It is beguiling to think brain science can help us tell right from wrong—and unlikely tooby Guy Kahane / February 24, 2010 / Leave a comment
Neuro-imaging can now trace the processes that underlie our ability to tell right from wrong. It allows us to analyse the brain tissue of psychopaths, and to map the areas responsible for feeling guilt or indignation, charity and racial prejudice. Recent studies have identified brain areas sensitive to fairness, and even common neural pathways in the frontal and temporal lobes that are active whenever we make a moral response: brain areas that might embody our very “moral sense.” But what is unclear, and both worries and excites ethicists, is how these advances might change the way we think about ethics.
To what extent is morality built into the brain? Experiments on chimpanzees suggest that they possess a primitive sense of fairness. The Harvard psychologist Marc Hauser postulates that all humans share an innate “moral grammar.” Meanwhile Jonathan Haidt, a psychologist at the University of Virginia, sees the basis of morality in a set of far messier, conflicting emotional responses due to both nature and nurture. But if there is a common biological basis to human morality, it must be compatible with a vast diversity of moral outlooks. And it offers little help in overcoming the profound disagreements that seem inherent to morality and politics.
Science has also begun to shed light on the biological sources of moral conflict. One important strand of recent research has focused on disgust. At some point in our evolutionary history, primitive disgust reactions (to toxic or contaminated food, for instance) seem to have extended into our moral lives. Haidt and others have shown that it is possible to replicate this response by asking people a moral question while placing them in a messy or tidy environment—the messier it is, the more people are likely to be judgemental or critical, thinking that a given action is wrong or immoral. More astoundingly, Haidt and his colleague Thalia Wheatley have used hypnosis to prime people to feel a sharp pang of disgust whenever they read the word “often” in a sentence. The result was an inclination to treat even innocent acts as morally suspect: so a subject would claim the sentence “he often makes decisions quickly” implied an immoral intent (which it clearly does not), but would change their mind when the offending word was removed.
Going further, neuro-imaging has located overlapping neural networks common to physical disgust and moral repugnance. Psychologists from the University of Toronto have…