A thought experiment on free will

Rusty fence and snow

Consider the following: what we know about physics and chemistry suggests that matter and energy interact on the basis of two things – physical laws and random chance. The fact that iron oxidizes is the result of physical characteristics of energy and matter that we understand well. Similarly, our understanding of the random elements in quantum mechanics is critical to a number of optical and electronic technologies. Acknowledging that we don’t fully understand either the laws of physics or the processes of randomness, it seems plausible to say that those two factors account for all the physical interactions in the universe.

If this is true, we can imagine a hypothetical computer with the capacity to store information on the nature, position, and trajectory of every particle in a human body, as well as all the types of energy acting on them. This model would allow us to project the behaviour of that collection of molecules in the face of any stimulus, at least on the basis of a range of outcomes as determined by the random elements in physical laws. Our model human could thus be exposed to any kind of prompt – from being attacked by another simulated human to being tempted by some unguarded treasure to being betrayed by a loved one – and a range of responses could be projected, with probabilities attributed.

Now, if human beings really do consist of particles and energy governed in the manner described, the behaviour of the computer model would be in no sense different from that of an actual person. The trouble here, of course, is that the model person cannot be said to have any free will. It is just a complex machine that responds to inputs in relatively predictable ways. Where outputs are not predictable, it is because of random chance. Our model person is like a computer game where the enemy you encounter is determined by a random number generator; while the outcome for any input is not entirely predictable, the system is nonetheless completely devoid of ‘will’ in the sense that we generally understand it.

How can free will be fit into a materialist model? Is free will something that exists outside of the laws of physics? Or is there some mechanism through which a macro-level entity like a person can be said to affect the particle level interactions that define them fundamentally?

Regardless of the answer, the thought experiment raises serious questions about whether we are responsible for our actions.

[Update: 2:06pm] Tristan wrote a post in response to this.

Author: Milan

In the spring of 2005, I graduated from the University of British Columbia with a degree in International Relations and a general focus in the area of environmental politics. In the fall of 2005, I began reading for an M.Phil in IR at Wadham College, Oxford. Outside school, I am very interested in photography, writing, and the outdoors. I am writing this blog to keep in touch with friends and family around the world, provide a more personal view of graduate student life in Oxford, and pass on some lessons I've learned here.

42 thoughts on “A thought experiment on free will”

  1. Milan,

    You are simply wrong in thinking this is anything new or special about 20th century science. It follows logically from assuming everything in the universe moves according to a single set of physical laws, that humans move according to that set and are unfree. This is why Kant had to come up with his strange solution of 2 ways of considering the human being – as an object of science and as an object of freedom which obeys a different law.

    Basically, the fundamental mistake you are making is expressed here: “if human beings really do consist of particles and energy governed in the manner described”

    What is this “really are”. Do you mean, they are this way, in the exclusion of other ways? Are you an eliminative materialist, in other words, any phenomena that supervene onf these interactions, like say, anger, where you can’t tell a meaningful story about the thing (anger) in terms of matter and energy, is simply a mistaken concept which we need to get rid of? So, “anger” exists if and only if it is a manner of the interaction of energy and matter that can be described as those interactions? That seems wrong, any idiot knows anger exists, and it doesn’t matter if the neuro scientists can find it or not. Any philosopher who denies the existence of these things is rediculed.

    But for some reason, if instead of “anger” you substitute” freedom” everyone freaks out and says “oh we arn’t responsible for our actions”. If we take science seriously in your sense, not only can we not affirm freedom, we can’t affirm states, or the law, or schools, none of these phenomena can be described meaningfully as the interaction of energy and matter – you will never find a law. Looked at as energy and matter, the law will appear to be a totally incomprehensible supervenient phenomenon, a “mistake”, like folk psychology.

    The mistake is moving from “the current model we have of the world is the interaction of matter and energy across space-time”, to, “the world really is this model”. This is Platonism – you’re assuming the world is in itself a differentiation according to permanently enduring laws. The mistake is to think that Empiricism automatically gets you away from Platonism – empiricism is a method, it doesn’t imply a metaphysical position. If you assume the world is in itself the kind of thing that works like a model, then you believe in Platonic forms.

