11 March 2016

Freewill is Back on the Menu

“There is now no safer occupation than talking bad science to philosophers, except talking bad philosophy to scientists.”

- Mary Midgley.

I don't find freewill a particularly interesting problem, but it does come up from time to time. Because it is essential to Buddhist ethics I've ended up writing about it a few times despite my reluctance, mainly to try to counter what I see as a pernicious trend to Determinism amongst Buddhists influenced by Advaita Vedanta. My essays on the subject include: Do We Have Freewill?(6 Feb 2015), A Sutta on FreewillExperience and Free Will in Early Buddhism (4 Apr 2014). The problem has become a cause célèbre amongst scientists since the 1980s when Benjamin Libet (1916-2007) first published results of his experiments on the so-called "readiness potential". The correct interpretation of these experiments has always been hotly disputed, though Determinists seldom cite any dissenting voices when they reference this material (so readers might be unaware of the controversy). We have seen a number of physicists in recent years citing Libet in the media and in books for the general public as "proving" that there is no freewill. But as Peter Clarke observes:
Despite the fame of the Libet experiment and its frequent acceptance in popular and semi-popular writings, it has been the subject of intense controversy. Indeed, most specialists in the philosophy of free will who have addressed the Libet claim have rejected it. (2013)
Philosophers and physicists seem to fall out in public quite often these days. See for example, Goldhill (2016) for a typical complaint about facile arguments from prominent physicists on the subject of philosophy. Physicists seem to take a perverse delight in dismissing philosophy out of hand, but often show their deep ignorance in the process. Stephen Hawking infamously declared philosophy dead. Paraphrasing Goldhill, this is a very stupid thing for a very smart person to say. Which just goes to show that smart people do make mistakes and do say stupid things. We can't just abdicate the responsibility for evaluating what people say, even when they are experts. As Richard Feynman said, "science is the belief in the ignorance of experts". And if we are not in a position to judge, then we can always seek out those who are and get their opinion. Unfortunately physicists are often seen as authorities and thus their views on philosophy are widely taken seriously, even when they are out of their depth and saying stupid things. 

In this essay, sparked by a blog by Deric's MindBlog, I will outline Libet's findings, explore some responses from other scholars, and look at the philosophical implications. We might not be able to put to rest the wailing of "there is no freewill" by Determinists, but we can at least give them something to chew on for a while.


Libet's Experiments

Libet was investigating the phenomenon of readiness potential (RP). The RP is a slowish build up of electrical potential in the brain, measured at the scalp over the motor cortex by an electroencephalograph (EEG). It occurs a second or more before people make voluntary movements. As the name suggests, this build up of electric potential was assumed to be the brain "getting ready" to initiate a movement. Libet was interested in the timing of the RP and the decision to move.

Libet's classic experiments (Libet 1985, Libet et al. 1983) asked people to make a simple movement, usually flexing their hand or wrist. The subjects were instructed to move whenever they felt like it (within a 20 sec window). At the same time they observed the position of a spot moving in a circle on an oscilloscope screen and reported the position of the spot when they felt the "urge to move". What he found was that there was a delay of some 200 milliseconds (ms) between becoming consciously aware of an urge to move and the actual movement. However the readiness potential began to build up 350-500 ms earlier.


Note, this is a very short-range phenomenon. The voltage measured on the scalp is in the order of a few micro-volts (10-6 V). The amplitude drops off sharply. Another few centimetres from the scalp and the electrical activity would be undetectable (so no, this is not a mechanism for telepathy!). Indeed one of the drawbacks of EEG for measuring brain activity is that it doesn't detect electrical activity below the cortex layer. The technique is also poor at localising the activity - multiple electrodes and sophisticated analysis of the activity can improve this, but EEG is still a pretty blunt instrument. The technique is famous for the early discovery that the activity in the cortex occurs in waves.

Libet controversially interpreted the initiation of the readiness potential as the "decision" to move, the point where the brain unconsciously began preparing to move. Becoming conscious of an "urge to move" came significantly later, and then finally the action itself was initiated. The whole process taking almost half a second. In this interpretation, the experience of willing our hand to move comes quite a long time after the brain has decided to move. In other words the experience of willing our hand to move is a secondary feature in the process. Hence, freewill, interpreted as contra-causal freewill, is not what initiates a voluntary movement.


