The clockwork universe: is free will an illusion?

Towards the end of a conversation about some of the deepest puzzles of human existence, the philosopher Galen Strawson paused, then asked me: “Have you spoken to anyone else yet who’s received weird emails?” He began reading from messages he and several other scholars had received in recent years. Some were plaintive, others abusive, but all were fiercely accusatory. “Last year you all played a part in destroying my life,” one person wrote. “I lost everything because of you – my son, my partner, my job, my home, my mental health. All because of you, you told me I had no control, how I was not responsible for anything I do, how my beautiful six-year-old son was not responsible for what he did… Goodbye, and good luck with the rest of your cancerous, evil, pathetic existence.” “Rot in your own shit Galen,” read another note, sent in early 2015. And then, days later: “I’m coming for you.” “This was one where we had to involve the police,” Strawson said.

Strawson, like others receiving this abuse, had merely expressed a position in an ancient debate that strikes many as the ultimate in “armchair philosophy”, wholly detached from the entanglements of real life. They all deny that human beings possess free will. They argue that our choices are determined by forces beyond our ultimate control – perhaps even predetermined all the way back to the Big Bang – and so nobody is ever wholly responsible for their actions. Reading over the emails, Strawson found himself empathising with his harassers’ distress. “I think for these people it’s just an existential catastrophe,” he said. “And I think I can see why.”

The feeling that we are the authors of our choices is so basic to everyone’s existence that it can be hard to get any mental distance on it. Suppose you find yourself feeling moderately hungry one afternoon, so you walk to the fruit bowl in your kitchen, where you see one apple and one banana. As it happens, you choose the banana. But it seems obvious that you were free to choose the apple – or neither, or both – instead. That’s free will: were you to rewind the tape of world history, to the instant just before you made your decision, with everything in the universe exactly the same, you’d have been able to make a different one.

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And yet according to a growing chorus of philosophers and scientists, for a variety of different reasons, it also can’t possibly be the case. “This sort of free will is ruled out, simply and decisively, by the laws of physics,” says one of the most strident of the free will sceptics, the evolutionary biologist Jerry Coyne. Psychologists such as Steven Pinker and Paul Bloom agree, as apparently did the late Stephen Hawking. According to the historian Yuval Noah Harari, free will is an anachronistic myth – useful in the past, perhaps, as a way of motivating people, but rendered obsolete by the power of modern science.

Arguments against free will go back millennia, but the latest wave of scepticism has been driven by advances in neuroscience. Now that it’s possible to observe – thanks to neuroimaging – the brain activity associated with our decisions, it’s easier to think of those decisions as just another part of the mechanics of the material universe. From the 1980s, various specific neuroscientific findings have offered troubling clues that our so-called free choices might actually originate in our brains several milliseconds, or even much longer, before we’re first aware of even thinking of them.

The stakes could hardly be higher. Were free will to be shown to be non-existent – and were we truly to absorb the fact – it would “precipitate a culture war far more belligerent than the one that has been waged on the subject of evolution”, wrote Sam Harris, author of the 2012 bestseller Free Will. Arguably, we would be forced to conclude that it was unreasonable ever to praise or blame anyone for their actions, since they weren’t truly responsible for deciding to do them; or to feel guilt for one’s misdeeds, pride in one’s accomplishments, or gratitude for others’ kindness. And we might come to feel that it was unjustifiable to mete out punishment to criminals, since they had no ultimate choice about their wrongdoing. Some worry that it might fatally corrode all human relations, since romantic love, friendship and neighbourly civility alike all depend on the assumption of choice: any loving or respectful gesture has to be voluntary to count.

Peer over the precipice of the free will debate for a while, and you begin to appreciate how a psychologically vulnerable person might be nudged into a breakdown, like Strawson’s email correspondents. Saul Smilansky, a professor of philosophy at the University of Haifa in Israel, who believes the popular notion of free will is a mistake, told me that if a graduate student who was prone to depression sought to study the subject with him, he would try to dissuade them. Smilansky is an advocate of what he calls “illusionism”, the idea that free will as conventionally defined is unreal, but that it’s crucial people go on believing otherwise. “On the deepest level, if people really understood what’s going on – and I don’t think I’ve fully internalised the implications myself, even after all these years – it’s just too frightening and difficult,” Smilansky said.

The logic of the argument that nobody ever truly chooses freely to do anything, once glimpsed, seems coldly inexorable. Start with what seems like an obvious truth: anything that happens in the world, ever, must have been completely caused by things that happened before it. And those things must have been caused by things that happened before them – and so on, backwards to the dawn of time: cause after cause after cause, all of them following the predictable laws of nature, even if we haven’t figured all of those laws out yet. It’s easy enough to grasp this in the context of the physical world of rocks and rivers and internal combustion engines. But surely “one thing leads to another” in the world of decisions and intentions, too. Our decisions involve neural activity – and why would a neuron be exempt from the laws of physics any more than a rock?

