[fair_enough]

The OP's article does a lot more to disprove such a hypothesis by instead offering a more credible alternative explanation:

Neurons found in the CNS have tubles large enough to allow transport of ions and even relatively large polypeptides similar to, but more permissive than, the well-known gap junctions found between smooth muscle and cardiac muscle cells.

Penrose's hypothesis is crank science about quantum gravity messing with your CNS in a way comparable to "body thetans" in Scientology.

[sarchertech]

Penrose doesn’t hold the microtuble hypothesis strongly at all.

He’s very very careful to say that it’s just something he’d like to see tested and he has no idea whether it’s true or not.

That very much distinguishes it from Crank science.

[btilly]

In 1989, Penrose picked up Lucas' 1961 argument that no computer can possibly simulate intelligence. The argument rests on fundamental misunderstandings of logic, that are well-known among logicians. See, for example, https://www.ams.org/journals/bull/1995-32-03/S0273-0979-1995... for an article explaining this, written some 30 years ago.

The fact that Penrose has maintained his misunderstandings for 30 years, demonstrates that, on this topic, he has been a crank for a long time. No matter his other accomplishments.

[sarchertech]

Penrose essentially wrote an entire book responding to that critique.

Which side you support largely comes down to a philosophical question. The notion that he just made a stupid mistake and doubled down on it is absurd.

Having a different opinion about the soundness of a proof could make him wrong but it hardly makes him a crank.

[btilly]

The fact that he repeated the same logic errors at book length doesn't change the fact that they are errors. And the question of whether they are logic errors is a question of mathematics, not philosophy. Dismissing the conclusions of logic on the basis of philosophy, is a mistake of the same type as dismissing the conclusions of science on the basis of theology. Logic cannot speak to the philosophy that Penrose pushes forth. But it can and does speak to the validity of the argument from logic that he puts forth in support.

Hilary Putnam did a good job of explaining the mistakes. I am not a logician, but my background in logic is good enough to verify the explanation. And every logician that I personally know has come to the same conclusion.

Like you, I find it absurd to claim that Penrose has been doubling down on a basic logic error. And yet we have the basic logic error, and Penrose has clearly been doubling down on it.

You don't even need to be an expert to understand that he can't be right. Penrose argues that the capacities of human reasoning is such that Gödel's theorem proves that a mathematician's brain cannot be replicated by any mechanical process. But the reasoning process that mathematicians use is fallible. The output most emphatically is not logically consistent. The appearance of consistency is only obtained after much reexamination of those errors which were discovered. Absolute certainty of lack of error is unachievable by any kind of human reasoning. The history of mathematics is filled with examples of errors that were not discovered for shockingly long periods.

So we do not have a proof of the consistency of human reasoning, or its products. Therefore Gödel doesn't apply. Human reasoning, including the outputs that Penrose cites, do not strictly follow first order logic. Therefore Gödel again doesn't apply. And Gödel is entirely silent on the potential prospects of a heuristic algorithm that can produce inconsistent results. Which is what our brains do.

The inapplicability of Gödel's theorem to our thinking process is an absolute barrier to Penrose's attempts to prove that our thinking process cannot be the result of a mechanical system. It may be that it is not. Personally I fail to see how a strictly mechanical process can create my experience of consciousness. But this is a question that Gödel's theorem cannot address.

[sarchertech]

The mistake you are making is the same that I think a lot of people who dismiss his argument make.

You aren’t reading his actual argument. You are reading a characterization of his argument by a critic.

You can read his rebuttal of those critiques here:

https://calculemus.org/MathUniversalis/NS/10/01penrose.html

The summary is that there is no requirement that human reasoning is infallible in his actual argument.

Again his proof may be faulty. But it is not because of a “basic logic error”. The disagreements people have with his actual argument are much much subtler than a basic logic error.

[btilly]

The mistake that you are making is to imagine that I must be making a mistake.

Let's take a few examples.

