It claimed to know the personality of individuals by looking at the the shape of the skull, which in turn allowed them to classify them according to their innate aptitudes.
Many people are familiar with that one scene from Quentin Tarantino’s Django Unchained where Leonardo DiCaprio’s character goes on a rant about how African-American skulls differ from Caucasian skulls. Those differences were supposed to make black people more submissive, and thus more suitable for slavery. It’s nonsense, yet it’s not far from what people actually believed at the time. The “science” that DiCaprio’s character was quoting is phrenology, and it was very popular during the 19th century.
Phrenology was the study of human personality and human nature by the measurement of the skull. Phrenologists believed that the shape of our heads was indicative of our individual temperaments, so by making some classifications of shapes and measurements, they were supposed to be able to tell whether someone had criminal tendencies, high intelligence, or aptitude for a given job.
According to phrenologists, human brains had specialized “organs” for different faculties (there was an organ for benevolence, for instance). They also believed these organs developed more or less like muscles, so that exercising the organ led to an increment in its size. A benevolent individual, for example, would have a large “benevolent organ” within the brain, which would then push against the skull, creating a measurable dent which could be identified by experts.
Though phrenology may have started as an honest —if biased— inquiry into the relations of the mind, body, and human nature, eventually it disregarded all scientific standards and became concerned only with profit and political agendas. Nonetheless, it did set off from a legitimate hypothesis: that the brain is the organ of the mind and, as such, its shape can tell us something about consciousness. The problem is it went too far with its suppositions and ultimately engaged in what can best be described as biased guesswork to determine the details. The danger, of course, was that under the guise of a legitimate science, phrenologists went around classifying people all over the western world —ruining lives in the process and acting as the basis for many racist and sexist beliefs.
Since science during the 19th century was already generating an impressive amount of prestige, many people of European descent were looking for the scientific confirmation of their own prejudices. Convinced that Europeans were the “superior race” to begin with, they found in phrenology exactly the justification they were seeking, as it allowed them to claim, without real basis, that Caucasian skulls were more developed or that male skulls were better suited for intellectual pursuits than female skulls (which, according to phrenologists, were conveniently better developed for child care). In fact, Franz Joseph Gall, the father of phrenology, argued that since women’s skulls were larger in the back and less prominent in the front, they had inferior organization skills and were prone to superstition.
Phrenology was never a proper science to begin with by today’s standards (in the sense that it never had a sufficiently rigorous methodology and theory backed up by significant evidence). By the end, however, it was plainly a popular pseudo-science whose proponents irresponsibly advanced. Unsurprisingly, it turned out that their basis for believing in the racial hierarchy of brains in terms of cerebral organs was utterly wrong. Same goes for their sexist discrimination, but even though phrenology fell into disrepute long ago, it wasn't until the 21st century that a study (employing contemporary standards) disproved the theory once and for all.
Though they had some basis in reality (at first, anyway), phrenologists incorporated arbitrary guesses and ungrounded assumptions into their model. For example, to think that there is an organ within the brain that regulates malevolence (in just the way phrenology thought) lacks scientific evidence. Yet many phrenologists simply assumed this to be the case. What’s worse, they went further and arbitrarily selected regions of the brain where their supposed organs putatively were. Without any confirmation or proper experimentation, relying solely on anecdotal accounts, phrenologists called this supposition knowledge.
Now, this might be somewhat unfair to phrenologists —especially those who actually meant well. After all, scientific methodology were still being polished at the time. For the standards of Victorian England, phenology was in fact a proper science. This goes to show how malleable scientific practices have been during the last few centuries. After all, science has self-correcting measures built into its very conception.
Also, phrenology did have some good consequences, in spite of everything. Beyond the unfortunate agendas of its advocates, it opened the doors for proper sciences such as neuropsychology. The problem lied, however, in the pop scientists and the public, who stubbornly adhered to their biases and used partial scientific results as a means to advance some form of oppression.
Not all phrenologists were like that, though. Phrenology was in fact the first scientific-like current to spouse the notion that rehabilitation was possible so that mere punishment may not always be the answer. Nonetheless, evidence against phrenology mounted as the 19th century went by, until eventually it was disregarded by the scientific community. Unfortunately, many still held on to its pernicious racial and sexist classifications well into the 20th century.
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