A post on the consistently interesting British Psychological Society Research Digest blog has got my head spinning somewhat. It seems that a team of researchers in Berlin have used brain imaging technology to show that when it comes to certain motor decisions, human free will is, in the words of the Digest, “an illusion.”
The researchers scanned the brains of subjects who had been asked to decide whether to press a button with their left or right finger. The subjects indicated when they had made their choice. But the brain scans showed that activity in the frontopolar and parietal cortices roughly ten seconds before the subjects reported their decision was correlated with that decision. In other words, monitoring brain activity in these areas could indicate whether the subject would choose left or right—well before the subject was consciously aware of having made the choice.
Is this a blow for free will? Not necessarily. Ever since Hume, all but the most far-out defenders of the proposition that human beings have some form of free will have acknowledged that our account of free will must not contravene physical laws. Moreover, most acknowledge that a “free” action is not best understood as an “uncaused”—ie random—one. The difficulty for defenders of free will is to come up with an account of what a free action is that doesn’t contradict the laws of science, but that at the same time cannot be reduced to them—for if a fully realised scientific account of the world can explain every human action, it’s difficult to see what room is left for the idea of free will.
But defenders of free will don’t place human actions outside the realm of causality. When the subjects in the experiment described above make their decision to press the button with one finger or the other, their decision is not akin to that made by a random number generator. Their decision will have a cause, or more likely a vast number of causes. Our understanding of the neuroscience of decision-making is presumably nothing like sophisticated enough to be able to tell us what these causes are, but there’s no reason why we should be aware of them, as opposed to being aware of the decision we make as we make it. It just so happens that brain-scanning technology is now sufficiently advanced to be able to detect the first neurological stirrings of those parts of the brain that come into play when we make decisions like these before our conscious understanding. Yet if someone was to place you in this experiment and tell you that you are not making your choices between left and right freely, it wouldn’t be difficult to produce evidence suggesting otherwise.
And yet, and yet… it’s easy to see why evidence like that adduced by the Berlin team might be seen as some as weighing against free will. If a scientist monitoring my brain activity knows what I’m going to do before I do, in what sense can I be said to have made my decision freely? What all this really shows is how intractable the problem of free will is, and how, in the light of increasingly sophisticated levels of scientific, particularly neuroscientific, understanding, the defenders of free will need to produce a correspondingly sophisticated definition of freedom.
Prospect readers might like to note that the free will/determinism problem is given rather more exalted treatment by AC Grayling in the May 2008 issue of the magazine, published later this week.