|Antonio R. Damasio
EMOTION, REASON, AND THE HUMAN BRAIN
Grosset / Putnam 1994
Although I cannot tell for certain what sparked my interest in the neural underpinnings of reason, I do know when I became convinced that the traditional views on the nature of rationality could not be correct. I had been advised early in life that sound decisions came from a cool head, that emotions and reason did not mix any more than oil and water. I had grown up accustomed to thinking that the mechanisms of reason existed in a separate province of the mind, where emotion should not be allowed to intrude, and when I thought of the brain behind that mind I envisioned separate neural systems for reason and emotion. This was a widely held view of the relation between reason and emotion, in mental and neural terms.
But now I had before my eyes the coolest least emotional, intelligent human being one might imagine, and yet his practical reason was so impaired that it produced, in the wanderings of daily life, a succession of mistakes, a perpetual violation of what would be considered socially appropriate and personally advantageous. He had had an entirely healthy mind until a neurological disease ravaged a specific sector of his brain and, from one day to the next, caused this profound defect in decision making. The instruments usually considered necessary and sufficient for rational behavior were intact in him. He had the requisite knowledge, attention, and memory; his language was flawless; he could perform calculations, he could tackle the logic of an abstract problem. There was only one significant accompaniment to his decision-making failure: a marked alteration of the ability to experience feelings.
Flawed reason and impaired feelings stood out together as the consequences of a specific brain lesion, and this correlation suggested to me that feeling was an integral component of the machinery of reason. Two decades of clinical and experimental work with a large number of neurological patients have allowed me to replicate this observation many times, and to turn a clue into a testable hypothesis.
Reason may not be as pure as most of us think it is or wish it were, emotions and feelings may not be intruders in the bastion of reason at all: they may be enmeshed in its networks, for worse and for better. The strategies of human reason probably did not develop, in either evolution or any single individual, without the guiding force of the mechanisms of biological regulation, of which emotion and feeling are notable expressions. Moreover, even after reasoning strategies become established in the formative years, their effective deployment probably depends, to a considerable extent, on a continued ability to experience feelings.
This is not to deny that emotions and feelings can cause havoc in the processes of reasoning under certain circumstances. Traditional wisdom has told us that they can, and recent investigations of the normal reasoning process also reveal the potentially harmful influence of emotional biases.
It is thus even more surprising and novel that the absence of emotion and feeling is no less damaging, no less capable of compromising the rationality that makes us distinctively human and allows us to decide in consonance with a sense of personal future, social convention, and moral principle. Nor is this to say that when feelings have a positive action they do the deciding for us; or that we are not rational beings. I suggest only that certain aspects of the process of emotion and feeling are indispensable for rationality.
At their best, feelings point us in the proper direction, take us to the appropriate place in a decision-making space, where we may put the instruments of logic to good use. We are faced by uncertainty when we have to make a moral judgment, decide on the course of a personal relationship, choose some means to prevent our being penniless in old age, or plan for the life that lies ahead. Emotion and feeling, along with the covert physiological machinery underlying them, assist us with the daunting task of predicting an uncertain future and planning our actions accordingly.
I propose that human reason depends on several brain systems, working in concert across many levels of neuronal organization, rather than on a single brain center. Both "high-level" and "low-level" brain centers, from the prefrontal cortices to the hypothalamus and brain stem, cooperate in the making of reason.
The lower levels in the neural edifice of reason are the same ones that regulate the processing of emotions and feelings along with the body functions necessary for an organism's survival. In turn, these lower levels maintain direct and mutual relationships with virtually every bodily organ, thus placing the body directly within the chain of operations that generate the highest reaches of reasoning, decision making, and, by extension, social behavior and creativity.
Emotion, feeling, and biological regulation all play a role in human reason. The lowly orders of our organism are in the loop of high reason.
It is intriguing to find the shadow of our evolutionary
past at the most distinctively human level of mental function, although
Charles Darwin prefigured the essence of this finding when he wrote about
the indelible stamp of lowly origins which humans bear in their bodily
frame. Yet the dependence of high reason on low brain does not turn high
reason into low reason. The fact that acting according to an ethical principle
requires the participation of simple circuitry in the brain core does not
cheapen the ethical principle.
The edifice of ethics does not collapse, morality is not threatened, and in a normal individual the will remains the will. What can change is our view of how biology has contributed to the origin of certain ethical principles arising in a social context, when many individuals with a similar biological disposition interact in specific circumstances.
