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on May 5, 2007
Will knowing how the brain works--in particular, what consciousness is--transform our view of human knowledge itself? This is the question that looms large in Second Nature, Gerald Edelman's latest book. Though compact at 157 pages (excluding preface, footnotes, and index), this work represents Edelman's ambitious consideration of the implications of his view (likely the correct view) of the brain and mind for the broader world of human concern. Edelman seeks to understand the nature of knowledge as it is generated within a biological entity--the brain--that is shaped both by individual history and evolutionary forces. Astonishingly, in this little book, he succeeds in this quest marvelously. The result is no less than a new type of epistemology--what Edelman refers to as "brain-based epistemology."

Gerald Edelman is no mere dilettante or interloper in neuroscience. Since the publication of The Mindful Brain (a volume he co-edited and co-authored with Vernon Mountcastle) nearly thirty years ago, Edelman has diligently toiled in the theoretical vineyards to construct a comprehensive theory of higher brain function that is consistent with the latest available neuroanatomical, neurophysiological, and behavioral data. Perhaps the most significant fruit of these labors, the Theory of Neuronal Group Selection, or Neural Darwinism, proposes that, during neurogenesis, a vast "primary repertoire" of physically connected populations of neurons arises. Later, in a process akin to Darwinian selection, a "secondary repertoire" of functionally defined neuronal groups emerges as the animal experiences its world, and that world in turn selects patterns of connectivity (the so-called neuronal groups) that provide a good enough fit in a given moment to engender some kind of positive outcome. Underlying this selection is a neural "value system," established over the course of evolution and believed to comprise small populations of neurons within deep brain structures, that assigns salience to particular stimuli encountered by the animal. When the response to a given stimulus leads to a positive outcome (i.e., eating satisfies hunger), the value system will reinforce, or strengthen, those synaptic connections between neurons that happened to be firing at that particular moment. There is now a greater likelihood that, when the animal encounters similar stimuli in the future, many of the same neurons that fired the first time will fire together again. When a stimulus is noxious, the value system will similarly strengthen the connections between neurons that happened to be firing at the time the stimulus was encountered, thus increasing the salience of that stimulus. When a stimulus has no salience, synaptic connections between neurons that fired upon first exposure to that stimulus will become weaker with successive exposures. Simply stated, neurons that fire together wire together. Keep in mind that the mapping of the world to neural substrate is degenerate; that is, no two neuronal groups or maps are the same, either structurally or functionally. Nor are the populations of neuronal groups that make up the neural mappings of the world exactly the same each time similar stimuli are encountered. These maps are dynamic, and their borders shift with experience. And finally, since each individual has a unique (and privileged) history, no two individuals will express the same neural mappings of the world. Indeed, from the establishment of the primary repertoire during development, no two brains are wired in exactly the same way, not even those of identical twins.

Notwithstanding any of the various attempts at historical revisionism that you may have encountered if you've read broadly across neuroscience and the philosophy of mind, the selectionist view of the nervous system begins with Edelman's highly original work. What follows from others making selectionist arguments is (whether they like it or not) purely derivative.

Although Edelman's theoretical framework has expanded to include the Dynamic Core hypothesis, a proposed mechanism for consciousness (See Edelman and Tononi's A Universe of Consciousness) that he discusses throughout Second Nature (and I will not unpack here), I believe that Neural Darwinism is his most fundamental contribution to modern neuroscience. To this day, it remains the most detailed and comprehensive theory of higher brain function ever proposed. Perhaps most importantly, and likely to the great consternation of those critics capable of lobbing only ad hominem attacks at Edelman himself, the theory is, in the best traditions of empirically grounded science, eminently testable. I have laid out a brief (and wholly inadequate) sketch of Neural Darwinism here because many of the critiques of Edelman's work are colored either by misapprehensions about this theory or the unrealistic expectation that its underlying mechanism can and should be easily described and readily digested. But unless you can appreciate the vast complexity of a biology shaped by evolutionary principles that are not well understood by the lay public (or even some scientists, for that matter), you will probably struggle to understand much of what Edelman has to say, even in this little book. The fault lies not in Edelman's prose, but rather in the nature of the subject matter he seeks to describe (contrary to the complaints of a few critics--see below). Persevere; if you love biology, are fascinated by the mysteries of the brain, and are curious about the implications of modern brain science for the nature of human knowledge and endeavors, then this book should be your touchstone.