    You do believe in Platonic forms. They are called “energy and matter”. It’s an indefensible position – Platonism is wrong, for reasons that are so obvious I can’t begin to discuss them. So your thought experiment doesn’t actaully say anything meaningful at all about freedom, although it does express quite clearly the platonic skeletons empiricism tries to hide in the closet.

  2. You are simply wrong in thinking this is anything new or special about 20th century science. It follows logically from assuming everything in the universe moves according to a single set of physical laws, that humans move according to that set and are unfree.

    I made no such claim. The argument above could have been made just as well on the basis of less advanced scientific understanding. All that it requires is acceptance that universal laws and random chance are the only determinants of physical outcomes.

  3. In general, I think you are placing far too much emphasis on how we describe things. In the end, that doesn’t matter hugely. It has as much effect on the physical basis of the world as changing the category we file Pluto under (from ‘planet’ to ‘dwarf planet’) does upon the physical characteristics of the object itself.

    You can’t just wave a rhetorical hand and reject the argument above as one kind of thinking. You need to argue where within a material world free will could reside, that there is no free will, or that the world is not material.

  4. Tristan,

    If we actually had a computerized Tristan model that you could observe behaving as you would, could you still consider yourself free?

  5. I was thinking about this last week while doing my ironing…

    Let me begin by stating the obvious. When it comes to conscious agents like human beings, there are definitely things that are not currently understood. There is essentially no scientific understanding of consciousness and qualia, for example. Here be dragons.

    Given that this isn’t presently a scientific question, we can happily disagree about it all day long – as indeed philosophers have been doing at least since Hobbes. I think the best way to make progress towards real understanding is to do more neuroscience and build better robots.

    For what it’s worth though, I tend to believe that Milan’s “replica” is possible. The traditional view that “a human being is an independent point of departure”, while initially obvious, becomes much less obvious on reflection. At what point in your thinking do you do the “choosing”?

    For example, say that you want to become president of the United States. Given your current knowledge, you can consider all actions open to you and score each action based on how likely it is to lead to your goal. You then follow the course of action with the highest score (moderated of course by the effect this has on all the other things that you might want). The only freedom you have here is the freedom to choose badly. Choosing any action other than the one with the highest score would be acting contrary to you will (i.e. to become president).

    So, if free will exists, it must exist earlier in the process – in choosing what to want. Yet, I think most people’s intuition here is that we don’t choose what to want. Our wants are the part of us most clearly tied to our biology – things like eating, sleeping, mating. Of course, humans have more abstract wants – the desire to be loved, the desire to be dutiful; I think these are ultimately biological too.

    How this affects things like legal responsibility and notions of morality is another huge question. I think (perhaps surprisingly) it doesn’t actually change things too much, but that is another mammoth discussion, and this comment is long enough already.
    In fact, I think that whether or not we have free will changes remarkably little. We are all acting towards our goals. The idea that the things we want are innate or determined by our experience in ways that we do not choose is almost a commonplace. It takes nothing away from that fact that we experience joy and terror, love and hate. I have no doubt that these are real, and they certainly pose a challenge to scientific understanding. It may even turn out that the gap in our scientific understanding that permits conscious experience also permits free will, but I suspect that it does not, and I think we as a species need to be ready for the possibility.

  6. My personal response to this question is pragmatic, and based on two binaries:

    1) Either we have free will or we do not

    2) Either we choose to act as though we have free will or we do not.

    If we lack free will, then we have no choice whatsoever in any matter and all morality is moot.

    If we possess free will, we want to behave as though we do. If we get it wrong and act as though we don’t (it’s not clear how we actually could), we would be making a mistake. If we actually have any freedom to choose, choosing to believe in free will is necessarily correct.

  7. You are right, it doesn’t matter hugely how we describe the world. And then you say where in a material world could free will reside. Well, it doesn’t matter, because the material world is the described world.

  8. Well, this is quite the mountain you’ve decided to tackle in this post. I just want to quickly dismiss materialism altogether, and then follow up with an observed contradiction in post-materialist theory (Chalmers, etc).

    Setting aside the subject of free will for the moment, your example of the “human replica” rather directly mirrors Chalmers’ zombie; the idea that a whole physical description of a human being could be made, but in his example, this description lacks something inherent to the human experience; the experience of being, as Tristan noted, qualia. We can easily imagine an experience-less individual; all we need to do is look at a person other than ourselves. This immediately leaves us with a number of problems.