Contra-causal Freewill

I was alerted to idea of contra-causal freewill by reading Patricia Churchland's book Touching A Nerve: The Self as Brain (2013) in which she argues against it. Contracausal freewill is the idea that we have an abstract capacity called "will" that is like the executive branch of the abstract capacity of "reason". To be considered contra-causally free, this capacity to make decisions or initiate actions must be free from any influences other than itself. Specifically emotions, motivations, desires, goals, and knowledge must be excluded as potential influence. If any of these influence our decision making then, in this view, our will is not free. Thus for Libet, if some unconscious part of the brain is making the decision to move and then placing the idea in our conscious minds, then even though our brain is still making a decision, it does not count as freewill because it is not based on the abstract reasoning capacity.

Any long time readers of this blog will know that this definition of freewill is suspect at best. There are two main problems with it. Firstly the definition makes an egregious mistake in considering reason to be an abstract capacity. I follow Lakoff and Johnson in taking reason to be a function of an embodied mind. Reasoning specifically uses metaphors grounded in our experience of the world to enable abstraction. It is not that we have an abstract capacity for reason, but that we have an embodied capacity for abstraction. Research by Antonio and Hannah Damasio (amongst others) has shown that emotions are involved in all decision making. As I have explained it, emotions tell us how salient any fact is to our decision making process (see Facts and Feelings, 25 may 2012). There is simply no plausible way for contra-causal freewill to operate. Secondly the definition involved legacy understandings of how reasoning works. I also follow Mercier and Sperber in seeing reasoning as an argumentative capacity. It is well known that individuals are generally very poor at reasoning tasks. Most of us do not to make rational decisions and when we try to, we almost inevitably fall into cognitive bias or logical fallacy. On individual tests of reasoning we frequently score worse than random guessing. The long lists on cognitive biases and common logical fallacies that we are prone to bear stark witness to this. Reasoning is not activated until we are assessing someone else's argument or retrospectively justifying our own actions (see An Argumentative Theory of Reason, 10 May 2013). 

As Churchland has said, contracausal freewill is not particularly interesting. Even if the experiment showed that we do not have contracausal freewill, this would still not be interesting as the concept is a legacy of a bygone era that has no place in modern discussions about the mind or morality. Clearly many scientists are poorly informed on developments in philosophy because they think philosophy is worthless. They cannot be relied on, in general, to be guides to the philosophy of freewill. This is an important caveat when considering this question. My suspicion is that the criticism cuts both ways. That as much as philosophers like to comment on science, they are often too poorly informed about it to be trustworthy guides to it. All too many philosophers in this field seem to be ontological dualists who do not believe that studying neurons can tell us how the mind works, for example. Sorting out whether or not any individual commentator on this issue makes sense is really quite difficult. No doubt I am also a poor guide to this issue. However, other scholars have been trying to reproduce Libet's experiments and assessing his interpretation of the results since it was published. And we can turn to them to get some balance.


Re-evaluating Libet.

As I say, the interpretation of Libet's experiments has been the subject of intense controversy since they were first published. It seems, from my outsider point-of-view, as though physicists have lined up to say that they prove that human beings are Deterministic and that there is no freewill. But even casually reading around this subject we see that philosophers have lined up to deny that Libet tells us anything about freewill.

For example, what exactly is a voluntary movement? Peter Clarke (2013), for example, cites the example of a tennis player serving a ball. The decision to serve may be voluntary and the movement of the arm might even be partially under conscious control, but the myriad movements that coordinate the whole body as it moves and balances to support the motion of serving are almost entirely unconscious. The motions that direct the ball to the precise location on the opposite players court are mostly not under the direct control of the player. Tennis players have developed a kind of reflex that allows them to serve accurately at speeds that does not require conscious thought. Indeed in many sports we know that thinking too much about key muscle movements is counter-productive. So is serving the ball a voluntary act? I get this playing the guitar. I train my fingers to find and pluck the notes I want so that I don't have to think about them and this enables me to sing at the same time. If I was consciously seeking out notes on the fretboard and dredging up lyrics and all the other components of articulation and delivery I could not play the simplest tune, let alone something as complex as, say, the Beatles tune Blackbird. The assumption that a decision to act cannot occur without being conscious of it is deeply problematic. In playing a tune like Blackbird I initiate hundreds of actions with no consciousness of doing so because my attention is usually elsewhere. So this question is far from trivial and it ought to make us pause before considering what it means for an experimental subject to make a "voluntary movement". Even if Libet relies on a single movement, how do we know that this is representative, or that the experiment is able to isolate that movement from everything else that is going on in a conscious subject?

