hypothetical class of theories that evade Bell's theorem by virtue of being completely deterministic

In the context of quantum mechanics, superdeterminism is a term that has been used to describe a hypothetical class of theories that evade Bell's theorem by virtue of being completely deterministic. Bell's theorem depends on the assumption of "free will", which does not apply to deterministic theories. It is conceivable, but arguably unlikely, that someone could exploit this loophole to construct a local hidden variable theory that reproduces the predictions of quantum mechanics. Superdeterminists do not recognize the existence of genuine chances or possibilities anywhere in the cosmos.


  • I am absolutely convinced that one will eventually arrive at a theory in which the objects connected by laws are not probabilities, but conceived facts, as one took for granted only a short time ago. However, I cannot provide logical arguments for my conviction, but can only call on my little finger as a witness, which cannot claim any authority to be respected outside my own skin.
  • If we did not have free will, we could never decide to test a scientific theory. We could live in a world where objects tend to fly up in the air but be programmed to look only when they are in the process of falling. I must admit, I have no proof that you have free will, but I certainly enjoy free will, and you will never be able to show otherwise. This kind of discussion can often go round in circles. It is logically possible, but totally uninteresting, rather like solipsism which asserts that I am the only person in the world and that everyone else is just an illusion inhabiting my own mind. This hypothesis of superdeterminism hardly deserves mention and appears here only to illustrate the extent to which many physicists, even among specialists in quantum physics, are driven almost to despair by the true randomness and nonlocality of quantum physics. But for me, the situation is very clear: not only does free will exist, but it is a prerequisite for science, philosophy, and our very ability to think rationally in a meaningful way. Without free will, there could be no rational thought. As a consequence, it is quite simply impossible for science and philosophy to deny free will.
    • Nicolas Gisin, Quantum Chance: Nonlocality, Teleportation and Other Quantum Marvels (2014), Chap. 9. Is Nature Really Nonlocal?
  • There is the so-called idea of ‘superdeterminism’. Recall Schrödinger’s class of identically prepared students. We are told they can all answer any of a set of questions correctly, but each can only answer one, and then forgets the answers to the rest. It’s an odd idea, but we can still test it: we ask the questions at random, and find that we always get the right answer. Of course it is possible that each student only knows the answer to one question, which always happens to be the very one we ask! But that would require a massive coincidence, on a scale that would undercut the whole scientific method. Or else we are being manipulated: somehow we are led to ask a given question only of the rare student who knows the answer. So we switch our method of choice, handing it over to a random number generator, or the throw of dice, or to be determined by the amount of rainfall in Paraguay. But maybe all of these have been somehow rigged too! Of course, such a purely abstract proposal cannot be refuted, but besides being insane, it too would undercut scientific method. All scientific interpretations of our observations presuppose that they have not have been manipulated in such a way.
    • Tim Maudlin, "What Bell Did", Journal of Physics A: Mathematical and Theoretical (2014)

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