examples. But of course those were not pure philosophy, but philosophy combined with physics and mathematics.
 
  • #7
hilbert2
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Einstein was influenced by Ernst Mach, who was both a physicist and philosopher and invented some surprisingly practical things given that background...
 
  • #8
vanhees71
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In his younger years (up to about 1930) Einstein was the master to pick up unwell explained phenomena and build a theory on these observations of problems with the "contemporary description", as made clear most explicitly in the introductory paragraph of his 1905 paper "On the Electrodynamics of Moving Bodies". From the time on when Einstein lost interest in phenomenological approaches, even his genius couldn't discover new laws. As with his soulmate Schrödinger, all his as well as Schrödinger's sophisticated attempts to invent a "generalized field theory" failed. Einstein is the prime example, justifying my claim that profound physical laws, models, and theories cannot be invented from pure thought but have to be discovered by analyzing empirical facts.
 
  • #9
A. Neumaier
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I think, if you are thinking about quantum gravity you must come to the conclusion that you need to rely on philosophy out of desperation, because there are no empirical facts you can rely on.
Well, there are the multitude of empirical facts explained by the standard model and those explained by general relativity. The quest is to explain them in a joint framework. This is an empirically sufficiently constrained problem, even so much constrained that so far no solution was found.
Einstein is the prime example, justifying my claim that profound physical laws, models, and theories cannot be invented from pure thought but have to be discovered by analyzing empirical facts.
How do your two remarks square with Einstein's discovery of general relativity?? At the time of his discovery, there were no facts he explained beyond those already explained by special relativity or Newtonian gravitation. Only the joint framework was missing. Both Einstein and Hilbert found it by pure thought.
 
  • #10
vanhees71
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I think the problem to find a quantum theory of gravitation is that there are no quantum-gravitational empirical facts known. Everything observable with respect to gravity is about (very) macroscopic objects, for which the non-qantum description is sufficient. So there is no empirical guidance towards a description of quantum gravity (yet).

Einstein found GR in his typical way of extracting the one important empirical fact about the gravitational interaction, the equivalence principle (or put in another way the equivalence between inertial as well as active and passive gravitational mass). Hilbert nearly scouped Einstein, because he was the better mathematician ;-).
 
  • #11
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theories cannot be invented from pure thought but have to be discovered by analyzing empirical facts.
Nobody said that theories can be invented by pure thought, that is pure philosophy. But pure empirical facts are also not enough. What one needs is a combination of both.
 
  • #12
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I think the problem to find a quantum theory of gravitation is that there are no quantum-gravitational empirical facts known. Everything observable with respect to gravity is about (very) macroscopic objects, for which the non-quantum description is sufficient.
I don't think this is the case for the early universe. Even the macroscopic objects there need a quantum description.
 
  • #13
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Einstein found GR in his typical way of extracting the one important empirical fact about the gravitational interaction, the equivalence principle (or put in another way the equivalence between inertial as well as active and passive gravitational mass).
I'm an amateur here, but didn't GR also resolve the instantaneous action at a distance of Newton's gravity? That seems a philosophically motivated endeavor, especially in light of the then-current accuracy of predictions using Newton's theory.
Nobody said that theories can be invented by pure thought, that is pure philosophy. But pure empirical facts are also not enough. What one needs is a combination of both.
Yes, so if you know from Maxwell that EM has a propagation speed c, and from SR that c is the overall speed limit, then "philosophically" you need a theory of gravity with a propagation speed.
 
  • #14
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Rovelli wrote: "I suspect that part of the problem is precisely that the dominant ideas of Popper and Kuhn have misled current theoretical investigations."

Kuhn is essentially not even a philosopher, but a historian of science. I cannot see anything misleading in Popper, but beyond a caricature version of falsification, Popper is widely ignored by the physics community. So, for the actual problems physicists have to blame themselves. First of all, the primitive positivist rejection of philosophy and interpretations in general.

But Rovelli is correct if he emphasizes that there is also such a thing as credibility of theories, and one would better have to take into account the Bayesian interpretation of probability. The rejection of Bayesian probability was certainly a point where Popper failed.

Whatever, the key point of Rovelli is worth to be repeated:

But because philosophers have conceptual tools for addressing the issues raised by this continuous conceptual shift. The scientists that deny the role of philosophy in the advancement of science are those who think they have already found the final methodology, that is, that they have already exhausted and answered all methodological questions. They are consequently less open to the conceptual flexibility needed to go ahead. They are the ones trapped in the ideology of their time.
Three questions:

1) What are some, most, or all physicists currently doing wrong?

