You may have heard a lot about a thing called “quantum consciousness.” Most of what you’ve heard is bullshit.

The Not Bullshit

First let’s discuss the bit that isn’t bullshit. Many papers in various sciences that have words in their titles like “quantum cognition” and the like aren’t actually about quantum mechanics or even physics at all. So, if you or the internidiot you are interacting with didn’t read beyond the title (or indeed, even the abstract), well, please don’t do that. Most of this work means something other than you think: they are not arguing that quantum mechanics has anything to do with brains, minds, or cognition; they are pointing out that some of the ways brains solve problems or make decisions resembles the probability logic of quantum mechanics. All of which can be explained with classical physics.

For example, if you ever took a physics class in your life that did any unit on quantum mechanics, you will have watched double-slit experiments performed in front of you using sheets of common craft material and a tank of water. Not a single thing you saw was quantum mechanical. All you saw was that classical systems that carry waves (like, say, the sea; or the air; or literally anything) can do weird things very similar to what quantum mechanical systems do. Thus, you can have static wave interference patterns with just ordinary waves in water, a totally classical system. No quantum mechanics is required for this. This is not quantum mechanics.

Likewise, you can have quantized interacting systems—from standard digital computers to agricultural dykes—where there are only two states, and the system flips between one and the other (on or off, one or zero, contained or flooding) once the classical system reaches a threshold. The brain can do this too: where you can be in two states (imagining turning right or left, running sims for both outcomes), and when a threshold is reached (eventually enough neurons fire on one side over the other to cause a cascading outcome), a state is chosen. This is “quantum” in the merely analogous sense that it is an undecided either/or, on/off state that can be flipped (“collapsed”) under the right quantitative conditions; yet no actual “quantum mechanics” is involved.

We can thus talk about modeling consciousness by analogy to quantum mechanics, just as we can do wave mechanics in a bathtub, or acoustic mechanics in the design of a concert hall, or design decision-making computer circuits. For example, to speak of a cognitive state of considering options as “quantum superposition” is loosely true (there are two states being considered simultaneously and one of them hasn’t been chosen yet and thus the superposed state has yet to “collapse” into a decision), but not at all literally true. There is no “quantum superposition” going on. The entire system is an analog “classical” computer. Not a quantum computer.

So, a lot of “quantum cognition” work you’ll see published is doing this: looking at how our brains work as classically mechanical computers, and only finding analogous operations to quantum mechanics, just like looking at how ocean or sound waves work in classical mechanics, and finding behaviors that resemble ones we observe in quantum mechanics. But it’s not quantum mechanics. Which means, for example, most quantum cognition models allow no “fundamental indeterminism” to hang your hat on. They are all deterministic macro-systems. They just share behaviors in common with quantum systems in physics.

Which is actually evidence that quantum mechanics is itself also just classical mechanics, only we can’t observe the operating variables so it only “looks” weird; as if we could not see the ocean but could only see the peaks of waves as individual particles, and found the behavior of those particles incredibly bizarre, and then invented a bunch of woo bullshit about it—when really, all along, it was just a perfectly sensible deterministic system in classical mechanics. We don’t know if this is the case. Maybe quantum mechanics behaves the way it does because it is somehow fundamentally indeterministic. But we don’t really know that either.

More and more scientists are reproducing even the weirdest quantum mechanical phenomena with entirely classical systems (so far, both with fluids and sound; and yet hydrons and phonons entirely obey classical physics). And Superstring theory would indeed reduce all quantum phenomena to classical, in much the same way I just suggested (what we think are particles are something akin to the peaks of waves we cannot otherwise see, moving in more dimensions than are visible at our scale: see Superstring Theory as Metaphysical Atheism). Conversely, even truly indeterministic systems logically entail deterministic classical systems at scale; so it does not even matter which is the case (see All the Laws of Thermodynamics Are Inevitable).

The human brain is a classical-scale system and therefore cannot really be guided in any meaningful way by quantum phenomena. Because even a single perception or decision involves the operation of millions if not billions of neurons, which are massive systems already (even just one neuron is a cell comprised of trillions of atoms). So any quantum indeterminacy there even could be will be completely washed out by the system as a whole. This is the reason hardly anyone (especially experts actually in neuroscience, rather than other fields nosing in) buys the quantum consciousness thesis beyond the role of analogy.

