In 1971, the psychologist B.F. Skinner expressed the hope that the vast, humanly created problems defacing our beautiful planet (famines, wars, the threat of a nuclear holocaust) could all be solved by new “technologies of behavior.” The psychological school of behaviorism sought to replace the idea of human beings as autonomous agents with the “scientific” view of them as biological organisms, responding to external stimuli, whose behavior could be modified by altering their environment. Perhaps unsurprisingly, in 1964 Skinner’s claims about potential behavior modification had attracted funding from the CIA via a grant-making body called the Human Ecology Society.

Skinner was extremely dismayed that his promise of using his science to “maximize the achievements of which the human organism is capable” was derided by defenders of the entirely unscientific ideal of freedom. When Peter Gay, for instance, spoke of the “innate naïveté, intellectual bankruptcy, and half-deliberate cruelty of behaviorism,” Skinner, clearly wounded, protested that the “literature of freedom” had provoked in Gay “a sufficiently fanatical opposition to controlling practices to generate a neurotic if not psychotic response.” Skinner was unable to present any more robust moral defense of his project of social engineering.

In spite of the grandiosity of Skinner’s vision for humanity, he could not plausibly claim to be a moral expert. It is only more recently that the claims of psychologists to moral expertise have come to be taken seriously. Contributing to their new aura of authority has been their association with neuroscience, with its claims to illuminate the distinct neural pathways taken by our thoughts and judgments.

Neuroscience, it is claimed, has revealed that our brains operate with a dual system for moral decision-making. In 2001, Joshua Greene, a philosophy graduate student, teamed up with the neuroscientist Jonathan Cohen to analyze fMRIs of people’s brains as they responded to hypothetical moral dilemmas. They inferred from looking at neural activity in different regions that moral judgment involved two distinct psychological processes. One of the processes, a fast and intuitive one, took place by and large in areas of the brain associated with emotional processing, such as the medial prefrontal cortex and the amygdala. The other process, which was slow and rational, took place by and large in regions associated with cognitive processing, such as the dorsolateral prefrontal cortex and the parietal lobe.

Greene interpreted these results in the light of an unverifiable and unfalsifiable…