Taking Aim at Free Will
Scientists think they can prove that free will is an illusion. Philosophers are urging them to think again.
As humans, we like to think that our decisions are under our conscious control — that we have free will. Philosophers have debated that concept for centuries, and now experimental neuroscientists are raising a new challenge. They argue that consciousness of a decision may be a mere biochemical afterthought, with no influence whatsoever on a person’s actions.
According to this logic, they say, free will is an illusion.
You may have thought you decided whether to have tea or coffee this morning, for example, but the decision may have been made long before you were aware of it.
Philosophers aren’t convinced that brain scans can demolish free will so easily. Some have questioned the neuroscientists’ results and interpretations, arguing that the researchers have not quite grasped the concept that they say they are debunking. Many more don’t engage with scientists at all.
There are some signs that this is beginning to change. Some say that, with refined experiments, neuroscience could help researchers to identify the physical processes underlying conscious intention and to better understand the brain activity that precedes it. And if unconscious brain activity could be found to predict decisions perfectly, the work really could rattle the notion of free will.
In the 1980s, Benjamin Libet, a neuropsychologist at the University of California, San Francisco, rigged up study participants to an electroencephalogram (EEG) and asked them to watch a clock face with a dot sweeping around it. When the participants felt the urge to move a finger, they had to note the dot’s position. Libet recorded brain activity several hundred milliseconds before people expressed their conscious intention to move.
Libet’s result was controversial. Critics said that the clock was distracting, and the report of a conscious decision was too subjective. Neuroscience experiments usually have controllable inputs — show someone a picture at a precise moment, and then look for reactions in the brain. When the input is the participant’s conscious intention to move, however, they subjectively decide on its timing. Moreover, critics weren’t convinced that the activity seen by Libet before a conscious decision was sufficient to cause the decision — it could just have been the brain gearing up to decide and then move.
Some researchers have literally gone deeper into the brain. One of those is Itzhak Fried, a neuroscientist and surgeon at the University of California, Los Angeles, and the Tel Aviv Medical Center in Israel. He studied individuals with electrodes implanted in their brains as part of a surgical procedure to treat epilepsy. Recording from single neurons in this way gives scientists a much more precise picture of brain activity than fMRI or EEG. Fried’s experiments showed that there was activity in individual neurons of particular brain areas about a second and a half before the subject made a conscious decision to press a button. With about 700 milliseconds to go, the researchers could predict the timing of that decision with more than 80% accuracy.
Philosophers question the assumptions underlying such interpretations. If neuroscientists find unconscious neural activity that drives decision-making, the troublesome concept of mind as separate from body disappears, as does free will. The trouble is, most current philosophers don’t think about free will like that, says Mele. Many are materialists — believing that everything has a physical basis, and decisions and actions come from brain activity. So scientists are weighing in on a notion that philosophers consider irrelevant.
Nowadays, the majority of philosophers are comfortable with the idea that people can make rational decisions in a deterministic universe. They debate the interplay between freedom and determinism — the theory that everything is predestined, either by fate or by physical laws but Roskies says that results from neuroscience can’t yet settle that debate. They may speak to the predictability of actions, but not to the issue of determinism.
Neuroscientists also sometimes have misconceptions about their own field. In particular, scientists tend to see preparatory brain activity as proceeding stepwise, one bit at a time, to a final decision. He suggests that researchers should instead think of processes working in parallel, in a complex network with interactions happening continually. The time at which one becomes aware of a decision is thus not as important as some have thought.
There are conceptual issues — and then there is semantics. Even within philosophy, definitions of free will don’t always match up. Some philosophers define it as the ability to make rational decisions in the absence of coercion. Some definitions place it in cosmic context: at the moment of decision, given everything that’s happened in the past, it is possible to reach a different decision. Others stick to the idea that a non-physical ‘soul’ is directing decisions.
Neuroscience could contribute directly to tidying up definitions, or adding an empirical dimension to them. It might lead to a deeper, better understanding of what freely willing something involves, or refine views of what conscious intention is.
Philosophers are willing to admit that neuroscience could one day trouble the concept of free will. Imagine a situation (philosophers like to do this) in which researchers could always predict what someone would decide from their brain activity, before the subject became aware of their decision.
The practical effects of demolishing free will are hard to predict. Biological determinism doesn’t hold up as a defence in law. Legal scholars aren’t ready to ditch the principle of personal responsibility