    A purely physical description of a human being, or more importantly, a group of human beings, leaves us without a fundamental, and essential, piece of information: how is this described reality experienced? Which one of the humans is me, and which ones are not-me? This bit of information seems scientifically trivial, but philosophically, and self-evidenty, it is of ultimate importance. This is the indexical fact, something seemingly un-physical but of absolutely non-trivial importance: given a full description of all physical reality, how can one evaluate the truth value of the statement “I am happy” without knowledge of the indexical fact? Such a statement could never have truth-value of any kind if we were dealing with “zombies” or “human simulations”.

    Things get really messy when you consider that the indexical fact, simply having been conceived of and discussed by us, has now had physical consequences on reality: such as the words now appearing in your web browser. If the indexical fact is non-physical, as our materialist accounts of reality seem to indicate it is, how can it have physical consequences?

    In short, this is a big philosophical mess. Materialism, as we once knew it, is dead.

  9. Mek,

    I just had the fairly unpleasant realization that if we had met in a regular metaphysics class its quite unlikely we would have become friends. Whose Chalmers? Indexicals? What about transcendence! Corrigibility!

    I still hold, that it isn’t the task of philosophy to prove that we’re free, but rather show what it means when you say “you are free”. The problem with the “is there freedom” question is it leaves “what is freedom” completely uninterrogated, kind of like how separatists leave aside their real differences on social issues to pursue independence.

  10. I vacillate between being completely deterministic in my views on free will and believing in some sort of chaotic principle that is also not free will, but not quite randomness, either.

    I think that recursion is what makes the free will illusion so pervasive, and so strong — the actor acting on itself over and over again.

    But I am done, pretty much, arguing over free will. Years ago, I would’ve written, depending on my mood, what you wrote, or what Tristan posited — since then, though I’ve realize the only tenable position is to act as if free will exists, even if it does not.

  11. Hi Milan. No doubt you know this, but there’s a huge debate in contemporary (and not-so-contemporary) philosophy about (1) whether there are notions of free will that are “compatibilist” – that is, consistent with determinism; and (2) whether there are notions of moral responsibility that are compatibilist; and (3) whether moral responsibility requires free will.

    For a way into the literature, try:

    Incidentally, there are also questions about whether *indeterminism* would be any better. Some people (e.g. Galen Strawson) think not only that free will is inconsistent with determinism, but also that it’s inconsistent with indeterminism. According to this view, we’re no more free in irreducibly chancy worlds than we are in deterministic worlds. If this is right, debates about whether determinism is actually true in this world are moot, because free will is impossible: it doesn’t exist in any possible world, deterministic or not.

  12. What is it like to be a bat?
    -Thomas Nagel

    [From The Philosophical Review LXXXIII, 4 (October 1974): 435-50.]

    Consciousness is what makes the mind-body problem really intractable. Perhaps that is why current discussions of the problem give it little attention or get it obviously wrong. The recent wave of reductionist euphoria has produced several analyses of mental phenomena and mental concepts designed to explain the possibility of some variety of materialism, psychophysical identification, or reduction.1 But the problems dealt with are those common to this type of reduction and other types, and what makes the mind-body problem unique, and unlike the water-H2O problem or the Turing machine-IBM machine problem or the lightning-electrical discharge problem or the gene-DNA problem or the oak tree-hydrocarbon problem, is ignored…

  13. The ethics of brain science
    Open your mind

    May 23rd 2002
    From The Economist print edition

    Screening, privacy and enhancement are all important issues, to be sure. For many critics, though, they are side-shows. The really uncomfortable questions raised by brain science are those that go to the heart of what it is to be human. Or, more specifically, what philosophers and theologians have claimed is the heart of what it is to be human.

    In the West, at least, that defining quality is the concept of “free will”. Although some philosophers see free will as an illusion that helps people to interact with one another, others think it is genuine—in other words, that an individual faced with a particular set of circumstances really could take any one of a range of actions. That, however, sits uncomfortably with the idea that mental decisions are purely the consequence of electrochemical interactions in the brain, since the output of such interactions might be expected to be an inevitable consequence of the input. It also sits uncomfortably with the separate, but parallel, argument that correct moral choices are the result of a sort of biological decision-making programme, shaped by evolution, rather than being arrived at by abstract reasoning.

