Benjamin Libet proved we don’t have free-will? Didn’t he?

Most of us interested in topics that span metaphysics and neuroscience will have, undoubtedly, heard of the famous Benjamin Libet experiments, which according to some commentators and interpreters of these experiments have proved that free-will is an illusion (although Libet did not proclaim this himself). But is that the conclusion we can draw from these experiments?

Libet was interested in testing the moment when the subject became consciously aware of the intention of flexing her wrist, although it could have been any simple motor task, such as tapping one’s fingers, snapping one’s fingers, twirling your toes etc. To record the time that the subject was consciously aware of the decision to flex their wrist, Libet created his own timing device, an oscilloscope with a dot quickly circulating around it like the hands on a clock (image in the header of this post). Libet also had his subjects fixed to an electroencephalogram (EEG) machine attached to their scalp to measure the brain activity during the experiment, notably when they formed the intention to flex their wrist and when the action to flex the wrist was initiated. Libet_clock

Libet’s motivation in performing this experiment was to test the assumption, formed by the neurobiologist John Eccles, that the subject must “become conscious of the intention to act before the onset of this readiness potential.” (information philosopher) For those that believe in the existence of free-will (and for it to be explained in a scientific manner) this assumption would be appear to make perfect sense, the conscious agent is the cause of the intention, and this sets off the relevant readiness potential (RP) to enact the target of the said intention. This type of explanation would give credence to free-will and explain mechanisms of action in a biologically plausible manner, particularly appealing to free-will believing neurobiologists.

Although a complete explanation of how free-will works would have to explain how voluntarily chosen intentions lead to an onset of the relevant RP, and what, if any, physical manifestations in the brain does a conscious intention have? Is it affected by prior conditions, events and natural laws in any shape or form? All questions that hindsight has caused Philosophers and Neuroscientists to become extremely sceptical towards answering in an affirmative manner. However, these questions in principle would not need to be explained for the free-will assumption of John Eccles to be correct: some type of free-will appears to exist, and this is because first we have the conscious intention and then we have the onset of the relevant RP. Further scientific investigations would eventually explain how free-will works in a scientifically and biologically sound manner within this process.

Yet the Libet experiments have caused doubts to the free-will hypothesis by denying the assumption asserted by John Eccles. In fact, the results of Libet’s experiments found just the opposite: his subjects had a RP to act which preceded the conscious intention of the subjects to flex their wrists. It was found that a rise in the RP to act was 300 milliseconds before the conscious intention was formed to flex their wrist. This supposedly shows that it had already been decided unconsciously that they were about to form the intention to flex their wrist, entailing that the conscious intention was not the originator of the intention itself, but more of an experiential reporter of an intention already formed. Overall the rise of the RP was 550 milliseconds before the subject flexed their wrist, and the conscious intention to flex their wrist was roughly 200 milliseconds before they did so.

The illusion of free-will here, if it is an illusion, is that consciousness believes itself to be in charge of decisions which it is duped to think it makes voluntarily. When in fact, it is just the experiential process of repeating the party-line of decisions made without its input. That is, the intention to flex the wrist had already been made before the subject consciously formed the intention to flex their wrist.

So –do the results of these experiments prove that free-will is an illusion?

A quick caveat before we attempt to briefly answer such a question. There have been countless methodological issues pertaining to the Libet experiments, but these – at least in this post – will be pushed to the side. Also it is not to say, however, that the experimental method detailed by Libet is the only one available to the determinist, this is not the case: the illusion of free-will is possible without unconscious RP preceeding conscious intentions or decision making.

As a researcher, without getting into debates about whether it is compatible or incompatible with moral responsibility, I am generally persuaded by the philosophical arguments and suggestive empirical evidence that the metaphysical nature of the world is of a determinist bent. However, at the same time, evidence emerging from the neuroscience labs, whilst promising, inspiring and progressing, is riddled with interpretive issues and we simply just do not know enough about the brain at the current time to prove irrefutable determinist processes at work.

The major obstacle to those thinkers that believe the Libet experiments demonstrate that free-will is an illusion is that the results of the experiment are not strong enough for the conclusion it wants to prove. If free-will is to be demonstrated to be an illusion on the basis of the Libet experiments, the experiment needs to demonstrate that in complex scenarios, rather than performing simple motor actions, we are determined to act by prior brain activity and neural impulses that have nothing to do with conscious decision making itself playing an efficacious and starring role. That the intention or result of the complex decision making were based on unconscious RP’s rather than the conscious reasons themselves. For example, take a game of classical chess where complex decision making, evaluating factors, analysing situations, running through different variation of actions is present, and this information informs the decision of the next move we should play. Using Libet’s experiments it would have to be shown that unconscious RP’s preceeded the conscious decision making of the subject. Neither Libet nor any neuroscience experiment comes close to showing such a conclusion is present.


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