The Ethical Brain. Michael S. Gazzaniga. xx + 201 pp. Dana
Envision this scene: Socrates sits in prison, calmly awaiting
execution, passing the time in philosophical discussions with
students and friends, taking the occasion to inquire into the
fundamentals of ethics: Where do moral laws come from? What is the
root of moral motivation? What is the relation between power and
morality? What is good? What is just?
Ever modest, Socrates confesses ignorance of the answers. The
pattern of questioning strongly hints, however, that whatever it is
that makes something good or just is rooted in the nature of humans
and the society we make, not in the nature of the gods we invent.
This does not make moral rules mere conventions, like using a fork
or covering one's breasts. There is something about the facts
concerning human needs that entails that some laws are better than others.
From the time of Socrates to the present, people have sought to give
a natural basis for morals—that is, to understand how a moral
statement about what ought to be done can rest on hard facts, albeit
facts about conditions for civility and peace in social groups. How
can ethical claims be more than mere conventions? How can such
claims be rooted in facts about human nature but have the logical
force of a command?
Developments in evolutionary biology have helped to explain the
appearance of moral motivation in humans and in other eusocial
animals—animals that display behavior involving cooperation,
sharing, division of labor, reciprocation and deception. In these
species, various forms of punishment (shunning, biting, banishing,
scolding) are visited on those who threaten the social norms.
Ethological studies help us appreciate that, at a basic level, human
social behavior has much in common with that of other species.
Developments in neuroscience hold out the promise of extending the
naturalistic perspective to aid in the understanding of how the
brain and its circuitry underlie the capacity to learn social norms
and to behave in accordance with them. Many of us ponder the
possibility that discoveries about brain function and organization
will challenge the conventional wisdom on which our system of
justice relies and will allow us to see more deeply into the biology
of social behavior, including moral behavior. In his new book,
The Ethical Brain, Michael S. Gazzaniga takes an
unflinching look at the interface between neuroscience and ethics,
and offers his own thoughtful perspective on some of the tough questions.
As a graduate student at Caltech, Gazzaniga studied under one of the
towering figures of neuroscience, Roger Sperry, whose lab pioneered
research into the cognitive effects of cutting the fibers connecting
the two cerebral hemispheres (a procedure used to treat intractable
epilepsy). Ingenious testing of these so-called "split
brain" patients revealed that their two brain hemispheres
operated independently, each hemisphere acting almost like a
distinct person. These were profoundly important results, both for
philosophy and for neuroscience. Gazzaniga went on to explore the
neurobiology of higher mental functions—attention, memory,
choice, consciousness—more generally, always with a
philosophical question biting his heels. He currently serves on the
President's Council on Bioethics. Thus it is especially fitting that
he should now pen his thoughts on neuroethics.
The most fundamental neuroethical issue concerns free will and
responsibility. The mind is what the brain does, and the brain is a
causal machine. Consequently, deliberations, beliefs, decisions and
ensuing behavior are the outcome of causal processes. Typically, the
causal processes leading to awareness of a decision are
nonconscious. The "user illusion," nevertheless, is that a
decision is created independently of neuronal causes, by one's very
own "act of will." Some philosophers—usually called
libertarians—resolutely believe that voluntary decisions
actually are created by the will, free of causal
antecedents. Like flat-earthers and creationists, libertarians
glorify their scientific naiveté by labeling it
Gazzaniga, like many a philosopher, realizes that it would make a
mockery of the criminal justice system if the accused could escape
punishment simply by pleading that the brain is a causal machine and
hence he or she lacked free will. So when and how ought we to hold
people responsible for their behavior?
Gazzaniga's answer has two components: First, he claims that we hold
a person responsible, causality notwithstanding, so long as his or
her behavior was unconstrained—so long as the person could
have done otherwise. Second, Gazzaniga identifies responsibility as
a social, not a neurobiological, property. His point is that our
institutions for assigning responsibility derive from the need to
maintain and protect civil society, which must figure out suitable
criteria for when and how to punish those who violate the rules.
Gazzaniga sums up his solution to the problem of free will by saying
that "the brain is determined, but the person is free."
The logic of this brain/person duality is not particularly
compelling, or even coherent, yet as Gazzaniga's writing implies, it
may be in our collective interest to live by this dualistic legal fiction.
