Evidence against free will?

What would count as evidence against free will?

I’ve said before that there can be no evidence for or against free will because it is a doctrine about the ontological status of things that don’t happen. A person with free will might very well do precisely the same things as a person without free will — the only difference being that the former could have done otherwise. But what “could have happened” is invisible to us; we can only observe what actually happens. Therefore, a person with free will and a person without free will are empirically indistinguishable. I’ve said before that this means all we can do is assume that we have free will (or not), and that it makes more practical sense to assume that we do. But what it would actually mean, if it were true, is that free will vs. determinism is a fake question, a distinction which makes no difference. If it is indeed true that the one belief is more practically useful than the other, then the two beliefs must be empirically distinguishable, at least in principle.

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My argument that there can be no evidence for or against free will could also be used to argue that there can be no evidence for or against the proposition that nature is governed by laws. The sun rose in the east today, but could it have risen in the west instead? We believe that the sun and the earth move in accordance with fixed laws of gravity and that it is impossible for them to do otherwise — but isn’t it also possible that they are free, that they just happen to choose to behave in a uniform way but could just as easily choose otherwise? G. K. Chesterton somewhere discusses the possibility that every single day God freely chooses to tell the sun (or rather the earth) to “do it again.” Have we no empirical grounds for favoring Kepler/Newton/Einstein over Chesterton? After all, we only observe what happens, not what could have happened.

I’ve been conflating absolute proof with mere evidence. There can be no conclusive disproof of Chesterton’s “do it again” hypothesis, but we can and do have evidence against it. Suppose an astronomer predicts precisely where and when the sun will rise tomorrow. If the sun and earth are bound by the laws the astronomer thinks they are bound by, what is the probability of the prediction coming true? 1. If they could behave otherwise, what is the probability of the prediction coming true? Unknown, but necessarily less than 1. You can do the Bayesian math and see that, whatever prior probability we assign to the Chesterton hypothesis, it should be revised downward if the astronomer’s prediction comes true. Therefore, every successful prediction is evidence that things could not have happened otherwise. (How strong that evidence is cannot be calculated, though.)

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When it comes to human behavior, things are less straightforward, since no one claims to be able to predict it. Determinists say it is predictable in theory but, due to the fantastic complexity of the human brain, not in practice. Indeterminists say it in not predictable even in principle. The two theories do not therefore make distinct predictions.

However, if someone were to make a detailed and accurate prediction of human behavior, comparable to the predictions of astronomers, that would be evidence for determinism and against free will. The more specific the prediction, the stronger the evidence (though, again, we cannot assess exactly how strong).

Prophecies like those featured in Greek tragedy would be relatively weak evidence against free will. One gets the impression that Oedipus and his parents were free to do many different things, but that some unseen power was seeing to it that, whatever they chose to do, the final result would be the same. (It could be compared to a chess master’s prediction that, whatever his novice opponent may choose to do, the master will still win in the end.) Much stronger evidence can be found in the Gospels, where Jesus says to Peter, “Before the cock crow twice, thou shalt deny me thrice” — and then, despite knowing the prophecy and being unwilling to do any such thing, Peter proceeds to fulfill it. If the story is true, it offers strong evidence against free will, since specific details of Peter’s behavior (which Peter, apparently erroneously, believed were under his control) were successfully predicted. No wonder the poor devil “went out and wept bitterly” at this revelation that he was, despite appearances, a robot!

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What, then, would count as evidence for free will? Well, any failed prediction of human behavior. Granted, that seems like a very strange thing to say. If I am unsuccessful in predicting the behavior of a given system, that doesn’t mean the system isn’t governed by rules — it just means it isn’t governed by the particular rules I thought it was governed by. But, logically, that is evidence (very weak evidence) that it isn’t rule-governed at all — just as the fact that I wasn’t born on February 12 is evidence that I wasn’t born in February at all.

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The problem is that none of this evidence is at all quantifiable, so it remains impossible to say whether, on balance, there is more evidence for free will or against it. In the end, then, there’s still nothing to do but to make an assumption one way or the other.

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3 Comments

Filed under Philosophy

3 responses to “Evidence against free will?

  1. It’s a pretty good argument – although it does immediately fall into the old chestnut about whether inductive logic reasoning from the specific to the general has any validity. Does one totally accurate prediction logically entail the generalization that everything is predictable? If not one accurate prediction, then how many?

