Why the quantum gravity problem is metaphysics, not science

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Before 1901 the metaphysics of science was simple (and simplistically wrong). Scientists were naive materialists. It helps to think in Kantian terms – materialistic science never accepted Kant’s claim that noumena is unknowable and continued to assume that mind-external reality was a 3-D clockwork universe. Science never accepted a philosophical refutation of this, but physicists could not simply ignore Einstein.

In 1915, therefore, the idea of a Newtonian noumenon was replaced by spacetime. This wasn’t just a scientific claim – it is fundamentally metaphysical. It claims the past and future are ontologically real, and that mind-external reality is a 4-dimensional block. These two metaphysical accounts of reality are fundamentally incompatible – they cannot both be true.

BUT…before physics had a chance to digest this, in 1926 along came quantum mechanics and made yet another completely incompatible claim. Strictly speaking it took until Bell’s theorem in 1966 for it to be accepted as proved, but the new claim is that mind-external reality isn’t 4-D spacetime but something much closer to a platonic/pythagorean realm of pure information. Science calls this “Hilbert Space” – the uncollapsed, unobserved wavefunction.

So we now have *three* different science-based claims about the nature of noumenal reality. And while naive materialism can easily be rejected once the problem is understood, the clash between General Relativity and QM remains unsolved after 100 years. Physicists have spent a century trying to force QM and GR into a single mathematical structure, precisely because they know they cannot have two clashing claims about what mind-external reality is made of. But they cannot make this work, because the mathematics is impossible – if you try to merge the mathematics you end up with unresolvable infinities.

My point is this: this problem isn’t empirical. Scientists have no right to continue claiming this problem is scientific at all, because their century-long failure is conceptual, not empirical. What is required from science is an admission that the problem has been physicalism all along – and not just that physicalism leads to unresolvable philosophical problems (such as the hard problem of consciousness) but that it is now hamstringing physics itself.

In response to this they will wail and scream, claiming that if we admit physicalism is broken, science will end and the sky will fall in. This is not the case, but we need to be careful. Many metaphysical claims do indeed break science, including every position which denies that brains are necessary for consciousness. But there is a family of metaphysical theories which reject both physicalism and disembodied minds. This family includes neutral monism, dual aspect monism and some process metaphysics. But, of course, the debate is rarely that nuanced. In reality it usually devolves into a punch-and-judy match between physicalism and idealism/dualism/panpsychism, where neither side can win, but neither will settle for anything less than total victory.

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Can you present the case for why? I don’t see why.

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Mind-external reality cannot be both

(1) a Newtonian 3D universe existing in the present moment, where time “passes” just as it does for conscious observers

and

(2) a 4D universe where time is like a 4th dimension of space.

These two concepts are fundamentally incompatible with each other, because they involve completely different notions of what time is.

So that was already a problem in 1915. Then in 1926 it got worse, because we now have

(3) a non-local, non-spatiotemporal realm of possibility or potential.

Assuming there actually is such a thing as an objective, mind-external reality, it can only be one of these three things. It cannot be two or all of them. And of course some people (objective idealists) claim it is none of them.

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I thought the two claims you were saying were incompatible were these:

“It claims the past and future are ontologically real, and that mind-external reality is a 4-dimensional block”

Nothing about it being a Newtonian 3d universe in there.

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As far as metaphysics, Newton has been superceded. In practical terms his formulas are still extremely useful.

So, if there is a problem, it’d be between qm and Heck I’m not sure what to call it, the Einsteinian classical physics as far as metaphysics.

Physicalism is not an actual position, though many people don’t realize this. If it’s real, regardless of quailties, it is considered physical, as if we are making a claim about substance.

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Both QM and GR are incomplete theories, it doesn’t follow that the quantum gravity problem is metaphysics. None of these theories produce a complete model of reality, and that’s unrelated to objective idealism. (And even a complete model would probably just be a model, it would probably be nonsensical to ask based on that model, what reality “is”.)

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I get what you’re saying here, but I also get disagreement.

I guess you’re saying something like, if something casually affects the physical, it goes into the bucket of things we call “physical”. Right? Something like that?

But I also get why some people wouldn’t want to include certain concepts in that bucket even if those concepts supposedly affect the physical

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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.

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It is an ever-expanding family of incompatible positions.

Heck I’m not sure what to call it, the Einsteinian classical physics as far as metaphysics.

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.

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Hmm guess I got caught up on the word “both”

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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. This is what instrumentalist, pragmatist philosophers do, but most scientists find it deeply unsettling. If they were more comfortable with it then they’d be less allergic to people linking consciousness and wavefunction collapse – they would not be so quick to treat people like Penrose as heretics. All he is trying to do is complete the model.

The question is whether they are ontologically real. Most physicsts think spacetime is real. The idea that it might be emergent from quantum reality is knee-jerk rejected by most of them.

Scientific realism is a commitment to the idea that science does indeed aim to tell us “what reality is”.

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Anyway, the reason I prefer the many worlds interpretation is because of the conflict between general relativity and qm. Many worlds is compatible with the pure locality required by general relativity.

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I could be open to that argument if we had stuff that was really like what we used to mean by the physical over here and then the more exotic stuff that affecst it but isn’t like it over there. But there’s the problem: the stuff that seems like what the physical used to me, isn’t any less exotic.

If physical means what it historically meant—solid matter, corpuscles, billiard-ball contact mechanic s- then nothing in modern physics is actually physical. 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.

So, yes they have causal effects but it’s between stuff that isn’t like what we once meant by physical. It’s really an epistemological position, not a metaphysical one.

Physicalism has slidfrom an ontological claim about substance into an epistemic commitment to scientific verificationism. If it has effects - on what we know is real - we can measure it and repeatedly measure it, it’s real. Then we call it physical. What is it ruling out?

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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.

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What if there were stuff governed by mathematical or computable laws here, but stuff not governed by anything mathematical or computable there?

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But isn’t that what models are? Incomplete. They work until they don’t. They give productive research directions, but not all work out. They get superceded. 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.

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I don’t see why this is a problem. I mean qm doesn’t talk about minds explicitly at all, just physical stuff, and not everyone who agrees with many worlds necessarily agrees that “splitting” is the correct term, but still… I don’t see what the problem is here. How would people behave differently if they REALLY believed in the splitting?

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Oh that original scientific realism has been pretty much dead for at least a century, whether those scientists like it or not. 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”.

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.

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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. But chemistry is indeed incomplete – it doesn’t even pretend to be a theory of the whole of reality. 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. On the contrary, if you think there is such a thing as objective reality then a complete theory must exist. 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.

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If we really believed it then we would go mad. Literally insane. Which is why it is a massive problem. This is exactly why MWI cannot become a consensus scientific model of reality – the only people who defend it do so out of a desperate need to escape the metaphysical quagmire. They see it as the “least bad option”. But that’s not good enough.

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