A SIMPLE insect can help us understand free will, and the lack of it. When a female digger wasp is ready to lay her eggs, she hunts down a cricket or similar prey, paralyses it with a sting, drags it back to the lip of her burrow, and then enters to check for blockages. If you move the cricket a few centimetres away before she re-emerges, she will again drag it to the threshold and again leave it to check for blockages. She will do this over and over. The wasp has no choice. This mindlessly inflexible behaviour has led to the wasp, Sphex ichneumoneus, becoming a byword among biologists for determinism, the idea that what we think of as a “choice” is in fact a path dictated by pre-existing factors.
It is tempting to think that we aren’t like the wasp – that what we do is the result of choices that are freely made. Yet the more we learn about the neuroscience of decision-making, the more “sphexish” we seem to be. You hear people arguing that humans are mere biological machines trapped in cycles of behaviour that are ultimately beyond our control – that free will is just an illusion.
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As a cognitive scientist who studies decision-making, I disagree. Of course, humans are animals. The problem, I believe, is our misguided intuitions of what it means to be a biological machine. In an attempt to dispel some of these misconceptions, I have created an interactive essay on Twitter called The Choice Engine.
Waspish behaviour
How Sphex came to be linked with free will is a long story. Charles Darwin was studying this wasp while working on his theory of evolution. We know from his notebooks that its behaviour had a big impact on him. He wasn’t aware that it would ceaselessly check its burrow – that discovery was made decades later by Nikolaas Tinbergen, the founder of ethology, the science of animal behaviour. What interested Darwin was what the wasp does once it has dragged a cricket into its burrow: it lays its eggs in the body of the immobilised but still living prey. When the larvae hatch they eat it from the inside out.
Darwin was so appalled by this behaviour that he cited it as one reason for his loss of faith. “I cannot persuade myself that a beneficent & omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within… living bodies,” he wrote. Meanwhile, his theory wasn’t just undermining God. Some took it as support for the idea that humans are mere animals and that animals are mere machines, fanning the flames of a millennia-old debate about free will.
To Darwin, Sphex was emblematic of the cruelty found in nature. Tinbergen exposed it as emblematic of nature’s mindlessness. But it was the philosopher Daniel Dennett of Tufts University in Massachusetts, to describe the nature of human choices if we say they are like those of other animals. In doing so, he highlighted a common misconception: that we must either reject the idea that biology influences our choices or reject the notion of free will.
This fallacy is the nub of the problem. Biology certainly influences our choices, as plenty of evidence shows. Perhaps the most famous example is an experiment on free will done in the 1980s by Benjamin Libet. He showed that brain activity associated with an action occurs before the subjective feeling of choosing that action. More recently, Libet’s experiment was replicated with the addition of an functional MRI scanner. This time, the researchers were able to predict some actions from brain activity up to 10 seconds before a conscious decision was taken. If the brain activity precedes the feeling of choice, some have argued, all choosing is just an illusion.
These results aren’t the great challenge to free will that they might seem at first. Their apparent force relies on misguided intuitions about what it means to have free will. We tend to think in terms of the self versus other causes. And we assume that the more of these other causes that are involved in the decision-making process, the less self-determination, or free will, is involved. The misconception arises because we have difficulty comprehending causation in complex systems. We tend to think about cause and effect as a one-to-one relationship: A causes B. In reality, it is always a set of things happening (or not happening) that cause another set of things to happen (or not happen). Discovering that A was involved in causing B doesn’t mean that other factors aren’t important too.
“Simple rules can generate an endless, unpredictable set of behaviours”
Causality encompasses everything from your genes to your ideas about the future. As we find out new facts about genes and brains, the space in which your self exists – your free will, responsibility and choices – doesn’t diminish. This is something I have been pondering for years. What really brought it home to me was interacting with a complex, chaotic system called a cellular automaton, and seeing that the simplest of rules can generate an endless, unpredictable set of behaviours. This is a grid world created on a computer with basic rules for changing each tile in the grid from black to white and vice versa. With the right rules and the right starting conditions, it can generate an infinite number of unpredictable patterns. Seeing, from so simple a beginning, endless forms being born, made me realise that the fear we are sphexish is baseless. There is no need to worry that something as complex as a human can be caught in a meaningless loop.
It was to explore these ideas and more, that I created The Choice Engine. You can find this interactive essay by tweeting @ChoiceEngine START, and the bot will guide you, letting you choose your own unique path through the story, following the areas that most interest you. In it, I argue that our intuitions mean that the problem of free will never feels solved, but it is. The solution is that we are part of nature – we are complex machines. If you change your intuitions about what such a machine can do, and what those actions can mean, then you realise that we are free to make real meaningful choices. Yes, our thoughts are caused by our brains, our environment and our history, but this causal mix is unique to each individual at each moment. That explains why human behaviour is so difficult to predict.
My career researching the brain and how we choose has made me optimistic that we do have free will. Darwin’s theory of evolution gave us a fear of being mere creatures. I simply disagree with the word “mere”. There is enough tangled complexity in relation to the brain and mind that we can retain a meaningful view of free will and at the same time recognise our nature as living machines.
Article amended on 9 April 2019
We clarified the use of the word “sphexish”