Feeling is the central topic of this book, and one to which I was drawn not by design but by necessity, as I struggled to understand the cognitive and neural machinery behind reasoning and decision making. A second idea in the book, then, is that the essence of a feeling may not be an elusive mental quality attached to an object, but rather the direct perception of a specific landscape: that of the body.
My investigation of neurological patients in whom brain lesions impaired the experience of feelings has led me to think that feelings are not as intangible as they have been presumed to be. One may be able to pin them down mentally, and perhaps find their neural substrate as well. In a departure from current neurobiological thinking, I propose that the critical networks on which feelings rely include not only the traditionally acknowledged collection of brain structures known as the limbic system but also some of the brain's prefrontal cortices, and, most importantly, the brain sectors that map and integrate signals from the body.
I conceptualize the essence of feelings as something you and I can see through a window that opens directly onto a continuously updated image of the structure and state of our body. If you imagine the view from this window as a landscape, the body "structure" is analogous to object shapes in a space, while the body "state" resembles the light and shadow and movement and sound of the objects in that space. In the landscape of your body, the objects are the viscera (heart, lungs, gut, muscles), while the light and shadow and movement and sound represent a point in the range of operation of those organs at a certain moment.
By and large, a feeling is the momentary "view" of a part of that body landscape. It has a specific content - the state of the body; and specific neural systems that support it - the peripheral nervous system and the brain regions that integrate signals related to body structure and regulation.
Because the sense of that body landscape is juxtaposed in time to the perception or recollection of something else that is not part of the body - a face, a melody, an aroma - feelings end up being "qualifiers" to that something else.
But there is more to a feeling than this essence. As I will explain, the qualifying body state, positive or negative, is accompanied and rounded up by a corresponding thinking mode: fastmoving and idea rich, when the body-state is in the positive and pleasant band of the spectrum, slow moving and repetitive, when the body-state veers toward the painful band.
In this perspective, feelings are the sensors for the match or lack thereof between nature and circumstance. And by nature I mean both the nature we inherited as a pack of genetically engineered adaptations, and the nature we have acquired in individual development, through interactions with our social environment, mindfully and willfully as well as not. Feelings, along with the emotions they come from are not a luxury. They serve as internal guides, and they help us communicate to others signals that can also guide them. And feelings are neither intangible nor elusive.
Contrary to traditional scientific opinion, feelings are just as cognitive as other percepts. They are the result of a most curious physiological arrangement that has turned the brain into the body's captive audience.
Feelings let us catch a glimpse of the organism in full biological swing, a reflection of the mechanisms of life itself as they go about their business. Were it not for the possibility of sensing body states that are inherently ordained to be painful or pleasurable, there would be no suffering or bliss, no longing or mercy, no tragedy or glory in the human condition.
At first glance, the view of the human spirit proposed here may not be intuitive or comforting. In attempting to shed light on the complex phenomena of the human mind, we run the risk of merely degrading them and explaining them away. But that will happen only if we confuse a phenomenon itself with the separate components and operations that can be found behind its appearance. I am not suggesting that.
To discover that a particular feeling depends on activity in a number of specific brain systems interacting with a number of body organs does not diminish the status of that feeling as a human phenomenon. Neither anguish nor the elation that love or art can bring about are devalued by understanding some of the myriad biological processes that make them what they are. Precisely the opposite should be true: Our sense of wonder should increase before the intricate mechanisms that make such magic possible. Feelings form the base for what humans have described for millennia as the human soul or spirit. This book is also about a third and related topic:
the body, as represented in the brain, may constitute the indispensable frame of reference for the neural processes that we experience as the mind; that our very organism rather than some absolute external reality is used as the ground reference for the constructions we make of the world around us and for the construction of the ever-present sense of subjectivity that is part and parcel of our experiences; that our most refined thoughts and best actions, our greatest joys and deepest sorrows, use the body as a yardstick.
Surprising as it may sound, the mind exists in and for an integrated organism; our minds would not be the way they are if it were not for the interplay of body and brain during evolution, during individual development, and at the current moment. The mind had to be first about the body, or it could not have been. On the basis of the ground reference that the body continuously provides, the mind can then be about many other things, real and imaginary. This idea is anchored in the following statements:
(I) The human brain and the rest of the body
constitute an indissociable organism, integrated by means of mutually
interactive biochemical and neural regulatory circuits (including
endocrine, immune, and autonomic neural components);
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