Can science ever tell us whether free will exists?
Brain experiments have yet to shed light on the ‘freedom that matters’, says philosopher Markus Schlosser
In recent experiments, scientists have identified “unconscious determinants” in the brain which can be detected before decisions are made. Photograph: Getty Images
Few pieces of research have caused such a tizzy among philosophers as Benjamin Libet’s pioneering experiments on human consciousness. In the first of these in 1983, participants were asked to flex one of their wrists when they felt like doing so.
Libet monitored their brain activity and discovered the conscious decision to move was preceded – by roughly 350 milliseconds – by unconscious brain activity initiating the movement. In other words, the movement seemed to begin before the participant “willed” it.
In more recent experiments, scientists have identified “unconscious determinants” in the brain which can be detected several seconds before decisions are made. In one study, researchers were able to predict with 60 per cent accuracy whether subjects would press a button with their left or right hand up to 10 seconds before the subjects became aware of making the choice.
In philosophy, he notes, the reception to such research has been negative, “often even dismissive”, which he traces to “a mismatch between the philosophical conception and the neuroscientific operationalisation of free will”.
In particular, he says, the experiments have nothing to say about more advanced forms of decision-making, especially those based on reasons. This is the “kind of freedom that we care about”, he says, not the freedom to press one button or another in an artificial laboratory setting. Thus, he argues, “the operational definition of free willshould be revised in accord with the philosophical conception”.
What do experiments, like those conducted by Benjamin Libet, tell us about free will?
“It has been claimed, in newspapers and in the popular science press, that neuroscience has now shown that we don’t have free will. In philosophy, virtually no one thinks that neuroscience has really shown this.
“First, I should note that none of the experiments have uncovered unconscious determinants of conscious choices. For the Libet experiment, we simply don’t know whether participants would move without making also a conscious choice. In follow-up experiments, the decoded brain activity is only very weakly predictive of the conscious choice.
“It raises the likelihood of the choice to just above the level of chance, which seems to leave quite a lot of freedom. This means also that it is misleading to say that ‘the brain decides before you do’ – as it is sometimes put. At best we can say that the brain generates unconscious tendencies before a conscious choice is made.
“It should also be noted here that this way of talking creates a rather strange separation between ‘you’ and ‘your brain’.
“Further, experiments of this kind differ from everyday choices in significant respects. Most importantly, most of our choices are in one sense or another based on reasons. We choose one thing rather than another because we see something favourable in it, and our choices matter to us for that reason.
“The neuroscientific research has so far studied only choices that are utterly care-free. There is no reason to perform the movement now or to use the left rather than the right index finger to press a button – without any consequence. In philosophy, we call this ‘freedom of indifference’ and we distinguish it from the kind of freedom that grounds responsible decisions.
“The main point here is that there is no obvious reason to think that the findings from those studies apply to everyday choices - that are based on reasons.
“Another issue is that participants decide at the beginning of the experiment to perform the requested task. Presumably, they make those decisions consciously, in response to instructions, and so their actions appear to be governed by conscious decisions that were made before the recordings of brain activity.
“So, the neuroscience of free will has made some very interesting discoveries, but it has also generated a lot of debate and controversy. As things stand, I think it is safe to say that this research has not conclusively proven anything significant about free will.”
How might one design an experiment that tested whether free will exists?
“If scientists want to study the freedom of indifference by studying care-free choices, then that’s absolutely fine. But if they want to make claims about the kind of freedom that matters in everyday life and that has a bearing on the issue of moral responsibility, then they should design experiments in which participants are given reasons for and against certain options.
“It is rather unlikely, however, that any such experiment will settle the issue once and for all. Any experimental design has to be based on certain assumptions about free will, and those assumptions can always be questioned from a philosophical point of view.”
You say the operational definition of free will should be revised to capture “the kind of freedom that we care about” but doesn’t this go to the heart of the neuroscientists’ objections? They might say that we can only talk about the “free will” that is observable, and that anything else is just wishful thinking, or worse, it amounts to “smuggling in” something non-physical like “the soul”.
“The issue here is not whether free will is observable or not. Choices that are based on reasons are as unobservable as care-free choices of indifference. But they are also as observable, in the sense that they have the same connections with observable events – such as overt behaviour, the subject’s verbal reports, and evidence from neuro-imaging techniques.
“Physicalism is not the issue either, in my view. Some think that free will requires something like a non-physical self that is not constrained by the laws of nature. Some scientists seem to share this view, but in contemporary philosophy it is widely rejected.
“Presumably, deliberation and decision-making are psychological processes that are realised by the brain. It would be a mistake to think that this alone renders our choices unfree. Our brains and their activities are, after all, very important parts of who we are.
“I suppose that a debate about this would bring us back to the issue of definition. If one defines free will in terms of a non-physical self, then neuroscience does provide evidence for the claim that we don’t have free will. But I see no compelling reason to define free will in this way.”