# Why the quantum gravity problem is metaphysics, not science
**URL:** https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487
**Category:** Philosophy
**Created:** [October 24, 2026, 7:46am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487 "2026-10-24T07:46:48Z")
**Posts on this page:** 20
**Page:** 2
### Author:  [@Flannel\_Jesus](https://www.ilovephilosophy.com/u/Flannel_Jesus)
#### Post date: [October 24, 2026, 10:20am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/21 "2026-10-24T10:20:38Z")
> [@Geoff](#):
>
> If we really believed it then we would go mad. Literally insane.
I don’t buy this. Plenty of people really think it’s true. There’s nothing maddening about it. Maybe you would go mad… but I doubt even that.
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### Author:  [@Geoff](https://www.ilovephilosophy.com/u/Geoff)
#### Post date: [October 24, 2026, 10:21am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/22 "2026-10-24T10:21:09Z")
> [@Atla](#):
>
> Oh that original scientific realism has been pretty much dead for at least a century, whether those scientists like it or not.
Naive realism is dead. But scientific realism in a more general sense is very much alive. It is just missing a coherent holistic model.
> [@](#):
>
> Then again imo Kant has been pretty much refuted too, and pure instrumentalism is a tool for working physicists, but just nonsense as a philosophy. What is most likely the case is the third option in between, indirect perception (representationalism) with “partially knowable noumenon”.
Yes, but the devil is in the details.
> [@](#):
>
> Emergent things are just as ontologically real as other things. Some scientists have just been trying to smuggle magic into science for a long time through the idea of emergence.
“Emergence” is a nice word. Again, the devil is in the details.
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### Author:  [@Geoff](https://www.ilovephilosophy.com/u/Geoff)
#### Post date: [October 24, 2026, 10:26am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/23 "2026-10-24T10:26:57Z")
> [@Flannel\_Jesus](#):
>
> I don’t buy this. Plenty of people really think it’s true. There’s nothing maddening about it. Maybe you would go mad… but I doubt even that.
Do you acknowledge that it will never be accepted as a consensus model of reality by scientists?
If so, you need to decide whether that is because of human inadequacy, or the inadequacy of the theory itself.
IMO, the answer is clearly that the theory is inadequate – people have very good reasons for rejecting it as prima facie absurd. If it was believable, there would not be 15 other interpretations.
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### Author:  [@Flannel\_Jesus](https://www.ilovephilosophy.com/u/Flannel_Jesus)
#### Post date: [October 24, 2026, 10:30am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/24 "2026-10-24T10:30:30Z")
> [@Geoff](#):
>
> Do you acknowledge that it will never be accepted as a consensus model of reality by scientists?
Do I acknowledge some future you imagined? I have no idea how science will progress, I may suffer from hubris at times but my hubris isn’t that bad
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### Author:  [@greenfuse](https://www.ilovephilosophy.com/u/greenfuse)
#### Post date: [October 24, 2026, 10:38am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/25 "2026-10-24T10:38:45Z")
> [@Geoff](#):
>
> Absolutely not. If you are a scientific realist (and I am) then the goal of science is to produce true theories. These are theories which don’t stop working, because they are accurate structural representations of mind-external reality. Such theories do already exist – the whole of chemistry is a perfect example.
Right off the bat I think chemistry is a kind of red herring - though perhaps I was too general by referring to ‘models’, but I meant models at the metaphysical level. Chemistry is about the most instrumentalist science there is. Chemists don’t care about ultimate noumenal ontology; they care about predictive utility and domain-specific modeling. Further chemistry’s rule fall apart. They fit local conditions. We have no idea how local our ideas about reality are.
> [@Geoff](#):
>
> We have never had a scientific theory which succeeded in being both correct and holistic – we’ve never had a complete scientific model of reality. But just because no such thing has ever existed, it does not follow that it cannot exist or should not exist.
And that’s the type of model I’m talking about. And yes, it may well exist, in fact, I left that as possible at the end of my post.
> [@greenfuse](#):
>
> I don’t think we can know that further empirical work cannot come up with a new better model that encompasses both. But that doesn’t mean we work out the model in advance as the only way forward.
But there may also not be one.
> [@Geoff](#):
>
> On the contrary, if you think there is such a thing as objective reality then a complete theory _must_ exist.
I don’t think you can know this. We can have an objective reality without being able to put it in some human theory. Objective reality can exist independently without nature being under any obligation to be fully encodable into a single, closed, finite human theory. Reality being real does not imply that reality is syntactically reducible to a human conceptual framework. Or, at least, I’d need to see the argument demonstrating this. And we really have no idea how flexible reality is or how complicated. We know what we’ve experienced of it so far.