I'm not going to give you a detailed rundown of the contents of Second Nature here; I'll simply recommend that you read it. In the remaining paragraphs, I hope to provide you with something I think will be of even greater value: a discussion of some of the most commonly raised criticisms of Edelman and his work. I hope that this will allow you to read the book--if not totally free of misconceptions--at least less encumbered by what I believe to be unfair attacks on one of the most constructive and distinguished bodies of work in modern theoretical neuroscience.

It is curious that Edelman's work engenders as much vitriolic reaction as it does. If you've read my review up to this point, you've certainly concluded that I'm firmly in Edelman's camp. That said, what follows are the most common claims about Edelman and his ideas from his most vocal critics. These can be clearly stated and quite easily dispensed with. In no particular order, here they are:

1) There is nothing original in his ideas.

2) Natural selection is not an apt analogy for what the brain does.

3) His models are instantiated on computers even though he claims that the brain is not a computer (look up the review by George Johnson).

4) He doesn't understand, or mischaracterizes, the views of modern philosophers.

5) He denigrates philosophers and their work.

6) He omits the work of others.

7) He doesn't communicate his ideas effectively, i.e., he does not write clearly or well.

Now, my rejoinders to the above claims:

Claim #1: Quite simply, those who make this claim need to practice better scholarship. Edelman first suggested the idea of neuronal group selection nearly thirty years ago. Back in the late 1970s, no one else in neuroscience ventured any such selectionist ideas. Moreover, early on, Edelman took quite a lot of heat for this notion. His transition from immunology to neuroscience, though logical from a theoretical perspective (moving from one selectional domain to another), may have offended stalwarts of the neuroscientific establishment. In any case, later, when the evidence suggested that Edelman was indeed correct about competition among groups of neurons (see, for example, the work of M. Merzenich), the attitude of many within and outside of neurobiology was something along the lines of, "oh yeah, but of course there are competitive interactions between functional neuronal assemblies; everybody knows that!" Well, clearly not everybody, and certainly not back in 1978. Over three decades, an original idea had thus been unfairly relegated to derivative status. It wasn't derivative; it was the source.

Claim #2: There is much evidence to suggest that neural representations of the world are dynamic and based on the competitive interactions between functionally defined and degenerate (e.g., non-identical) groups of neurons. Many alternative views of the central nervous system (CNS) have invoked formal computational principles. But everything we know about the CNS suggests that it functions nothing like a computer. If it were a sort of Turing machine, it would represent the only such example known to biology. Most modern biologists steeped in evolutionary principles (whether strictly Darwinian or of the Punctuated Equilibrium variety championed by Stephen Jay Gould and Niles Eldredge) would probably balk, first, at the notion of the emergence of organized populations of cells (or proteins or molecules, for that matter) capable of executing computations in the same manner as a digital computer, and second, at the idea that this sort of arrangement, if it had appeared at all, would have appeared only once over the course of evolutionary history. Finally, a challenge to those who too easily dismiss Edelman's Theory of Neuronal Group Selection and all that has followed from it: Go ahead and TRY to formulate a detailed, testable theory of brain function that takes account of the underlying biology of the central nervous system. Any takers? No? Enough said.

Claim #3: A number of Edelman's critics, such as the science writer George Johnson (Miss Leavitt's Stars), see little distinction between Edelman's characterization of the workings of the brain and computation-based information processing. But there is one profound difference. In selection-based systems such as the immune system or the CNS, meaning or "information" is imposed from within; in instruction-based systems such as digital computing, meaning is imposed from without; there is no internal meaning--a lot of lights may be on, but nobody's home. Often, traditional digital computers fail in tasks that involve discriminating novelty in a changing environment or generalizing across categories; brains excel in such tasks. But brains built like computers would be neither flexible nor adaptive. Moreover, a computer built like a brain, with little or no specific point-to-point wiring, would not be a functional computer. Precise instructions could not be implemented on such a machine in the absence of point-to-point wiring.

Some critics perceive something of a contradiction in the fact that, while Edelman has strongly rejected the notion of brain-as-computer, he and his colleagues have created simulations of the brain using massively powerful supercomputers. This point is either a red herring or simply represents a woeful ignorance of the nature of computer-based modeling and its applications in biology. When one models biological structures and their interactions on a computer--whether these are proteins folding a certain way, bones reacting to mechanical forces, or brains that can interact with, and adapt to, a world of novelty--one essentially uses software to approximate the analog and not infrequently stochastic behaviors of elements within the biological system being modeled. So, in the case of a biologically based brain simulation, the software instantiates on the computer a functional approximation of neurons with firing thresholds which shift in a circuit interaction- and context-driven fashion. The computer's overt behavior--or that of the device it controls--is not binary when this software is being run. The computer--or more properly, the simulation running on it--does not behave like a classical Turing machine. Why is this so hard to understand?

