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In The face of God (Gifford Lectures), Scruton discusses in passing the Libet Experiments as an unimportant framing of the discussion of free-will and determinism; without presenting any arguments, taking the ground as granted.

What are the serious arguments that are presented, and framed in what context?

note: The main position, at least to me, appears to be that a physical ground for the will is apparent before a conscious decision is registered by some device.

Granting all this, doesn't suggest to me that the will doesn't exist but merely that is spread in time.

After all we know that the minimal registerable time period is the plank time; and it is inconceivable, that the minimal moment of human time is this minimal physical now.

So we know human time is not minimal but a duree, a span; and it seems plausible that it extends both forward and backward in time (I'm not talking about physical time here)

This seems a more plausible interpretation of the experimental results, if we grant them the reality that they appear to wish to possess.

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  • +1 Interesting suggested interpretation. BTW related
    – Drux
    Jul 25, 2015 at 8:35

6 Answers 6

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For a discussion of the Libet experiment see the post Contradiction between the selfish gene and lack of free will demonstrated by Libet experiment

The Libet experiment deals with at least two different topics (Benjamin Libet: Mind time. 2004):

  1. Unconscious versus conscious. Libet derives from the measurements of his experiment: A deliberate action starts as unconscious process and becomes conscious to the proband about 500ms later.

  2. Free will versus determinism. Libet is very cautious whether his experiment rules out free will and can be explained by a deterministic approach only. He does not draw any conclusion on this topic. Until proof of the contrary he votes for the hypothesis of free will. He prefers the latter because it conforms to our sense of self.

Concerning your considerations on our subjective sense of time which may differ from the physical time: Please note that all time-related results of the Libet experiment refer to physical time.

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Libet himself concluded that our awareness of decision making appears to be an illusion, that consciousness is "out of the loop".

This appears to be different than denying free will. We are conscious of the need to make a decision but we are not necessarily conscious of how that decision is made.

The neuroscientist Vilayanur Ramachandran, gives an interesting take on Libet's results:

Given that we have on the order of 30 billion neurons in the neocortex, there is always a lot going on there, and we are consciously aware of very little of it. Decisions, big and little, are constantly being processed by the neocortex, and proposed solutions bubble up to our conscious awareness.

Ramachandran then goes on to suggest that, rather than free will, we should be talking about "free won't" - i.e., the power to reject solutions proposed by the nonconscious parts of the neocortex.


Daniel Dennett commented on Libet's result:

The action is originally precipitated in some part of the brain, and off fly the signals to our muscles, pausing en route to tell you, the conscious agent, what is going on (but like all good officials, letting you, the bumbling president, maintain the illusion that you stared it all).

One might wonder: If the subject is unaware of when s/he is aware of making a decisions, then who is? But the point is well taken - what we are conscious of is far from clear.

(Both of the quotes I have given are taken indirectly from Ray Kurzweil's book, How to Create a Mind.)

EDIT

Something that has always intrigued me, and that we have all experienced, is the ability to access our memory, and even our reasoning, without consciously thinking about it. We may be asked a question which we should know the answer to but we cannot seem to form the answer, no matter how hard we try. We might say "I'll have to think about that", although we give it no further conscious thought. Some time later, perhaps days later, the answer will suddenly pop into ones mind. We have submitted our will to our subconscious, where it has been subsumed (intact) and acted upon. Why should the decision making undertaken by the subconscious be any different (less free) than that of the conscious.

EDIT 16 Aug 15

I have (or more precisedly, Kurzweil has) incorrectly attributed the notion of free-won't to Ramachandran. According to Susan Blackmore, it was Libet himself who suggested this alternative.

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It is important to realise that the Libet experiments have been subject to a range of criticisms and that Libet never intended his experiments to prove/disprove free will.

There are persuasive claims that free will is logically impossible, most of which run along the lines of: nothing (as far as we have currently observed) can be 'casua sui' (the cause of itself), and insofar as a free decision would need to be independent of prior causes, free will cannot exist.