    But this is still an experiment – and somebody with free will has to be able to observe and interpret it, or it cannot tell anybody anything.

    So in the end we are back to metaphysics, I think.

  2. “…A person with free will might very well do precisely the same things as a person without free will — the only difference being that the former could have done otherwise…. Therefore, a person with free will and a person without free will are empirically indistinguishable…..”

    A person without free will cannot choose anything or prefer anything, or argue anything, or debate anything or assert something is objectively true.

    A person with free will can do all of these things.

    “…My argument that there can be no evidence for or against free will could also be used to argue that there can be no evidence for or against the proposition that nature is governed by laws..”

    There are no fixed laws in nature. Laws are a human social construct. ‘Natural laws’ is just a useful metaphor and not to be taken literally (although sadly it usually is taken literally by mainstream science).

    “No falling apple has ever obeyed any law of gravity. To do so would make it a person, and a citizen” – I forget who said that but it’s a good quote.

    FWIW the values for the gravitational constant and the speed of light vary all the time. Scientists got so annoyed by these natural fluctuations that they eventually fixed those values arbitrarily to create ‘constants’ to make their calculations easier.

    “..However, if someone were to make a detailed and accurate prediction of human behavior, comparable to the predictions of astronomers, that would be evidence for determinism and against free will. ..”

    Or….. it could be evidence of someone with free will who is behaving predictably.

    There is nothing about having free will which dictates we will not behave predictably. One could argue that the predictability of human behaviour suggests we have free will because a strictly causal universe would probably produce far more acts that defy prediction (far more billiard balls flying off the table, as it were).

  3. “One could argue that the predictability of human behaviour suggests we have free will because a strictly causal universe would probably produce far more acts that defy prediction (far more billiard balls flying off the table, as it were).”

    I would agree with this assessment. What suggests that humans have free will is observing how they commit themselves to patterns of behaviour which do not proceed in any obvious way from lower-level laws. (of biology, psychology, physics)

    I think a fallacy of thinking about free will is conceiving of a decision as something that (a) happens instantaneously — rather than persisting over time — and (b) is some kind of intervention into a ‘normal’ order of being.

    Suppose on the other hand for the sake of thought experiment there was a race of beings, let us call them the Disjoint Ones, who are truly ‘unmoved movers’ in their will, having a coherent identity and memory, but making a completely ‘independent’ decision what to do at each moment of their existence. That a Disjoint One decides something _now_ does not in any way restrict their ability to decide something completely different _later_. Therefore they are unable to make promises, pursue long-term goals only sporadically if at all, and tend to provide an incoherent motivation or rationalization if asked why they _are_ doing something. They would variously contemplate this inability to follow any defined course of action, and it would drive them mad with rage (and therefore they might commit further acts of vandalism and self-sabotage), or they would try to forget their situation in spur-of-the-moment distractions. If they did something wrong, they would be unable to repent of it. Dealing with one of these creatures would be rather like bargaining with a demon, and having to rely on purely mechanical measures to enforce an agreement.

    An observer would more quickly speak of The Disjoint Ones having no free will, rather than an excess thereof.

    So, to make a coherent decision at one point in time generally means to restrict one’s behaviour at other points. (CS Lewis pointed this out in Abolition of Man, but on the scale of the entirety of humanity rather than the individual person.) Observing this, we realize that there are varying degrees of decision-making ability; human free will is actually rather imperfect, since although we are rather more successful at restricting our future decisions than the Disjoint Ones are, we are still far from perfect at it. (It is interesting to distinguish ‘changing one’s mind’ as going back on an earlier decision vs. ‘changing one’s mind’ in response to knowledge that the future situation is outside the bounds of that was anticipated in an earlier decision.)

    How this leads me to think of free will, is somewhat more by analogy with God’s creation. To make a decision, necessarily means that one could also have decided otherwise. Thus the laws of physics have to be _somewhat_ underdetermined with regard to outcome. This nondeterminism is observably resolved down to one actual outcome, and this can be done either through pure randomness, or according to some intelligible higher principles (imposed by a being with free will — either God on the scale of the universe, or a human being with respect to their own actions). These higher principles do not proceed logically out of the laws of physics as known before — but once introduced, they continue to exist (to whatever extent, and in whatever sense) and contribute to determining future events.

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