Claim #4: Actually, Edelman's descriptions and characterizations of various philosophical stances are generally detailed and accurate, and show a depth of understanding that could only have come from a thorough and voracious reading of much of philosophy, not just the philosophy of mind. Edelman has obviously taken in and "gets" the bulk of what philosophers have to say about the nature of knowledge.

Claim #5: In fact, I think Edelman has pulled his punches when it comes to taking on modern philosophical approaches to brain, mind, and the nature of knowledge. Although in his review of Second Nature, David Papineau clearly took offense at Edelman's characterization of philosophical approaches to epistemology as "armchair operations" (Nature, 2007, 446(5):614-615), it is not at all clear that Edelman actually meant this as an attack. When he makes this statement, though, I think he is clearly on the right track; he just doesn't follow that track far enough. Like it or not, these are armchair operations, and few philosophers have ventured beyond such musings to explore the actual neural substrate that generates knowledge in the first place. There are notable exceptions; the efforts of some philosophers, including most prominently John Searle, Hilary Putnam, Ned Block, and Thomas Metzinger, demonstrate a truly deliberative and concerted effort to incorporate what is known about the biology of the brain into thinking about the nature of cognition in general, consciousness in particular, and human knowledge. But many modern philosophers, I believe, are not merely armchair theoreticians; they are intellectually lazy. They think that, when considering the nature of mental processes, it is actually possible to do an "end-run" around neurobiology. Why bother actually relating organic structure and function to cognition? This stance is, quite simply, bizarre; it seems to be akin to a sort of a holdout syncretism of the ideas of Fodor and Skinner. Whatever the roots of this particular philosophical strain, it is wrong and intellectually dishonest. That Edelman has never actually expressed this in print I can only ascribe to some sense of old school propriety and intellectual fairplay. Would that his critics could exercise the same measure of propriety and fairplay.

Claim #6: Nothing obligates Edelman to give a précis of the state of the art of all of theoretical neuroscience (such as it is), particularly in such a compact book. In his review of Second Nature, David Papineau takes Edelman to task for the absence of "scientific comparisons" and suggests that "[a] naïve reader could easily form the impression that Edelman and his associates are the only people trying to use scientific information to cast light on the human mind." (p.615) Well, this is a rather silly point, as a book of this size is clearly not intended to serve as a reference text or primer. Moreover, had any other neuroscientists actually offered competing comprehensive and testable theories of higher brain function and/or consciousness, I have no doubt that Edelman would have felt obliged to take full account of these in Second Nature. So far, they haven't. David Papineau offers that the book presents a senior scientist's "potted cultural history." (p.615) For what it's worth, I eagerly await Prof. Papineau`s version of the cultural history of the science and philosophy of mind. What would such a [presumably] unexpurgated historical landscape actually look like, Prof. Papineau, and precisely who and what, in the way of deep theoreticians and theory, would populate this landscape? Offer some examples and I might even relent and recant my denigration of your odd and useless proclamation.

Claim #7: This is a very old criticism, dating way back to the publication of Neural Darwinism in 1987. In his thick body of work, Edelman has tried to explain nothing less than the workings of the most complicated object in the known universe. Moreover, early on, he attempted this at a time when there were no commonly accepted terms for the interactions he sought to describe ("reentry" and "degeneracy" are examples of terms Edelman coined more than twenty years ago to describe phenomena and properties not previously recognized by neuroscientists). There are many biological properties, principles, and concepts that, by their nature, don't lend themselves to simple descriptions or easy explanations. In Second Nature, Edelman's prose and its organization are clear and amazingly methodical for such a brief book. The book is densely packed, and the subject matter is obviously difficult. Unlike some philosophers, whose abstractions of cognitive properties resemble nothing more or less than a functionalist's "black-box," offering [biologically] context-free and meaningless thought experiments and little depth or intellectual satisfaction, Edelman has gone to great pains in previous works to describe very complex neural properties in the clearest possible manner. With Second Nature, he has taken on the additional task of reconciling his view of brain function--specifically consciousness, that most mysterious of all neural processes--with the nature of human knowledge itself. Edelman addresses the question of whether the highest expressions of human concern--creative pursuits such as art, poetry, and music, or the ethical and moral codes that glue human societies together--can ultimately be " . . . reduced to a series of epigenetic rules of brain action." (p. 156) Unlike Patricia Churchland, Edelman is not a reductionist, so his answer to this question is a resounding "no." (playing or listening to the Chaconne from Bach's Partita #2 cannot be boiled down to an orderly, reproducible code of neuronal firing; and, contrary to the view offered in Churchland's Neurophilosophy, the terms that refer to complex neural function will not simply fall away as neural mechanism reduces to the description of the electrochemical properties of firing neurons; nor, finally, will consciousness come down to the subatomic states of microtubules, as Penrose has suggested). But within the subtext of Second Nature is another, very provocative, question that few before have posed in earnest: Would knowing how the brain works down to the finest detail fundamentally alter the nature of human concern? Although he offers no explicit answer to this question, I suspect Edelman's answer would be "probably not."