  14. Do Subatomic Particles Have Free Will?

    By kdawson on painting-fences-white-very-quickly

    An anonymous reader sends in a Science News article that begins: “Human free will might seem like the squishiest of philosophical subjects, way beyond the realm of mathematical demonstration. But two highly regarded Princeton mathematicians, John Conway and Simon Kochen, claim to have proven that if humans have even the tiniest amount of free will, then atoms themselves must also behave unpredictably” Standard interpretations of quantum mechanics, of course, embrace unpredictability. But many physicists aren’t comfortable with that, and are working to develop deterministic interpretations of quantum mechanics. Conway and Kochen’s proof argues that these efforts will be fruitless — unless one is willing to give up human free will, in a very strong sense. The article quotes Conway: “We can really prove that there’s no algorithm, no way that the particle can give an answer that is unique and can be specified ahead of time. I’m still amazed that we can actually manage to prove that.”

  15. “what we know about physics and chemistry suggests that matter and energy interact on the basis of two things – physical laws and random chance.”

    I used to think this was at least a somewhat difficult polemic problem – but now I see the mistake is in the first sentence. We don’t “know” anything about physics and chemistry. We have some models which have excellent predictive power, but empiricism blocks us from having “knowledge” of the way things are.

  16. Tristan,

    I don’t think that objection is too serious. Naturally, we don’t completely understand the real physical processes that are the objects of study for physics and chemistry, respectively.

    What is important here isn’t perfect understanding, but understanding of the causes for which things occur. Are there any types of causes we know about aside from (a) random chance and (b) the operation of potentially knowable physical laws?

  17. “but understanding of the causes for which things occur.”

    But this is exactly what we don’t understand. We posit reasons for changes occuring, but we don’t understand whether those are actually the reasons. Our models give good results, are excellent for making cell phones. But we can’t know the causes for which things occur – Hume already clarified this hundreds of years ago.

  18. The point is, you don’t get to know that. It’s not a question we can ask without making basic mistakes.

    The interesting question about freedom was never “are we free or not”, but “what does it mean to be free”. All the scientistic folks making argumentss that try to say we are not free, none of them are actually pushing a political system that stops valueing freedom. If we all agree that political freedom is what we want, why do we need to talk about this silly metaphysical debate?

  19. If we’re not free, we can’t choose anything, by definition.

    What is interesting about the problem is simply the contradiction between the experience of consciousness and free will and the lack of any good explanation for the latter.

    It’s the kind of question where investigations are likely to yield a lot of interesting experimental data.

  20. You don’t get to know the causes behind things, that is outside the realm of empirical knowledge. So you don’t know if there is one kind of causality (like science presumes), or two kinds (as Kant speculates). You don’t get to know this through empiricism because it is by definition not the kind of thing you can test for, Hume established that.

    What interesting experimental data results from questions about which we can’t do experiments?

  21. Sure we can do experiments. Every day, we are investigating the operation of the brain and neurons in new ways. Eventually, that will help us understand consciousness and will better.

    Already, we have a much improved understanding of things like epilepsy, hallucinations, and so forth, compared to what we knew prior to modern biology and neurology.

  22. We can’t do an experiment to show causality. We need to assume causality in order to do experiments.

    Ergo, if there are different kinds of causality, this is exactly the question we can’t interrogate by experiment.

  23. If We Have Free Will, Then So Do Electrons

    “Mathematicians John Conway (inventor of the Game of Life) and Simon Kochen of Princeton University have proven that if human experimenters demonstrate ‘free will’ in choosing what measurements to take on a particle, then the axioms of quantum mechanics require that the free will property be available to the particles measured, or to the universe as a whole. Conway is giving a series of lectures on the ‘Free Will Theorem’ and its ramifications over the next month at Princeton. A followup article strengthening the theory (PDF) was published last month in Notices of the AMS.”

  24. John “Game of Life” Conway: particles have the same kind of free will that people have

    By Mark Frauenfelder on Science

    Kevin Kelly linked to a paper “co-authored by mathematician John Conway, inventor of a cellular automata demonstration known as the Game of Life, [who] argues that you can’t explain the spin or decay of particles by randomness, nor are they determined, so free will is the only option left.”

