The Responsible Brain

Commentary on neuroscientist Michael Gazzaniga’s views on freedom and responsibility.

A neuroscientist's views of free will and determinism

Neuroscientist Michael Gazzaniga says “brains are determined; people are free.”  This means freedom and responsibility are compatible with being neurologically determined creatures.  But strangely enough, Gazzaniga also says we remain free and responsible even if the brain is compromised in its capacities for rationality and impulse control.  He therefore holds that the insanity defense is misguided.  On a neuro-deterministic account of free and responsible action, such a view is manifestly self-contradictory. 

In a commissioned paper and recent book,[1] Dartmouth neuroscientist Michael Gazzaniga joins the debate over moral responsibility generated by our burgeoning understanding of the brain. The problem seems to be that in order to hold people responsible, they have to have free will, but neuroscience shows our brains are deterministic mechanisms.  So how can we hold each other responsible?  The solution Gazzaniga proposes is that “brains are determined; people are free.” 

To the unwary, this might suggest that people are free because they aren’t determined.  But a careful reading of Gazzaniga reveals that this is not at all what he means.  In a chapter of his book called “My brain made me do it,” he endorses A. J. Ayers’ compatibilist notion of free will, which holds that free will and responsibility are compatible with determinism (italics are in the original, underlining is added):   

In 1954, A. J. Ayer put forth the theory of “soft determinism.”  He argued, as had many philosophers such as David Hume, that even if determinism exists, a person can still act freely.  Ayer posits that free actions result from desires, intentions, and decisions without external compulsion or constraint.  He makes the distinction between free action and constrained action (not between uncaused and caused action).  Free actions are those that originate in oneself, by one’s own will (unless one is suffering from a disorder) whereas constrained actions are those caused by external sources (for example, by someone or something forcing you physically or mentally to perform an action under hypnosis, or by disorders like kleptomania).  When someone performs a free action A, he or she could have done B.  When someone is constrained to do A, he or she could only have done A.  Ayer thus argues that actions are free as long as they are not constrained.  Free actions depend not on the existence of a cause, but rather the source of the cause. Though Ayer did not explicitly discuss the brain’s role, one could put it in terms of the brain: the brain is determined, but the person is free (pp. 98-99, The Ethical Brain).

So, on Gazzaniga’s view of freedom and responsibility, people’s actions and their wills are just as determined as their brains.  And indeed, this is what neuroscience tends to show.  The neural mechanisms of the brain give rise, in the context of the rest of one’s body and environment, to the phenomenon of a unique, conscious individual who can act deliberately and rationally. But there is nothing about these processes which could endow the person with a sort of freedom exempt from causality.  If brains and bodies are determined, then so are people, since nothing contra-causal arises as personhood emerges.

Since freedom and responsibility are not a matter of being uncaused, but a matter of one’s actions being unconstrained (that is, uncoerced) and caused by a disorder-free brain, one would suppose that the brain’s health would figure in our ascriptions of responsibility.  And indeed it does, since we don’t ordinarily hold people responsible who suffer from neural defects that seriously compromise rationality and impulse control.  People with such defects are incapable of conforming their behavior to the law since they can’t properly anticipate or fear criminal sanctions, so it would be unfair to punish them.  Rather we treat them (occasionally curing them) so that they become capable of behaving responsibly. 

But strangely, and despite such commonsense considerations, Gazzaniga says that “In neuroscientific terms, no one person is more or less responsible than any other for actions” (pp. 101-2, The Ethical Brain).   Now, why would a neuroscientist who specializes in understanding the difference between normal and abnormal brains say that the state of a person’s brain is immaterial to responsibility?  After all, such a claim is manifestly counter to all our intuitions and practices concerning the mentally ill. And it’s neuroscience that makes clear the connection between brain defects and the irrationality and impulsivity that sometimes count as exculpatory. 

