Quantum theory, free will and justice

A student of mine is writing his bachelor thesis on “free will, quantum mechanics and the system of justice”. I’m very happy about that, because it gives me an excuse to dive into matters I’ve been interested in since childhood. I want to use this blogpost as a noteblock on which I roughly sketch my thoughts on these matters. Sometimes the attempt to write down a coherent story about your point of view shows you that there are gaps in your argumentation you hadn’t expected.

Do we have free will? And can justice function if our will isn't free?
Do we have free will? And can our system of justice function if our will isn’t free?
Credit: francescoch/Getty Images

Do the theories of physics rule out the possibility of human free will? It is a popular thought that there is no room for free will in classical physics while in quantum mechanics there is room for free will (because of the uncertainty principle). It is very important that there is free will, so the popular story continues, because our system of justice presupposes the possibility of human choice – How else could a thief be held accountable for a misdeed?

As with any philosophical discussion, we need to be very clear on what we are talking about, so let’s start with some concepts:


I have a physicalist view of the human mind, in which consciousness emerges from the workings of the brain, and nothing else. So in my view ‘will’ is just matter (particles and energy) moving about in certain ways.


The word ‘free’ expresses a relation. The question whether something is free without further context has no meaning and therefore cannot be answered. Free is always understood as free with regard to something else. For example, something can be free in the context of a certain set of laws.

Using these definitions, we see that the question “does free will exists?” is incomplete. The question should be replaced by other questions:

  1. Is the human will free with respect to the laws of physics?
  2. Is the human will free with respect to the laws of criminal justice?

Question 1: Too early to tell

The first question, “Is the human will free with respect to the laws of physics?”, has a strange form. What are the laws of physics? Regardless of philosophical standpoints, the laws of physics describe what is going on on. Our will is one of the things that are going on, so the question whether our will can be free with respect to the laws of physics is circular: for our will to change the laws of physics would have to be different.

So, where are we? Is the human will free with respect to the laws of physics? No, it isn’t: the laws of physics are our will – but perhaps there is some other set of laws with respect to which the human will is free.

What the definitions tell us is that if the human will is completely described by physics it can not be free from the laws of physics. Whether perhaps there is an aspect of the human mind which is not described by current physics is a different question, which the future of scientific research will answer (what comes to mind is that Einstein himself did not believe that quantum theory is a final and complete description of reality).

I will explore the second question in my next blog post. Can our system of justice function if we have no free will with respect to the laws of physics?

“The laws of physics do not dictate our will; the laws of physics are our will”

About fbenedictus

Philosopher of physics at Amsterdam University College and Utrecht University, managing editor for Foundations of Physics and international paraclimbing athlete
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8 Responses to Quantum theory, free will and justice

  1. Amelie McCoy says:

    You will find this much more satisfying to read and think about than most comments.
    What is Man? by Mark Twain (Samuel Clements)https://pinkmonkey.com/dl/library1/digi036.pdf

  2. Dan Langlois says:

    ‘I have a physicalist view of the human mind, in which consciousness emerges
    from the workings of the brain, and nothing else.’

    I disagree, but I want to pinpoint where the disagreements start. I take ‘consciousness’ to be a rather vague abstraction, the word is thrown around in different ways. It’s not an obviously useful concept in ‘science’. I might be reminded about neuroscience, But I’m not afraid of neuroscience — I might emphasize a more physicalist view of neuroscience itself — that it is the study of how the nervous system develops, its structure, and what it does. Of course we can add something about how neuroscientists focus on the brain and its impact on behavior and cognitive functions. When it comes to ‘cognitive functions’, I prefer to try to be exact. How many are there? Like, eight? It’s a rhetorical question, I’m emphasizing vagueness. I might be more patient with ‘neurocognitive functions’, though we probably are quicker, with ‘neurocognitive functions’, to take these to be associated with specific pathways or loci within the brain. Something affected by different disease processes, maybe, these are ‘neurocognitive functions’.

    Now, of course, it sounds reasonable to assert that conscious experience in humans
    depends on brain activity, so neuroscience will contribute to explaining consciousness. But I incline to emphasize the question here — To bridge the gulf between brain and consciousness, we need neural data? Or what? What else? Some philosophical analysis, for example? Well, I want to be reasonable, but I incline to emphasize that the term “neuroscience” covers those scientific fields whose explanations advert to the properties of neurons, populations of neurons, or larger parts of the nervous system.

    Given the breadth even of neuroscience so conceive, I figure that an overview of sufficient depth must restrict breadth.

    ‘So in my view ‘will’ is just matter (particles and energy) moving about in certain ways.’

    Such could be taken as a claim that ‘will’ does not exist — otherwise, I think it seems
    a dodge. Note, you seem close to being happy with my interpretation, here:

    ‘Is the human will free with respect to the laws of physics? No, it isn’t..’