> [@Geoff](#):
>
> This is exactly why Penrose is trying to link physics, consciousness and cosmology, and it is why Jung and Pauli spent 25 years trying to integrate physics and psychology.
Penrose isn’t a great example for your argument here. While he does use consciousness to highlight the gaps in current physical models, his central ideas focus a lot on Gödel’s Incompleteness Theorem to show that no formal system can ever be complete.
You are arguing that because an objective reality exists, a complete, closed formal theory must exist to represent it. Penrose doesn’t believe that: objective truth exists, but no formal system, algorithm, or finite set of mathematical rules can ever encompass all of it.
Penrose states this directly in _Shadows of the Mind_:
> **“Mathematical truth is not determined arbitrarily by the rules of some ‘man-made’ formal system, but has an absolute nature, and lies beyond any such system of specifiable rules.”**
I don’t have a position. Perhaps one can, perhaps not. But I don’t think not being able to formulate one means that there is no objective reality.
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### Author:  [@Atla](https://www.ilovephilosophy.com/u/Atla)
#### Post date: [October 24, 2026, 10:42am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/26 "2026-10-24T10:42:06Z")
(Meanwhile the universe could be laughing its ass off, for example it could consists of 6 world-antiworld pairs that are loosely overlapped and connected through gravity and antigravity. And the humans can see one small part of one half of one pair, and they will never be able to see beyond it.)
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### Author:  [@greenfuse](https://www.ilovephilosophy.com/u/greenfuse)
#### Post date: [October 24, 2026, 10:49am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/27 "2026-10-24T10:49:48Z")
> [@Geoff](#):
>
> Naive realism is dead.
Isn’t your position that if there is an objective reality then there must be a TOE model we can formulate a kind of naive realism. You say naive realism is dead, but isn’t your claim - that an objective reality _guarantees_ a complete, closed TOE model - actually a form of naive scientific realism?
It’s not naive about human perception/sensing, but naive about human conceiving. Same brain.
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### Author:  [@Flannel\_Jesus](https://www.ilovephilosophy.com/u/Flannel_Jesus)
#### Post date: [October 24, 2026, 10:51am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/28 "2026-10-24T10:51:41Z")
> [@greenfuse](#):
>
> Chemistry is about the most instrumentalist science there is. Chemists don’t care about ultimate noumenal ontology; they care about predictive utility and domain-specific modeling.
Fully agree with all of this. Chemistry isn’t any closer to objective reality than Newtonian mechanics. Chemistry is an ad hoc Hodge podge of approximations of behaviours. And when a piece of chemistry doesn’t approximate a behaviour well enough, they ad hoc a new bit into it so that it does a bit better.
Which isn’t a knock against chemistry, that’s what it’s for. Completely instrumental, as you say.
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### Author:  [@MistressOphelia](https://www.ilovephilosophy.com/u/MistressOphelia)
#### Post date: [October 24, 2026, 10:52am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/29 "2026-10-24T10:52:52Z")
I’m pretty sure that Sean Carroll believes it and he seems perfectly sane to me.
You talk as if there is some kind of battle going on between science and philosophy. That’s simply not the case. Scientists are well aware that the line between science and philosophy is becoming increasingly blurred and that philosophy has much to contribute to solving the mysteries of the universe.
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### Author:  [@Flannel\_Jesus](https://www.ilovephilosophy.com/u/Flannel_Jesus)
#### Post date: [October 24, 2026, 10:59am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/30 "2026-10-24T10:59:08Z")
Ah but if he’s still sane then he doesn’t REALLY believe it. Wink wink.
I think most rhetorical devices that end up concluding “nobody REALLY believes this thing I disagree with” look silly. There may be some successful examples of such rhetoric but I’m failing to think of one.
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### Author:  [@anew1](https://www.ilovephilosophy.com/u/anew1)
#### Post date: [October 24, 2026, 11:32am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/31 "2026-10-24T11:32:28Z")
> [@Geoff](#):
>
> I said there are three clashing claims, and that the 3D clockwork universe was both the oldest and the most easily dismissed. Not many scientifically informed people still believe that, even if they are philosophically backwards – those people think spacetime is ontologically real instead. The real clash is between General Relativity (spacetime) and QM (Hilbert Space). Objective reality can be one of those things, but it cannot be both of them.
Until the supposed and alleged ‘real clash’ is specifically written out and presented, how they are actually Unified, and why they are just perceived as ‘a clash’, cannot be explained in a way that specifically address any perceived ‘problem’ or ‘disharmony’ here.
