A journey into the human brain starts with the usual travel decisions: will you opt for a no-frills jaunt, a five-star luxury cruise, or trek a little off the beaten track, skipping the usual tourist attractions?
Now that science's newfound land is suddenly navigable, hordes of eager guides are offering books that range from the basic to the lavishly appointed to the minutely subspecialised. But those who prefer wandering off-trail may opt for two new tomes, neither written by a neuroscientist.
When philosopher Patricia Churchland says her book represents "the story of getting accustomed to my brain", she is speaking as a human being and a career humanist. An emerita professor at the University of California, San Diego, she has spent a career probing the physical brain for the self and its moral centre. And unlike many humanists who hate the science for the irritating violence it does to centuries of painstaking intellectual labour, she is entranced by the power of the data, and her delight is utterly contagious.
Churchland loses little time in dispatching the archaic notion of the soul, and suggests that near-death visions of heaven simply represent "neural funny business" in a malfunctioning brain.
Can humans still live a moral and spiritual life even without the ideas of soul and heaven? You bet they can. "We may still say that the sun is setting even when we know full well that earth is turning," Churchland says - and she is off and running.
Where do values come from? Does a "brainstem-limbic system shaped by reward-based learning and problem solving" suffice? Can behaviour be genuinely moral if the consciousness is not involved? Does the "me" that is you include the many levels of your unconscious? Do you have free will? Is there such a thing as criminal intent? Does criminal behaviour prompted by misaligned circuits, aberrant neurotransmitters or tumours in vital areas imply innocence? Should we empty out the prisons?
It is hard to conceive of a better guide to this difficult terrain than the MacArthur award-winning Churchland, who knows the science inside out and writes with surpassing clarity, elegance, humour and modesty, punctuating the hard parts with accessible lessons about the brain she learned during a hardscrabble childhood on a Canadian farm.
She recalls a recent encounter with a fellow academic: "My very presence brought her to fury, and she hissed: 'You reductionist! How can you think there is nothing but atoms?'" But surely, Churchland muses, "if reductionism is essentially about explanation, the lament and the lashing out are missing the point". Her understated bottom line: "To rail against reality seems unproductive."
If Churchland tours the moral brain in a mood of joyous discovery, Sally Satel and Scott Lilienfeld, traversing much of the same territory, are just plain annoyed. Satel is a psychiatrist and Lilienfeld a psychology professor at Emory University; their mission is to debunk the pop neuroscience that keeps making headlines with "facile and overly mechanistic explanations for complicated behaviours".
Their primary target is functional MRI scanning, a technique that has been deployed to localise instinct and emotion to specific brain areas, positing sites for such intangibles as love, hate, fear, political preferences and consumer behaviour.
Satel and Lilienfeld offer a methodical critique of this oversimplified neuro-nonsense, convincingly arguing that in many ways the MRIs of today are simply the phrenology heads of yesteryear, laughably primitive attempts to wrangle human character and behaviour into tractable form.
Thus launched, they head out to evaluate the contributions of neuroimaging to behaviours more complex and weighty than choosing which SUV to buy, homing in on the age-old questions of blame, responsibility and punishment among criminals, addicts and the criminally insane.
Can brain imaging help sort it all out? Not in their view: when it comes to the legalities of bad behaviour, "the capacity of functional brain imaging to mislead currently exceeds its capacity to inform". It doesn't do much better than the old polygraphs for evaluating alibis, they conclude, and utterly fails to explain why some people do unspeakable things.
The "my amygdala made me do it" school of criminal defence was around as early as 1924, they note, when Clarence Darrow defended Nathan Leopold and Richard Loeb, two teenage psychopaths who kidnapped and killed a 14-year-old boy for no reason except to commit a crime.
"They killed him because they were made that way," Darrow told the jury, pleading for clemency.
But Satel and Lilienfeld are having none of this, arguing that senses of free will, justice, retribution and fair play are all too deeply ingrained in human nature for neuroscience to erase them - at least, as the science now stands. Similarly, Satel has long argued against calling drug addiction a disease, and she and Lilienfeld reaffirm that position here, writing that such a conception "threatens to obscure the vast role of personal agency in perpetuating the cycle of use and relapse".
Ah, but what underlies that personal agency? Are there not neural circuits there as well? The duo's polemic ultimately seems a little abrupt and shortsighted to a reader who has watched a world-class philosopher gaze with eager intensity at the brain and find in it an infinite series of mirrored selves.
The New York Times