The Bullshit

For a good breakdown of the distinction between “metaphorical” quantum cognition theories, and “literal” ones, see Weak vs. Strong Quantum Cognition by Paavo Pylkkänen (one proponent of “weak” quantum cognition, which is the metaphorical and not the literal kind: see his book Mind, Matter and the Implicate Order). Pylkkänen mentions an example that “strong” quantum cognition proponents try to lean on against the obvious problem that the brain is far too complex to be a quantum system, or even be affected meaningfully by any: the role of quantum mechanics in the way photosynthesis works. The example only dooms their project by proving their critics’ point: thought is indisputably an emergent phenomenon caused by a massive system of interacting cells (see The Mind Is a Process Not an Object); energy capture by a single chlorophyll molecule is not.

Even if quantum effects become relevant somewhere within a single molecule within a single neuron, and even if this were somehow pertinent to the I/O protocol of the neuron (and thus had any effect at all on computation)—and that’s already two “ifs” for which still no evidence exists—that cannot explain consciousness in any way. All it would explain is how each neuron runs its I/O protocol (how the neuron decides what the output signals should be, given the input signals). Single neurons are not conscious. And there won’t be any shared quantum states between neurons, because any molecule doing anything meaningful quantum mechanically in one neuron will be separated by any other neuron by umteen trillions of atoms chugging along as a classical system.

So there cannot be any superposed macrostates in the brain. Moreover, anything the proposed quantum effect “does” to determine a neuron’s I/O protocol can be replaced by a classical circuit doing exactly the same thing and therefore won’t even be necessary to the output of the neuron, much less the whole brain. Therefore consciousness can never and will never be explained by quantum mechanics. All sorts of classical systems can replicate quantum outcomes (well-weighted dice are just as random; classical waves do many of the same things as quantum waves; matrix mechanics can be replicated with any classical algorithm).

This is also why quantum consciousness cannot rescue contra-causal free will (which doesn’t exist, and no one should want to exist anyway: see Free Will in the Real World … and Why It Matters). For quantum indeterminacy (if that even exists) to change the output of the otherwise-deterministic system of the brain, it would require spontaneous coordinated events across trillions of atoms, which even at most (at literally the most ridiculously most) won’t happen but once in a trillion decisions. Which at a decision a second is once every thirty thousand years or so—so, definitely don’t hold your breath for that. This is the problem with vast macrosystems like the brain: quantum phenomena simply can’t cause or explain anything relevant about them.

Still, as bullshit as it is, not all “strong” quant-cog proponents are cranks (the legit cosmologist Roger Penrose has been pushing it for years, albeit implausibly, and impressing literally no one in neuroscience); but many are cranks (Wikipedia provides a list). Pretty much only “weak” quant-cog proponents are worth taking seriously. For example, there is a really good summary of this school of thought and its prospects in Zheng Wang et al., The Potential of Using Quantum Theory to Build Models of Cognition. One thing you will get from their summary is how legitimate quant-cog is actually rooting cognition even more firmly in classical mechanics, by seeing neural computing as a geometric process (a multidimensional exploration of a vector or concept space) rather than a linear process (like a hand calculation on paper, or a Turing machine; although a Turing machine, being a universal machine, can replicate all vector-space systems and thus could still produce cognition, the machine itself is not that; just as a computer chip can produce a video game, but is not itself a video game). And it just happens that the geometric process (with its features like vector completion and amplitude transition) better matches how a brain works physically (as it explores a geometric space within a neuralnet).

So legit quant-cog researchers can say the brain functions like a wave-tank that can produce analogous circumstances of superposed wave-forms, interference patterns, and quantum switching between binary states; without being literally quantum mechanical. For example, we know the human brain cycles at around 40 Hz, which seems related to our conscious perceptual threshold of about 20 Hz (hence why film and television media shoot to exceed that in frame-rates to get our visual system not to notice). But even individual perceptual or decisional events often involve waves of coordinated signals across neural-nets in the brain, hence entertaining two thoughts simultaneously, and using interference patterns to locate and determine outcomes. So, obviously, we will get some analogous phenomena to wave-particle duality; but none of this is quantum mechanical, it is all entirely explicable with classical mechanics, just like waves and sound (even hydrons and phonons, though no analog to those has been discovered yet in neuroscience).