    Note, I think the human will *is* free with respect to the laws of physics, though
    I take this to be a mere definition of ‘the human will’ — whether it actually exists or not,
    would be a separate question. I do think it actually exists, though. I might just
    want to put out a point about this, that even biology, is not just ‘the laws of physics’ — it has its own emergent laws. The point isn’t anti-scientific. Yet I can make an anti-scientific point, too — there are, perhaps, limits to scientific knowledge, in principle. Our methods involve studying things with microscopes and telescopes. If it’s invisible, it might as well not exist. I mean sure, you can use different instruments, but you can’t use *no* instruments. Yet, we get the concept of ‘free will’ by using no instruments. There are, I think, two issues. What is free will? And does it exist? You can follow why I think it has to transcend the laws of physics — even biology, transcends the laws of physics. Does it exist? Well, to science it looks like randomnesss. Which at least, does exist.

    I might say that mysteries exist, including some profound ones. I don’t feel that it has to be humiliating for scientists, that when they trace a visibile ’cause’ for every visible ‘effect’, they don’t reduce everything to utter predictability. These are actually extremely unimaginative and modest methods.

    It’s not that I care about a ‘soul-substance’, something to survive death or whatever,
    I’m just thinking in perfectly methodological terms, about the limits of science.
    We know we have free will. You don’t sit around and speculate about whether you
    can get up out of a chair by your own free will, and if you do, you have no theoretical
    proof that you can do it until you do it.

  3. I think you’re right about that. Free will is free subject to the laws of physics.

  4. Jody Geiger says:

    I find your posts very interesting, but surprisingly, this is very high level and too simplistic, as you have not really addressed the problem from the ‘laws of physics’ point-of-view. I will clarify.

    Notably, the ‘laws of physics’ are designed such that all behavior at the macroscopic and cosmological level are understood to be complete. Sure, there’s a few cosmological mysteries unsolved, but to that we can probably agree that there will always be unsolved mysteries merely because humans can always pose new questions. Therefore unsolved mysteries will always be present and cannot be used as a means of negating the physical support for the position, the ‘laws of physics’ describe all macroscopic and cosmological behavior.

    Quantum behavior should be classified also as part of the body of the ‘laws of physics’. But, QM is also recognized as seemingly non-deterministic, thus opening the door to the notion of free will, by some sense. But can one argue that if free will is in fact free by some means of resolution of the human mind and QM is a system of non-deterministic and in this way a non-precise predictable behavior, then how could one test the notion of free will? Clearly, we have just admitted that QM does not follow our free will instructions, thus QM cannot be used to open the door to this possibility.

    This ends the classical approach to this investigation. But, hope you will find the following proposal of significance. Consider two blobs of material. One we recognize as a rock with many minerals. The other is what we might consider a representation of an advanced Artificial Intelligence (AI). We can state by design of this thought experiment that both have equal composition of materials. Only, the rock is rather stupid, in our thinking. The AI system, in contrast, has been designed to take in information from the environment and then react to the environment. In some respects, the AI system may be smarter than the humans. At some point in the distant future, the rock is tested for free will. The same test is used on the AI. And finally the same test is used again on a human. The results are compared.

    But that’s not the complete test, and this is very important! Before the test was even conceived, a human asked an AI system to write a response to this blog post. The human also wrote a response. An algorithm designed to make truly random selections was used to select which response you received. Notably, the source input for this random selection used quantum properties of starlight that originated during the earliest moments of the universe. Now, the question can be assessed correctly. Do the test results demonstrate that rocks, humans and/or AI are free of the laws of physics and if so, for who?

    • Jody Geiger says:

      PS: The rock also was asked to write a response, but there is some uncertainty with respect to the AI and the human as to what that response was.

    • fbenedictus says:

      Thanks for this! ? I will certainly take these thoughts into consideration when I write the follow up blog posts.

    • Hugo Buddelmeijer says:

      The Strong Free Will Theorem by John Conway and Simon Kochen is essential in considering the relation between quantum mechanics and free will.

      They prove from three experimentally verified quantum mechanics axioms the following: If humans have free will (by several definitions of free) to measure the state of a particle in a particular way, then that particle has a minuscule amount of this free will (of the same definition) to decide how to respond to that measurement.

      Conway has subsequently hypothesized that the essence of life is ‘aligning’ this microscopic free will to achieve free will at macroscopic scales, in analogy to creating magnets from the spin of elementary particles. A rock has virtually no free will, because the free will of its particles cancel each other out, just like most rocks are not magnetic.

      I’m very interested in theories that explore this hypothesis of deriving macroscopic freedom from this microscopic free will, but I’m not aware of any. It seems that such a theory could possibly provide ways to quantify the amount of free will something has. It seems conceivable that humans could create devices that have more free will than is otherwise achievable by nature; just like we can create extremely strong but compact magnets.

      My takeaway from this post is that such a theory should always take into account that this quantified freedom should always be “with regard to something else”. The freedom of the electron with regard to the scientist. The freedom of the scientist with regard to society. The freedom of each hemisphere, the cerebellum, the brain stem, etc, with regard to the brain as a whole. Etc.

  5. Anonymous says:


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