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### Author:  [@anew1](https://www.ilovephilosophy.com/u/anew1)
#### Post date: [October 24, 2026, 11:34am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/32 "2026-10-24T11:34:53Z")
> [@Geoff](#):
>
> It is should be called “spacetime” (the ontological-theoretical object) and “General Relativity” (the theory itself). Whatever you call it, it mathematically clashes with quantum mechanics.
But they do not clash. This is just what some people keep saying, what some keep hearing, and what some keep on repeating. But why there just ‘appears’ to be ‘a clash’ is because people are NOT ‘looking at’ things here from the proper perspective.
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### Author:  [@pseudoai](https://www.ilovephilosophy.com/u/pseudoai)
#### Post date: [October 24, 2026, 11:39am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/33 "2026-10-24T11:39:35Z")
> [@Geoff](#):
>
> they cannot have two clashing claims about what mind-external reality is made of
Yes, that may be something many scientists claim, but science doesn’t. For science you can even have three or more. As long as you come up with useful enough relationships (be that formulas, graphs or whatever) between past measurements, it’s all good and proper.
Indeed, unificiation or diversification : those are not problems of science.
There are at least three different things that people confuse:
- Science
- Academia
- What scientists do
I’m glad in here ‘reality’ doesn’t get mixed with that either, but I think that if you are precise enough, you see that there is no actual contradiction nor problem. If anything, it’s more of an ‘allocation of resources’ thing - meaning that why would you pay someone to unify in just one theory what, in the end, makes no difference? Why wouldn’t you then pay someone to make an alternative theory that matches measurements as good as that but is contradictory with that unified theory? (Essentially returning to the same ‘problem’)
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### Author:  [@anew1](https://www.ilovephilosophy.com/u/anew1)
#### Post date: [October 24, 2026, 11:46am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/34 "2026-10-24T11:46:30Z")
> [@Geoff](#):
>
> That argument works, but at the cost of losing realism. It downgrades both theories to incomplete models, which implies that they are not literally true claims about the nature of objective reality.
NO ‘theory’ is a true claim.
> [@Geoff](#):
>
> All he is trying to do is complete the model.
If anyone wants to ‘complete the model’, then just ‘look at’ what is actually True and Real, instead of ‘looking at’ the previous models as being true or right.
> [@Geoff](#):
>
> Most physicsts think spacetime is real.
But ‘spacetime’ is a word like ‘time’, ‘space’, and ‘gravity’ are words, for example, which are not ‘real things’ but are words that are used to denote things that really happen, but which are not things in and of themselves.
> [@Geoff](#):
>
> Scientific realism is a commitment to the idea that science does indeed aim to tell us “what reality is”.
Science looks at and studies physical things to work out what they are made up of and/or how they work. To find out what something is, we just use a dictionary.
What ‘reality’ is, exactly, is, contrary to popular belief. NOT what happens and occurse ‘now’, but rather what ‘we’ create and make real.
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### Author:  [@anew1](https://www.ilovephilosophy.com/u/anew1)
#### Post date: [October 24, 2026, 11:50am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/35 "2026-10-24T11:50:54Z")
> [@Flannel\_Jesus](#):
>
> Anyway, the reason I prefer the many worlds interpretation is because of the conflict between general relativity and qm.
There is NO conflict. Some people just believe there is a conflict, as usual just because they were told there was.
> [@Flannel\_Jesus](#):
>
> Many worlds is compatible with the pure locality required by general relativity.
But there is only One Universe, and not any more.
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### Author:  [@anew1](https://www.ilovephilosophy.com/u/anew1)
#### Post date: [October 24, 2026, 11:56am UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/36 "2026-10-24T11:56:01Z")
> [@greenfuse](#):
>
> If physical means what it historically meant—solid matter, corpuscles, billiard-ball contact mechanic s- then nothing in modern physics is actually physical.
How is matter itself not actually physical?
> [@greenfuse](#):
>
> When you zoom in on what we call “matter,” you don’t find solid stuff; you find excitations of quantum fields, force interactions, energy distributions, and mathematical probability waves.
> [@greenfuse](#):
>
> When you zoom in on what we call “matter,” you don’t find solid stuff; you find excitations of quantum fields, force interactions, energy distributions, and mathematical probability waves.
Is there an apparatus that we can actually use that has shown within the smallest particle of matter that is what you call no ‘solid stuff’?
If there is, what is that apparatus called, exactly, and where is the picture it took?
