[Paleopsych] Nature Neuroscience: Book Review: The Ethical Brain

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Book Review: The Ethical Brain

Nature Neuroscience  8, 1127 (2005) doi:10.1038/nn0905-1127
Reviewed by: Charles Jennings

Charles Jennings is at the Harvard Stem Cell Institute, Harvard University, 42 
Church Street, Cambridge, Massachusetts 02138, USA. 
charles_jennings at harvard.edu

Michael Gazzaniga is a leader in the field of cognitive neuroscience, and since 
2002 he has been a member of President Bush's Council on Bioethics. In a group 
dominated by conservatives, Gazzaniga is sometimes a dissenting voice, for 
example, in his support for embryonic stem cell research. His work on 
split-brain patients has profound implications for understanding the neural 
basis of self, and his presence on the council has brought a neurobiological 
perspective to many current bioethical controversies. The Ethical Brain is a 
wide-ranging, yet short and readable, summary of his views.

Gazzaniga is a technological optimist, with little patience for the vague 
'slippery slope' arguments that are often invoked by those who worry about 
where biotechnology is leading us. A deeper concern—articulated, for example, 
by fellow council member Michael Sandel—is that the desire to manipulate human 
nature is a form of hubris that threatens to undermine our appreciation for 
life's gifts. Gazzaniga, however, will have none of this. He welcomes the 
prospect of genetic enhancement, prolongation of lifespan, memory pills and so 
forth, arguing that humanity's innate moral sense will always guide us to use 
our powers wisely.

I would like to think he is right, but I did not always find his arguments 
persuasive. A case in point is his discussion of sex selection. In some Asian 
countries, notably China, a cultural preference for boys, combined with easy 
access to methods for sex determination and selective abortion, has led to a 
large distortion of birth ratios. Gazzaniga acknowledges the potential concern, 
but because some US fertility clinics are now starting to discourage sex 
selection, he concludes that humans can be trusted to do the right thing in the 
long run. Maybe so, but I am less sanguine than Gazzaniga about this massive 
biotechnological experiment, and about the world's largest country soon having 
15 million young men unable to find marriage partners.

Gazzaniga's faith in human destiny is based in part on his belief in a 
biologically based universal morality, and his discussion of this idea is one 
of the most interesting aspects of the book. He argues that our sense of right 
and wrong has been shaped by evolution, and that there consequently exists a 
core of moral instincts that are shared across all societies. Religious 
traditions, in his view, represent attempts to explain and validate these 
biological instincts. Our brains have a strong tendency to form beliefs as a 
way of making sense of the world, and as Gazzaniga's own work has emphasized, 
these are often confabulated on the basis of limited evidence, yet refractory 
to change once formed. As an explanation of religious faith, this viewpoint is 
surely anathema to many conservatives, but Gazzaniga (who was raised Catholic) 
shows no animosity toward religion, which he regards as a natural aspect of 
human biology.

Gazzaniga hopes that a deeper understanding of our shared moral instincts and 
their biological basis could help to overcome ideological conflicts between 
different belief systems. This is an appealing idea ('biology good, ideology 
bad'), even though only a chronic optimist could think that universal education 
in cognitive neuroscience will lead to world peace. A skeptic might counter 
that our brains come prewired not only for moral reasoning but also for 
prejudice, tribalism, warfare—less attractive but no less universal aspects of 
human societies. Moreover, the scientific evidence for a moral instinct is 
based largely on simple test scenarios in which decisions have immediate and 
visible consequences for another individual. Although people tend to show 
similar responses on such tests, most real-world dilemmas are not like this. It 
seems unlikely that divisive societal debates on questions such as abortion or 
capital punishment could ever be resolved by an appeal to biology.

Perhaps the most pressing issue in neuroethics is how (if at all) neuroscience 
should inform the justice system, and Gazzaniga devotes several chapters to 
this topic. The central problem is this: if decisions are made by the brain, a 
physical object that obeys physical laws, in what sense can they be considered 
'free'? But if people are constrained by their brains, how can we hold them 
responsible for their actions? This quickly leads to problems, of course; if 
defendants could be acquitted simply by arguing "my brain made me do it," the 
entire justice system would collapse. Gazzaniga's proposed solution is to argue 
that responsibility is "a social construct that exists in the rules of a 
society [but not] in the neuronal structures of the brain." Yet I did not find 
this argument convincing. The justice system, held together by moral rules and 
concepts of accountability, is an emergent property of large numbers of brains. 
It may be dauntingly complex, but that does not put it beyond the realm of 
scientific study. Indeed, social neuroscience is an emerging field of research, 
and neuroimagers can now examine the mechanisms underlying not only people's 
own moral decisions, but also their perceptions about the accountability of 
other individuals.

Gazzaniga is understandably concerned about neuroscience being drawn into the 
courtroom, but he acknowledges that it is inevitable. The challenge for 
neuroethicists, then, will be to help lawyers sort the wheat from the chaff, to 
recognize valid arguments for exculpation or leniency, while rejecting the 
abuses that will surely become increasingly tempting to defense counsels as 
brain science continues to advance.

The Ethical Brain is not the last word on these difficult issues, but it does 
provide a clear and useful introduction to the field. Gazzaniga's fans include 
Tom Wolfe, who gives the book a cameo role in his novel I Am Charlotte Simmons, 
where it appears as recommended reading for a college course. In this case life 
would do well to imitate art—The Ethical Brain would be an excellent 
introduction for anyone who is interested in learning more about 'the next big 
thing' in bioethics.

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