An important criticism of the Libet experiment is that it is very difficult to judge when one experiences the "urge to move". Clarke (2013) did the experiment himself and commented "When I try this, I find it very hard to judge the precise time when I decided to move my finger / wrist." Clarke describes studies on the reliability of the subjective timing of events which have shown it to be very imprecise. Additionally the experiment involves an attention shift from the movement to the timing "may have introduced temporal mismatches between the felt experience of will and the perceived position of the clock hand." Attempts to eliminate this mismatch have shown that the RP occurred before the "urge to move" only in about two thirds of subjects. To try to improve accuracy the experiment was performed using functional magnetic resonance imaging (fMRI) and this also showed that "the activity of prefrontal and parietal cortex was correlated with the decision [to move] with 60% prediction accuracy, up to 10 sec before the conscious decision." These findings seem to say that there cannot be a causal relationship between the RP and the "urge to move", else it would occur every time. In which case Libet appears to have misinterpreted what the RP is.

Clarke (2013) lists a number of other published criticisms of the Libet experiments. Firstly Libet takes the RP to represent a decision to move, i.e. he believes that there is a causal connection between the beginning of the RP and the action if and when it comes. However it appears that there is no neural connection between the areas that build up potential in the RP (the sensory motor-cortex) and the parts of the brain associated with decision making (in the parietal lobe). Thus, in addition to there being a disconnect in practice, there is no obvious mechanism for the RP to cause the urge to move either.

Secondly, if the RP was the cause of the movement then we would expect a strong correlation between the timing of the onset of RP and the timing of the urge to move. But this correlation does not occur. Experiments to test this seem to rule out the RP as cause of the urge to move, though not of the movement itself. So at the very least the mechanism proposed by Libet has a missing link. And that link might play an active role in the process (i.e. might be directly causal).

Alfred Mele offers a third criticism of the Libet experimental set up, noted by Clarke (2013). In Libet's experiments, the data was only stored when a movement is initiated. Libet collected no data on what happened if the subject decided not to move. This vitiates his finding because it's entirely possible to prepare to move, which would presumably initiate an RP, and then not experience the urge to move. If an RP can exist and not give rise to an urge to move, then RP may not related to the urge to move at all. This possibility ought to have been excluded, but was not. A variation on the experiment by Trevena and Miller did collect data on cases where the decision was made not to move. The RP was the same whether they moved or not. And this suggests that RP does exist without giving rise to the urge to move, or an action, which undermines Libet's conclusion that RP represents a decision to move. 

A fourth weakness was pointed out by Hermann et al. They set the experiment up as a decision to press one of two buttons in response to a stimulus. They also found the RP appearing before the urge to move occurred, but the RP occurred even before the stimulus appeared and thus is unlikely to have been related to a decision about which button to press. Again the evidence points away from a coupling of RP and the urge to move. In fact Schurger et al (2012) showed the decision to move occurs very late in the course of the RP, not at the initiation of it.

Libet himself argued that his interpretation showed that, although freewill in the sense of consciously initiating actions was ruled out, that we still had the option of inhibiting actions between the initiation of the RP (what he called the decision to move) and the urge to move. Some people called this "free-won't". This might be an interesting thread to follow up, except that considering the various critiques of Libet's experiment and interpretation, it seems that treating the initiation of the RP as the decision point makes no sense.