The obvious test of the "let's pretend" solution is to see
whether it can specify relevant criteria for distinguishing between
those who could have done otherwise and those who could not have,
and between those cases in which mens rea (literally, a
guilty mind) obtains and those in which it does not. (Mens
rea is a criminal law concept requiring proof that the mental
state of the accused was such that he or she committed the crime
purposely, knowingly, recklessly or negligently; strict liability,
in which state of mind has no relevance, is fairly rare in criminal
law.) Here, however, the wheels fall off Gazzaniga's solution.
Worried that ever-cunning defense attorneys will try to extract more
exculpatory mileage out of neuroscience than the facts can support,
Gazzaniga magnifies the incompatibility of responsibility as applied
to persons and the causality that governs functions of a person's
brain. He says, "The issue of responsibility . . . is a social
choice. In neuroscientific terms, no person is more or less
responsible than any other for actions." This implies that
there are no relevant factual differences between someone with, say,
obsessive-compulsive disorder and someone who can resist impulses.
Can this conclusion be right? As the British neuroscientist Steve
Rose has pointed out, badness, just as much as madness, involves the brain.
The flaw in Gazzaniga's argument is that although responsibility is
assessed in a social context, the capacity to learn social norms and
the capacity to act in accordance with them are matters of
individual brain function. It is precisely because an important
difference exists between a normal brain and the brain of someone
who is seriously demented or unreachably deluded that such people
are not considered responsible for crimes they might commit.
Moreover, judicial institutions rely on threat of punishment to
deter. The late maturation of the prefrontal cortex (with reference
to neuronal density, synaptic density, dendritic length and
myelination) means that the brains of mature adults are critically
different from those of young children—which almost certainly
accounts for the child's more modest ability to appreciate the
consequences of his or her choices and to resist temptation.
Satisfied that the brain/person duality is workable, Gazzaniga
pushes the hypothesis further. He says that because assignment of
responsibility is a social matter, not a matter of fact about the
brain, neuroscience cannot possibly "settle" whether a
person is responsible. Granted, determining legal
responsibility is complicated, and neuroscientific knowledge cannot
be substituted for knowledge of the law and of community standards.
What kicks up sand, however, is the unfortunate choice of the word
settle. Neuroscientific evidence can surely be
relevant, even if the disposition of the case is
settled by members of a jury whose brains follow some form
of constraint-satisfaction algorithm. Yet Gazzaniga resolutely
insists upon the stronger point: Neuroscientific data are not even relevant.
Why not? His reasoning goes like this: As a group, schizophrenics,
for example, are no more prone to violence than individuals in the
general population. Ditto, he says, for people with prefrontal
lesions. If a given schizophrenic, Mr. Jones, kills someone, it is
mere theater to display his brain scans in court, picking out some
abnormality or other as "the cause" of his homicidal
behavior. There are no relevant differences that neuroscience knows
about that can explain why Jones killed, but Smith (also
schizophrenic) did not. Not everyone with low glucose levels engages
in violence; not all citizens raised in an inner-city hell become
drug dealers; not all premenstrual women beat their children. We can
assume there are differences in the brain, but whatever these
differences happen to be, they are not, he believes, relevant to
determination of responsibility. Why? Because there is no
"responsibility" area whose functionality can be examined
through a scanner or with electrodes—not now, not ever.
Responsibility is a social construct, not a brain function. This
point, he believes, holds generally—for schizophrenics, for
patients with prefrontal cortex lesions, and so forth. And for good
measure, he suggests that the insanity defense itself is too
imprecise and problematic to be of practical value.
It is widely expected that neuroscience has, or soon will have,
something to say about competence to stand trial, about whether the
mens rea condition has been met and about appropriate
sentencing. Thus Gazzaniga's bold thesis raises important concerns.
I share his worry that defense attorneys and hired experts from
neuroscience may get out in front of what current science can
honestly say—it's bad enough that venal psychiatrists have
sown wholesale distrust of their discipline by selling their
"expertise" to the highest bidder. On the other hand,
perhaps Gazzaniga overstates the case.
Consider the Virginia man who at around age 40 became obsessed with
child pornography and eventually molested his eight-year-old
stepdaughter. He had no previous history of pedophilic inclinations,
and his interest in child pornography completely disappeared with
the surgical removal of a tumor of the frontolimbic system, which
had invaded the hypothalamic area of his brain. Along with other
appetites, sexual drive is regulated in the hypothalamus. Some
months later, when the tumor grew back, his preoccupation with
pornography returned, only to vanish again with repeat surgery.
