When explaining to someone why I don't believe in freewill, it is almost certain that they will flap their arms around or do some sort of strange dance with their arms.

I know the reason why they do this is because of our conversation, but what is it about arm flapping that makes this such a prevalent mechanism when discussing freewill?

Have any philosophers mentioned this, either to disprove it's validity or to prove that arm flapping (or any seemingly random body movements) while having a conversation about freewill, is a true act of freewill?

  • 4
    Because it's a simple and arbitrary action which most directly exhibits will. Most people's sole experience in moving their body is a sense of will; they don't know how they are controlling their muscles, they only know that if they want their arms to move, they move. Your interlocutors are trying to demonstrate two things: that they can choose (demonstrated by will) to do whatever they want (demonstrates by an arbitrary action and which otherwise has no reason to occur; no reason outside their pure will).
    – Dan Bron
    Commented Aug 11, 2017 at 9:10
  • @DanBron Yes but it's clear that the determined cause of this action is the fact that we're having a conversation about freewill. I know what they're trying to do, I'm just wondering why it is such a widespread phenomenon. You answered my question with "because". and when I ask people why they just flapped their arms, they also say "because...", immediately showing that there was a reason for this action. I'll edit my question, because now I'm curious to know if any philosophers have made any serious attempts to prove freewill with arm flapping.
    – Cannabijoy
    Commented Aug 11, 2017 at 9:19
  • 7
    It's called 'hand-waiving'. Philosophers do a lot of it.
    – user20253
    Commented Aug 11, 2017 at 9:23
  • @PeterJ If that is a pun, it's hilarious
    – Cannabijoy
    Commented Aug 11, 2017 at 9:31
  • 1
    I suspect that CogSci will ask for more evidence than anecdotal observations. So I think this question can use more research before asking it on any SE. But your last comment is more of a philosophy question, something like: can spontaneous body movements confirm or infirm free will? Libet and others conducted experiments to test folk intuitions about it and identified some popular misconceptions about the nature of simple actions, like finger movements. But on the substantive issue they are inconclusive, see Roskies.
    – Conifold
    Commented Aug 11, 2017 at 22:50

4 Answers 4


Looks like Paul Rée got to this very issue back in the 1800s. So the answer is, yes, at least one philosopher has mentioned this issue of "arm flapping", as you call it, and, in this case, to show that it does not prove free will exists:

From Determinism and the Illusion of Moral Responsibility, Paul Rée:

We see that, from whatever point of view we look at willing, it always appears as a necessary result, as a link [in a chain of events], and never as an absolute beginning. But can we not prove by means of an experiment that willing is an absolute beginning? I lift my arm because I want to lift it...Here my wanting to lift my arm is the cause of the lifting, but this wanting, we are told, is not itself causally determined; rather, it is an absolute beginning. I simply want to lift my arm, and that is that.

We are deceiving ourselves. This act of will, too, has causes; my intention to demonstrate by means of an experiment that my will is free gives rise to my wanting to lift my arm. But how did this intention come? "I want to demonstrate my freedom” has the effect that I want to lift my arm. There is a gap in this chain. Granted that my intention to demonstrate that my will is free stands in some relation to my wanting to lift my arm, why do I not demonstrate my freedom by means of some other movement?

Why is it just my arm that I want to lift? This specific act of will on my part has not yet been causally explained. Does it perhaps not have causes? Is it an uncaused act of will? Let us note first that someone who wishes to demonstrate that his will is free will usually extends or lifts his arm, and in particular his right arm. He neither tears his hair nor wiggles his belly.

This can be explained as follows. Of all of the parts of the body that are subject to our voluntary control, there is none that we move more frequently than the right arm. If, now, we wish to demonstrate our freedom by means of some movement, we will automatically make that one to which we are most accustomed...Thus we first have a conversation about or reflection on the freedom of the will; this leads to the intention of demonstrating our freedom; this intention arises in an organism with certain [physiological] habits [such as that of readily lifting the right arm], and as a result we want to lift (and then lift) the right arm.

I remember once discussing the freedom of the will with a left-handed man. He asserted “My will is free; I can do what I want.” In order to demonstrate this he extended his left arm.

  • Thanks for digging that up. I knew I wasn’t the only person who experienced this phenomenon. I’m gonna keep an eye out for whether the right arm moves first. That’s hilarious.
    – Cannabijoy
    Commented Aug 10, 2018 at 0:14
  • @anonymouswho Thanks for making me dig it up. I've wondered for many years (20+) why smart people somehow don't seem to get this point, which doesn't seem particularly difficult, so it's great to have this old reference.
    – Chelonian
    Commented Aug 10, 2018 at 0:28

It's mostly because philosophers are looking for a monistic theory of will that deniers of will go for determinism. Personally, that is why I like A's claim that, in the phenomenal world, contraries obtain.

Thus to demonstrate determinism, pick up a stone and drop it. It moves in a determined manner until it hits the ground.

To demonstrate free will, just wave your hands.

Free will is generally constrained by the facts of the world. When I wave my hand, I don't then see it float away into the sky; but then so is determined motion.

Actually spontaneous motion of my limbs doesn't demonstrate free will, but it might demonstrate epilepsy. This is involuntary motion, ie, motion not connected to my will, as the name itself says: voluntary comes from the Latin volutarius, which means of one's free will; and so involuntary is a lack of free will.