The Stanford Encyclopedia of Philosophy deals with logical arguments for and against free will:

https://plato.stanford.edu/entries/freewill/,

and describes the impact of determinism upon free will arguments:

https://plato.stanford.edu/entries/determinism-causal/#DetHumAct https://plato.stanford.edu/entries/incompatibilism-arguments/ https://plato.stanford.edu/entries/compatibilism/

In 2019, a 68-page white paper, Free Will: Recent Work on Agency, Freedom, and Responsibility was also released by the John Templeton Foundation, freely available here:

https://www.templeton.org/wp-content/uploads/2020/09/FreeWill-JTF-Final.pdf

See also:

Radder & Meynen, 2012: https://doi.org/10.1177/0959354312460926

Seifert, 2011: https://www.jstor.org/stable/23055749

A 2019 article in The Atlantic: https://www.theatlantic.com/health/archive/2019/09/free-will-bereitschaftspotential/597736/

...and the Scientific American (2019) https://blogs.scientificamerican.com/observations/how-a-flawed-experiment-proved-that-free-will-doesnt-exist/

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My five cents.

Libet-style experiments are about the finding of the readiness potential (RP), which allegedly could predict the outcome of the agent's choice, some time before the agent reported making the choice. Thus the interpretation is that the choice was already made, before the person was aware of it.

The actual relevance of Libet-style experiments is solely due to that interpretation (of RP). But what exactly is RP?

What the Bereitschaftspotential actually meant, however, was anyone’s guess. Its rising pattern appeared to reflect the dominoes of neural activity falling one by one on a track toward a person doing something. Scientists explained the Bereitschaftspotential as the electrophysiological sign of planning and initiating an action. Baked into that idea was the implicit assumption that the Bereitschaftspotential causes that action. The assumption was so natural, in fact, no one second-guessed it—or tested it.

A Famous Argument Against Free Will Has Been Debunked, The Atlantic

But one aspect of Libet’s results sneaked by largely unchallenged: the possibility that what he was seeing was accurate, but that his conclusions were based on an unsound premise. What if the Bereitschaftspotential didn’t cause actions in the first place? A few notable studies did suggest this, but they failed to provide any clue to what the Bereitschaftspotential could be instead. To dismantle such a powerful idea, someone had to offer a real alternative.

A Famous Argument Against Free Will Has Been Debunked, The Atlantic

In 2012 Aaron Schurger et al made several studies that provided a definite explanation of RP, which not only was confirmed, but at the same time provided an alternative interpretation of Libet-style experiments that made them irrelevant to free will debate by undermining the very premise of the experiment, since now the decision time was compatible with subject's own report time.

As Aaron Schurger, Jacobo Sitt, and Stanislas Dehaene report, “it is widely assumed that the neural decision to move coincides with the onset of the RP” (2012, p. E2909). Like Trevena and Miller and myself, they challenge that assumption. In their view, the brain uses “ongoing spontaneous fluctuations in neural activity” (p. E2904) – neural noise, in short – in solving the problem about when to act in Libet-style studies. A threshold for decision is set, and when such activity crosses it, a decision is made. They contend that most of the RP – all but the last 150 to 200 ms or so (p. E2910) – precedes the decision. In addition to providing evidence for this that comes from the work of other scientists, Schurger et al. offer evidence of their own. They use “a leaky stochastic accumulator to model the neural decision” made about when to move in a Libet-style experiment, and they report that their model “accounts for the behavioral and [eeg] data recorded from human subjects performing the task” (p. E2904). The model also makes a prediction that they confirmed: namely, that when participants are interrupted with a command to move now (press a button at once), short response times will be observed primarily in “trials in which the spontaneous fluctuations happened to be already close to the threshold” when the command (a click) was given (p. E2905).

