The Disproven Science of Phrenology; From Hume to Broca Through Gall’s Idea

Phrenology, or psychophrenology (the study of the skull in relation to the mind), is one of the outdated historical sciences; it was once accepted as a scientific theory and today is a tool used by fraudsters.

The history of science, through cases such as phrenology, reminds us that modern scientific methods, even when they have mistakes and problems, will gradually correct themselves over time.

As an outdated science and a tool for fraudsters, phrenology has no particular value for learning or even becoming familiar with; however, studying its history contains fascinating and important points. In this Blogpost, we will examine the background and claims of phrenology.

Historical Background

To understand the context that led to the formation of phrenology or psychophrenology, we need to go back slightly earlier than the period when it was established. In the mid-18th century, the religious sciences of the Church still dominated society. Education and discussion in fields such as philosophy, ethics, psychology, and similar areas belonged to priests or religious missionaries, and (Secular) thinkers had no place in these discussions.

Hume’s Revolutionary Idea

David Hume, Scottish philosopher, was one of the people who opposed this situation. Hume wrote various treatises and works on ethics, philosophy, nature, human understanding, and other subjects. During his lifetime, David Hume did not publish works that directly conflicted with religion or the Church, and these works were only published 30 years after his death; nevertheless, his other published works had displeased the Church so much that he was never employed by any university or government institution.

David Hume’s fundamental idea was that all sciences are, to some extent, connected with human nature. Hume was among the first to use the names of different sciences, including natural philosophy (natural sciences), logic, ethics, politics, and others in his works, and to separate them from religious sciences. He argued that because all sciences are connected with human nature, awareness of them is necessary for everyone.

Hume, who had a relatively close connection with Newton, was influenced by Newton’s efforts to organize natural philosophy (natural sciences), and he intended to create a similarly clear structure for moral philosophy. In his works, Hume categorized thoughts and ideas, distinguished perception from thought, described simple and complex ideas and imagination, and explained the association of ideas and the analysis of causality.

The distinction between perception and thought led Hume to pay special attention to the analysis of the mind. He especially proposed a theory regarding emotions and behavior:

"Throughout history, humans have had the same emotions, and these emotions have produced similar behaviors."

(Hume quoted by Steinberg, 1977)

This argument, which seems very simple, was revolutionary for Hume and his peers. Later, Hume referred to the stable patterns of emotions and behaviors using the term “personality.” Despite all these revolutionary ideas, Hume’s positivism was not well received by Reid.

Reid’s "Mental Faculties"

Thomas Reid, Hume’s fellow countryman, disagreed with him on many details. From Hume’s perspective, emotions experienced internally are influenced by external factors; therefore, in reality, nothing from outside enters the body, and consequently, reaching the reality of the external world is impossible.

The basis of Thomas Reid’s ideas was reasoning. Reid, who had stronger religious beliefs than Hume, believed that the reality of the external world exists inherently within us and that emotions and stimuli are merely tools of our reasoning.

Reid explained in "Essays on the Intellectual Powers of Man" that feelings and emotions are not merely reactions to the real world, but immediate reflections of it; based on this, through common sense, we can gain access to the reality of the outside world. Reid’s book, Essays on the Intellectual Powers of Man, laid the foundation for the psychology of "mental faculties".

In an attempt to demonstrate the reasoning he discussed, Reid introduced several mental faculties, each with a specific function that begins with receiving a reflection from the real world and ends with producing an appropriate response based on its nature.

Overall, Thomas Reid mentioned 43 mental faculties in this book, including abstraction, attention, consciousness, reflection, generalization, imitation, judgment, perception, compassion, and others. One outcome of Reid’s reasoning was physiognomy. Based on Reid’s thoughts and ideas, people believed that by examining and analyzing outward features, they could discover the moral or behavioral characteristics of others. The most well-known example of physiognomy is phrenology, which was once accepted as a science.

Phrenology or Psychophrenology

Less than half a century after the publication of Thomas Reid’s works, his list of mental faculties entered physiological studies. Magendie, Helmholtz, and Hering had already made significant advances in physiological studies and attracted the attention of many people. One of these people was Franz Joseph Gall.

In support of and continuation of the psychology of mental faculties, Gall added three principles:

Mental faculties are not the same in all humans.