He claims that a robot which is able to engage in Gödelian reasoning, cannot possibly be computable. Logicians agree that this claim is false. Indeed https://link.springer.com/article/10.1007/s10817-021-09599-8 shows a version of Gödel's theorem that has been fully checked via proof assistant. While we still lack AIs that are able to produce such proofs (other than by regurgitating such proofs in their input data), in principle a proof checker filtering the output of a brute force search through possible proof attempts will achieve any possible machine checked proofs. But proof checkers can proof check Gödelian reasoning. Thus we already know how to write a (rather impracticable) robot that does exactly what Penrose claims to be impossible.

Here's a whopper. Let's go to this passage from 4.2 of his rebuttal.

However, I had been disturbed by the possibility that there might be true mathematical propositions that were in principle inaccessible to human reason. Upon learning the true form of Gödel's theorem (in the way that Steen presented it), I was enormously gratified to hear that it asserted no such thing; for it established, instead, that the powers of human reason could not be limited to any accepted preassigned system of formalized rules. What Gödel showed was how to transcend any such system of rules, so long as those rules could themselves be trusted.

This is complete and utter bullshit. Gödel did not show that we could transcend any such system of rules. What Gödel demonstrated is what those rules can prove of themselves. Namely, "If this set of axioms proves itself consistent, then it is inconsistent." Which statement can be proven using nothing more than arithmetic. Our ability to prove this doesn't prove that our mathematical reasoning is somehow beyond what a mere formal system can prove. It is just a demonstration that we can follow a piece of arithmetic to its logical conclusion. Any other understanding of the result is simply a mistake.

He's also wrong about whether there are problems that, in principle, are beyond human reason. For example consider the BB(n) problem. Identifying which Turing machine gives us BB(643) is impossible from ZFC. (See https://github.com/CatsAreFluffy/metamath-turing-machines for more.) If you go to BB(1000), no set of axioms that mathematics has ever debated can suffice. Going beyond human comprehension doesn't take much more than that.

Of course those are weak estimates. In fact it is likely that BB(10) is going to be forever beyond us. And no, some magic quantum decoherence in the microtubules isn't going to fix that.

Let's move on. Section 4.5. He admits to the logical possibility that he is wrong, then asks whether unsoundness is plausible. How is it not plausible? The only form of intelligence that we have an existence proof for, us, thinks in notoriously unreliable ways. LLMs are our best attempt to replicate our verbal abilities by computers. They are likewise extremely unsound.

The burden of proof that soundness is possible here is on Penrose. And he needs to prove it soundly enough to overturn the generally accepted conclusion that the known laws of physics suffices, in principle, to explain the manner by which our brains operate. Because that is the conclusion that he is aiming to convince people of.

He doesn't even try. He waves his hands, declares absurdity, and moves on. That may be fine from the point of view of his philosophy. It is not fine from the point of view of a logician. It's a gap. And a mighty big one at that.

I could go on, but what's the point? If you refuse to believe what logicians say about logic, then no explanation of what logicians have to say will convince you. And if you do believe what logicians say about logic, then you should already know that Penrose is wrong.

[spot]

yup and his book was reviewed as such at the time. mention of the rejection of his theory by professional philosophers however keeps getting edited out of the wikipedia page. See this exchange on the talk page https://en.wikipedia.org/wiki/Talk:The_Emperor%27s_New_Mind

>> "The book's thesis is considered erroneous by experts in the fields of philosophy, computer science, and robotics."

> Wooooah, there. That's a massive accusation to add, unsourced, and without any discussion. There needs to be a source for this statement, not to mention an opposing view. It seems unlikely the guy would win an award for a book no one thinks is right. I'm deleting it unless someone comes up with a pretty good source. Joker1189 (talk) 20:43, 27 July 2010 (UTC)

The source was provided with the edit: L.J.Landau (1997) "Penrose's Philosophical Error" ISBN 3-540-76163-2 http://www.mth.kcl.ac.uk/~llandau/Homepage/Math/penrose.html Spot (talk) 03:08, 31 July 2010 (UTC)

[sarchertech]

You say keeps getting edited out but I see one instance of that happening 15 years ago.

