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.
Preface-IntroductionChapter Summaries & Analyses
Preface Summary
In the preface of the 2005 edition, Damasio offers a brief overview on the development of neuroscience. The early 20th century pioneers of the scientific world—Charles Darwin, William James, Sigmund Freud, and Charles Sherrington to name a few—tackled the issue of human emotions. However, rather than flourishing into the field of neuroscience, the following decades saw a dissociation between research on feelings and research on the human brain. After the publication of Descartes’ Error, the scientific world saw a renewed interest in viewing emotion as part of the field of neurobiology. The preface reiterates Damasio’s somatic-marker hypothesis, which posits that emotions are invaluable to reasoning and decision-making; although they can cause bias if felt too strongly, they do not always hinder reason. The preface then briefly addresses common misconceptions about Damasio’s hypothesis that have circulated over the years.
Descartes’ Error’s main contribution to the field of neuroscience is the hypothesis that the reasoning system evolved from the automatic emotional system. Emotions, which associate (or “mark”) specific physiological responses with specific stimuli, can increase decision-making expediency and effectiveness, ensuring better chances of survival in the natural selection process. The “gut feeling” is an overt instance of this marking, while neuromodulation (such as the automatic release of certain hormones in the body after encountering a particular type of stimulus) is considered a covert response. In other words, the quality of human instinct depends on past instances of successful reasoning, how that information has been classified, and how well it processes and remembers that information. As Damasio demonstrates, emotional makers are especially important for managing social cognition and behavior. Patients who have early-onset illness (those who have cognitive injury before adulthood) cannot continue to learn the cues for appropriate social conduct, while patients who have adult-onset illness know the social conventions but cannot govern their behavior. By establishing the interconnectedness of emotion and rationality, Damasio hopes that his work can further bridge the gap between the humanities and neurobiology.
Introduction Summary
In the introduction, Damasio recounts how he came to question conventional views on rationality. He met a patient who was as intelligent and capable of reasoning as any other but due to a neurological disease that altered a specific region of his brain could no longer experience feelings. After this biological altercation, he became incapable of making “socially appropriate” or “personally advantageous” decisions (16). Damasio realized that emotions did not necessarily always intrude on reason, as old adages suggested. He hypothesized that human reason evolved from mechanisms of biological regulation to help the organism make efficient and accurate decisions—and that reason therefore requires the ability to experience feelings.
Damasio began to develop this hypothesis into a workable theory after 20 years of clinical research. His work proposes that the brain is not the only center for reasoning; human thoughts are regulated by several brain systems in a complex and tiered framework of neuronal organization. Emotion, feeling, and biological regulation therefore affect human reasoning, such as the capacity to adhere to moral principles or social conventions: “The lowly orders of our organism are in the loop of high reason” (18). Damasio notes, however, that this does not cheapen human reasoning or ethical concepts but enhance our understanding of our biology.
The second contribution of Descartes’ Error is the idea that feelings are not simply fleeting mental reactions to a particular stimulus but rather a direct reflection of the body’s landscape. In other words, feelings are regulated not only by the limbic system, but also by the brain’s prefrontal cortices and by sectors “that map and integrate signals from the body” (18). Feelings are internal guides that enable continuous monitoring of the state of the body. Without them, we would lack a way to sense pain, pleasure, or bliss—and would have no way to assign morality to the human condition.
Additionally, Descartes’ Error hypothesizes that the body is the ultimate frame of reference for all neural processes we experience in the mind. Humans explore and understand the world in reference to their own body because the body must have come first in the process of evolution. With the brain, it forms an indissociable organism that as a unit interacts with the outside world. Therefore, human reasoning—as it consists of physiological operations in the brain—derives from the unified system of the body and the mind.
In the final paragraphs of the introduction, Damasio details his methodology and approach. Descartes’ Error is written for a lay audience and attempts to encourage additional research on emotion and rationality. Damasio expresses skepticism about science as entirely objective, especially in the field of neurobiology. Despite years of research, he only feels confident providing theories based on approximations that we can willingly discard as new evidence becomes available.
Preface-Introduction Analysis
Damasio comments on the existing biases in neuroscience and in the broader field of medicine. Discoveries in the field of emotions did not resound with neuroscientists, who seem to detach biology from emotions. Damasio believes that this bias largely stems from the Cartesian model of mind-body duality, which Descartes championed. This philosophical theory argues that the mind is immaterial and operates outside of the realm of the body. Therefore, damage that the body sustains does not affect the spirit. Although Cartesian thought and, more broadly, philosophy are hardly scientific, they affected people’s understanding of human biology. This understanding views emotions as a nuisance to rational reasoning and dismisses diseases of the mind, if invisible, without proper diagnosis.
In addition, the prologue and introduction chapters explain the book’s title and subtitle: Damasio’s theory on how emotions aid in the process of reasoning largely disproves the fundamental points of Cartesian philosophy.
The neuroscientific world at the time dismissed the study of emotions as the realm of psychology. In other words, few experts thought of emotions in terms of biology. However, this is slowly changing. The preface to the 2005 edition mentions that new neuroscientific discoveries have been made since the book’s initial publication. The interconnectedness of emotion and reason has invited more scrutiny and research from experts in the medical field.