Hence we get serious work like that of Tomás Veloz, whose dissertation explores quant-cog models that involve no quantum mechanical ontology but rely solely on classical computational physics. And we get sensible descriptions of what these scientists are doing, like:

The quantum cognition research programme concerns the application of quantum probability theory (the rules for how to assign probabilities to events from quantum mechanics, without any of the physics) to cognitive modelling.

Emmanuel M. Pothos et al., An Overview of the Quantum Cognition Research Programme

“Without any of the physics.” Real quantum cognition research has nothing to do with quantum mechanics and posits no strange physics like indeterminism. It is thoroughly classical and deterministic. It deviates from classical probability theory (which is linear), not classical physics. See Pothos and Busemeyer’s Review for a detailed discussion. And see Pothos et al.’s Progress and Current Challenges with the Quantum Similarity Model (and the detailed analysis of Surov et al.) for examples of how describing the brain’s thought-process with quantum mathematics (not quantum physics) can actually explain a lot of cognitive biases and innate fallacies in human reasoning, which arise from the way the brain computes information. Which is still entirely classical and deterministic. Thus “quantum cognition” tends to be distinguished from any “quantum mind” nonsense. Wikipedia provides a decent summary of the reasons the latter is bollocks.

Cranks who try to push that stuff include Christian apologists who want quantum consciousness to be a thing so they can somehow rescue free will, or a soul. One once proposed to me that it is established science, and sent me a list of links. They jumbled together articles by Diederik Aerts and Peter Bruza, with crank nonsense—like this ridiculous paper from Iran: Pegah Imannezhad and Ali Ahanj, “A Quantum Cognition Analysis of Human Behaviour,” Axiomathes 2022. I hardly need critique it, as anyone who reads it will see at once that it is a bizarre collage of non-sequiturs attempting to prove that customer hesitation in economic transactions proves consciousness violates the laws of physics (is this a Poe?).

The apologist obviously didn’t read these papers, or understand them. They actually fell for the worst science paper written this century (from a bullshit journal that had to change its name to Global Philosophy to make clear it is not even a science journal, but a speculative philosophy journal). And then they mistook remarks in Aerts and Bruza about classical vs. quantum systems as referring to physics—when in fact they refer to classical vs. quantum mathematics, and clearly explain they are not talking about quantum physics, but adapting its math to the classical system of the human brain. There is no quantum mechanics in them. And yet the apologist confused Aerts with Imannezhad, as if they were talking about the same thing (or anything at all of the same scientific merit). Please don’t do that, either.

There are also middle cases, where someone is trying to get there but just sucks at it. As an example, I came across Shan Gao’s paper for the Journal of Consciousness Studies (2021), “Does Quantum Cognition Imply Quantum Minds?” This seems to attempt to argue that the quantum mathematics of human brain-function entails a quantum physics of human brain-function, but being a really terrible philosophy paper, it is never clear in any of its pertinent terms. For example, it goes on a lot about how if a wave-function equation describes a brain-state as quantum, then that brain-state is ontologically quantum. Which is trivially true. But it’s also true of wave tanks in high school classes.

Gao seems to confuse “quantum mind” (as in a mind explained by quantum physics) with “quantum cognition” (a mind explained by quantum mathematics) in the very attempt to distinguish them. Gao never mentions the issue that quantum mathematics can describe classical systems; so there can be no entailment from “the brain uses wave mechanics for computation” to “the brain uses quantum physics for computation,” any more than there can be any entailment from “the ocean uses wave mechanics to structure its surface” to “the ocean uses quantum physics to structure its surface.” But as the paper is worded so badly, it could be that this is even the point Gao was trying to make, and he is actually using the phrase “quantum mind” in a completely different sense than everyone else, as not referring to quantum physics. Then he’s just a standard quant-cog guy.

And that was the least bogus example I could find.