The real nail in the coffin however was published in Feb 2016 (just a couple of weeks ago as I write this). Libet was focussed on spontaneous voluntary movements (SVM) and it turns out that these are rather different in their underlying dynamic than movements initiated in response to a stimulus. Citing from Deric Brown's blog:
"A new generation of experiments is now suggesting that brain activity preceding spontaneous voluntary movements (SVMs) 'may reflect the ebb and flow of background neuronal noise, rather than the outcome of a specific neural event corresponding to a ‘decision’ to initiate movement... [Several studies] have converged in showing that bounded-integration processes, which involve the accumulation of noisy evidence until a decision threshold is reached, offer a coherent and plausible explanation for the apparent pre-movement build-up of neuronal activity.'" (Shurger et al. 2016)
So what looks like a build up of "readiness potential" is in fact happening because of anticipating having to make a decision at some point (and in the experiment the subject is explicitly primed to do so). The actual decision is reached when background neural activity reaches a peak:
"In particular, when actions are initiated spontaneously rather than in response to a sensory cue, the process of integration to bound is dominated by ongoing stochastic fluctuations in neural activity that influence the precise moment at which the decision threshold is reached. ... This in turn gives the natural but erroneous impression of a goal-directed brain process corresponding to the ‘cerebral initiation of a spontaneous voluntary act’"
In other words if we look again at the graph of "readiness potential" the decision to move comes at the peak of neuronal activity not at the onset of the RP. The RP is an accumulation of more or less random neuronal activity. This would explain some of the contradictory results mentioned above.


But crucially what this suggests to me is that the urge to move precedes the decision to move. The urge to move may in fact be an important factor in the decision to move. So it seems that Libet's interpretation of his experiment was flawed in these various ways and that freewill is back on the menu.


Conclusions

I discovered this information because I happen read a number of neuroscience blogs and Twitter feeds and one of them happened to mention this new article by Shurger et al. (2016) which drew me into the subject anew. But there was always debate. Over what freewill means. Over what the readiness potential represents. Over the causal relationship between the readiness potential and the urge to move; or between the RP and the actual movement. Over Libet's experimental methods.

This experiment is so often presented with a one-sided interpretation, with no mention of the mass of contradictory evidence that make Libet's interpretation look doubtful. There is no mention of the intense debate that has ensued. Any reader could be forgiven for thinking that it was an open and shut case or that Libet had definitively shown that freewill could not exist. But this was never the case. The interpretation of the experiment could never be considered unequivocal proof of anything. The weakness of Libet's experimental design and the many contra-indications for Libet's interpretation of the readiness potential as a decision or even as causal, ought to have been given more prominence in the discussion of freewill.

Most scientists are aware of the problem with "proving" an hypothesis anyway. As Karl Popper observed, an hypothesis can really only be disproved or a conjecture refuted. A scientific theory may make more or less accurate predictions. For example, the Higgs Boson has not in fact been proved to exist. However, the theory (The Standard Model of Particle Physics) did predict a particle would be found in a certain energy range and such a particle was found in the Large Hadron Collider. So the theory survives another test, and we now try to test other predictions that it makes. The theory could fail at any point and many scientists hope that it does, because that would make their work far more interesting and open up the field to new discoveries. The failure of the Standard Model would initiate a golden age of inquiry into the nature of the universe. Scientists are frankly bored by the idea that everything has been discovered. Which is the opposite of how they are sometimes portrayed and the opposite of religious approaches to knowledge. 

When so-called scientists give a biased presentation of an issue, citing only the evidence for their interpretation and avoiding even mentioning that there is considerable evidence against it, then that is a kind of fraud. Scientists committing such fraud ought to be censured by their peers. False statements ought to be retracted. And I think in this area of freewill many scientists are guilty of this kind of fraud. And many laypeople have repeated the fraudulent claims and perpetuated a falsehood.

In this the public have been extremely badly served by lazy journalists who have simply failed to report the experimental evidence. Whether this also amounts to fraud depends on your point of view. I see the primary function of journalism as being entertainment. Entertainers are always allowed some "poetic licence" to deceive us about facts if the version of events they present is more entertaining than reality. Hollywood films almost always distort history because the real story is often boring. Science journalists are a mixed bag and you never know which kind of story you are reading, but these days I just assume, with very few exceptions, that if a journalist is writing that they are seeking to entertain rather than inform.

