Skip to Content

Determined Shatters Illusion of Free Will and Human Behavior

Human behavior is often assumed to be the result of free will, the ability to choose and act according to our preferences and values. But what if free will is nothing but a myth, and our behavior is determined by a complex web of causes that we have no control over?

This is the provocative and fascinating argument that Robert Sapolsky, a renowned behavioral scientist, makes in his latest book, Determined: A Science of Life Without Free Will. In this book, Sapolsky explores the various scientific disciplines that reveal how our actions are influenced by factors ranging from genetics, neuroscience, psychology, sociology, and even quantum mechanics. He challenges us to rethink our notions of agency, responsibility, morality, and selfhood, and to embrace a more compassionate and realistic view of human nature.

If you are interested in learning more about the science and philosophy of free will and human behavior, and how they affect our personal and social lives, you should definitely read this book. In this article, I will provide a summary and review of Determined, highlighting its main points, strengths, and weaknesses. I will also share my personal opinion and rating of the book, and some suggestions for further reading. So, without further ado, let’s dive into the book!


Science, Philosophy, Psychology, Sociology, Neuroscience, Ethics, Biology, History, Culture, Education, Society

How Determined by Robert Sapolsky Shatters the Illusion of Free Will and Human Behavior

Determined is divided into four parts, each consisting of several chapters that cover different aspects of the free will debate. The first part, titled “The Final Seconds”, focuses on the neuroscience of decision-making, and how our brain activity precedes and predicts our conscious choices. Sapolsky reviews various experiments and studies that show how our actions are influenced by subconscious processes, such as priming, framing, heuristics, biases, emotions, and hormones. He also discusses the role of chaos theory and quantum mechanics in introducing randomness and uncertainty in our behavior, and whether they can save free will from determinism.

The second part, titled “The Final Minutes”, zooms out from the brain to the body, and examines how our physiology and anatomy shape our behavior. Sapolsky explains how our genes, epigenetics, hormones, immune system, microbiome, and even parasites can affect our personality, mood, preferences, and actions. He also explores how our behavior is influenced by our evolutionary history, and how we share many traits and tendencies with other animals, especially primates.

The third part, titled “The Final Hours”, shifts from the biological to the social, and analyzes how our behavior is influenced by our environment and culture. Sapolsky discusses how our behavior is affected by factors such as upbringing, education, religion, politics, economics, media, and technology. He also examines how our behavior is shaped by our interactions with other people, such as family, friends, peers, strangers, and enemies. He shows how our behavior is influenced by social norms, expectations, roles, identities, and stereotypes.

The fourth and final part, titled “The Final Years”, zooms out even further, and considers how our behavior is influenced by our history and future. Sapolsky explores how our behavior is influenced by our memories, experiences, traumas, and regrets. He also speculates how our behavior might change in the future, due to advances in science, technology, and artificial intelligence. He also reflects on the implications of determinism for our morality, responsibility, justice, and free will. He argues that we should adopt a more nuanced and flexible approach to these concepts, and that we should cultivate more empathy, forgiveness, and understanding for ourselves and others.


Determined is a remarkable book that offers a comprehensive and compelling case for the nonexistence of free will and the determinacy of human behavior. Sapolsky is a brilliant and engaging writer, who combines rigorous scientific evidence with witty anecdotes and humorous examples. He makes complex and abstract concepts accessible and relatable, and he anticipates and addresses possible objections and counterarguments. He also balances his skepticism and realism with optimism and compassion, and he does not shy away from the ethical and existential challenges that his thesis poses.

The book is not without its flaws, however. One possible criticism is that Sapolsky does not define or clarify what he means by free will, determinism, or human behavior, and he does not engage with the philosophical literature on these topics. He seems to assume a simplistic and strawman version of free will, which is incompatible with determinism and requires a ghostly self that transcends causation. He also seems to conflate determinism with fatalism, and he does not consider alternative or compatibilist views of free will, which can accommodate both determinism and moral responsibility. He also does not address the potential paradoxes or contradictions that his own view might entail, such as the question of why he wrote the book, or why we should read it, if everything is determined.

Another possible criticism is that Sapolsky does not provide a clear or consistent framework or methodology for integrating the various scientific disciplines that he surveys. He seems to jump from one field to another, without explaining how they relate or interact with each other. He also does not address the limitations or uncertainties of each discipline, or the possible gaps or conflicts between them. He also does not acknowledge the role of interpretation or perspective in science, or the possibility of alternative or complementary explanations for the same phenomena. He also does not consider the ethical or social implications of some of the scientific findings or applications that he discusses, such as genetic engineering, brain manipulation, or artificial intelligence.

