Quantum social science exploits ideas and methods from quantum physics in order to model and understand social behaviour. For example, quantum cognition models human decisions as the collapse of a kind of mental wave function to a particular state, in a process akin to the wave function collapse in physics. But is this social wave function an actual physical thing, or just a metaphor?
Most researchers in quantum cognition adopt the stance that quantum techniques just offer a more flexible toolbox for analysing things like interference between incompatible concepts, or social entanglement between people, while distancing themselves from the idea that the brain is actually based on quantum processes. This is obviously prudent from a strategic perspective, since – while quantum biology has revealed a role for quantum effects in things like avian migration or photosynthesis – they have yet to be detected in the brain. And any assertion that humans are actually quantum entities tend to be met with extreme skepticism (even though comparing them with mechanistic entities, as is customary in the social sciences, gets a pass). It also reflects the “shut up and calculate” approach that is common in physics. In this view, quantum physics is therefore just a metaphor for human behaviour.
A few social scientists however do point out that, just because we haven’t yet detected quantum effects in the brain, doesn’t mean they aren’t there; that it seems reasonable that, if bird brains exploit quantum effects to get around, our own brains might make use of them too; and that areas such as quantum cognition provide circumstantial evidence for the radical notion that we are what Alexander Wendt calls “walking wave functions.” In other words, quantum social science is based not on a metaphor, but on physical reality.
Now, one might think that this question can only be settled by physical proof. Either experiments will eventually show that our brains are quantum, or they won’t. However, as with all things quantum, I think the real answer is more complex.
To start with, if quantum physics is being used as a metaphor, it isn’t a very good one.The usual purpose of a metaphor is to explain something that is difficult or abstract in terms of something that is more simple and concrete. When Shakespeare had an actor read “All the world’s a stage” in As You Like It, he was comparing the vastly complex world to a wooden platform on which the actor was actually standing. In quantum physics, we might think of a wave function as real because it can be expressed using mathematical equations, at least for the most simplified of situations. But no one has actually seen or felt an electron’s wave function (for one thing, it involves imaginary numbers). And one of the major drawbacks of the Copenhagen interpretation is that there is no explanation for how a wave function collapses during a measurement.
It would therefore make more sense to explain the quantum world using human behaviour as a metaphor, then the other way round (it is easier to relate to the experience of a state of uncertainty collapsing to a particular decision, than it is to an electron’s wave function collapsing to a particular eigenvector). But we don’t do that because quantum physics was discovered first. And this raises another question, which is why – given its similarities with human behaviour – quantum physics is usually described as being somehow alien.
Einstein for example said quantum reality reminded him of “the system of delusions of an exceedingly intelligent paranoiac, concocted of incoherent elements of thoughts.” Physicist Steven Weinberg said in an interview that “quantum mechanics, although not inconsistent, has a number of features we find repulsive … What I don’t like about quantum mechanics is that it’s a formalism for calculating probabilities that human beings get when they make certain interventions in nature that we call experiments. And a theory should not refer to human beings in its postulates.” Yet concepts such as duality, indeterminacy, and entanglement seem quite reasonable when applied to our own thought patterns. And consciousness is of course one thing that all human beings have direct personal experience of, no physics course required.
So it doesn’t seem right to say that quantum physics is a metaphor for human behaviour, given that we know less about the former than the latter. But another problem with the metaphor vs physical reality question is that physical proof of quantum processes in the brain would not directly show that our mental processes are best understood as quantum. In the end, everything in the physical world, including our brains, is based on quantum reality at the level of subatomic particles – so in a trivial way we are quantum creatures. But a common argument directed against quantum social science is Bohr’s principle of correspondence, which states that these effects wash out at large scales. So even if quantum effects were shown to play a role in the brain, this wouldn’t in itself indicate that social behaviour is a quantum phenomenon.
Now, while the correspondence argument makes sense for many phenomena, it ignores the fact that quantum effects do scale up all the time, because we design them to. Quantum technologies include everything from lasers to semiconductors to atom bombs. If we can learn to exploit quantum effects to build devices, why shouldn’t eons of evolution accomplish the same thing? Futhermore, quantum behaviour can also appear at large scales in things like phonons – sound waves in crystals or metal bars which appear as discrete quasi-particles and have their own quantum properties. So demonstrating that the brain is quantum would not prove that social behaviour is quantum. And conversely, proving that the brain is based on mechanistic interactions wouldn’t in itself prove that social interactions are not best modelled as quantum phenomena.
This is seen clearly in quantum economics, where money has its own dualistic properties because it merges the incompatible concepts of number and value, and prices are best seen as an emergent property of the money system. As physicist Robert Laughlin notes, “physical law is a rule of collective behavior, it is a consequence of more primitive rules of behavior underneath (although it need not have been), and it gives one predictive power over a limited range of circumstances. Outside this range, it becomes irrelevant.” Quantum behaviour at the level of the money system is not the same as quantum physics at the subatomic level; so while one can make a convincing argument that the brain is probably based on quantum processes, and evidence that this is the case would certainly change the conversation around quantum effects in the social sciences, it isn’t necessary or even apposite in economics to try and draw a direct connection between the two (proof that neurons are quantum wouldn’t prove that dollars are quantum). Instead, each should be handled on its own terms.
One answer to the question of interpretation, then, is to say that we can usefully model society as if it were a quantum system; while at the same time remembering that any mathematical model is only a sketch of the real thing. This might seem like a kind of intellectual dodge – the social sciences version of “shut up and calculate” – but in fact it is the standard practice in mathematical modeling: we model reality as if it obeyed our quantum rules too, even though we know the theory has limitations, which is why physicists continue to work on new ones. And when Max Planck first proposed the idea of the quantum, he didn’t do it in order to make a profound point about the ontology of the universe, he did it because it worked.
In this view, rather than quantum physics being a metaphor for human behaviour, it is more accurate to say that quantum models are a kind of metaphor for both physics and society. And the fact that these have something in common might be telling us something interesting about the nature of both.
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