The talk is unavailable, but that and a chapter in Landau’s book hardly seem like appropriate sources for “everyone disagrees with him”.

The vast majority of critiques of his argument that I’ve read are by people who are actively working in AI not professional logicians.

[spot]

who said "everyone" or did you make a strawman?

https://en.wikipedia.org/wiki/Penrose%E2%80%93Lucas_argument

this actually puts it better:

The Penrose–Lucas argument about the implications of Gödel's incompleteness theorem for computational theories of human intelligence was criticized by mathematicians,[16][17][18][19] computer scientists,[20] and philosophers,[21][22][23][24][25] and the consensus among experts[7] in these fields is that the argument fails,[26][27][28] with different authors attacking different aspects of the argument.[28][29]

so, rejected by consensus. someone should update the book page so this expert rejection is clearer.

[sarchertech]

Everyone is obvious hyperbole because I didn’t want to both copying and pasting the actual quote.

That is merely a compiled list of people who disagree with him without listing any of his supporters.

There are at least 5 philosophers who support his position if you follow those links and 5 who reject it.

Link 7 doesn’t support the statement “consensus among experts in these fields” because it only refers to a single field—philosophy.

Many of those sources are just links to lists that other people have compiled of arguments for and against Lucas’ argument. They aren’t even all critiques. And many of the ones that are, are already linked directly in the article.

There’s is nothing more to support the notion that there is widespread consensus against his argument.

There may be. But this isn’t good evidence of it.

[russdill]

That's the problem with Penrose's thinking though. He's absolutely convinced that consciousness cannot boil down to something computable. So he reaches for the quantum shelf, but not just the quantum shelf, the quantum processes we don't yet understand since otherwise it'd just be something computable, but with more steps.

[sarchertech]

I mean most AI researchers are utterly convinced that the human brain is a Turing machine. There’s not reason to presuppose that. And if everyone presupposes that and it isn’t true, we’ll be stuck spinning our wheels until someone questions it.

[russdill]

This isn't a viewpoint coming from AI, is been a view that's been around for quite some time. The standard model does an exquisite job of predicting the day to day physics we experience. To find search for new physics where we might find discrepancies, we have to build absolutely huge colliders, and even those don't really effect our "day to day" physics.

For consciousness to be based on some non computable function there would have to be some unknown physics occurring in the brain. Sure, that's hard to disprove, but it also strains credulity, hard.

Penrose picking "quantum" for being the element of physics that would have to change to allow this non computibility is just woo. Why not just say magic?

[pmontra]

I agree with you that picking quantum was probably the fad of the time and it was an easy pick as quantum is everywhere. He cold have said "electrons". However the argument against unknown physics is not very sound IMHO.

There has been unknown physics at play inside brains since forever and it still is and always will be, by definition of science.

The point is that we don't even know how to define consciousness and humanity doesn't have a shared agreement about which living beings are conscious or are not. We're still like engineers building things millennia or centuries ago with only a shadow of a theory of why their creations worked. And yet we still walk on bridges from 2000 years ago and we had electric batteries and power plants before knowing how an electro magnetic wave moved.

[russdill]

If it were known that there where physical interactions occurring within the brain that deviated from the standard model, we wouldn't bother building didn't colliders.

[sarchertech]

> This isn't a viewpoint coming from AI

It has always been related to AI. Shortly after Church and Turing formalized computability, people started squaring off into 2 camps. People who believed strong AI was possible and those who didn’t.

We know the standard model is incomplete. Penrose’s ideas come directly from his his explorations of the gaps he suspects exist.

[russdill]

There are people that come to it from the direction of AI because they think they know something about consciousness. That's certainly putting the conclusion first.

But there are also physicists who come at the problem from the direction of physics. We know the standard model is incomplete, but we also know it covers everyone we experience with exquisite precision. Unless there is a black hole or temperatures on par with the big bang going on within our brain, the standard model will tell you what you need to know

[BurningFrog]

Penrose may well be completely wrong about this, but I think he's easily done enough important science work to not be called a crank.

