Hardwired Behavior: What Neuroscience Reveals about Morality (review)

Laurence Tancredi is a Clinical Professor of Psychiatry at New York University School of Medicine, a psychiatrist in private practice, and a lawyer who consults on criminal cases involving psychiatric issues. This extraordinary combination of expertise and experience puts him in a position to write this book on the contemporary status of the classic nature–nurture debate.

Hardwired Behavior suffers from two connected rhetorical problems that should be addressed up front. First, the main title suggests neurological–genetic determinism of human behavior. Yet, the actual content of the book supports a more balanced view, with genetically based and neurologically expressed propensities for behavior situated in a social context that is usually capable of regulating or exacerbating them. Relative to the social constructivism that has dominated theories of behavior since the collapse of social Darwinism decades ago, Tancredi's case does push hard in the direction of neurological–genetic determinism of human behavior, but the end result is still a balance between nature and nurture.

Second, the subtitle suggests that neuroscience can reveal something about morality, and that this book will tell us what that is. This, too, is misleading. The book has little to say about morality as such. It focuses on behaviors that are commonly considered to be morally bad because they can harm individual happiness or the social fabric of life, such as violent crimes and unhealthy sexual activities, pathological gambling, and lying. Tancredi shows that such behaviors are profoundly influenced by neural hardwiring. This is relevant to morality, to be sure, but the most Tancredi says about that is to notice that people generally think of such behavior as wrong and to speculate that, if they knew about the underlying biological component in the behavior, they might have to rethink how they assign culpability. In particular, the infamously complex philosophical linkage between behavior and morality, between the "is" of the description and the "ought" of the prescription, is not explored here, nor is the puzzling question of the evolutionary emergence of moral systems.

These issues can be put down to marketing bluster, which often influences book titles, and to the author's profile of expertise in what is a prodigiously complicated multidisciplinary area. Similarly, a number of distracting errors in the book, which should have been caught in proofing, probably can be put down to a rushed process mandated by a marketing deadline. Readers of this journal will also need to know that there is also almost no discussion of religion in the book, though much that is said bears on the study of religion. With these concerns out of the way, I now turn to the marvelous heart of the book's argument.

Tancredi marshals a formidable array of evidence to show that human behavior is more strongly influenced by biological factors such as genes and brain damage than is usually realized. The main supply of evidence is research studies built around functional imaging of the brain. These are non-invasive brain scans that capture signs of neural activity (such as changes in blood oxygen level) while the brain is doing an activity. A single PET or fMRI scan tells us little of relevance to the issue of morality; comparative studies matter more. Scans of brains operating normally establish a basis for identifying unusual or abnormal function, such as reduced activation in a region of the brain associated with empathy or greater activation in a region associated with aggression. Such comparisons allow neuroscientists to infer that distinctive variations in the behavior being studied have neurological underpinnings, or what Tancredi calls "hard-wiring."

This sort of evidence necessarily presupposes a modular approach to understanding brain activity, which focuses on correlations between a bodily or mental function and one or more brain regions. Though Tancredi never addresses the problems with modular models, he appears to believe that the modularity thesis is sound enough to support the inferences he wants to draw from the imaging data. Where possible, he includes findings from other sources—such as...