2) What should physicists be doing instead?

3) If physicists starting doing the right things and stopped doing the wrong things, what problems would they be able to solve that they currently cannot solve?

"Trapped in the ideology of their time" is a nice soundbite, bit what does it actually mean?
 
  • #15
vanhees71
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Three questions:

1) What are some, most, or all physicists currently doing wrong?

2) What should physicists be doing instead?

3) If physicists starting doing the right things and stopped doing the wrong things, what problems would they be able to solve that they currently cannot solve?

"Trapped in the ideology of their time" is a nice soundbite, bit what does it actually mean?
ad 1) If I'd know this, I'd write a paper.

ad 2) If I'd know this, I'd do it.

ad 3) If I'd know this, I'd solve the problems.
 
  • #16
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I think, if you are thinking about quantum gravity you must come to the conclusion that you need to rely on philosophy out of desperation, because there are no empirical facts you can rely on.
Without anything new from experiment, it becomes at least obvious that "shut up and calculate" no longer brings any progress. You cannot forbid philosophy if you have no experiments as a guidance.

If you have a lot of experiments, you can do Kuhnian "normal" science without any philosophy. So, the SM is theory of the same type as QED, which can be reached without caring about philosophy at all, because all you have to do is more of the same.
I've not a single example, where philosophy lead to some new scientific discovery though.
GR is such an example.
E.g., what was thought to be a paradox in the infamous EPR paper triggered a vigorous research effort to clarify the foundations of QT (with the known result that QT is correct but philsophical prejudices wrong) leading to an entirely new branch of physics, which we nowadays call quantum information, leading right now to new engineering with applications in quantum cryptography and quantum computing.
No. What is wrong is yet open (at least to those who don't accept a preferred frame, and even those have to admit that a preferred frame allows for different answers). QT was, btw, not what was questioned, but philosophical ideas about QT.
 
  • #17
atyy
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3) If physicists starting doing the right things and stopped doing the wrong things, what problems would they be able to solve that they currently cannot solve?
They would be able to stop Rovelli writing complaining papers (maybe).
 
Last edited:
  • #18
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Three questions:

1) What are some, most, or all physicists currently doing wrong?

2) What should physicists be doing instead?

3) If physicists starting doing the right things and stopped doing the wrong things, what problems would they be able to solve that they currently cannot solve?
1.) "Shut up and calculate". It works if there are new results of new experiments which can be handled with the same established methods (Kuhnian normal science).
If I'd know this, I'd write a paper.
Your paper would not be published.
2.) Start with caring about interpretations and methodology.
2) If I'd know this, I'd do it.
In your free time only. You will get no grant for doing it.
3.) Quantum gravity almost for sure. Because it is a purely metaphysical problem (the conflict between QT and GR does not show up in any physical effect).
3) If I'd know this, I'd solve the problems.
Your solutions, even if you would be able to publish them, would be ignored.
"Trapped in the ideology of their time" is a nice soundbite, bit what does it actually mean?
Trapped in "shut up and calculate".
 
  • #19
atyy
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Trapped in "shut up and calculate".
Isn't Rovelli a supporter of shut up and calculate? Unless you think his "interpretation" actually solves any problems?
 
  • #20
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Isn't Rovelli a supporter of shut up and calculate? Unless you think his "interpretation" actually solves any problems?
No. I would say he takes the interpretations seriously. He thinks that the scientists of the past have taken principles of the existing theories seriously, more seriously than others, and used them as guiding principles for the development of their new theories. He also accepts that the question which of the principles should be preserved and used to guide the new theory has a straightforward and obvious solution. And that a rejection of principles of old theories is not a good idea. But this choice of the principles of the old theories to be preserved is, essentially, a choice between interpretations.

I do not thing his personal choice is a choice worth to be considered, except for mentioning that this direction has been already tried out without success.
 
  • #21
PeroK
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Trapped in "shut up and calculate".
That's just another soundbite.

Rovelli is a brilliant physicist. Why isn't he using philosphy to revolutionise modern physics?

It seems to me that, on the contrary, physicists and scientists in general have been trying and are trying with every means to their disposal to progress modern physics. If you want a soundbite "no stone is left unturned". There is lots of interest in the foundations of QM and major interpretations like Bohmian mechanics and MWI. And all sorts of ideas on the origin of the universe.

