On the first day of his trial, Anders Breivik admitted to planting a bomb that killed eight people outside the Norwegian prime minister’s office in Oslo on July 22, 2011, then shooting dead sixty-nine people, most of them teenagers, hours later at a summer camp on Utoya Island. Given there is no question of guilt, the principal responsibility of the Oslo court trying Breivik’s case, which will rule on August 24, is to establish whether he was sane at the time of the attacks. Two psychiatric examinations have so far produced conflicting diagnoses. The initial examination in November last year found that Breivik was, during and after the attacks, a psychotic paranoid schizophrenic and criminally insane. A subsequent psychiatric report concluded that Breivik suffers from a narcissistic personality disorder but is sane.

Breivik’s mental state during the attacks is of interest to the court because it is central to establishing criminal responsibility. The court began with the premise that it is possible for a person to be responsible for murder, and that sanity and responsibility are synonymous. It has assumed that, as long as Breivik was of sound mind during the attacks, he exercised control over his actions (that is to say, he had a choice between good and evil, and he chose evil). The ability of humans to act with such free will—uncritically accepted in modern legal systems—is the subject of extensive debate among philosophers and scientists in other contexts. If doubters of free will are correct, the foundation of Breivik’s trial—that if he is sane he is responsible—is false.

What ultimately turns on the court’s determination in regard to sanity is whether Breivik is made to suffer for his crimes.

Criminal punishment is based on three standard justifications: community protection from dangerous individuals, deterrence of future crimes, and retribution for past crimes. Without knowledge of whether he is technically sane, it is obvious that Breivik, who has told the court that he would carry out the attacks again if given the chance, must be separated from society. As with community protection, sanity is similarly not central to deterrence. Whether Breivik spends his long detention in Oslo’s Ila prison, or in a psychiatric ward that will be specially built for him inside the prison in the event that he is found to be insane, the court will have reinforced the deterrent to mass murder. The main difference is that, if found to be sane, Breivik will be held criminally responsible for his actions and punished accordingly. The Norwegian justice system prides itself on its orientation toward treatment and rehabilitation rather than revenge. Yet even under Norway’s comparatively humane system, Breivik can be jailed, that is to say incarcerated in a punishment setting, for up to twenty-one years.

Obtaining revenge for heinous crimes appeals to our moral intuitions; if someone intentionally harms others, he or she should suffer the consequences. Revenge has been an understandably present theme in Norway in the aftermath of Breivik’s killing spree. On the opening day of the trial, the daily newspaper Dagsavisen carried the headline, “The Hour of Reckoning,” surrounded by the name of every person killed on Utoya. VG, Norway’s most-read paper, quoted a survivor who said, “I’m looking forward to him receiving his punishment.”

Our conviction that punishment is just in the face of crimes like Breivik’s is so strong that it obscures a built-in assumption. We take for granted that humans possess free will, and that each individual is therefore at liberty to act as he or she chooses. Our assumption is rooted in the powerful feeling of free will we experience: if I want to raise my hand right now, I will. Free will does not, however, flow from a materialistic (non-supernatural) understanding of the world. Without resorting to the supernatural, it is difficult to make a case for the existence of free will, at least for the type that would imply moral responsibility.

Three main schools of thought have emerged from the long-running debate on free will. Determinism holds that every state of affairs, including every human act, is the inevitable consequence of antecedent states. If we could comprehensively describe point A in the past (the precise location and momentum of every atom in the universe), then holding fixed the laws of nature, we could predict the (only possible) future at point B. Because determinists see human behavior as fully determined by the laws of nature in this way, they reject the notion of free will.

Determinism is in accord with the understanding of human behavior given to us by cognitive neuroscience. Behavior is a product of the brain, the structure and function of which are determined by factors outside our control—our genes and our environment. (Our environment is, of course, influenced by our choices, but our choices are themselves fully determined.) One way to think about determinism, offered by Sam Harris in his latest book Free Will, is the following: had you been born with Anders Breivik’s genes, grown up in the same environment, been dealt the same life experiences and woken up on that July 22 morning with an identical brain, you would have committed his crimes (after all, you would have been him).