[Marazan]

You can be a genius in one field and a crank in another.

For example: Penrose.

[NegativeLatency]

example: Shockley was a eugenicist https://en.wikipedia.org/wiki/William_Shockley

And plenty more: https://archive.is/2021.06.21-140221/https://www.nationalgeo...

[oh_my_goodness]

This feels a bit like a circular argument.

[r2_pilot]

How about Linus Pauling and vitamin C then?

[sarchertech]

It happens. It’s surely possible. But does it happen enough that anytime a Nobel laureate says something a little out there, this is the immediate explanation?

Especially if what he’s saying has lacks a major hallmark of crackpot theories. That is he is very open to his theory being wrong and he won’t even say that it’s probably correct. He just thinks it’s possible and would like to see more work done on it.

[Retric]

Yes in that when they something outside their field that’s ‘a little out there’ Nobel laureate’s aren’t as a group more useful than random noise. Similarly a crank can happen to say a true statement, but the issue is the process with which the statement is derived is flawed to the point of uselessness.

The derogatory aspect of calling someone a crank is obviously uncalled for, but as a shorthand it’s not unreasonable to use the term.

[oh_my_goodness]

Yeah, that's fair.

[jibal]

Maybe review what a circular argument is, because that isn't one.

[oh_my_goodness]

Sure! Happy to. Here's an example of a circular argument: "Penrose could be a crank. We know that kind of thing is possible because, for instance, Penrose is a crank."

[jibal]

The argument made was nothing like that. The assertion made was

"You can be a genius in one field and a crank in another."

Supporting evidence was offered: "For example: Penrose."

One can dispute the evidence, but there's nothing circular about the argument--your version is a strawman created precisely in an attempt to turn a non-circular argument into a circular one. And even rejecting that evidence there's plenty of other evidence and others here gave examples. Not that examples are even needed, as the assertion is self-evident, and was offered as a counter to a textbook fallacious argument from authority: "he's easily done enough important science work to not be called a crank". There is no basis at all for such a claim. Perhaps Penrose is not a crank in re consciousness, but it certainly doesn't follow from the fact that he's done the highest caliber non-crank science ... that claim is fallacious, disingenuous, and intellectually dishonest.

[nrml_amnt]

I think of Linus Pauling

[joquarky]

The fact that you couldn't pick a different person as an example makes for a very weak assertion.

[jibal]

There's no evidence that they couldn't pick a different person. There are quite a few other persons and some other commenters pointed out some of them.

[dboreham]

Newton.

[BurningFrog]

Newton pretty much invented several fields of science, like Classical Mechanics, Optics, Calculus, and Gravitational Astronomy.

He started out as a novice in all of them.

That Alchemy failed to pan out as a science doesn't make him a crank in my book. You can't know Alchemy is impossible until you try pretty hard.

[rf15]

or even within the same field! Further examples: Newton, Chomsky

[chvid]

Why is it crank science? He clearly states that it is hypothetical, speculative and open research.

[markhahn]

The main reason is because it's arbitrary.

His "speculation" is litereally: I think quantum is mysterious, and brains are mysterious, so there must be quantum in the brain. That's just silly - even if only because his opinions about mysteriousity is of no importance.

[halifaxbeard]

If the universe is closed and knowable, free will can't exist. Fortunately, Heisenberg left the door open.

[drdeca]

I don’t think non-commuting observables really helps much in the “free will existing” department.

[oh_my_goodness]

I don't see that offering an alternative hypothesis disproves anything.

[tsimionescu]

By Occam's razor, it could be said that offering an alternative hypothesis that explains all facts equally well but is also simpler does "disprove" more complex hypotheses. For example, it is often said that Einstein's special theory of relativity disproved the idea of an aether - but special relativity is compatible with the existence of an aether with certain properties, it just is a completely unnecessary extra complication.

[oh_my_goodness]

Special relativity is a lot more than a hypothesis at this point. I think the ideas in this paper may be a little bit more speculative than that.