The real difficulty, as far as I can see, is that no one knows (including Rovelli) how the next breakthrough will come. Rovelli thinks a change in philosophical mindset is what's needed. Or, is he even saying that? Is he actually saying that IF scientists changed their philosophical midset, THEN the breakthroughs would inevitably come? Or, is he saying that maybe something would be found? How does he know?
 
  • #22
Both Einstein and Hilbert found it by pure thought
It starts with an idea! Good luck calculating without one.
 
  • #23
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Rovelli is a brilliant physicist. Why isn't he using philosphy to revolutionise modern physics?
He tries. Being brilliant is not enough. Even doing things right which the mainstream makes wrong is not enough. You also need some amount of luck to have the right idea.
It seems to me that, on the contrary, physicists and scientists in general have been trying and are trying with every means to their disposal to progress modern physics. If you want a soundbite "no stone is left unturned".
Wrong. There are quite big stones with clear marks: "Touching this stone is anathema."
There is lots of interest in the foundations of QM and major interpretations like Bohmian mechanics and MWI.
The situation with interpretations of QT has certainly improved during the last years, in this forum too. QT interpretations can be discussed now, are no longer anathema.
The real difficulty, as far as I can see, is that no one knows (including Rovelli) how the next breakthrough will come. Rovelli thinks a change in philosophical mindset is what's needed. Or, is he even saying that?
As explained, his main argument is that simply rejecting established principles to start a "revolution" is stupid and will not give anything. That one should rely instead on the principles of the established theories. But there are many such principles, and some of them are in some conflict. So you have to make a choice. Making the wrong choice you will end nowhere.
Is he actually saying that IF scientists changed their philosophical midset, THEN the breakthroughs would inevitably come? Or, is he saying that maybe something would be found? How does he know?
No, he is saying that if you simply reject whatever principles have remained THEN there will be certainly NO breakthrough. And this is quite easy to guess. Without any guiding principles, you have essentially no chance to make the correct guesses.
 
  • #24
vanhees71
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Without anything new from experiment, it becomes at least obvious that "shut up and calculate" no longer brings any progress. You cannot forbid philosophy if you have no experiments as a guidance.

If you have a lot of experiments, you can do Kuhnian "normal" science without any philosophy. So, the SM is theory of the same type as QED, which can be reached without caring about philosophy at all, because all you have to do is more of the same.

GR is such an example.

No. What is wrong is yet open (at least to those who don't accept a preferred frame, and even those have to admit that a preferred frame allows for different answers). QT was, btw, not what was questioned, but philosophical ideas about QT.
I don't want to forbid anything in science. The freedom of education and research is among the most important consitutional rights in free democratic states. I only doubt that the use of philosophy without empirical input will put us theoretical physicists to the right track.

I don't believe in the Kuhnian picture of the progress of science either, but the "revolutionary acts" in physics from 1900-1925 (the little one with the discovery of relativity was just the final corner stone of classical physics, the big one with the discovery of quantum (field) theory a real revolution) were all based on the huge discrepancy between empirical facts and the theoretical description of the corresponding phenomena. The physicists at the time had to be forced into these "revolutionary acts" by the empirical evidence, which came with the progress of technology and the refinement of measurements, not by pure philosophical thought.

Of course, there's no direct deduction of theories from empirical results either, but to build new models and theories is also a creative act as in the arts, but you need the empirical facts to guide this creative act. Otherwise you are lost in speculation and the best you can expect is some interesting new math (as for example string theory).
 
  • #25
vanhees71
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1.) "Shut up and calculate". It works if there are new results of new experiments which can be handled with the same established methods (Kuhnian normal science).
Your paper would not be published.
2.) Start with caring about interpretations and methodology.
In your free time only. You will get no grant for doing it.
3.) Quantum gravity almost for sure. Because it is a purely metaphysical problem (the conflict between QT and GR does not show up in any physical effect).Your solutions, even if you would be able to publish them, would be ignored.

Trapped in "shut up and calculate".
Hm, if I had a solid quantum theory of gravitation, which is not crackpot nonsense, I'm pretty sure, I'd get it published after (hopefully very careful) peer reviewing. Whether I'd get 3rd-party funding, is another question. Usually it's not easy to get money for high-risk projects, where the probability is low getting something out.

I don't think that the inconsistency between GR and quantum theory is a purely metaphysical problem, because as long as there is no theory covering both realms of observations our knowledge is incomplete on a purely scientific level, but it's precisely my point that with pure metaphysical ideas without empirical guidance there's no chance to find a more comprehensive theory either.
 

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