Despite these shortcomings, Determined is a stimulating and provocative book that challenges us to rethink our assumptions and beliefs about free will and human behavior. It is a book that will make you think, question, and wonder, and it will also make you laugh, cry, and empathize. It is a book that will inspire you to learn more about yourself and others, and to live with more awareness and compassion. It is a book that I highly recommend to anyone who is interested in the science and philosophy of free will and human behavior. I give it a rating of 4.5 out of 5 stars.

Introduction: A radical rebuttal of free will

If you’re like most people, you’ve been conditioned to believe that you are ultimately responsible for your own actions – in other words, that you have free will. But what if that weren’t the case?

This summary to Robert M. Sapolsky’s Determined lays out some of the key arguments contending that all human behavior and decision-making is ultimately predetermined by complex biological and environmental factors outside our control.

You’ll learn how genetics, childhood experiences, cultural conditioning, and more shape the very way your mind operates and responds to stimuli. Be prepared to reexamine your assumptions about choice, accountability, punishment, and the extent to which you author your own life.

Your life is determined by biological and cultural factors beyond your control

If you’re anything like most people, you probably wouldn’t be too happy to hear that every decision you’ve made and action you’ve taken, from choosing a life partner to sneaking the last doughnut, has absolutely nothing to do with your own free will and absolutely everything to do with a complex set of biological and cultural cues which are completely outside your control.

So, let’s start on a lighter note, shall we?

Sometime around the turn of the twentieth century, the famous philosopher and psychologist William James was giving a lecture on the nature of the universe. One attendee, an elderly woman, approached him after the lecture to tell him he’d gravely misunderstood the whole thing. The world, she informed him, was balanced on the back of a giant turtle. Bemused, James asked what the turtle was balancing on. “Another turtle,” responded the woman. Well, what was that turtle balancing on? Exasperated, the woman replied, “Don’t you see? It’s turtles all the way down!”

It sounds preposterous, right? And yet there’s a logic to it. Because, preposterous as it is to believe that the world is balancing on a sequence of turtles, it’s even more preposterous to believe that at some point that sequence of turtles just stops, leaving one turtle floating in mid-air. If you accept that the world is balanced on a giant turtle, you also need to accept that those turtles continue downward forever.

So, back to our central argument that everything, including all human action, is governed by factors outside of our individual control – an argument which in a scientific context is referred to as determinism.

Basically, when you behave a certain way, it’s because your brain generates that behavior. And why, you might then ask, does your brain generate that specific behavior and not a different one? Well, it’s because the neurons in your brain acted a certain way seconds before the behavior in question. Which they did so because of a thought, emotion, or stimulus stored in your brain.

Which was stored to begin with, because of the way your hormones shaped that stimulus, along with how sensitive your brain should become to it. Which they did so because of formative experiences at times when your brain was in different phases of development, like adolescence, childhood, and even in utero. All of which, in part, are a result of your genetic inheritance and to the cultural influences of the society you were born into, which is itself shaped by the ecological and evolutionary pressures that created culture in the first place…

In other words, it’s turtles all the way down.

You might think it’s silly to say that the world balances on the back of a series of turtles which extend infinitely downward. But it’s even sillier to suggest that, at some point, the turtles just stop and some other support system randomly comes into play.

Think about it – you probably accept some iterations of deterministic theory. For example, you probably accept that things like learning disabilities and clinical depression occur because of a mixture of brain function and genetic predisposition. You probably accept that no one chooses whether they’re left-handed or right-handed. You probably accept that people who are abused and neglected as children may grow up to be abusive and neglectful themselves.

Essentially, there are scenarios in which you’re prepared to concede that free will doesn’t come into play. How can you – or more accurately “we,” as the belief in the existence of free will is close to universal across all groups and cultures – accept that some behavior is biologically determined, but not accept that all behavior is biologically determined?

The next few sections will argue that free will doesn’t really, in any meaningful sense, exist; what’s more, they’ll show why accepting this proposition might actually be a good thing.

Your decisions are formed unconsciously

You’re in a car approaching a red traffic light.

You’re holding a gun and aiming it at a target.

You’re walking past a bar advertising two-for-one cocktails.

In the moment, don’t you have the power to decide whether or not you’re going to run the red light, pull the trigger, or order two daiquiris? Don’t you have intent?

According to a neuroscientist called Benjamin Libet, no. You don’t.