Because the waxing and waning of his sexual compulsions corresponded
to the waxing and waning of the tumor, his was not a standard
molestation case. So long as his limbic structures are tumor-free,
it seems rather pointless to punish him for a pornographic pursuit
that was alien to his character. Punishment would not make sense
either as deterrence or as retribution.
Consider a more complicated discovery. In a landmark longitudinal
study in New Zealand that followed the lives of about 500 men from
infancy to about age 26, a significant subpopulation showed a strong
and unmodifiable disposition to engage in antisocial behavior,
including irrational and self-destructive violence. Genetic analysis
revealed that most of the men in that subpopulation carried a
mutation for a particular enzyme, monoamine oxydase A (MAOA). The
enzyme metabolizes three neuromodulators (serotonin, norepinephrine
and dopamine, all of which are relatively concentrated in prefrontal
areas of cortex), thereby inactivating them. Environment was also a
factor: In the group with the MAOA mutation, the criteria for
adolescent conduct disorder (a measure of antisocial behavior) were
met in about 85 percent of those who had been severely maltreated as
children, in about 38 percent of those who had probably been
maltreated and in only about 22 percent of those who had not been
maltreated. Among those who did not carry the MAOA mutation but had
been severely maltreated, only about 42 percent had the conduct disorder.
These findings are preliminary, and further research is needed on
the exact nature of the effect of early maltreatment on the
circuitry affected by low MAOA levels. Still, on the face of it, the
capacity of maltreated children with the MAOA mutation to acquire
and act on social norms appears to be diminished. If Gazzaniga is
right, however, these data are irrelevant to determining
responsibility. The fact that the men are irrationally violent means
that society needs protection from them—fair enough. Even so,
it is important to distinguish between custody and punishment. Why?
For the sake of the integrity of the institution of justice, because
as a social institution, the criminal sanction depends on broad
social support to keep functioning properly. When the criminal
sanction is applied to cases that violate common beliefs about
fairness—to young children, for example—support is
replaced by resistance and reform. In order to be broadly accepted,
the legal fiction that the brain is determined but the person is
free will have to make peace with the widespread conviction
that because of brain abnormalities, we are not all equally masters
of our fate.
On other bioethical issues, Gazzaniga is just as forthright. The
book begins with a discussion of the medical use of embryonic tissue
and the debate over whether a blastocyst (which is a ball of a few
hundred cells) is a person. This section is thoughtful, clearheaded
and informed by developmental neuroscience. One fallacy Gazzaniga
exposes depends on the common idea that graded differences block
principled legal distinctions. In the version referred to as the
fallacy of the beard, the logic goes like this: If we cannot say how
long a man's whiskers must be to qualify as a beard, we cannot
distinguish between a bearded man and a clean-shaven one. Although
this form of argument fools nobody on the topic of beards, it has
been seductively employed elsewhere, especially regarding embryos.
Criticizing the blastocyst-as-baby argument, Gazzaniga sensibly
points out that we can draw a reasonable, if imperfect, line. When a
distinction is needed, we devise laws that draw one, typically
erring on the side of caution, given prevailing community attitudes.
There is no precise moment at which a child becomes an adult, or a
blastocyst becomes a sentient person, but reasonable humans
unencumbered by superstition can nonetheless come together to
"draw a line," and we can redraw the line when the facts
merit a revision. Eighteen as the age of majority is not the perfect
line for all adolescents, but on the whole it works well enough.
Gazzaniga also presents an eloquent defense of personal choice in
end-of-life matters, while recognizing that there are bound to be
fundamental differences across people regarding euthanasia. Most
people understand the concept of brain death and see the wisdom in
equating death with brain death. In large part, this acceptability
may be owed to personal experiences concerning the remarkable
benefits conferred by organ harvesting.
Other topics covered, if not fully, then sufficiently well to
provoke thought, concern the neurobiological and evolutionary
explanations of religious beliefs, in all their amazing variety and
conflicting manifestations. Gazzaniga discusses also the remarkable
nature of autobiographical memory, and the susceptibility of memory
to suggestions, reconstruction, invention and wholesale
confabulation. Because it is brief, compelling and free of technical
jargon, the whole book can be easily read during a transcontinental flight.
At a time when intellectuals may feel cowed by the heavy hand of the
fervently religious, it is a relief to see that Gazzaniga neither
shies away from controversial opinions nor waters them down so as to
offend nobody. At the same time, he is respectful of moral
convictions that do not line up with his own. His opinions are
delivered not as dogma but as part of an ongoing reflection and
conversation, in which seeing all sides of a moral problem is itself
regarded as a moral achievement.