    Some readers may object to our use of the term “free will” to describe the indeterminism of particle responses. Our provocative ascription of free will to elementary particles is deliberate, since our theorem asserts that if experimenters have a certain freedom, then particles have exactly the same kind of freedom. Indeed, it is natural to suppose that this latter freedom is the ultimate explanation of our own.

  25. This problem is pathetically stupid. It was solved in 1781, when Kant pointed out that if what counts as an explanation is a lawlike formula, all the explanations for human behavior you will find will be lawlike. Freedom is denied a priori by scientific inquiry.

    Free will is not a third explanation aside from lawlike behavior or random behavior.

    The idea that something is neither random nor lawlike is a category error. If something is not lawlike, then it is not explainable. If “random” has become a new kind of lawlikeness, rather than the non-lawlike, then random actually means law – and the fact that something isn’t law like does not mean its “free”.

    Freedom is a description of the kind of beings the beings which we ourselves are see ourselves as having. Anyone who tells you they think they aren’t free ignores the fact that they presuppose their own spontaneous choice in their declarations of themselves as non-free. It’s just a fact about how humans comport to themselves that they are “free” and can therefore be imprisoned.

  26. Silicon brain
    By David Pescovitz

    Researchers have built a chip with the equivalent of 200,000 neurons and 50 million synapses in an effort to mimic a human brain in silicon. I, for one, welcome our simple-minded overlords. From Technology Review:

    Although the chip has a fraction of the number of neurons or connections found in a brain, its design allows it to be scaled up, says Karlheinz Meier, a physicist at Heidelberg University, in Germany, who has coordinated the Fast Analog Computing with Emergent Transient States project, or FACETS.

    The hope is that recreating the structure of the brain in computer form may help to further our understanding of how to develop massively parallel, powerful new computers, says Meier…

  27. It seems to me immensely unlikely that mind is a mere by-product of matter. For if my mental processes are determined wholly by the motions of atoms in my brain I have no reason to suppose that my beliefs are true. They may be sound chemically, but that does not make them sound logically. And hence I have no reason for supposing my brain to be composed of atoms.

    J. B. S. Haldane
    “When I am Dead” in Possible Worlds (1927)

  28. “Have religious beliefs caused any wars, or have all wars just been caused by the interactions of quintillions (to underestimate the truth absurdly) of infinitesimal particles according to the laws of physics? Does fire cause smoke? Do drones cause boredom. Do jokes cause laughter? Do smiles cause swoons? Does love cause marriage? Or, in the end, are there just myriads of particles pushing each other around according to the laws of physics – leaving, in the end, no room for selves or souls, dreads or dreams, love or marriage, smiles or swoons, jokes or laughter, drones or boredom, cars or smog, or even smoke or fire?”

    Hoefstadter, Douglas. I am a Strange Loop. p.33 (paperback)

  29. What if Freedom and Freewill had nothing to do with each other?
    September 14, 2010 by northernsong


    “Imagine if in some deep sense life were determined. Now, somehow avoid the immediate rejoinder that, “this means I am not typing this, because presupposed in every activity and every description of activity, including me describing the activity of believing to be determined, spontaneous will is presumed”. Instead, assume that what we mean by “spontaneous will” that we experience (we do, after all, experience ourselves as free) is simply an explanation of how it feels to be free, not proof that our will is radically free, i.e. somehow self-engendered rather than a result of natural processes.

    Does this mean, “freedom doesn’t exist”? Or, does it mean that the assumption that freedom was the self-engendering spontaneous creative spark of the will, rather than a description of a certain form of the will’s activity. If there is an experience of freedom, then certainly it could be simulated – you could be wired up such that you experienced a set of actions as the result of your own will but n fact you were being controlled. This doesn’t mean “freedom doesn’t exist”, it just means it is primarily a moral political idea rather than a metaphysical one. Are people really “behind” their actions – perhaps in some sense not. But do people experience themselves as the cause of their actions – yes! And this experience is not neutral – it points towards democratic political structures which respect this human need for free creative work.

    It might be perfectly coherent to believe that humans are computers, and at the same time call for deeper, more meaningful forms of political engagement and an end to alienated labour. Certainly, it is no less coherent than to believe humans are computers and call for anything at all – because the potential nature of man as determined does not contradict any more with the desire for the potentially “false” feeling of free creation than with the desire for any other feeling – feelings need not be “true” to be desirable.