In the 1980s, Libet ran a series of studies. Participants were placed in a room with a clock that displayed the time down to fractions of seconds, and were asked to make a choice – let’s say between pressing button A and button B. They were told to note the exact time on the clock when they decided to make this choice. The results of participants’ electroencephalograms, which monitor neuronal excitation, revealed that their neurons were commanding their hands to press their button of choice roughly two hundred milliseconds before the moment the participants believed they decided to press the button.

This phenomenon, in which your neurons start gearing up for action before you’ve consciously decided to act, is known as readiness potential. Libet’s findings have been replicated many times and in many ways – basically, the moment you decide to do something is the moment after your brain has decided it for you. According to Libet and his acolytes, when you decide to take advantage of a happy hour special you’re not acting of your own free will; you’re carrying out an intent that has already been set in your unconscious mind.

That doesn’t leave us totally powerless, though. Libet also found that while we don’t have free will, we have something a little bit like it: free won’t. In the 200-millisecond space of time between your unconscious forming your intent and your conscious acting on it, you can exercise your veto power – whether you’re about to jump off the high-dive board or tell your boss what you really think.

Displaying readiness potential doesn’t mean you’ve made an irreversible decision until you reach the point of no return, when your neurons tell your muscles to leap into action. You might not be able to freely choose the course of action you take. But in some circumstances, you’re capable of inhibiting it.

There’s a more pressing issue to address here, though: the question of why you formed the intent that you did. Arguments about the milliseconds between an intent forming and an intent being acted on seem trivial when we zoom out and look at how that intent was formed in the first place – which is exactly what we’ll be doing next.

Decisions have decades of cognitive and cultural conditioning behind them

All your decisions – even the split-second, spontaneous, spur-of-the-moment ones – are the product of a lifetime’s worth of cognitive and cultural conditioning.

Let’s consider a 40-year-old cop who has seconds to decide whether or not to shoot a suspect. You might think this is a simple case of free will at work – the cop assesses the suspect, then decides whether to shoot or not. But that’s not really all there is to it.

In the seconds or minutes before the cop makes their decision, they assess certain factors. Let’s say the suspect is holding an object – it might be a gun, it might be a smartphone. Other factors, like race and gender, have been shown to influence how ready that cop is to perceive the object as a gun and make the decision to shoot.

What’s more, studies have shown that our prejudices can be exacerbated by “sensory disgust” – for example, people sitting in a foul-smelling room were more likely to express disapproval of gay marriage. Hunger makes you less forgiving. Having a high level of testosterone in your system heightens your sensitivity to perceived threats. Is the cop really acting out of free will if their decision is influenced by factors including how recently they ate a sandwich?

Let’s go further back in time. Ever heard of neuroplasticity? It’s the very cool way in which our brain rewires, changes, and adapts. When a man becomes a father, for instance, his testosterone levels drop and he becomes more nurturing. And did you know that if someone is blindfolded for a week, their auditory capacities start colonizing their dormant visual cortex and sharpen their hearing? Amazing, right?

But the brain’s plasticity also means that experiences you don’t choose – like trauma or neglect – can permanently alter the pathways in your brain. Chronic stress enlarges your adrenal glands. When contemplating a split-second decision, your brain brings everything that has shaped, expanded, or curbed its functioning to the table.

Your frontal cortex is where your complex decision-making abilities and executive function reside. This section of the brain is formed in adolescence, making it the region of the brain that is least shaped by genes and most shaped by environmental factors. So the distress, pain, love, and stimulation you experienced at 13 still shape the way you approach hard decisions when you’re 93.

Our capacities for reasoning, cognition, empathy, and impulse control are largely formed in childhood. The way these capacities form are influenced by factors including but not limited to how loving, permissive, authoritative, or negligent your parents were; the interactions you had with your peers; the type of neighborhood you lived in; and even the weather. That’s right – kids who grow up in mild-weathered locations are generally more open-minded and outgoing than those who grow up in extreme weather conditions, where stepping outside comes with the threat of hypothermia or heatstroke.

You certainly don’t choose whose womb you gestate in. But the levels of alcohol, drugs, and stress in your mother’s system all impact your brain chemistry. You don’t choose your genes. But if you posses a variant of the gene that breaks down serotonin, and if this gene is activated by environmental factors like childhood abuse, then you’re genetically predisposed to exhibiting antisocial behavior – and that’s just one of hundreds of examples of how the interplay between your genetic makeup and environment can define your actions. You also don’t choose your ancestry. But if you’re East Asian, your dopamine reward system will activate when you look at a calm face rather than a smiling one; if you have European roots, the reverse will be true.