Recent experiments in neuroscience support the conclusion that physical states of the brain, operating under the known laws of science, determine our behavior. In one pioneering experiment, the physiologist Benjamin Libet used electroencephalography (EEG) to measure the time lag between brain activity and the emergence of a conscious intention to make a physical movement. Volunteers wearing scalp electrodes were asked to carry out a simple motor activity such as flexing a finger. Libet found that significant activity in the brain’s motor cortex could be detected 300 milliseconds before the volunteer registered the intention to make a movement. This has been interpreted as evidence that the brain makes the decision to move before we become conscious of our intention to move.

If we look at Anders Breivik as determinists, he appears a victim of his undesirable brain. In Free Will, Harris uses a thought experiment to demonstrate that this is exactly how we should regard murderers. He asks the reader to consider a twenty-five-year-old man raised by wonderful parents who shot dead a young woman “just for the fun of it.” He then asks the reader to imagine that a scan of the man’s brain finds a golf ball-sized tumor in his medial prefrontal cortex (a region important for the control of emotion and behavioral impulses). When we learn of the tumor, Harris points out, we automatically feel differently about the man. The fact that his brain was affected by a tumor seems to strip him of at least some responsibility for his actions. But, had the man not suffered from a tumor, his behavior would still have been every bit as much the product of the physical composition of his brain, which he did not himself design.

A second approach to the analysis of free will is libertarianism. Libertarians typically believe that there is a physical part of the human brain that operates independently of the natural laws of physics (a religious person might call it a soul), and that this non-determined part of the mind endows humans with free will. The dubiousness of this idea was deftly captured in a Dilbert cartoon, in which Dogbert (Dilbert’s dog) asks his owner:

“Do you think the chemistry of the brain controls what people do?”

“Of course,” Dilbert answers.

“Then how can we blame people for their actions?” counters Dogbert.

“Because people have free will to do as they choose.”

“Are you saying that ‘free will’ is not part of the brain?” inquires a perplexed Dogbert.

“Of course it is,” replies Dilbert. “But it’s the part of the brain that’s out there just being kind of free.”

Dogbert is confused: “Do you think the ‘free will’ part of the brain is attached, or does it just float nearby?”

This line of thinking is hardly restricted to Dogbert. Stephen Hawking and Leonard Mlodinow are also puzzled by how it is possible for our behavior to be determined by the chemistry of our brains, while at the same time being subject to our autonomous control. They write in The Grand Design: “It is hard to imagine how free will can operate if our behavior is determined by physical law, so it seems that we are no more than biological machines and that free will is just an illusion.”

While there is no scientific evidence whatsoever to support the existence of a mysterious section of the brain that operates outside the laws of physics, humans are naturally libertarians. It comes instinctively to us to see our minds as an entity somehow separate from our brains. It would be considered perfectly reasonable to suggest in conversation, for instance, that Anders Breivik should have resisted his impulse to kill, as if there were a little man in his head who could have directed his brain to choose right over wrong.

Quantum physics might at first appear to give reprieve to libertarianism. Quantum chance, some libertarians have argued, provides the scientific basis for a non-determined mind. However, it is thought that quantum events don’t significantly interfere with traditional mental faculties, which are determined by material states of the brain. And even if they did interfere, quantum indeterminacy wouldn’t amount to the kind of free will libertarians purport. Were our decisions subject to quantum chance, it would not feel as though we had free will. Rather, it would feel as though every decision were made by a roll of the dice. As Harris puts it, “every thought and action would seem to merit the statement ‘I don’t know what came over me.’”

Compatibilism, the approach by which many philosophers, including Daniel Dennett, argue for the existence of free will, doesn’t offend scientific principles as libertarianism does, but it also doesn’t offer an argument to justify the assumption that a person can be morally responsible. Compatibilism derives its name from its assertion that a deterministic world and free will are, in contrast to what determinists would say, compatible. This is possible, compatibilists contend, because as long as we act according to our uncompelled preferences, we are effectively exercising free will.