It was the French polymath Pierre-Simon Laplace, in 1814, who most succinctly expressed the puzzle: how can there be free will, in a universe where events just crank forwards like clockwork? His thought experiment, known as Laplace’s demon, and his argument went as follows: if some hypothetical ultra-intelligent being – or demon – could know the position of every atom in the universe at a single moment, along with all the laws that governed their interactions, it could predict the future in its entirety. There would be nothing it couldn’t know about the world 100 or 1,000 years hence, down to the slightest quiver of a sparrow’s wing. You might think you made a free choice to marry your partner, or choose a salad; but in fact Laplace’s demon would have known it all along, by extrapolating out along the endless chain of causes. “For such an intellect,” Laplace said, “nothing could be uncertain, and the future, just like the past, would be present before its eyes.”

By far the most unsettling implication of the case against free will is what it seems to say about morality. Consider the case of Charles Whitman. After midnight on 1 August 1966, Whitman – an outgoing and apparently stable 25-year-old former US marine – drove to his mother’s apartment in Austin, Texas, where he stabbed her to death. He returned home, where he killed his wife in the same manner. Later that day, he went to the top of a high building on the campus of the University of Texas, where he began shooting randomly for about an hour and a half. By the time Whitman was killed by police, 12 more people were dead.

Within hours, the authorities discovered a note that he had typed the night before. “I don’t quite understand what compels me to type this letter,” he wrote. “Perhaps it is to leave some vague reason for the actions I have recently performed. I don’t really understand myself these days. I am supposed to be an average reasonable and intelligent young man. However, lately I have been a victim of many unusual and irrational thoughts, and it requires a tremendous mental effort to concentrate on useful and progressive tasks… After my death I wish that an autopsy would be performed to see if there is any visible physical disorder.” After the first two murders, he added, “Maybe research can prevent further tragedies of this type.” An autopsy revealed the presence of a substantial brain tumour, pressing on Whitman’s amygdala, the part of the brain governing “fight or flight” responses to fear.

Almost everyone, on hearing about the tumour, undergoes some shift in their attitude towards him. It doesn’t make the killings any less horrific. But it does make his rampage start to seem less like the evil actions of an evil man, and more like the terrible symptom of a disorder. If you find the presence of a brain tumour in any way exculpatory, though, you face a difficult question: what’s so special about a brain tumour, as opposed to all the other ways in which people’s brains cause them to do things? When you learn about what was unfolding inside Charles Whitman’s skull, it has the effect of seeming to make him less personally responsible for the terrible acts he committed. But by definition, anyone who commits any immoral act has a brain in which a chain of prior causes had unfolded, leading to the act.

It’s tempting to try to wriggle out by protesting that, while people might not choose their worst impulses – for murder, say – they do have the choice not to succumb to them. You can feel the urge to kill someone but resist it, or even seek psychiatric help. You can take responsibility for the state of your personality. But this is not the escape clause it might seem. After all, the free will sceptics insist, if you manage to change your personality in some admirable way, you must already have possessed the kind of personality capable of implementing such a change – and you didn’t choose that. In the end, as Strawson puts it, “luck swallows everything”.

Given how watertight the case against free will can appear, it may be surprising to learn that most philosophers reject it: according to a 2009 survey by the website PhilPapers, only about 12% of them are persuaded by it. What’s still harder to wrap one’s mind around is that most of those who defend free will don’t reject the sceptics’ most dizzying assertion – that every choice you ever make might have been determined in advance. Rather, they claim that this doesn’t matter: that even though our choices may be determined, it makes sense to say we’re free to choose. They’re known as “compatibilists”, because they think determinism and free will are compatible: “being free” is not a kind of magic, it’s a mundane skill, a matter of having the capacity to think about what you want, reflect on your desires, then act on them. When you choose the banana in the normal way, you’re clearly in a different situation from someone who picks the banana because a fruit-obsessed gunman is holding a pistol to their head; or someone afflicted by a banana addiction. (There are many other positions in the debate, including some philosophers, many Christians among them, who think we really do have “ghostly” free will.)

It’s tempting to dismiss the free will controversy as irrelevant to real life, on the grounds that we can’t help but feel as though we have free will, whatever the philosophical truth. I will keep responding to others as though they had free will. And I personally can’t claim to find the case against free will ultimately persuasive: it’s just at odds with too much that seems obviously true. Yet even if only entertained as a hypothetical possibility, free will scepticism is an antidote to that bleak individualism which holds that a person’s accomplishments truly belong to them alone – and that you’ve therefore only yourself to blame if you fail. It’s a reminder that accidents of birth might dictate our talents and our weaknesses, our capacity for joy, and our ability to overcome tendencies toward violence, laziness or despair, and the paths we end up travelling. There is a deep sense of human fellowship in this picture of reality – in the idea that, in our utter exposure to forces beyond our control, we might all be in the same boat, clinging on for our lives, adrift on the storm-tossed ocean of luck.

A longer version of this article by Oliver Burkeman first appeared in The Guardian © 2021 Guardian News and Media Limited