So, in sum, don't be put off by the acerbic musings of Edelman's critics (or the length of this review); go ahead and read Second Nature. It may change profoundly your perspective on the nature of human knowledge and its ultimate creator and locus, the human brain.
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on December 28, 2006
Printed small, Edelman's "Second Nature" is a bit-sized flight through how consciousness relates to larger cultural phenomena. This book is supposed to be a bridge between neurobiology and philosophy.

Edelman coins the term "brain-based epistemology" which he calls an extension of W. V. O. Quine's naturalized epistemology (pg. 2). Edelman also says that he follows in the footsteps of William James who said that consciousness is a process whose function is knowing (pg. 4).

Edelman has 3 graphs (2 on pg. 16 & 1 on pg. 29). The 1st graph is a rudimentary localization of cortical functions, the 2nd graph is a rudimentary visual of synaptic connections, and the 3rd graph is a simple (but important) directional illustration of "Reentry." For Edelman, the brain is a selection system which selects based on an evolutionary drive. "Neural Darwinism," which Edelman says has 3 tenets basically refers to the plasticity of brain development and processes. "Reentry" is the most important part of Neural Darwinism because "reentry in the enormously complex dynamic core distributed to the thalamus and across the cortex was the key integrative event that led to the emergence of conscious experience" (pg. 39).

Much of the book's middle is dedicated to finding a place where the modern divide between the literary and the scientific (Edelman is here borrowing from C. P. Snow) can meet. In order for the arts to meet the sciences the arts much respect the divide between "ought" and "is," and the "qualified realism" (pg. 154) where the scientific method (i.e. Edelman's "Neural Darwinism") is the best method to practical truths about beings and things) while the sciences must admit that ontological quality of "Qualia" (Edelman draws here from Thomas Nagel's ""What is it like to be a bat?" in Nagel's book "Mortal Questions") and science must admit that a "fully reductive scientific explanation" of the humanities is "not desirable, likely, or forthcoming" (pg. 66).

Furthermore, the "underlying historical processes" of our epistemic condition "rule out simple reduction" to scientific description (pg. 87). This can be seen as a critique of Paul Churchland's materialistic approach and Daniel Dennett's similar "heterophenomenology." Edelman aligns with John Searle when he says that "consciousness is a first-person affair" (pg. 89). This leads me to my first critique of Edelman....

Edelman reiterates the Humean "naturalist fallacy" of deriving an "ought" from an "is" when in fact John Searle has written particularly on this subject in his essay "How to Derive "Ought' from "Is'" (1st published 1964) showing that the Humean fallacy must be reappraised. Edelman refuses to recognize Searle's nuanced discussion in his text and/or in his footnotes. Secondly, if we take Edelman's notion seriously that "Science derives from a variety of cultural events and it generally does not necessarily impel or predict such events...it is as good as we can get" (pg. 156), then we must understand that Neural Darwinism is just one way among others of coping with whatever reality is, it just happens that so far Neural Darwinism is the best way to cope. Edelman seems to hint at this while at the same time he prioritizes science: "The main strength of the brain-based approach is that it provides scientific grounds for a pluralistic view of truth" (pg. 148). Edelman seems to be vaguely conflating a best approach and the "True" approach. The problem, again, is his hard-and-fast line between "Is" and "Ought." (So for example, the debate between evolutionists and creationists should not be over "Truth" but instead over what John Dewey calls "warranted assertability"). Edelman should argue instead that since brain-based epistemology explains that we are probably selectionalistic dynamic systems in an econich and culture it follows that our knowledge of Neural Darwinism is not so much a discovery as the best available way to cope with phenomena. If Edelman truly wants to "follow in the footsteps of William James" then he'll find this criticism a reasonable corrective.