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### Author:  [@Geoff](https://www.ilovephilosophy.com/u/Geoff)
#### Post date: [October 24, 2026, 12:05pm UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/37 "2026-10-24T12:05:23Z")
> [@Flannel\_Jesus](#):
>
> Do I acknowledge some future you imagined? I have no idea how science will progress, I may suffer from hubris at times but my hubris isn’t that bad
Then you are in denial. MWI has been around for 65 years now, and while it is popular in Hollywood, it is nowhere near capable of resolving the impasse in quantum foundations. It’s just one of 15+ interpretations which failed to resolve the problem because they are either wrong or fundamentally incomplete.
It is also a fourth claim about metaphysics – and an incoherent one, because it claims that mind-external reality is both classical and quantum.
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### Author:  [@anew1](https://www.ilovephilosophy.com/u/anew1)
#### Post date: [October 24, 2026, 12:08pm UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/38 "2026-10-24T12:08:09Z")
> [@Geoff](#):
>
> MWI solves some problems but creates many others. The biggest of which is that it implies our minds are continually splitting, and absolutely nobody actually behaves as if they believe this is true.
>
> This is characteristic of _all_ the main positions, including all of the well known interpretations of QM and all theories of consciousness – they solve a few problems, but end up creating bigger ones in the process.
One reason is because you people literally believe you have ‘your own minds’ and that ‘this’ is how you work out and solve things.
If and when ‘you’ observe things as they Really are, instead of ‘looking at or for’ things with preconceived ideas, like ‘one model’ is superior to another, then, and only then, things like WHY there only ‘appears’ to a conflict or clash but really there are none, becomes resolved.
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### Author:  [@pseudoai](https://www.ilovephilosophy.com/u/pseudoai)
#### Post date: [October 24, 2026, 12:11pm UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/39 "2026-10-24T12:11:22Z")
Check up on the Pondicherry interpretation
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### Author:  [@Geoff](https://www.ilovephilosophy.com/u/Geoff)
#### Post date: [October 24, 2026, 12:12pm UTC](https://www.ilovephilosophy.com/t/why-the-quantum-gravity-problem-is-metaphysics-not-science/86487/40 "2026-10-24T12:12:42Z")
> [@greenfuse](#):
>
> Right off the bat I think chemistry is a kind of red herring - though perhaps I was too general by referring to ‘models’, but I meant models at the metaphysical level. Chemistry is about the most instrumentalist science there is. Chemists don’t care about ultimate noumenal ontology; they care about predictive utility and domain-specific modeling. Further chemistry’s rule fall apart. They fit local conditions. We have no idea how local our ideas about reality are.
Chemistry can be taken as a kind of structural realism, not just instrumentalism. Just because molecules aren’t billard balls, it does not follow that the structure is wrong.
> [@](#):
>
> > [@Geoff](#):
> >
> > On the contrary, if you think there is such a thing as objective reality then a complete theory _must_ exist.
>
> I don’t think you can know this. We can have an objective reality without being able to put it in some human theory. Objective reality can exist independently without nature being under any obligation to be fully encodable into a single, closed, finite human theory. Reality being real does not imply that reality is syntactically reducible to a human conceptual framework. Or, at least, I’d need to see the argument demonstrating this. And we really have no idea how flexible reality is or how complicated. We know what we’ve experienced of it so far.
I fundamentally and vociferously disagree. The idea that reality could have a logical structure which humans aren’t capable of encapsulating in a theory is, to me, both unsupported and deeply unhelpful. Unless we have a very good reason for ruling it out, we should operate on the assumption that it is possible.
> [@](#):
>
> > [@Geoff](#):
> >
> > This is exactly why Penrose is trying to link physics, consciousness and cosmology, and it is why Jung and Pauli spent 25 years trying to integrate physics and psychology.
>
> Penrose isn’t a great example for your argument here. While he does use consciousness to highlight the gaps in current physical models, his central ideas focus a lot on Gödel’s Incompleteness Theorem to show that no formal system can ever be complete.
Depends what you mean by “complete”. If it can involve infinity itself, then it can be completed. All explanations have to end somewhere.
I don’t think Penrose’s model is correct, by the way. I just don’t think he deserves the level of dismissal and disgust that he’s been subjected to. He’s actually trying, and the people who are attacking him aren’t – they’re like the postmodern deconstructionists in this respect.
> [@](#):
>
> > **“Mathematical truth is not determined arbitrarily by the rules of some ‘man-made’ formal system, but has an absolute nature, and lies beyond any such system of specifiable rules.”**
That is just platonism, which I do not disagree with.
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