• Each mental faculty corresponds to a specific part of the brain.

• The development of a mental faculty in the brain causes that specific area to protrude beneath the skull, creating a corresponding indentation on the opposite side.

Based on this, Gall believed that mental faculties could be determined by measuring indentations and protrusions of the skull. The study of these features became known as phrenology. Although today we consider phrenology a tool of fraudsters, Gall’s idea was very advanced for its time. At that point, not all thinkers accepted that psychological and moral characteristics were directly related to the brain. What removed Gall and phrenology from the domain of science was the method of study and the type of data collected.

Gall recorded the psychological characteristics of an individual, then examined their skull and attempted to make his notes correspond with his observations. In addition, Gall generalized this relationship between characteristics and the physical condition of the skull to all humans. Alongside Gall’s incorrect and inaccurate works and information, several correct observations were also recorded.

For example, Gall was the first to argue that the larger cerebral cortex of humans compared with other creatures was the reason for greater human intelligence. Furthermore, Gall was the first person to identify the characteristics and functions of gray matter and white matter in the brain.

Popularity of Phrenology

The name “phrenology” was first proposed by Thomas Forster. Gall, Forster, and Spurzheim (Gall’s assistant) worked together to write phrenological observations in different languages. These works quickly spread throughout Europe. Many famous thinkers, including Auguste Comte, had accepted phrenology; according to Barkan (1966), the reason for this widespread acceptance was Gall’s popularity and reputation, while the observations themselves were weak.

One reason for the public popularity of phrenology was that it created a framework and guidance for identifying and studying the mind in an objective and materialistic way. People no longer needed to read complex lessons in philosophy and ethics or the treatises of thinkers in order to form an understanding of the mind; instead, simply by memorizing the list of mental faculties and their locations, they could judge all the characteristics of their subject at a glance. Very quickly, phrenological resources reached America, and in 1822 the Central Phrenological Society was established in Philadelphia.

Caldwell, the founder of this society, published Elements of Phrenology two years later, which became a university textbook for this field. Six years later, when Spurzheim (Gall’s assistant) was invited to America by Caldwell, he received a warm welcome and gave lectures at Harvard and Yale universities. After Spurzheim’s death, more phrenological centers were established throughout America, and the Phrenological Journal also began operating.

During the same period, phrenology entered education. Many researchers in the Phrenological Journal argued that mental faculties could be developed through practice and training; therefore, educational programs aimed at strengthening these mental faculties were created. During these years, Edward Thorndike, who was deeply interested in education, became familiar with phrenology. Thorndike carefully examined the claims of phrenology through several parallel studies and quickly concluded that these claims were not true.

Thorndike’s findings, along with the studies of Pierre Flourens, were the final nails in the coffin of phrenology.

Contributions of Gall and Phrenology

Although Gall and phrenology have a negative reputation today, his idea and the discussions it created led to important findings in neuroscience. In addition to his arguments about the size of the cortex and the function of gray and white matter, one hundred years after Gall, his idea (although strongly rejected) motivated many studies on brain lateralization.

Before this, Pierre Flourens, one of the strongest opponents of phrenology, rejected it by proposing the ablation method of study. Ablation studies are studies in which a researcher removes part of an organ, in this case the brain, and studies the deficits resulting from this damage. Before the invention of advanced imaging devices, ablation studies were the most important and trusted method for studying the brain.

In these studies, Flourens argued that the brain functions as a whole and that the idea of specialized functions was entirely wrong.

Several years after Pierre Flourens demonstrated that phrenology was incorrect, Paul Broca, after performing an autopsy on a case who lacked expressive language ability, introduced Broca’s area in the brain as a region specialized for this function. After Broca, many others, in opposition to Flourens, discovered different brain areas with specialized functions, which reignited the debate about brain specialization or lateralization.

One reason for the formation of experimental psychology and scientific structures and frameworks for studying the mind and brain was these very debates, all of which were directly or indirectly reactions to Gall’s phrenology.

Final Words

As mentioned, after rejecting phrenology as a scientific theory, we should consider it a pseudoscience. Although today no one uses it under this name, fraudsters may present Gall’s ideas as their own ideas under different names. Nearly three hundred years after Gall, pseudoscientific discussions and simplistic ideas for complex concepts are still popular among the public.