Wider Than the Sky: The Phenomenal Gift of Consciousness (英語) ハードカバー – 2004/2/9
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Gerald Edelman describes how consciousness arises in complex brains and how it is related to evolution, to the development of self and to the origins of feelings, learning and memory. His theories offer a solution to the mind-body problem. --このテキストは、絶版本またはこのタイトルには設定されていない版型に関連付けられています。
The book, appropriately, opens with a poem by Emily Dickinson which describes the brain as "wider than the Sky," "deeper than the sea," and "just the weight of God." In this way Dr. Edelman affirms that to explain consciousness is no easy task, but it is nonetheless the task which he undertakes, and he mostly succeeds. The most basic premise on which Dr. Edelman's theory rests is that consciousness can be explained via scientific inquiry. He attempts to answer the question: "How can the firing of neurons give rise to subjective sensations, thoughts, and emotions?" The answer is framed for the lay reader, although at times the prose becomes dense and reads more like scholarly article than a book for a general audience. Still, the contents of the book are interesting enough to encourage the reader to push past the dense portions. The book provides an excellent overview of brain anatomy related to consciousness, connection and communication between different parts of the brain, the causality between the nervous system and consciousness, and the neurological differences between non-conscious activities and consciousness.
In the first brief chapter of the book, Dr. Edelman defines what he means by "consciousness" by outlining some of the key properties which his theory attempts to explain, such as that it is continuous, continually changing, not exhaustive, and integrative. Dr. Edelman also explains that consciousness as a process is the "dynamic accomplishment of the distributed activities of neurons in many different areas of the brain." This quote, indeed, is a very neat summary of his view and is representative of his writing style.
The first section of the book consists of a brief lesson on the anatomy of the brain focusing primarily on the thalamus, cortex, brain stem, basal ganglia and the various interactions between these regions. Special attention is focused on re-entrant pathways between the thalamus and cortex as Dr. Edelman asserts that it was the development of these connections that allowed the development of consciousness by allowing organisms to integrate present inputs from the environment with memory (neuronal memory) of past events and link the two via categorization. Additionally, Dr. Edelman explains Neural Darwinism (more specifically the theory of neuronal group selection, TNGS) which essentially states that due to the extreme variation in brain chemistry and pathways, a path must be selected, and the paths that are selected are based on value-systems from the brain stem. Essentially, neuronal or genetic memories of what is good and bad for the organism drive the selection of pathways via re-entrant pathways connecting the thalamus to the cortex. Thus, consciousness results from this never-ending selection of pathways at each instant in time driven by value-systems from the anterior brain. Dr. Edelman systematically explains this concept by linking the functions of the above-mentioned brain systems to Dr. Edelman's Theory of Neuronal Group Selection.
While most of the book focuses on primary consciousness and a thorough explanation thereof, the latter part is dedicated to explaining higher order consciousness. According to Dr. Edelman, "primary consciousness is the state of being mentally aware of things in the world, of having mental images in the present." Conversely, higher order consciousness is "the ability to be conscious of being conscious, and it allows the recognition by a thinking subject of his or her own acts and affections." Thus, only an organism with higher order consciousness has a concept of past and future and can plan accordingly. Dr. Edelman asserts that only humans and some higher primates (to a lesser degree) have higher order consciousness. Rather than really explaining a neurological basis for higher order consciousness, Dr. Edelman just states that like primary consciousness, it was evolved. He also hypothesizes that higher order consciousness probably stems from the ability to formulate language and develop a semantic system. Instead of delving into the highly interesting topics of identity and the mind-body problem as implied by the titles of his last two chapters, Dr. Edelman seems to avoid the titles of these chapters and really just summarizes his theory of consciousness.
Overall, Dr. Edelman accomplishes his goal of concisely and clearly explaining his theory of consciousness. However, it must be noted that some of the language in the book would be difficult for someone not accustomed to reading some scientific academic literature. Additionally, it can be vexing that Dr. Edelman does not seem to like recognizing other researchers' work within his text. Even his bibliography seems quite short given the range of information he covers. He seems to pose his theories and hypotheses as facts and does not recognize other biologically based theories of consciousness, which do exist. Additionally, he does not really address criticism of his theory. Still, I would recommend this book to anyone looking for an interesting and overall enjoyable account of a brilliant scientist's theory of one of the most interesting topics in philosophy, psychology, and now neurology.
consciousness, right up there A. Damasio's, T. Deacon's, & others , who've done serious
investigative work on the ultimate frontier: how the self, consciousness & related areas
evolve. As important, "Wider than the sky..." is generally reader friendly, tho' in some
parts focused attention is required to follow lines of reasoning & illustrations. Well worth
the reader's time in understanding the above subject area.
Not only has he exhibited the brain parts, chemical processes and functions responsible for consciousness, also he has mapped them into identifiable aspects of conscious processes themselves. And more importantly, in doing so, his research meets the highest cannon of scientific enquiry: It is empirically based, definitions and hypotheses are lay out clearly; and then they are systematically and clearly proven. Every aspect of the research is transparent and replicable. It is also simply explained, but following Einstein's famous edict, it is not explained simpler than necessary. Yet, even where it is not so simple, it is clear enough that the courageous reader -- bent on following this exiciting adventure to the bitter end -- can indeed follow and understand the meaning of these important conclusions.
In an inmaterial aside, I must say I had put all my bets on another horse in this race to immortality. I thought that Dan Dennett and his computer analogies would in the end prove weightier in this important scientific foot race.
Dispite my earlier misgivings about the Edelman approach, I now know that this always was the best horse in the race. I am thus a happy loser. Two cheers and five stars for the winner.