Conclusion

“Quantum consciousness” isn’t a thing. There are no scientific studies establishing any role for quantum physics in the construction of consciousness. The closest you can come are to discussing quantum mechanics in the molecular I/O protocol of individual neurons; but consciousness arises from millions and billions of neurons, and any role physics plays in the I/O of individual neurons can be replicated classically, and thus there is nothing distinctive about the role of quantum mechanics in producing it. And even this irrelevant role for quantum mechanics remains hypothetical and unproven—and if ever proved, would not be about consciousness at all, since it would simply describe the mechanics of all neurons, even in flatworms. It is thus as irrelevant as the role of quantum mechanics in the operation of cellular chlorophyll in plants. (Wikipedia has a surprisingly good summary on these points in its assessment of the CNET hypothesis.)

One might still ask why quantum cognition—the brain’s recourse to quantum mathematics in decision-making and model-building—would be a thing. A naive (or crank) reaction to this would be to declare this evidence that somehow consciousness is quantum mechanical, thereby explaining “why” the brain correlates to the same mathematics (like Gao may or may not have been arguing). But all of the computation models in quantum cognition (and physical evidence of them as well) indicate purely classical mechanisms are being used to replicate these mathematical structures. So some other analogy must be operating. This is best seen in Surov et al. Human thought appears to not only conceptually operate in a geometric vector space (as also described by Wang et al); it appears to physically do so.

For example, our brains model geometric space anamorphically with 3D arrangements of neurons in the brain, and can measure distance with time: the longer it takes a signal to go from one neuron to another registers as a correlate to physical distance, causing that point to “feel” far away to us in a neural map of the external world. The brain also does this with time itself, and with concepts, sounds, color, all kinds of things, to map similarity and difference between them. (See the discussion in Ramachandran & Hirstein.) This neuralnet method of computation allows multiple possibilities to be processed simultaneously in waves of electrochemical signaling across the brain that pass over and through each other and thus can produce the dynamics of wave mechanics: overlapping waves can cancel out or amplify, resulting in a “decision,” as one set of neurons ends up producing a stronger impetus signal than another. And this goes beyond conscious decisions. For example, how our brain subconsciously resolves its visual theatre constitutes “decisions” it has made regarding what you are seeing, which is why it can make mistakes, producing visual illusions and even starker errors like invisible gorilla effects (see What Does It Mean to Call Consciousness an Illusion? and Bayesian Analysis of the Barkasi-Sant’Anna Defense of Naive Memory Realism).

This process just happens to be the same way outcomes are decided in quantum mechanics, where a chaos of physical waves creates superposition which causes “transition amplitudes,” whereby “decisions” (like where a particle is or what its momentum is) get “resolved” in a similar way. Hence as Wang et al. describe it:

Description of human thinking in terms of transition amplitudes allows indistinguishable cognitive alternatives to interfere, producing deviations from classical set-theoretic probability calculus corresponding to the rational boolean logic.

The irony is that this results in more erroneous reasoning in humans. Quantum calculus is actually bad at epistemic probability calculation; because the physical phenomena it was built to describe isn’t interested in epistemic probability calculation. It is simply following the simplest way to behave, in the absence of any intelligent guidance or interference. Waves be waves. Whether at sea or in electromagnetic fields. They do what they do. They aren’t trying to calculate anything, much less the epistemic probability that a virtual model corresponds to reality; or how to win at poker. All we can do is observe their results and mathematically model the mechanism producing it.

But this also explains why brains would operate this way. Linear probability calculus is very computationally arduous, requiring time and resources—indeed absurdly, once you start trying to track a million probabilities of things. It’s also hard to develop by accident. Using wave mechanics as a shortcut—an easy adaptation for any electrochemical neuralnet to hit upon by natural selection—solves this problem. It’s vastly faster, and requires a vastly smaller resource contribution. But this comes at a cost: accuracy is lost. Errors result. But as with most cognitive biases mapped in the brain, this half-assed way of doing it is better than nothing. The erroneous ways our brain work are not ideal (which is why we seek to replace them with cultural firmware updates in the form of “logics,” “formal mathematics,” “critical thinking,” and “the scientific method,” but also why those things take work to apply, and hence why even people who know them often fail to use them). But the innate mechanisms are “pretty good” compared to the alternative; thus we tend to out-compete dumber animals, without having to be perfectly rational. (See my discussion of all this in The Argument from Reason.)

But none of this gets us to quantum physics explaining consciousness—at all, much less as would allow a fundamental indeterminism to play any role in it, or allow a disembodied soul to exist.