If I was locked in a cupboard which was exactly of my dimensions so I couldn't move my limbs, that would not mean I no longer had free-will, but simply that I could no longer physically actualize it.


I can't say whether any philosophers have made an argument on it, but I think a reasonable justification can be made using modal logic.

What sort of proof would you accept that freewill exists? Can you name anything you can test? I will assume the answer is no (because I don't believe such a proof can be made). Thus, we should accept that there is no "proof" to be had. At best, the person you are talking to can provide you with evidence, and leave it up to you to decide whether that evidence sways your opinion or not.

So let's talk about what sort of evidence can be offered. I think we can both agree that any action which you can predict is not evidence of freewill. If you could put in an envelope "Cort will flap their arms like wings," and unveil it at the opportune moment, I would have to admit that I failed to provide any evidence of freewill.

So what if I can do an action which you cannot predict? I think we can both agree that doesn't quite qualify as direct evidence of freewill, as much as I might wish it does. Trivially, if I observed a coin toss which decided my action, but you could not observe the coin toss, I could act in an unpredictable manner but it would not qualify as freewill.

However, what if I could do an action that is unpredictable? What if I could do something which you could not predict, not because you are a mere mortal, but because the information you would need to predict it is not available to the world outside of myself? What then? I would argue that would qualify as free will (and by argue, I mean it would start the debate where I argue it qualifies as free will and we see where you take the debate).

As it turns out, being truly unpredictable is hard. It takes a serious inner spark to be truly unpredictable. That spark is much of what makes actors and comedians great. So how important is this discussion to me? Am I willing to put a deep effort into providing you with an unpredictable action, or am I willing to accept a token instead.

Flapping ones arms is a well understood gesture in this sort of argument. It's kind of the go-to "I'm too lazy to be truly unpredictable" movement.

So what does a half-baked attempt at an unpredictable movement do? At best it brings us to modal logic. It argues that you should consider the possibility that you don't know if there is free will, because you can imagine an unpredictable movement, using our questionably-unpredictable movement as a muse. Once we're using modal logic, your claim of "there is no freewill" becomes something that needs to be clarified. Is this a strong negation: "there is no free will" or is it a weak negation "'there is freewill' is not a true statement". The former is certain there is no free will, the latter is only certain that we haven't proven there is freewill.

Once we're in this more "colorful" world of discourse, now the fun debate happens. Now we can start discussing the consequences of believing there is no freewill (strong or weak) and discussing the consequences of believing there is freewill.

So I'll flap away. It beats just ceeding the argument to someone who doesn't believe in freewill. Maybe I'll actually be unpredictable in the debate that follows.


There is a hierarchy of possibilities. Provided that my choice of the fundamental possibility was free (and it always is so) my choice of subordinate actions are less free because these actions are implied by the fundamental project: it demands them.

When I'm running cross-country I make certain body movements and breath controls which are "natural" to do as long as I'm engaged in the undertaking the run to the finish (and probably good run). I'm still free to amplify or decrease the pace of legs or to breath deeper or shallower, but free only to the extent that will help to run, because in the current actuality I've chosen my body to serve the aim to get to the finish at my best.

While I'm monitoring/controlling by muscles/breath by my consciousness I do not reflect on my possibility to seize the movements as long as I'm engaged in the project to race to. I only am considering ways or subordinate possibilities how to optimize the movements to reach that aim. In order for me to reduce the steps and turn away and kneel on the ground I have to redirect my self suddenly to another basic aim instead (for example "I'm too old, I want to be a retired sportsman doing easy jogging with my dog every morning" [that thought convoluted first, just intuition, a pin prick]). That re-decision is spontaneous and free, but it (its meaning) logically calls me to stop now and to lie on the grass, and these particular actions won't be free actually - like my treads/breath control weren't also two seconds ago. They are - like those were - free only within the project - and now the project "retired old sportsman" - and they are bendable by me as long as they serve it within its framework.

For many people, profound discussions on "free will" are projects of discourse or arguing where hands movements are implied or even necessary because they serve something (for example, to facilitate self-convincing property of the words spoken out or to show the audience that the topic is so ample, etc.). In doing these gestures they may pay some attention how to do them best, but they aren't currently free to stop doing them until they spontaneously (freely) drop out from the mood "doing discourse".

Note that I didn't speak of free will. I understand "will" in the narrow sense of reflective thought "I did it by myself" or "I must decide to do it". That thought is necessary for some people to feel their freedom, but not for others, who are equally free. Freedom is pre-reflective spontaneousness; people are free, not that they all have will.

  • I like this answer. I find some flaws, but that could just be my own misunderstanding. The first flaw (as far as how this escapes determinism) is, Why are you running?
    – Cannabijoy
    Commented Aug 12, 2017 at 11:33
  • @anonymouswho, to me (I'm trying to follow Sartre, as I understand him - correctly or not) human behaviour is free, not deterministic at all. Any particular (not philosophy's) "why" belongs to reasoning. Reasoning is about explaining (by some sort of causes), it has nothing to do with how one actually does decisions.
    – ttnphns
    Commented Aug 12, 2017 at 11:38

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