48 pages • 1 hour read
António R. DamásioDescartes' Error: Emotion, Reason, and the Human Brain
Nonfiction | Book | Adult | Published in 1994A modern alternative to SparkNotes and CliffsNotes, SuperSummary offers high-quality Study Guides with detailed chapter summaries and analysis of major themes, characters, and more.
Themes
The Impact of Cartesian Mind-Body Duality on Neuroscience
One of the book’s main themes, as evident in its title and subtitle, is the impact of the Cartesian concept of mind-body duality on the field of neuroscience. The book’s opening paragraphs point to a gap in knowledge on the topic of emotions in neuroscience. Instead of seeing them as part of human biology, scientists relegated emotions to the field of psychology. As a result, people like Elliot, who are perfectly intelligent yet have a compromised sense of self, have difficulty obtaining disability benefits. Psychological evaluations cannot detect their conditions, and evaluators downplay their problems. This is partly due to the widespread belief in the incorporeality of the human mind, a philosophical perspective that Descartes championed.
The mind-body duality theory posits that the body is simply a machine that responds to stimuli while the mind (or spirit) is immaterial. When inappropriate emotions do not cloud the mind, humans are capable of high reason. This philosophical view became popular in Descartes’ time, and Damasio insists that its impact stretched to the medical world. The author believes that Cartesian thought negatively influenced Western medicine and retarded its development by several decades. From the time of Phineas Gage to Elliot, research to scrutinize the neurobiological foundations of reason—especially in connection to emotion—has been scant. Given the widespread belief that the human mind is immaterial, it follows that any damage the body sustains cannot affect the mind.
The cases of Phineas Gage, Elliot, and other patients have sufficiently proven that damage to certain areas of the brain affect the capacity to feel emotions, which in turn impacts decision-making. Although these patients remain intelligent and coherent, their actions have clear negative effects on their personal, social, and professional lives. Their injury not only changes their behavior but compromises their independence. Without access to emotions, they lose an important part of their neural self. Because of their stunted capacity to make advantageous decisions, and their social standing and intrapersonal relationships suffer. However, without adequate tests to prove their disability, they remain at the mercy society’s (and sometimes even their physicians’) prejudiced views. Damasio concludes that the Cartesian philosophy of mind-body duality invalidates invisible illnesses: It desensitizes lay people and scientists like from considering the human mind as material and embodied; therefore, it biases diagnosis against properly detecting and considering diseases of the mind.
Emotions as Crucial to Effective Reasoning
Emotions have long been considered a nuisance to effective reasoning. Western philosophers such as Immanuel Kant, Plato, and Aristotle, all cautioned against letting emotions cloud judgment. The ensuing picture of the human mind is therefore one of separation between “basal” emotions and “high” reasoning. Before his research on emotions, Damasio imagined that separate neural circuitry likely transmitted emotional and rational information. However, after encountering Elliot, Damasio’s vision began to change.
Elliot’s brain tumor damaged most of his frontal cortices in both hemispheres. After a successful surgery, he clearly retained his mobility, language, and intelligence. However, his personality changed, and he became incapable of making advantageous inter- and intrapersonal decisions. He became indecisive and could not complete tasks in time. He pursued terrible business ventures despite the warnings of friends and family. His first and second marriages both ended in divorce. Nevertheless, he performed above average in intelligence tests, and his logic was sound. The evident change in him was his incapacity to feel emotions like before.
Elliot and other patients in the Phineas Gage matrix convinced Damasio that emotions were crucial in assisting decision-making. With additional testing, he began to form the somatic-marker hypothesis, which posits that the body can mark a type of stimuli to associate it with an emotion. With the help of working memory, the mind stores these somatic markers and can later use them to anticipate changes in the environment. For example, if the mind/body associates fear with the large wingspan of an eagle, then seeing another large bird might immediately prompt a flight or fight response. If the mind/body experiences this fear in relation to these birds at specific times in specific areas, the organism can learn to avoid that scenario. In humans, both instincts available at birth and experience throughout life inform somatic markers. Without emotions acting as bias, decision-making becomes an endless task of weighing often-countless pros and cons, which social scenarios further complicates, as every action might engender a response that requires another decision. Because Elliot and other patients with prefrontal damage lack emotional bias, they lose the ability to quickly decide and anticipate consequences; therefore, Damasio concludes, emotions are crucial to effective decision-making.
The Body and Mind as Ever Changing
Descartes’ Error paints the body and mind as being always in motion. Organisms constantly interact with their environment; human experiences are ever growing. The somatic-marker hypothesis posits that the body continuously reports its condition to the brain, both through neural and chemical signals. This enables the mind to consistently superimpose images of the current state of the body over images of how it generally is. Similarly, the body’s neural system continuously maps the concept of self, which includes information on identity, workplace, habits, etc. This mapping happens in the background (without the organism’s awareness) and helps the organism ascertain its geographical boundary and overall condition.
This mapping process is integral to having a complete understanding of self. When the neural system breaks down and becomes incapable of updating the body’s status, it compromises the organism’s selfhood. For example, patients with both anosognosia—a disease that prevents one from recognizing changes in one’s own body—who also have left-side paralysis insist that they are perfectly capable of moving both sides of their body and cannot recognize their left-side disability even when it is directly pointed out. This denial is not merely psychological, Damasio argues; it stems from a biological impairment that compromises their neural self. Their bodies have changed, and are ever changing, but the neural system responsible for relaying this information to the mind is impaired. Therefore, while the body is still in motion, the mind ceases to recognize this.
From an evolutionary standpoint, organisms must have had a body before developing a mind. It follows that the mind evolved primarily to care for the body. The advantage it gives the organism is the dual capability to regulate increasingly complex internal processes while also navigating changes in its environment. Both internal processes and the external environment are constantly changing, so it becomes crucial for the mind to map these changes on a moment-to-moment basis. In other words, mutual and consistent communication between mind and body is crucial for the organism’s survival and integrity; a static understanding of the body paints an erroneous picture of stagnation in a world in motion. Damasio’s theory illustrates how the body continuously interacts with internal and external worlds. The mind, whose evolutionary purpose was likely to ensure the body’s integrity and survival, communicates with the body to consistently map its condition and superimpose it on older data for comparison. Damasio’s hypothesis ingeniously connects mind and body as well as emotion and reasoning.