There will be those who cite this case as showing that the scientific method is broken. That in overturning a previous interpretation of the data science has proved that it cannot be trusted. To my mind it says completely the opposite. This is science in action. This is the scientific process at work. The overturning of previous interpretations is part and parcel of embracing science. What we think we knew today is quite likely to be overturned tomorrow. For the religieux seeking certain knowledge and believing that they have found it, this seems anathema. That knowledge could be transient and contingent makes it seem untrustworthy. Religion is predicated on the idea of absolute knowledge, from which comes certainty, and relaxation as all mysteries are resolved in the long run. But that is an impossible fantasy. In the real world things are messy. Knowledge is never absolute. There is always the possibility of being wrong.

Religieux seem very uneasy with the idea that they might be wrong. Buddhists in particular seem to find this concept deeply troubling. Scientists by contrast embrace uncertainty and the principle that all knowledge may be overturned by a better explanation. Science progresses by testing ideas to destruction. This attitude of contingency with respect to knowledge of the world is in fact far more in keeping with Buddhist ideology. Most Buddhists appear to believe that the world can be understood in absolute terms, that the Buddha was omniscient in this sense, and that the Dharma is an expression of this absolute knowledge, i.e. that it represents absolute truth. They further believe that we can come to this absolute knowledge through introspection and believe that we cannot come to knowledge through examining the world. I have been told by a colleague for example that "no amount of study of the brain will ever tell us anything about the mind". Which is just Cartesian Dualism as far as I can see and thus a thesis that has already been soundly refuted.

However, despite having cast considerable doubt on Libet interpretation, this is not the end of the story. There are other arguments against freewill that are much more difficult to tackle than Libet's and his Determinist fans. For example, the argument by Sabine Hossenfelder on the Backreaction blog. I don't necessarily agree that arguments from fundamental laws eliminate the possibility of unexpected emergent properties that are indistinguishable from free will, but she still makes a strong argument for anyone who acknowledges the laws of physics. And so the arguments will go on. But as religieux we do need to be wary of pursuing a conjecture only because it supports our doctrine. Freewill is interesting because without it Buddhist ethics would be meaningless. If we seek only to bolster our view, rather than to seek the truth, then the possibility of being wrong is excluded and we are unlikely to accept that we have been wrong when the evidence becomes unequivocal. I see this happening in the area of the afterlife for example. Intelligent people must always hold to the possibility of being wrong. But intelligent people are also the most reluctant to reconsider their considered views. Intelligent religious people are the worst. 

~~oOo~~


Bibliography

Alexander, P., et al. (2016) Readiness potentials driven by non-motoric processes. Consciousness and Cognition, 39: 38–47. doi:10.1016/j.concog.2015.11.011

Churchland, P. S. (2013) Touching A Nerve: The Self as Brain. W. W. Norton & Co.

Clarke, P. G. H. (2013). The Libet Experiment and its Implications for Conscious Will. Faraday Paper No. 17. Faraday Institute for Science and Religion. http://www.bethinking.org/download/faraday-paper-17-clarke-en

Fried, I., Mukamel, R. & Kreiman, G. ‘Internally generated preactivation of single neurons in human medial frontal cortex predicts volition’, Neuron (2011) 69: 548-562.

Goldhill, O. (2016). Why are so many smart people such idiots about philosophy? Quartz. March 05, http://qz.com/627989/why-are-so-many-smart-people-such-idiots-about-philosophy/

Libet, B. (1985). Unconscious cerebral initiative and the role of conscious will in voluntary
action. Behavioral and Brain Sciences, 8: 529-566.

Libet, B., Gleason, C.A., Wright, E.W. & Pearl, D. (1983). Time of unconscious intention to
act in relation to onset of cerebral activity (Readiness-Potential), Brain, 106: 623-42.

Schurger, A., Sitt, J.D. & Dehaene, S. (2012) An accumulator model for spontaneous neural activity prior to self-iniated movement. Proceedings of the National Academy of Sciences. USA doi:10.1073/pnas.1210467109

Schurger, A. et al. (2016) Neural Antecedents of Spontaneous Voluntary Movement: A New Perspective. Trends in Cognitive Sciences, 20 (2), 77 - 79.


Additional reading

Fischborn, Marcelo (2016) Libet-style experiments, neuroscience, and libertarian free will. Philosophical Psychology. 1(9) doi: 10.1080/09515089.2016.1141399
"The general result is that neuroscience and psychology could in principle undermine libertarian free will, but that Libet-style experiments have not done that so far."

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