Part of this is a celebration of the 17th century Rationalist philosopher Baruch Spinosa whose world view is very much in concert with that of Antonio Damasio. Spinosa's demolition of Descartes' mind/body duality is the thread that Damasio takes up and weaves into this graceful and agreeable narrative. Furthermore, it is Spinosa's recognition that we are part of, and contained within, nature and not materially different from nature (another of Descartes' errors) that attracts Damasio's admiration for Spinosa.
Leaving aside this framing device I want to concentrate on Damasio's argument about the nature of humans based on his experience as a neurobiologist, which is really the core of this book.
Damasio recognizes that feelings, like consciousness itself, are perceptions, not states of mind. What is being perceived is the state of the body itself, and what is doing the perceiving is the brain. In this understanding--and I think it is a felicitous one--the brain operates as a sixth sense, something like the so-called third eye of the Hindus. It is not, of course, a supernatural sixth sense, but a sense organ in addition to the other five whose job it is to perceive the homeostasis of the organism, a sense organ that looks within instead of without. Instead of the sensation of color or sound, the sixth sense perceives emotions.
Of course the Van Allen Distinguished Professor of Neurology at the University of Iowa Medical Center does not use such a term as "sixth sense" nor would he allude to the third eye of the Hindus. He is a neurologist, a scientist and (despite his demurral) a philosopher. I mention these other ways of "knowing" in an attempt to provide a larger context for Damasio's argument.
This argument is not original with Damasio (and I don't think he would claim it is). In one sense it is derivative from the growing understanding that consciousness itself, a kind of meta-awareness, is actually a perception. Damasio's "feelings" are part of this consciousness.
A further part of Damasio's argument is that emotions are prior to feelings. First there is an emotionally competent stimulus (ECS). Then there is an "appraisal" of that stimulus which results in appropriate and automatic emotion, followed by feelings based on a perception of the emotion and the external situation. This is on-going, and we usually don't notice it. In extreme cases, such as danger, our feelings are more pronounced. In Damasio's scheme, an ECS might be a grizzly bear come upon suddenly while hiking. The "appraisal" would be the recognition that this is a bear, that it is big and it is potentially dangerous. The "emotion" would be all the systemic glandular, chemical and muscular responses in preparation for the flight or fight response. The "feeling" itself would be what we call fear.
Damasio attempts to explain the experience of feelings in anticipation of "naysayers" who contend that such things are eternal mysteries. He makes a distinction between what, say, a Boeing 777 with all its sensing devices might "feel" and how humans feel. The crux of Damasio's distinction is the enormously greater complexity of the biological organism. But this argument, beginning on page 126, is not satisfactory because it does not explain the subjective experience of pain, which is what the "naysayers" are really talking about.
What I think Damasio should say is that we can never know what the Boeing 777 is feeling (or if it is "feeling") since feelings are subjective experiences. They can only be recognized in ourselves (if we have them) and identified with in the report of others. It is the same as trying to explain what the color red looks like to a blind person or how strawberries taste to someone who has never tasted one. Analogies and comparisons may be drawn, but there is no way that I can ever be sure that I feel what you feel or that the subjective nature of any sensuous experience between one entity and another is the same.
In the fourth chapter, "Ever Since Feelings," Damasio attempts to account for how feelings arose in an evolutionary sense. He believes they help complex organisms solve complex problems. (p. 177) "Body-state maps" work automatically for most organisms, but, Damasio argues, with emotions made conscious through the experience of feeling, humans are able to achieve not only a "concern for the individual self" but with "sufficient integration of the now, the past, and the anticipated future" a more effective game plan for survival and well-being. (p. 178) Feelings signal the conscious mind to become involved and this has proven adaptive.
What I think is profound about this argument is how naturally it would have arisen from the evolutionary experience. Before humans and other sophisticated animals arose, most creatures probably made little or no distinction between themselves and their environment. Their responses were mostly automatic and they had no sense of self. Along comes this great leap forward called consciousness and it works because it makes us more effective at protecting ourselves. It also makes us more fearful of death, of course, which is part of the human predicament.
Despite some difficulties, I am very much impressed with Damasio's effort, and I think that his approach from neuroscience and biological evolution, and through the use of scientific experiment, is eons ahead of the old schools in psychology which attempted to understand human beings based on arbitrary models such as psychoanalytic theory or on limited approaches such as behaviorism. But it must be realized (as I'm sure Damasio does) that we are at a tentative stage of understanding. Some even say that we will never be able to completely understand how our brain works. Some even cite Russell's paradox and Godel's proof about the limitations of self-referential systems (the brain/body is such a system) and deny that it is even theoretically possible for us to completely understand ourselves. Maybe only our artifacts, our computers will be able to understand us.