Another criticism: Edelman wrongly conflates Richard Rorty and Charles Taylor on a sensitive subject dealing mental representationalism and embeddedness in the world (pg. 45-46). Rorty is known, in part, for his attack on representationalism and Taylor is known, in part, for his defense of a kind of Heideggerian embodied-embedded approach. However, Taylor, attacks Rorty's approach with his own essay "Rorty and Philosophy" in the book "Richard Rorty: Contemporary Philosophers in Focus." Edelman presents Rorty and Taylor together like an undergrad presents Plato and Aristotle together (meaning the glaring differences go unnoticed under the heading of "the Greeks").

Another criticism: Edelman spends only one paragraph on the problem of free will (pg. 94). This is shameful. Better literature on free will includes Daniel Dennett's "Freedom Evolves." Another approach (more like Edelman's approach) is John Searle's "Freedom and Neurobiology."

Overall, this book talked very little about our "Second Nature." The author cited sources poorly. In order to dissolve C. P. Snow's dichotomization in "The Two Cultures" Edelman is going to have to write more than 157 bit-size pages.
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HALL OF FAMEon January 18, 2007
Gerald Edelman grieves the "divorce" science and the humanities have experienced. Since there is no final decree in the proceedings, he wants to heal the breach. He has a mechanism to further the reconciliation - something he calls "Second Nature". That "Second" is the human's brain's extensive capabilities - capabilities that exceed what we see in the rest of Nature. With his long career in brain science and as a scholar well versed in the evolutionary background that makes us human, he may have an appropriate answer. In this book, he makes an excellent case for why the divorce need not be permanent. It's offered as a conciliatory gesture under the banner of his theory of "Neural Darwinism".

The label implies the obvious - our brains - hence, our minds - hence our "conscicousness" is the product of natural selection. It's not something separate from the real world in any way. Edelman, like all philosophers today, must face the still unfinished task of eliminating Descartes' "dualism" from consideration. "Dualism" effectively denies our evolutionary heritage. What is that heritage? Edelman enquires, and offers us his view of it.

Humans are distinct from the rest of the animal kingdom in one important way - our version of consciousness. As our brain developed, it created a unique form of neural pathways. Not only is the neural net highly complex - in a single human brain, the potential connectivity "far exceeds the number of elementary particles in the universe" - the methods of connecting are unique. Our brain, which spends far more effort viewing itself and the rest of the body than it does dealing with incoming or outgoing signals, uses a host of internal feedback loops ["reentrant" processing] to do its job. These reentrant signals are reinforced by areas Edelman calls "degenerate". Degeneracy doesn't imply deterioration, but instead is a kind of redundancy - many areas in the brain handle the same or similar tasks. With this brain structure emerging in early humans, selection could favour certain brains and pass their patterns down the generations. Habits once erratic and highly individual, ultimately became the social norm - many individuals shared the trait. Language, of course, with syntax and vocabulary, enhanced those inherited abilities. However, Edelman is dismissive of the concept of a "language module". Instead, he feels that communication reinforced traits already present, enhancing social interactions and forging bonds. Those bonds further contributed to behaviour factors literature describes and philosophy analyses.

Much of Edelman's presentation is reminiscent of Edward O. Wilson's call for "Consilience" in the book of that name published a few years ago. Edelman, however, in a bizarre designation, calls Wilson's proposal "reductionist". One can only tremble at the thought of Wilson's reaction. Richard Dawkins' "memes" are also dismissed as almost unworthy of notice. The author's grand, comprehensive view of the brain rejects anything "mechanistic". Yet, in what seems to be unconscious irony, Edelman concludes the book with a discussion of robots. Recently, some scholars have proposed the idea of an unconscious robot. It may look, walk and talk like a human, but lacks "consciousness" under most definitions. Edelman's team has, however, constructed a series of devices with extraordinary capabilities. Aptly named "Darwin", they've constructed several versions. These devices are highly mobile, and possess numerous input devices that "hear", "see" and "feel". Instead of programming them to seek or avoid objects or obstacles, the Darwins are set loose to wander and examine. When they perform approved acts, they are given verbal approval. This leads to "better" behaviour in future excursions. These robots "learn" how to live. Clearly, this is rich fare for the humanities to savour. As is the entire book. [stephen a. haines - Ottawa, Canada]
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on January 25, 2007
This is the second Edelman book I've read, which was supposedly for a popular, albeit educated, audience, and like "Wider Than The Sky", I found his prose uniquely bad and off-putting. I've read loads of books now on the mind, from Searle, the Churchlands, Fodor, Pinker, Ramachandran, Gazzaniga, et al, and all of them are able to express themselves clearly even when discussing sophisticated concepts. But for me, reading anything by Gerald Edelman is a terrible chore - like some crazy reading comprehension test devised by a sadist - rather than an exciting journey through a brilliant mind. Indeed, I wondered a few times reading this book if Edelman might even feel a perverse pride in keeping his writing below the average standards of intelligibility.