It could be that Gazzaniga wants to hold the line against what Daniel Dennett calls “creeping exculpation.”  Since brains, healthy or not, are deterministic mechanisms that work “automatically,” as Gazzaniga puts it, perhaps he thinks we need the idea of the categorically free person to sustain the idea of  responsibility.  But he’s said that freedom and responsibility are compatible with our being, like our brains, fully determined.  And, he’s said, our acts are free “unless one is suffering from a disorder.”  So by Gazzaniga’s own lights we need a brain in good working order to be held responsible.  This makes his claim that all persons are equally responsible, neural defects or not, self-contradictory, in addition to being unworkable and unfair.

Just how unfair is revealed in Gazzaniga's adamant opposition to the insanity defense.  When asked about it in an interview with U.S. News and World Report, he says:

I never have [believed in the insanity defense]. You know one of the reasons is if you look at schizophrenics for example. Their rate of violent behavior is not above that of the normal population, especially when they're on their medication. So, if that's true, how can you use that as a defense, that they're doing something because they're insane. But the notion of personal responsibility has to do with the fact that people follow rules because they're in a social group and people with these various kinds of disorders can still follow those rules.

Asked about sociopaths with brain abnormalities, he continues:

You can always quote an extreme case and there certainly are some pretty extreme cases out there. But the vast majority of it is really dealing with people who know how to follow rules, can follow rules, and they choose not to follow rules. And there should be a consequence for that. I think we've just gone way over in the other direction in the thinking that we understand mechanisms that would excuse somebody from following those rules.[2]

Gazzaniga, remarkably, discounts his own neuroscientific evidence on the contribution of neural defects to behavior when he says the seriously mentally ill simply "choose not to follow rules."  On his own construal of free choice, significant brain-based mental disorders such as schizophrenia and psychopathy do compromise capacities for rationality and impulse control, and thus for morally responsible choices.** Demanding personal responsibility is all well and good, but to demand it of those whose rule-following capacities are objectively compromised is itself draconian and irresponsible. If, as Gazzaniga suggests, we should punish the seriously mentally ill, this undermines the very basis for our responsibility practices, which holds that punishment is only justified for those for whom the prospect of punishment serves as an effective deterrent.  Applying it outside such constraints is the gratuitous infliction of suffering for no good reason, except to toe a very hard, retributive line on criminal justice, consistent with that taken by the conservative administration he serves as a member of the president's Bioethics Commission. (**See here for a paper by UPenn law professor Stephen Morse arguing that "psychopaths lack moral rationality and that severe psychopaths should be excused from crimes that violate the moral rights of others.")

It’s true, as Gazzaniga says in his book, that responsibility is a human construct, designed to manage social interactions.  Nevertheless, our conception of responsibility must conform to what we know about brains and about persons, otherwise contradictions and injustices will surface as the law meets science.[3]  If neuroscience teaches us anything, it’s that a properly functioning brain subserves the higher-level capacities that our responsibility practices engage – our capacities for anticipation, deliberation, and self-control.  When the brain is defective, then indeed we can justly say on the basis of neuroscience that some people are less able to behave responsibly than others: they can’t properly anticipate, conform to, and thus be guided by legal sanctions.  Neuroscience won’t find responsibility in the head, but it can most definitely help decide whether a particular person has the (fully determined) capacity for being held justly accountable. Contrary to Gazzaniga's claim, in neuroscientific terms people are more or less responsible than others, depending on the state of their brains. On a naturalistic, materialist understanding of ourselves, science and the law can cooperate; they need not carve out incompatible domains of mechanism and responsibility.  

 TWC August 2005, revised August 2009


1. His paper is “Free will in the 21st century,” published in Neuroscience and the Law, Brent Garland and Mark S. Frankel, eds., Dana Press, New York, 2004.  His book is The Ethical Brain, Dana Press, 2005, insightfully reviewed by neurophilosopher Patricia Churchland here.  Chapter 6 of the book, “My Brain Made Me Do It,” is adapted from the paper.

2. That Gazzaniga doesn’t think the insane should be excused also comes up in his response to a question about the insanity defense in his Author Interview at American Scientist, the 4th question.  He ends his remarks on this saying “Schizophrenics stop at red lights.” 

3. In her review of The Ethical Brain, Patricia Churchland reaches much the same conclusion.