The problem with this conception of free will is that we have no control over our own preferences. A compatibilist would argue that my choice to have a ham sandwich rather than egg salad for lunch today—so long as my decision was not made at gunpoint or under some other kind of intimidation—demonstrates my free will. But did I have the capacity to change my preference such that my hunger pangs were better satisfied with ham? Was Breivik exercising free will because it was his preference to go on a shooting spree, even if he played no part in the formation of this preference?

We assume that we exert differing levels of control over different types of preferences. Some preferences (whether or not you like seafood), are just part of who we are. There are preferences that we used to be sure were self-chosen but which we now know are not (for instance, it’s now taboo to even suggest that sexual orientation is chosen). We’re still inclined, on the other hand, to see rapists and murderers as somehow accountable for their impulses (or their failure to resist them). Unless we subscribe to the idea of a libertarian mind separate from the brain, it is clear on closer thought that all of our preferences are determined by forces outside our control. Compatibilists can argue that being forced to do what you want is a kind of free will, but it isn’t the kind of free will that implies moral responsibility.

Joshua Greene and Jonathan Cohen, psychologists who have written an influential paper on the implications of neuroscience for the law, illustrate our powerlessness over our intentions using a thought experiment they call the “Boys from Brazil problem.” Imagine that Nazi fugitives living in South America after the war decide to bring Adolf Hitler back to life by raising a genetically identical child. Using some salvaged DNA, they create an individual genetically identical to Hitler. The Nazis plan the life of the newborn clone so as to recreate exactly Hitler’s life experiences. For example, Hitler’s father died when he was a child, so the clone’s surrogate father is killed at precisely the same age. Suppose then that, as an adult, the clone, who Greene and Cohen give the name Mr. Puppet, engages in violent criminal activity of some sort. He is caught and brought to trial. Should Mr. Puppet be held responsible? The fact that he was designed by the Nazis to be violent must divest him of at least some responsibility for his violent acts. In this case, where there are identifiable designers, this is obvious. But how different is Mr. Puppet really from me or you or Anders Breivik? We are all the product of forces outside our control. As Greene and Cohen identify, whether these forces are deliberate (like the Nazi scientists) or natural is not relevant to the question of moral responsibility.

Greene and Cohen predict that new conceptions of responsibility (or lack thereof) will have implications for the law. As neuroscience increasingly illuminates what they call the “black box of the mind,” revealing the mechanical processes behind human behavior, “more and more people will develop moral intuitions that are at odds with our current social practices.” In a world organized according to our new moral intuitions, we would still have compulsory detention for criminals. As Stanford neuroscientist Robert Sapolsky puts it: “Whereas you do not ponder whether to forgive a car that, because of problems with its brakes, has injured someone, you nevertheless protect society from it.” But criminal “punishment” would be limited to its forward-looking aims of community protection and deterrence—those aims that seek to maximize the total welfare of society. Retribution, which relies on a libertarian conception of free will, will be a thing of the past.

Once we view Anders Breivik as a Mr. Puppet, the premise of his trial—that he can by virtue of his mental state be judged responsible or not—is revealed to be a false dichotomy. Sane or not, it was his brain that made him do it. For the moment, the use of neuroscience in criminal law is limited to the functions of establishing guilt and supporting claims of mitigating circumstances. It remains to be seen whether advances in neuroscience will lead to a shift in thinking about free will and moral responsibility that is reflected in the law.

In the meantime, the Breivik trial demonstrates that, even in the world’s most humane system of justice, the debate on free will is in practice ignored entirely. The conclusion we might draw from this is as frightening as it is far-reaching: if Breivik’s actions on that fateful Friday were completely beyond any free will, then punishing him (as distinct from restraining him from further harm to the community) may be as immoral as our perception of Breivik’s criminal acts themselves.