    And is this not, in a sense, the lesson of Hegel? That real freedom is not freedom of the will, but the becoming adequate of social life to the nature of humans as desiring to be free – to engage in free creative activity, to have their own plans and carry them out. Freedom is the power to carry out the proper life of man as free. Radical freedom is the metaphysical correlate – that at any moment we can fail to be adequate to our nature by engaging in bad faith, i.e. by acting as if we did not have a choice, when in fact we did although that choice perhaps did not allow for the fulfilment of freedom as a self-creating life process.”

  30. I thought you might find this interesting:

    From “Mind and Supermind” by Keith Frankish

    “There is evidence that our verbal reports of our mental states and processes are sometimes confabulated. Psychologists have found that it is possible to influence a person’s behaviour by means of suggestions and other stimuli which are not obviously relevant to it. When the subjects of these experiments are asked to explain their behaviour, their responses are surprising. They do not mention the stimuli or confess ignorance of their motives, but instead invest some plausible reason for their action (Nisbett and Wilson 1977)(footnote). What is happening in these cases, it seems, is that the subjects’ actions are guided by non-conscious processes of which they are unaware, and their reports are attempts to interpret their own behaviour as if from a third person perspective….The problem is that in these cases the subjects do not realize that their reports are merely self-interpretations – they make them with complete sincerity, just as if they were reporting conscious mental states and processes.” (225)

    “Similar results occur with subjects who have undergone commisurotomy (surgical severing of the copus callosum which connects the two halves of the brain). If a command such as ‘Walk!’ is presented to such a subject in the left half of their visual field, so that it is received only by their right hemisphere, then they will typically comply with it. Yet when asked to explain their action, they will not mention the command, since their left hemisphere, which controls speech, has no information about it. Instead, they will invest some plausible reason for the action, such as they were going to get a drink (Gazzaniga 1983,1994).

  31. Everything is made of atoms. That is the key hypothesis. The most important hypothesis in all of biology, for example, is that everything that animals do, atoms do. In other words, there is nothing that living things do that cannot be understood from the point of view that they are made of atoms acting according to the laws of physics. This was not known from the beginning: it took some experimenting and theorizing to suggest this hypothesis, but now it is accepted, and it is the most useful theory for producing new ideas in the field of biology.”

    Feynman, Richard. Six Easy Pieces: Essentials of Physics Explained by Its Most Brilliant Teacher. p. 20 (paperback)
    Emphasis in original

  32. MY COLLEAGUE has a beautifully written post at Big Think on recent challenges to the idea of free will. He argues that the claim that free will is an illusion is itself illusory, as it misunderstands the idea of the term “illusion”. To claim that something is an illusion is to say that it is a deceptive representation of some other actually existing thing which one has experienced. For example, a desert mirage looks like the sea, but there ain’t no water out there. But internal experiences such as the sense of having free will don’t have any external referent; the sense of having free will is only an internal experience, and there’s no way someone could have an illusory experience of the sensation of freedom as opposed to a real experience of the sensation of freedom. It’d be like having an illusion of being angry. Or as he more elegantly puts it:

    “That free will you thought you felt, that was an illusion.” What? How would you know? Maybe you have a theory that says every event is necessitated by the laws of nature and the prior history of the universe. In such a world, can there be something it is like to experience the absence of necessitation?

    Now I deliberately and willfully touch the tip of my nose. I certainly don’t feel myself compelled by laws of the cosmos and the sum of time. Neither do I feel myself not so compelled. I feel myself willing a nifty little nose-touching.

    Is Mr Obama so dense as to miss that when America invents things other countries benefit, and vice versa? If a German discovers a cure for cancer, shouldn’t we be ecstatic about that, rather than angry? Indeed, shouldn’t we be quite happy and interested in ensuring that Germans and Britons and Indians have the capability and opportunity to develop fantastic new technologies? In the more nefarious reading, Mr Obama seems to accept that only relative standing really matters. A sick, poor world in which America always triumphs is preferable in all cases to one in which America maybe doesn’t “win” the race to discover every last little thing that’s out there to be discovered. And hell, one has to ask again whether the easiest way to prevent other countries from winning the race for the future isn’t simply to blow up their labs.

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