Australian philospher David Stove once remarked that he very much appreciated the contributions of John Stuart Mill, because while (he thought) Mill was wrong, his ideas were expressed with great clarity, allowing them to be more easily evaluated (which in turn facilitated greater understanding). Edelman must be a smart man, so I wish he was able to more effectively communicate his ideas. When so many of his colleagues can do it, I don't know why he can't.

Addendum Mar. 10, 2007: I just read John Horgan's book "The End of Science", and was surprised to find a section on none other than Edelman himself. I was even more surprised (and frankly, sort of thrilled) by the quotes there from Edelman's peers (like Daniel Dennett and the late Francis Crick), on the incomprehensibility of Edelman's gobbledygook (in the back of my mind I was still wondering whether it was just me...). In fact, one fellow scientist expresses his judgment that Edelman tries to disguise unoriginal ideas through the use of rhetorical bluster, pedantry, and new names.
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on September 10, 2009
Gerald Edelman won the Nobel Prize for Medicine in 1972 for his groundbreaking work on immunity. Though most Nobel Laureates either choose - or are forced to - rest on their laurels, Edelman soon began to move his attention to the brain and his first book on his theories was published as The Mindful Brain almost thirty years ago. In recent years he has suggested that the ways in which the complex adaptive system by which the body decides which lymphocytes to stimulate and mobilize may be similar to the way in which the brain functions.

His theory is known as "neuronal group selection" or "Neural Darwinism" and proposes that anatomical connections in the brain are selected during development. Secondly that there is a second selective process that occurs as a result of experiences after birth, and finally that there is a system of what is known as re-entrant signaling.

It is a beautiful and complex theory and over the last twenty years he has explored these ideas in a series of books: In 1987 he published Neural Darwinism: The Theory Of Neuronal Group Selection Three years later came Remembered Present: A Biological Theory Of Consciousness, and then Bright Air, Brilliant Fire: On The Matter Of The Mind in 1992. It was almost a decade before he returned to his theme in A Universe Of Consciousness How Matter Becomes Imagination. I have enjoyed all of them, though none is easy reading, and I kept coming away with the uneasy feeling that the work is ingenious, but does not explain quite as much as it seems.

This latest book, Second Nature, is much the most accessible of his works, but left me with a similar feeling: ingenious but lacking.

So what is it about? Edelman skims over the details of his theory of neuronal group selection but on this occasion he does not assume a lot of knowledge on the part of the reader. So he explains the basic ideas very clearly and sets the theory in context in thirteen chapters:
1. The Galilean Arc and Darwin's Program
2. Consciousness, Body, and Brain
3. Selectionism: A Prerequisite for Consciousness
4. From Brain Activity to Consciousness
5. Epistemology and Its Discontents
6. A Brain-Based Approach
7. Forms of Knowledge: The Divorce between Science and the Humanities
8. Repairing the Rift
9. Causation, Illusions, and Values
10. Creativity: The Play between Specificity and Range
11. Abnormal States
12. Brain-Based Devices: Toward a Conscious Artifact
13. Second Nature: The Transformation of Knowledge

He takes the view that any effective theory of consciousness must take a global, whole brain approach and must be based on selection rather than instruction.

In contrast to many books for the public, he emphasizes that "the brain is not a computer, and the world is not a piece of tape." This is important: complex systems are riddled with "noise" and computers have to get rid of it, while brains actively depend on it. The brain uses the enormous and ever-changing variability of sensory inputs - noise - to construct patterned responses.

A problem that has pre-occupied philosophers and scientist for generations is subjectivity or qualia: how do we generate those private experiences of sights and sounds? Edelman thinks that he has the answer: Complex looping neural circuits that make multiple discriminations, and the qualia are those discriminations.

This ingenious idea is hard to prove. It also fails to take into account observations on the continuity of awareness in meditators with negligible neurological activity. Or the hardest nut of all: does this truly help us to create a neurological model of consciousness? For some people such questions are unimportant, and simply await time and technology. But I think that they remain key tests of the theory.

