Touching a Nerve: The Self as Brain
Patricia S. Churchland
W. W. Norton, 2013 ($26.95)

When Galileo announced his observation of Jupiter's moons, his discovery challenged a deeply entrenched way of thinking about our place in the universe.

Modern neuroscience has kindled a similar revolution in the way we think about the brain. In Touching a Nerve, neurophilosopher Churchland argues that all things that we have traditionally ascribed to a higher power—morality, free will, the soul—are in fact products of the brain. The mysterious lump of matter inside our head is responsible not only for everything that makes us human but also for what makes us unique.

This view that the brain is responsible for every aspect of our physical and mental lives has gained traction among neuroscientists, but the idea of the self as brain has also encountered resistance. It's not hard to understand why, Churchland notes. Some research, for example, shows that patterns of brain activity can predict our choices or actions before we become consciously aware of having made a decision, and it may be hard to reconcile this evidence with the notion of free will.

Churchland illustrates how our understanding of the brain is beginning to reveal the biological basis of traits such as aggression and morality. For instance, zapping the temporal lobe using deep-brain stimulation can improve spatial memory, and using a powerful magnet to alter activity in the right temporoparietal junction can make our moral compass go haywire, causing behaviors we think of as immoral to become permissible.

Brain-damaged patients provide some of the strongest evidence for how our brain makes us who we are. Injuries to various parts of the frontal lobe can leave some people unable to talk or can alter personality, yielding impulsive or antisocial behaviors, and lesions to the medial temporal lobe can erase our memories or prevent new ones from forming.

Churchland also seamlessly weaves this research with experiences from her own life. She describes, for instance, how as a child growing up on a farm in British Columbia, a friend lost awareness of her legs after injuring them in a bicycle accident and how her grandmother lost her sense of self to Alzheimer's disease.

By drawing on personal stories and modern brain research, Churchland creates a compelling narrative to further the idea of the self as brain. Her well-supported, cautious analysis provides insights into how we evolved traits such as empathy and altruism and explores the genetic and biological factors that determine an individual's unique sense of self. Through her examples, we can all come to understand our actions and intentions more clearly.