[Apocryphon]

Someone oughta notify Peter Watts

https://www.rifters.com/real/STARFISH.htm#references

[IdSayThatllDoIt]

This seems like a straw man argument.

That the brain uses electrical/chemical signals is crank science about subatomic particles messing with your aura in a way comparable to "body thetans" in Scientology.

If that were not so, electrical/chemical engineers could upgrade our brains with their knowledge of electricity/chemistry.

Scientific progress is thinking about stuff. And my Occam's razor is leaning toward "if just arithmetic could yield consciousness we would have figured it out by now".

[Noaidi]

Wow, this is such an odd response. There’s plenty of research that link microtubules to consciousness. I don’t understand this pushback other than one being sped in a certain scientific dogma that doesn’t allow new thoughts or questioning to creep in.

Just say that Penrose is a crank is way off chart in my opinion

[ben_w]

The word "consciousness" means at least 40 distinct things; some of those (e.g. brain being alive and functioning) are obviously connected to microtubles; others (e.g. qualia, which is what most understand Penrose invoked microtubles to explain) are so ill-defined as to be untestable and unfalsifiable.

That Penrose also seems to have a fundamental error in his understanding of the implications of Gödel's incompleteness theorems, doesn't help.

[Noaidi]

It means one thing to people who study consciousness.

https://www.theintrinsicperspective.com/p/consciousness-is-a...

[ben_w]

That linked page is just a long-winded assertion that only their own definition counts.

It's also a definition which is completely untestable and presently unfalsifiable.

[Noaidi]

He’s a neuroscientist that studies consciousness. I think that gives him more valid reasons to have this definition than someone who programs computers.

[ben_w]

He himself would criticise you for doing so, even just on the basis of what he put in that blog post, as you're using an argument from authority.

[Byamarro]

I think we can do better than to have this level of argumentation. Regardless if the pretending comment had a merit to it or not

[galangalalgol]

But that accepted definition is that it means everything... "What it means to be a bat" isn't a useful definition. I will accept that is what the word means and defend the viewpoint the word is thus useless.

[Noaidi]

This is the last paragraph of his article for people who aren’t going to read the whole article.

“ So yes, there is scientific confusion about what consciousness is! And there’s metaphysical confusion about what consciousness is! But there’s no definitional confusion about the word “consciousness” itself. People know what needs to be explained, it’s just that explaining the phenomenon is very hard, and no one fully has yet.“

[mensetmanusman]

/anything I don’t understand is useless/

[tsimionescu]

To save everyone a click: this objective definition of consciousness is "the fact that an organism has conscious experience at all means, basically, that there is something it is like to be that organism". This is quite obviously circular, even though it sounds fun initially.

[markhahn]

that is NOT what the article says. read the article, it's a pretty good survey.

[Byamarro]

What he refers to is more specifically called phenomological consciousness afaik (just skimmed through tho)

[mensetmanusman]

I love his thoughts on connecting the halting problem to understanding ala Gödel.

[exe34]

Penrose's theory is this: consciousness is really weird. quantum is really weird. there's got to be a connection.

Just because he is brilliant in one field doesn't mean he's remotely competent in every field.

[Noaidi]

He came up with his idea in collaboration with scientist to study consciousness. It’s not his idea really it’s a group of people’s ideas. His brilliance in his field contributed to the brilliance of other people’s fields. This is how collaborative science works.

If you seen any of Penrose’s talks or read any of his books, you know that this was not fundamentally his idea.

[KingFelix]

Yup, even the Dioso-Penrose limit has two sides. https://arxiv.org/abs/2111.13490

Paraphrasing here: The paper above was looking for energy given off during collapse, (which they did not find) on the Diosi side, where Penrose' idea is more in the retro-causal, you wouldn't find an energy signature. I am sure someone can call out a better representation, but similar to your response that Roger has these ideas and looks for collaborators, but still has his own ideas on things that may differ.

Interesting seeing this conversation going on, Roger / Stuarts work has been trashed over the years, Max Tegmark did the maths and said brain is too wet/warm for any quantum stuff, but we've been finding this in tubulin* and other places, never retracted the paper.

