Philosophers, scientists, human beings: Touching a Nerve: The Self as Brain by Patricia Churchland will blow your mind—or brain, that is. To the author they are one and the same. “My brain and I are inseparable. I am who I am because my brain is what it is,” she begins her book. “Even so, I often think about my brain in terms different from those I use when thinking about myself. I think about my brain as that and about myself as me. I think about my brain as having neurons, but I think of me as having a memory. Still, I know that my memory is all about the neurons in my brain. Lately, I think about my brain in more intimate terms—as me.”

If we accept the brain as the source of feelings, thoughts and actions, as Churchland does, then we must abandon the concepts of an all-powerful god and an immaterial soul. Embracing the “existential facts of life” may be consoling to some, desolating to others, but for Churchland it’s a call to action. “Make your life here and do the best you can, here. Don’t defer for later and expect that everything is going to be made right in some magical place just beyond the stars,” she says. “When people have terrible tragedies happen to them I think it is a very natural thing to sort of want there to be an extension of this time into some other realm. I understand that, but I don’t believe in it.”

A professor emerita of philosophy at the University of California, San Diego, Churchland received a MacArthur Fellowship (aka the “genius grant”) for her work in neurophilosophy, an academic field she cofounded. Neurophilosophy applies neuroscientific advances to answering philosophy’s big questions: What makes us who we are? Do we have free will? Are we responsible for our actions? Or “What is control in neural terms? How do brains with weak self-control differ from those with strong self-control? And if self-control is not real, as the phrase ‘free will is an illusion’ suggests, then what is the point of trying to make reasonable choices—of trying to be responsible, courageous, decent, and honest?” she writes. The more we learn about the brain, the more apparent the answers should become.

What causes aggression, for example? Well, the balance (or imbalance) of testosterone and cortisol can strongly predict aggressive behavior in mammals. However, its effects are tempered by social customs, emotional responses and serotonin. Studies performed by geneticists Herman Dierick and Ralph Greenspan, who selectively bred aggressive fruit flies, show that “the relationship between genes and brain structures does not remotely reflect a simple ‘gene-for’ model,” Churchland writes. That is to say: aggression is caused by a complicated combination of social stimuli and brain processes—but not necessarily an unknowable one. To posit that it is all too complex to comprehend indicates a distinct lack of imagination.

In supporting this proposition, Churchland employs the work of many scientists, philosophers from Plato to Kant and her own experiences growing up on a family farm in British Columbia. A brother who exhibited poor impulse control, poor planning, difficulty growing facial hair and other traits was diagnosed with Klinefelter’s syndrome at age 25. Underlying his difficulties was the fact of three sex chromosomes, XXY, as opposed to the typical two for males, XY. “The relief that comes with insight into causation can be profound,” Churchland writes.

“That was the explanation for why he was so different,” she says. “It liberated him in the sense that it allowed him to kind of understand those cognitive differences and to seek help from other people.” A friend’s temporary belief that her leg was not her own (due to a concussion suffered in a bicycling accident) and even the small-town treatment of a charming hardware-store embezzler (they let him go with a promise to repay, which he never did) can be explained as brain-based phenomena. Churchland’s life-based insights are bound to generate eureka moments. 

That we are the sum of our brains’ machinations need not cast human experience as any less wondrous, nor render spirituality moot. Churchland bristles  at what she calls “neurojunk”: that “free will is an illusion” means the judicial system should be eradicated; that there will soon be a brain scanner that will read shoppers’ minds in the supermarket—and the cashiers will never ask “paper or plastic?” again. “Any science can have junk and neuroscience has some junk, too,” she explains. Nevertheless, neuroscience at its best could be the passport to universal truths. “The essential truth is that it seems that everything that we are really does depend on the brain. There isn’t some other kind of independent spooky thing that we are,” she says. “And that’s okay.”

Megan Labrise is a freelance writer and columnist based in New York. Follow her on Twitter.