So, back to our cop. Do they have a second to decide whether they squeeze the trigger? Or has this decision been 40-plus years in the making?

Does accountability exist without free will?

The idea that we have free will underpins the entire fabric of society. Our systems of law, governance, education, and more are all propped up by the notion that, at the end of the day, we have control over our actions.

If we accept that free will is, indeed, a fiction, and that the basis of all our actions is the culmination of our biological luck, where does that leave us? If we abandon the idea of agency, should we still take accountability for our actions? If we accept that we can’t control our behavior, should we be punished for decisions that are harmful or violent?

Let’s go back in time, to the Middle Ages. These days, we know that genetic epilepsy is caused when the body’s nerve cells function abnormally – essentially, when they’re unable to “cool off” after a period of high-intensity activity. The result? Convulsive seizures. But back then, no one knew that epilepsy was caused by a predetermined genetic mutation.

When an epileptic infant experienced seizures, people believed this was a result of witchcraft. And there was often a rush to hold someone – usually the nearest spinster – accountable. Women were hanged and burned because the medieval worldview simply couldn’t conceive that sometimes, in a way that’s totally outside of everyone’s control, children are born with predetermined neurological disorders.

Now that we understand how seizures work, let’s try a thought experiment. Someone who’s never experienced a seizure before – who’s never even been identified as at-risk for seizures – is driving down a road. As they come to a crosswalk, they suffer a grand mal seizure, losing consciousness and bodily control. They fatally hit a pedestrian. Should they be charged with murder? Probably not; we can accept this is a tragic accident.

OK, now try this: exactly the same thing happens, but this time the driver does have a history of seizures, and they’ve chosen to drive without taking their anti-seizure medication. Is this still a tragic accident, or have we entered a moral gray area?

You may be tempted to hold that person accountable. But think about what we’ve covered in the last few sections – myriad factors force that “choice” not to medicate, from the functioning of the frontal cortex to hormone levels in the body. Consider the idea that this person is no more personally responsible for the death of a pedestrian than the medieval witch is personally responsible for an infant’s epileptic seizure.

Right now, you might be thinking something like, If we accept that personal accountability kind of doesn’t exist, does that mean everyone can start mowing down pedestrians with impunity? Fair question. But what if we reframed how we conceived not only crime, but punishment? The unmedicated driver from the last example certainly, though through no fault of their own, poses a danger to others. Similarly, bears, through no fault of their own, tend to eat people.

No one proposes we share our city streets with bears. And in the same vein, there are models of justice – restorative justice is one – that work to remove people from society for as long as they remain dangerous, without punishing them for actions they have no control over. Accepting that free will doesn’t exist will hopefully allow society to move toward these more humane systems of justice.

Still feeling skeptical?

It’s true that our conventional understanding of behavior is underpinned by a fundamental belief in responsibility, accountability, and free will. But we can still understand aspects of behavior after we’ve removed those things from the equation.

We used to believe that left-handed people were evil or unlucky.

We used to believe that dyslexics were lazy.

We used to believe that veterans with PTSD were malingerers.

We used to believe that the parents of autistic children didn’t love them enough.

In each of these instances, we’ve seen how cruel and arbitrary it is to punish someone for conditions they have no control over. Time after time, we’ve moved toward a more humane and accepting view of human behavior. We can make that shift again.


Determined (2023) argues that free will is an illusion – all human behavior stems from biological and cultural factors we don’t control. Through scientific research and case studies, it lays out the argument in favor of determinism, and aims to persuade why rejecting the notion of free will might be a positive step.

About the Author

Robert M. Sapolsky

Nina Norman is a certified book reviewer and editor with over 10 years of experience in the publishing industry. She has reviewed hundreds of books for reputable magazines and websites, such as The New York Times, The Guardian, and Goodreads. Nina has a master’s degree in comparative literature from Harvard University and a PhD in literary criticism from Oxford University. She is also the author of several acclaimed books on literary theory and analysis, such as The Art of Reading and How to Write a Book Review. Nina lives in London, England with her husband and two children. You can contact her at [email protected] or follow her on Website | Twitter | Facebook

    Ads Blocker Image Powered by Code Help Pro

    Your Support Matters...

    We run an independent site that is committed to delivering valuable content, but it comes with its challenges. Many of our readers use ad blockers, causing our advertising revenue to decline. Unlike some websites, we have not implemented paywalls to restrict access. Your support can make a significant difference. If you find this website useful and choose to support us, it would greatly secure our future. We appreciate your help. If you are currently using an ad blocker, please consider disabling it for our site. Thank you for your understanding and support.