Either way, consciousness is amazing, and a mystery, anyone interested should come to Tucson in April for Towards a science of Consciousness, good conversations, interesting people, usually more questions than answers.

https://www.mdpi.com/2673-9321/4/2/19 https://pubs.acs.org/doi/10.1021/acs.jpcb.3c07936

[markhahn]

No, there's no evidence against Tegmark's math.

Finding isolated quantum effects is emphatically unsurprising: after all, everything is quantum. It's just limited in locality, which is basically what Tegmark is talking about (locality and decoherence time being somewhat dual).

There is no evidence for the kind of quantum effects that would involve multiple neurons. This is quite a block, since afaik, even the quantum-woo types (Penrose, emphatically) are not claiming that consciousness comes from the quantum behavior of a single neuron. (And that would be profoundly ignorant of basic neuroscience.)

[KingFelix]

There is this from Max - https://journals.aps.org/pre/abstract/10.1103/PhysRevE.61.41...

And response

https://journals.aps.org/pre/abstract/10.1103/PhysRevE.65.06...

[jibal]

> in collaboration with scientist

If you mean Stuart Hameroff, he's no scientist.

[red75prime]

Nah. He postulated that mathematicians don't make errors and proposed a hypothetical physical mechanism to make it work.

[ljlolel]

Also microtubules with quantum…

[westurner]

But does this help explain Representational drift?

From "Concept cells help your brain abstract information and build memories" https://news.ycombinator.com/item?id=42784396 :

> the regions of the brain that activate for a given cue vary over time

"Representational drift: Emerging theories for continual learning and experimental future directions" (2022) https://www.sciencedirect.com/science/article/pii/S095943882...

>> Future work should characterize drift across brain regions, cell types, and learning.

How do nanotubules in the brain affect representation drift?

There is EMF to cognition given that, for example, "Neuroscience study shows the brain emits light through the skull" (2025) https://news.ycombinator.com/item?id=44697995

Aren't there certainly quantum effects in the EMF wavefield of and around the brain?

[soulofmischief]

The common understanding is that at the molecular scale that your nervous system operates, quantum effects are averaged out and don't lead to instability of neuronal activity.

[markhahn]

Tegmark has used actual, you know, numbers and stuff to show that quantum effects in the brain are pretty implausible.

https://pubmed.ncbi.nlm.nih.gov/11088215/

[westurner]

Again there, does the EMF/RF field created by the electrovolt wave function of the brain affect the electrovolt wave function of the brain? If so, isn't that a feed-forward feedback loop (where there may be quantum behavior)?

Does this paper also fail to assess other fields relevant to understanding nonlocal neuroactivation in disproving that there is any quantumness in cognition?

How do humans simulate digital and quantum circuits with the brain?

And, why do attempts to localize activations in the brain weeks apart fail; why is there representation drift?

[westurner]

Actual evidence of:

/? quantum in the brain: https://scholar.google.com/scholar?hl=en&as_sdt=0%2C43&q=qua...

/? quantum cognition: https://www.google.com/search?q=quantum+cognition

gh topic: quantum-cognition: https://github.com/topics/quantum-cognition (2025: 7 results; all Julia)

2000: the referenced Tegmark paper

From https://scholar.google.com/scholar?q=related:-mGt9tzYwSUJ:sc... :

- 1998: "Quantum computation in brain microtubules? The Penrose–Hameroff 'Orch OR 'model of consciousness" (1998)

- 2002: "Quantum computation in brain microtubules: Decoherence and biological feasibility" (2002)

Quantum cognition: https://en.wikipedia.org/wiki/Quantum_cognition

[soulofmischief]

What behavior precisely do you think is hiding in quantum region?

I'm on board with Hofstadter's strange loops but at most, quantum-level interaction should just amount to noise that is stabilized by the higher-order chemical region in which the brain operates. What even are we looking for at this point?

What aspect of my experience is not likely to just be a result of chemical interactions in the brain?