This is a short, but extremely clear and thought provoking book that I recommend highly.

Richard G. Petty, MD, author of Healing, Meaning and Purpose: The Magical Power of the Emerging Laws of Life
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on May 23, 2007
Daniel Dennett once characterized Darwin's theory of natural selection as the best single idea anyone ever had. I generally agree with that, so I am naturally well-disposed toward selectionist accounts, of which Edelman's Neural Darwinism is an example. I also have run out of patience with the clever word games that unfortunately constitute far too much of epistemology as it exists in academic philosophy, and that makes me a receptive audience for this kind of selection-based approach. I also agree with Edelman's rejection of computer-based models of human cognition and of Chomksky's mythical language organ. So, yes, I liked the book, found many insights in it, and I recommend it as a stimulating read. All that said, and given the extremely informative review provided below by L. Guzman, I will focus on what I found less than satisfactory.

When it comes to psychology, Edelman's view of the field seems to be bounded by Piaget and Freud. He gives the occasional, semi-perfunctory nod to the environment, but never in serious detail considers the importance for both brain and behavior of the history of interaction between organism and environment. Nor does he show any knowledge of the huge literature describing detailed analyses of environmental effects on behavior, analyses that specifically emphasize the selective effects of environmental consequences. Edelman's account reminds me of how the genome-phenome distinction is sometimes treated in relation to selection, as if genes themselves are directly selected for or against, and then go forth and do things in the world. In this case, it's always the brain doing this or that, with little or no acknowledgment that it is behavior that makes contact with the environment and is subject to selection, with resultant effects on the brain. We know from sensory deprivation experiments that, absent a reasonably normal environment, brain activity quickly drifts into disorder and incoherence. One suspects that the well-known behavior-specific effects of certain brain injuries, which Edelman describes in some detail, have been overgeneralized, resulting in an overly brain-centric view of behavior. What's needed here is an explicit input-output model, where the inputs are the initial state of the organism and the functional characteristics of the environment in which it operates; the fact that computer-based models have used input-output terminology should be considered of no relevance. At some points in Edelman's presentation, I found it difficult to decide just what constituted the output side -- and whether we were ever finally emerging from the neurological realm to the world outside.

A key notion for Edelman is the idea that the organism's inherited neurological structure incorporates biases that will determine something about the way certain stimuli are responded to. This "value system" is considered to be a product of evolutionary history, but it's not entirely clear exactly what the particular functions of this value system are supposed to be. Is it a kind of pre-wiring that makes certain stimuli more salient? For example, the visual appearance and smells associated with a particular species' preferred food might as a matter of inherited tendency trigger consumatory behavior, or at least make it more probable. Besides in-born sensitivity to releasor stimuli, would the value system include inherited behavior itself, ranging from reflexes to simple fixed-action patterns to very complex response sequences? One thinks of the elaborate behavior observed in courtship displays, nest-building, or nurturing the young. Is the notion of value system meant to stand as a neurological-level explanation for the ordinary behavioral effects of reinforcing and punishing consequences? Or is it meant specifically to account for some built-in extreme susceptibility of certain behavior to its consequences, thus amplifying normal reinforcement-punishment effects? Edelman includes the inherited value system as a hypothetical entity or process in his theoretical system, but it's not clear from this book exactly what its functions are, or how they interact with behavior or with the environmental events that precede, accompany, or follow behavior.

In Chapter 12, on Brain-Based Devices, we find, as is typical, that when it comes to actually making something happen the environment suddenly becomes important. Edelman makes much of this extremely interesting work using robotic devices with simulated brains that allow them to learn through trial and error, rather than being driven by pre-programed instructions. It is noteworthy, and completely predictable, that the descriptions of these experiments turn out to be descriptions of (1) the initial structure and behavioral capabilities of the simulated organism, and (2) operations involving the provision of specific environmental stimuli and environmental feedback. Results indicate that interaction with the environment produces changes in the device's behavior and in the organization of its simulated brain. If results didn't turn out that way, the researchers presumably would tinker with (1) and (2) above until they did. One long-term potential here seems to be the rediscovery of behaviorism, but with much better illumination of its neurological underpinnings. That would be an outcome devoutly to be wished, but getting there will require a broader, less brain-centric view than Edelman's alone.
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If you take the naturalized epistemology of the philosopher Willard Quine and extend it beyond the role of sense perception, you might arrive at what the author of this book calls "brain-based epistemology." His opinions in this book are very sensible, especially if viewed from the standpoint of what is known in contemporary neuroscience. His expertise in this field is of course well known, but to apply cognitive neuroscience to the understanding of consciousness has only recently been attempted, with some experimental support. Due to its length, the reader will not find a detailed overview of this research in this book, but it will give an introduction to some of the author's essential ideas, which he like to encapsulate in the expression `Neural Darwinism.'

