Geoffrey Dean via The Committee for Skeptical Inquiry – CSI
Today, phrenology (“head reading”) is usually seen as the fossilized stuff of cranks and charlatans. But in the nineteenth century it had a huge influence at all levels of Western society, more than all of its later competitors (such as psychoanalysis) put together. It was influential because of its attractive philosophy and because practitioners and clients saw that it worked. But we now know that it could not possibly work; personal experience had led millions of people astray. Indeed, few beliefs can match phrenology for its extent of influence and certainty of invalidity. So it has valuable lessons about any experience-based belief.
In the nineteenth century, phrenology affected all levels of Western life and thought. In Britain, Europe, and America, its influence was felt in anthropology, criminology, education, medicine, psychiatry, art, and literature. In France, it eroded established power and led to wide social changes. In Australia, it rationalized the violence against Aborigines and explained the criminality of convicts. For ordinary people everywhere a head reading was often required for employment or marriage.1 But how could this happen if phrenology was totally invalid? For answers, we need to start at the beginning.
First Steps to Delusion
Around 1790, the German-born anatomist Franz Joseph Gall, one of the founders of modern neurology, put together his skull doctrine that later led to phrenology. He held that behavior such as painting or being careful had their own specialized organs in the brain, and that they influenced the shape of the skull. So the skull’s bumps would indicate behavior and abilities that were innate. Gall spent eleven years examining hundreds of heads to test his ideas: “If … he observed any mechanician, musician, sculptor, draughtsman, mathematician, endowed with such or such faculty from birth, he examined their heads to see whether he might point out a particular development of some cerebral part…. He also called together in his house common people, as coachmen and poor boys, and excited them to make him acquainted with their characters” (Spurzheim 1815, 271).
Gall’s seemingly logical approach had two fatal defects. First, his claims were often based on a single striking case, for example “Cautiousness” was placed above the ears because an extremely cautious priest had a large bump there. Second, Gall looked only for confirmingcases and ignored disconfirming cases, a flaw not lost on his critics. Thus David Skae (1847), a physician at the Royal Edinburgh Asylum, noted that once the truth is “fixed upon our minds,” looking for confirmation is “the most perfect recipe for making a phrenologist that could well be devised.” But to Gall and the thousands of phrenologists who came later, personal experience mattered more than procedural defects. Phrenology had taken its first giant step on the road to delusion.2 Note that the delusion of experience is not limited to artifacts of reasoning such as the Barnum effect.