Mele, Free Will and Neuroscience: Decision Times and the Point of No Return

Given these studies and the high implausibility that Libet-style experiments are really relevant to free will debate, since 2012 neuroscientists have refrained from any mention of them as disproving free will. For what is worth, Wikipedia's "Neuroscience of free will" page mentions no important studies nor experiments after year 2012.

[..]Schurger appeared to have unearthed a classic scientific mistake, so subtle that no one had noticed it and no amount of replication studies could have solved it, unless they started testing for causality. Now, researchers who questioned Libet and those who supported him are both shifting away from basing their experiments on the Bereitschaftspotential. (The few people I found still holding the traditional view confessed that they had not read Schurger’s 2012 paper.)

A Famous Argument Against Free Will Has Been Debunked, The Atlantic

Is consciousness-the subjective awareness of the sensations, perceptions, beliefs, desires, and intentions of mental life-a genuine cause of human action or a mere impotent epiphenomenon accompanying the brain's physical activity but utterly incapable of making anything actually happen? This article will review the history and current status of experiments and commentary related to Libet's influential paper (Brain 106:623-664, 1983) whose conclusion "that cerebral initiation even of a spontaneous voluntary act …can and usually does begin unconsciously" has had a huge effect on debate about the efficacy of conscious intentions. Early (up to 2008) and more recent (2008 on) experiments replicating and criticizing Libet's conclusions and especially his methods will be discussed, focusing especially on recent observations that the readiness potential (RP) may only be an "artifact of averaging" and that, when intention is measured using "tone probes," the onset of intention is found much earlier and often before the onset of the RP. Based on these findings, Libet's methodology was flawed and his results are no longer valid reasons for rejecting Fodor's "good old commonsense belief/desire psychology" that "my wanting is causally responsible for my reaching.".

Neafsey, Conscious intention and human action: Review of the rise and fall of the readiness potential and Libet's clock

Finally, it has to be noted that if (libertarian) free will exists, its outcomes can be as predictable or unpredictable as one chooses them to be (eg simply choose to follow any completely random or algorithmic process). This means that an amount of predictability by itself does not invalidate existence of free will.

Furthermore, and most importantly, all these experiments on free will (Libet's being the first) have consistently confirmed something that is related to a basic requirement of (libertarian) free will - the ability to do otherwise - what Libet termed "free won't". Even when the conditions were such that the prediction algorithm would confidently predict the subject's response, the subject was still able to do something else instead.

References:

  1. Aaron Schurger, Jacobo D Sitt, Stanislas Dehaene, An accumulator model for spontaneous neural activity prior to self-initiated movement
  2. Edward J Neafsey, Conscious intention and human action: Review of the rise and fall of the readiness potential and Libet's clock
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I would like to offer another plausible interpretation/explanation for the main Libet result - i.e. that a "deliberate action starts as an unconscious process about 500ms before" the conscious becomes aware of it.
Let me start by offering (without proof), that the "conscious" is aware that it takes about 400ms for the signals/commands to the muscles to get executed, and it takes 100ms for the "conscious" to process information.
It this is correct, then in any given situation were the "conscious" has to make the "best" decision, as fast as possible, at the last moment possible, the "conscious" has to issue commands to the subconscious processors 400ms ahead of time. This way, the 400ms muscle delay plus 100ms processing time, would make it appear that the decision was made instantaneously.
In the alternative, if the "conscious" makes the decision to flee and sends the command to the subconscious processors, it will be at least 400ms before the muscles react, increasing the provability of death.
This explanation clearly demonstrates that Libet's 500ms delay has nothing to do with free will!

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So basically, from a neuroscientist's perspective, even higher cognitive functions are much like spinal reflexes - touch a hot pan and the pain elicits an involuntary contraction of the flexor muscles that pulls the hand away from the pan. It's completely automatic.

Insofar as free will is concerned, that movement occurs before you intend it is a significant setback to free will proponents. Even though Libet expressely denies the implications of his expeirment on free will, they are obvious - we don't have free will because we're not in control of our minds and bodies.

Has the Libet experiment been replicated?

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