Here's why you don’t have free will, according to a top neuroscientist

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Did you really choose to read this article? Or was the decision just the product of neurons firing in your brain, caused by biochemical reactions, governed by the laws of physics?

 

Whether or not humans truly have agency over our decisions seems like a foolish question to ask. Experience tells us that we have the ability to choose to do – or not to do – just about anything presented to us at a given moment.

 

Even reading this article may seem like a bizarre action if we’re little more than meat puppets, wandering autonomously from one moment to the next.

 

But Robert Sapolsky says otherwise – that your sense of a being free agent is little more than an illusion conjured up by biology and how it interacts with your environment.

 

And Sapolsky is a man worth hearing out. He’s a professor of biology, neurology and neurosurgery at Stanford University and a recipient of the prestigious MacArthur Fellowship, often referred to as the ‘Genius Grant’. He is also the author of Determined: The Science of Life Without Free Will, an instant New York Times bestseller upon publication in late 2023.

 

Sapolsky sat down for a conversation with BBC Science Focus about all things free will; why we don’t have it and, perhaps more importantly, how we can still extract meaning from a life without it.

 

SF: So, starting with the basics, could you explain what we mean when we talk about free will?

 

RS: How most people define free will and how that gets them into the trouble of believing that it actually exists, is that they find themselves in some circumstance, and they get to make a decision.

 

Do I pick up this object with my left hand or my right hand? Do I pull the trigger and kill this person or let them live?

 

Decisions like that are situations where you form intent and do what you intend to do. At the same time, you’re reasonably aware of the consequences of an action and, most importantly, you know you have alternatives.

 

Acting on something and knowing you could have done otherwise is often necessary and sufficient to decide that free has just happened.

 

Where I come in pulling my hair out is that doing that misses the key question: how did you turn out to be the sort of person who would tend to do that at that moment? It’s like asking about what happened in a book having only read the final sentence of it. You’ve missed everything that has gone before.

 

Can you walk me through how I decided to put on a grey sweatshirt today, rather than a red one?

 

Most people are satisfied to ask just a few questions. What went on when you looked in your drawer and you had three sweatshirts to pick from? And what did you think at that moment when you decided to wear the one that you did?

 

That’s skipping 99 per cent of what’s going on. How did it turn out that you had a job that you needed to put on a sweatshirt for? How did it turn out that you’ve been successful enough to have more than one sweatshirt to choose from?

 

Essentially, how did you wind up being you at this moment?

 

It comes down to the fact that all we are is biology, over which we have no control, interacting with the environment, over which we have no control. There’s nothing else there.

Does a decision like that differ from an involuntary action like moving a hand away from a hot surface?

 

They are mechanistically the same, but moving your hand off a hot surface is less complex. There’s a biological phenomenon that has just gone on which is sensitive to interaction with the environment.

 

How fast you detect heat, how painful it is and how you move your hand away can be pulled off with about three and a half neurons in your spinal cord. For other decisions – such as what to wear – it’s the exact same circuitry just vastly more complicated.

 

When you look at how it works, that’s all it is. There’s no other place in there where you could posit that a neuron or a brain region or a person could do something completely independently of everything that came before.

 

What about quantum physics? Does that not introduce some independent randomness that could constitute free will?

 

Okay, this is where I often scream in agony. Quantum indeterminacy, to the extent at which I understand it as a simple-minded neuroscientist, says that at the itty bitty subatomic level stuff happens without prior cause. From there, people have been running with the idea that you can build free will.

 

But the quantum argument falls apart for three reasons.

 

First off, the level at which this stuff is happening is so many dozens of orders of magnitude below the level that would significantly influence the functioning of one neuron.

 

Secondly, suppose the effects do bubble up that far instead of getting lost in the biological noise. What you’ve just come up with is a means for generating random behaviour, not free will. If you believe that the randomness of subatomic particles is the basis of your moral compass and decision-making, then the mechanism for your moral compass and decision-making is random.

 

The third problem is the people who get fancy with a kind of high-wire act in which somehow we might have the means to harness the randomness in order to reach down from the macro level that makes us conscious and get those subatomic particles to all spin in the way that produces an outcome that was driven by your supposed free will.

 

It doesn’t work that way. The macro level can’t reach down and pull intent out of randomness, there’s no mechanism for it.

 

Does this mean that with enough information about a person’s genetics, upbringing and environment, we could predict how they would behave in any given scenario?

 

No. But the fact that you can’t does nothing to the argument that there’s no free will.

 

As soon as you start saying we live in a deterministic world and there’s no free will, people begin saying, ‘Oh, in other words, the entire future was already set two seconds after the Big Bang’.

 

The answer to that is: no, that would be a predeterministic mindset rather than a contemporary mindset of determinism. There are all sorts of things sewn into the fabric of the Universe that make it unpredictable.

 

At the level of chaoticism, at the level of nonlinear systems, at the level of non-additivity – those are things where no degree of looking at tinier and tinier things with better and better resolution can ever give you predictive power.

 

How does this fit into free will? The Universe throws random events at you and your behavioural outcome then occurs. Given that bit of randomness in the Universe at that point, you behave in a certain way because you turned out to be the sort of person whose neurons would respond in that way.

 

The future is not already determined, but how you will respond to that indeterministic future has already been determined by how you wound up being who you are in this instant.

 

Is it the complexity of this explanation of behaviour that makes it hard to agree with?

 

Absolutely, but it’s just a matter of framing.

 

If you give someone caffeine, for example, and see whether it has a significant influence on how fast they can solve a pressurised maths problem, then you’ve just shown one tiny piece where one lever is pulled to produce an effect.

 

In the biological machines that constitute us, you pile up 100 billion of these levers on top of each other. It’s like billions of levers of causality of the stuff that went before that brought you to this moment. We just don’t understand most of those levers at the moment.

 

Still, when you put all of the levers together in a kind of spider web, they form a steel arc that is just as deterministic as one on its own. It’s just harder to see where all of those came from.

 

How can we extract meaning from a life without free will? How do you do it?

 

Well, this is the ultimate question. What do we do with the fact that just we’re biological machines?

 

I love my wife desperately, and part of how that happened has to do with my upbringing, cultural values for what sort of face I find attractive and what olfactory receptor genes I have in my nose that make certain pheromones have such an effect. And everything in between that brought me to this point.

 

But that doesn’t take anything away from the feeling of love.

 

You know, if you see a gazelle on the Savannah and it has done the most amazing leap and your jaw drops, understanding exactly how the biomechanics of how a gazelle came to do that doesn’t take anything away from the fact that it’s still amazing to watch.

 

Love still feels like love. Pain is still painful. We’re these totally weird biological organisms that unlike any others on the planet have the ability to know that we’re biological organisms.

 

Where do we find meaning out of that? The only thing to fall back on is, yes, we’re biological machines, but nonetheless, we can be machines that in the face of incredible sunsets can say it’s all worth it. This is why we’re here; life is a gift; and I feel grateful for this.

 

The fact that there’s structure underneath the surface doesn’t rob the surface of what it’s capable of evoking in us.

 

This conversation has been edited for length and clarity.

About our expert

 

Robert Sapolsky is an American academic, neuroscientist, and primatologist. He is the John A. and Cynthia Fry Gunn Professor at Stanford University and is a professor of biology, neurology, and neurosurgery. Sapolsky is the author of several works of nonfiction, including A Primate's Memoir, The Trouble with Testosterone, Why Zebras Don't Get Ulcers and Determined: The Science of Life Without Free Will.

 

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