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Neuroscience and free will

Brian Leiter

Lots of philosophical/conceptual objections to Libet's famous research have been made over the years (by Alfred Mele, Gideon Yaffe, and others), but now comes new "empirical" evidence purportedly at odds with Libet's findings.   Any thoughts from readers working on these issues?

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8 responses to “Neuroscience and free will”

  1. J. David Velleman

    Well, I can't resist pointing out that these results would seem to confirm the "supervisory" conception of practical reason that a philosopher of action has recently proposed: http://quod.lib.umich.edu/m/maize/13240734.0001.001/1:14/–possibility-of-practical-reason-2nd-edition?rgn=div1;view=fulltext

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  2. ruiz

    Once we take an ecological view of animal action, it is not difficult to see that the first point of having a reason is neither the instrumental transfer of value from end to means nor to act as a fraudulent universal legislator, but to use reason as a simple delay or brake mechanism against one's dispositional-behavioral tendencies. Before asking what reason there is to act, we actually ask first what reason there is not to act. In other words, negative reason is built into the deeper sections of one's motivational structure than reason is (Patricia Greenspan argued for this years ago, I think).

    The anti-Libet finding creates this elbow room for negative reasons. But in order to accommodate practical reason or reasoning, as how philosophers discuss it, scientists must specify how an unconscious action potential can be indefinitely delayed and SUSTAINED until the emergence of reason. Without the perdurance of some action potentials across a long temporal span, there is really no ground for us to believe that such negative reasons and instrumental reasons or reasons as duty are empirically connected. Nor can we assume that animal action or simple actions by humans (such as pushing a pedal or button) and human rational action lie automatically on a continuum.

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  3. David Rosenthal

    "Neural Antecedents of Spontaneous Voluntary Movement: A New Perspective", Aaron Schurger, Myrto Mylopoulos, and David Rosenthal, Trends in Cognitive Sciences, advance online version, forthcoming, at

    http://tinyurl.com/drcunygc/DR-SMR-Spontaneous-Movement-TICS.pdf

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  4. Anon

    Is "negative reason" basically something like Socrates' daemon?

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  5. ruiz

    That depends on how to interpret Socrates' daemon. Daemon speaks in negations, but a negative reason does not have to be negatively expressed, and is rather characterized by its functional role in the ecology of action. Facing a cougar, a jogger stays put – the reason behind her action, however rendered in maxims, is a negative reason as long as her first instinct is to flee.

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  6. Eddy Nahmias

    The results of these new fMRI studies should be entirely unsurprising to a physicalist about the mind. Since people are posting their work here, I'll humbly(?) suggest my short SciAm piece: http://eddynahmias.com/wp-content/uploads/2015/01/Nahmias-Free-Will-in-Scientific-American-2015.pdf

    There I write: "Consider the Libet experiment. It began with study participants
    preparing consciously to make a series of repetitive and unplanned actions. When the experiment began, they flexed their wrists when a desire arose spontaneously. The neural activity involved in the conscious planning presumably influenced the later unconscious initiation of movements, revealing an interaction between conscious and unconscious brain activity."

    And regarding earlier fMRI studies by John Dylan Haynes (lead researcher of the research discussed in the post): "Brain activity cannot, in general, settle our choices four seconds before we act, because we can react to changes in our situation
    in less time than that. If we could not, we would all have died in car crashes by now! Unconscious neural activity, however, can prepare us to take an action by cuing us to consciously monitor our actions to let us adjust our behavior as it occurs."

    The Libet results and others like it are threats to free will only if (a) you assume free choices can only be made *outside* the brain in a non-physical mind (but even most non-philosophers don't assume that), or (b) if the neural processes implementing conscious decision-making is always bypassed: "It is possible that the neural activity that carries out [conscious] planning has no effect on what we do or that it just
    concocts stories after the fact to explain to ourselves and others what we did. But that would make little evolutionary sense. The brain makes up only 2 percent of the human body’s weight but consumes 20 percent of its energy. There would be strong evolutionary pressure against neural processes that enable intricate conscious thought yet are irrelevant to our behavior."

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  7. Jona

    "purportedly at odds with Libet's findings."
    This is false. In the original study (http://www.pnas.org/content/113/4/1080.full.pdf):

    "Our data suggest that subjects can still veto a movement even after the onset of the RP. "
    "One important question is whether a person can still exert a veto by inhibiting the movement after onset of the RP (13, 18, 21, 22)."
    "It has been previously reported that subjects are able to spontaneously cancel self-initiated movements (13, 38). This has been referred to as a “veto” (13). The possibility of a veto has played an important role in the debate about free will (13)"

    Looking up reference 13:
    "Libet B (1985) Unconscious cerebral initiative and the role of conscious will in voluntary action. Behav Brain Sci 8:529–566."

    The proposal that "[t]here could be a conscious 'veto' that aborts the performance even of the type of 'spontaneous' self-initiated act under study here" was originally made by Libet (et al., Brain 1983).

    To read this study as a defence against attacks on free will based on the Libet findings is misguided. This is, if at all, a vindication of Libet. Also, this study argues, in contrast to earlier work, for a "point of no return" around 200 ms before movement! The discussion also makes clear that the results are entirely compatible with standard computational models of the mind, such as race or Leaky Accumulator models.

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  8. Charles T Wolverton

    Jona –

    Thanks for the references. I recalled having encountered the idea of a "veto" but not that it was right there in the original paper!

    Since the question is whether the agency implicit in the concept of a "conscious decision" is real, isn't a "conscious veto" of that "decision" subject to exactly the same question? Perhaps perturbations in the RP associated with the veto are inseparable from those associated with the initial "decision"?

    Ie, can't a non-agent change its non-mind?

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