One interesting feature of the author's line of thinking, as in many systems of naturalized epistemology, is that it allows room for both scientific knowledge and knowledge derived from the "humanities". It would seem improbable that evolutionary pressures would not make poetry, art, and literature part of the human survival strategy, given the widespread occurrence of at least one of these areas in all human cultures throughout history. The author would view these areas as expressions of the "pattern recognition" capability of the brain, whereas science and mathematics are more in line with the ability of the brain to indulge itself in logical reasoning. But pattern recognition is the predominant mode for human thinking, with the immediate corollary that metaphors are the tool for which this is done. Scientific reasoning then is a highly specialized (and uncommon) mode of cognition, which is specific in scope and undetermined in justification. This would explain why scientific reasoning does not come as naturally to all as other modes of thought. However, the brain encompasses all of these modes, and so the sciences and the humanities could be viewed as facets of the same brain crystal. To separate them would be fallacious, and therefore the author spends an entire chapter "repairing the rift" between the natural sciences and the humanities.

The author's view of consciousness is one of an unabashed anti-Cartesianism, for he rejects dualism and views consciousness as a purely natural consequence of brain processes, these processes having the nature that they do because of evolutionary pressures. The author also rejects the notion of "brain as computer" but he does believe that it is possible to construct a conscious artifact, and spends a fair amount of time discussing on-going research devoted to this. In addition, and most interestingly, he views language as an "invention" and thus rejects the notion of an innate language mechanism that everyone is born with.

It remains to be seen whether the author's ideas on the origin and nature of consciousness will be justified in further research, but this book does have the virtue that it does not fall into the trap of pure philosophical speculation. This is not to say that such speculation is never of value, but one must know when to stop, when to put down the philosophical drink, lest one become lost in a maze of gigantic conceptual spaces that philosophers love to construct. Experimentation and observation should govern the investigation of consciousness, and artifacts or machines constructed that allow the testing of the more rudimentary ideas proposed. It is refreshing that cognitive neuroscientists have finally given the study of consciousness a genuine place in scientific investigation. No doubt there will be many surprises to come in this investigation in the decades ahead.
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on November 9, 2007
Second Nature, suitable for most any reader with a dictionary, is a mind expanding look at the science of the structures and functions of the human brain and how the mysterious activity we call mind arises from the complex interconnectedness between innumerable neurons and our external conditioning and experience. His hypothesis, which puts an end to Descartes' numbing splitting of mind from the physical body, not only gives a convincing explanation of how the wonderful consciousness humans have evolved and developed has arisen, but you can feel it in your head.
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on May 11, 2012
This is a special edition monograph booklet of Edelman's position. 5x7, consolidated presentation of what he's said before. So don't look for the "new". But you'll just have to possess this very cool monograph. There is a summary in the last chapter that is the highlight of the entire booklet and could be used to integrate with what you already know. This book is for readers who are already Edelman fans. If you want to study his position look elsewhere. This is for those who realize the significance of his contribution and just must have the monograph. I'm waiting for my "signed" copy. I just finished "the remembered present" and go their if you want to "study" his work. I had to have this monograph and the final summary was excellent. Thumbs up.
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on August 4, 2009
The author points out that, until recently, there has been no non-invasive method for studying the functioning brain. All this has changed.

The brain is not a computer. Computers use logic; the brain works by pattern recognition instead.

The author discusses the process of natural selection inherent in Darwinism, as well as the selective process that enables our immune system to identify and destroy invaders. He sees a comparable process active in the brain, which he calls neutral Darwinism. In this process, neural pathways that are fired tend to connect together, and become reinforced. Unused ones wither away. Because of this selection process, even twins' brains differ.

So how does human consciousness work? Edelman believes that first there was the brain capability for symbolic and semantic reference. Then the emergence of language made consciousness possible.

Many famous people are quoted in this book. For instance, Neils Bohr said: "Your theory is crazy but it is not crazy enough to be true." The author attempts to compare his ideas with those of intellectual predecessors such as Freud and Descartes.
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