Consciousness, as a philosophical issue, has been attracting increasing attention in recent years. There is now a Journal of Consciousness Studies, to which the author of this book contributed a keynote article, and a recent conference at the University of Arizona, Tucson, attracted entries from some 640 philosophers including David Chalmers. His book is essential reading for anyone interested in what philosophers are now saying on the issue of consciousness.

In his Introduction, the author confesses that "temperamentally, I am strongly inclined towards materialist reductive explanation and have no strong spiritual or religious inclination." This avowal sets the tone of the book which seems to assume that his critics are likely to be more materialistic than he is. Nevertheless, consciousness, whatever we may make of it, is a fact of life that cannot be ignored just because there is no ready materialistic explanation. On the contrary, "we are," the author points out, "surer of the existence of conscious experience than we are of anything else in the world." At the same time, from an evolutionary standpoint, there is no obvious reason why we should be conscious. We could just as well have evolved as intelligent automata or "zombies," to use the current philosophical jargon.

The author does not attempt to define "consciousness," but points out that a given object is conscious if there is "something that it is like to be that object" (to use Thomas Nagel's telling phrase). We do not normally ascribe consciousness to a computer, however impressive its cognitive capacities, simply because we do not believe that there is anything that it is like to be that computer. To maltreat a computer may indeed be an act of vandalism but hardly an act of cruelty! On the other hand, we are prepared to accord some degree of consciousness to organisms quite low on the evolutionary scale. However, in his penultimate chapter, on "Strong Artificial Intelligence," Chalmers concedes that we cannot rule out a priori the possibility of a computer or robot acquiring consciousness. Indeed, he offers an ingenious thought experiment in which the neurons of a live human being are replaced, one by one, by silicon chips that perform exactly the same functions as neurons. At what point, he asks, rhetorically, would the person in question be no longer a conscious being?

Eventually, the author comes to the conclusion that consciousness is a function of a cognitive system which exhibits the appropriate kind of "awareness" or "the availability of global control." Unlike consciousness, which is unique, awareness can be defined in purely behavioral terms. Given, therefore, the appropriate material substrate, we may assume that consciousness will supervene.

A final chapter discusses the role of consciousness in quantum theory. According to the prevailing interpretation of quantum theory, matter persists in an indeterminate state up to the point at which it is observed. This implies that consciousness does make a difference to the world that we know directly and must, therefore, be more than just an epiphenomenon of brain processes. However, little attempt is made to integrate these considerations with the interpretation of consciousness as set out in the previous chapters.

Such, then, is the tenor of this thought-provoking book but no such bald outline can do justice to its closely reasoned argumentation or to the author's conscientious rebuttals of alternative positions. However, given such thoroughness, it is all the more to be regretted that Chalmers sees no need to look beyond scientific orthodoxy. Parapsychology and the paranormal do not so much as figure in the index. Yet, had he deigned to take such evidence into account, he would have been hard put to treat the physical universe as a causally closed system. Since there is, by definition, no physical explanation for ESP or PK, the author would have been forced either to justify rejecting the evidence for such phenomena or to accept a type of mental causation that defies a physicalist analysis. In that case, he would have had to reconsider the "naturalistic dualism" which he here advocates in favor of an "interactionist dualism" which he here curtly dismisses. (p.163)

John Beloff
6 Blacket Place
Edinburgh EH9 1RL, Scotland UK

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The Conscious Mind: In Search of a Fundamental Theory by David Chalmers Oxford University Press, l996. 414 pp. $29.95.

The readers of this Journal may be familiar with Chalmers' work from his December l995 Scientific American piece entitled "The Puzzle of Consciousness." In that piece, and in this book, he offers an arresting thesis.

After all, it is no small thing to say that contemporary science, in spite of its self-congratulatory confidence is completely in the dark in understanding the nature of consciousness and its role in nature. Hence this exciting and well-written book is controversial in that it is a most serious challenge to the long-standing materialist orthodoxy in the philosophy of mind. Indeed, prominent philosophers have made the claim that it is the most serious challenge to date and may well change the focus and direction of future discussion on the basic question about human nature. Words such as "brilliant," "honest," "formidable," "instructive," "stimulating" and "stunning" often appear in the reviews. Even among those philosophers who are true believers in the current materialist orthodoxy to the effect that consciousness must be construed as a physical object not different in kind from any other object in the physical world, there is an increasing awareness that currently orthodox reductionist forms of materialism in neuroscience and cognitive-science may be problematic for some of the reasons Chalmers presents.

For Chalmers, contemporary science, neuroscience and cognitive-science have not even begun to answer the central question about the nature of consciousness. They simply assume, at the outset and in the name of taking science seriously, that consciousness must be reducible to a physical object of some sort (otherwise, as they say, it could have no causal role in explaining anything). But consciousness, or subjective experience, is not plausibly construed in that way; it is more an irreducible entity not unlike space, time and mass and it cannot be understood as the sum of physical parts.

The central question is how subjective experience (consciousness) emerges from neural processes in the brain. Science has not even started to answer the question because it misconstrues the nature of the entity from the outset, and therefore seeks to answer the wrong question, as if the question were essentially a matter of how the brain processes environmental stimulation, or how the brain integrates information, or how we produce reports on internal states.

For these reasons it is Chalmers' view that we are completely ignorant about how consciousness fits into the natural order. We answer the wrong questions and avoid the hard ones. Why are we not trying to answer instead, questions such as, "Why is all this mental processing accompanied by an experienced inner life?" For Chalmers, not to take such questions seriously is not to take consciousness seriously. Chalmers also takes science seriously, and seeks to answer the central question within natural science while also arguing against standard reductionist moves to classify consciousness as some sort of a physical object. No small task. He does not claim to have succeeded at the task of completing a scientific answer to the central question, but he does claim to have set the project on the right footing and moved along the correct path of showing how consciousness, while not being reducible to a physical object, is nonetheless subject to physical laws and thus understandable in natural science. Other than that, the book argues for the causal efficacy of consciousness, (as opposed to epiphenomenalism) and in the end, via a defense of strong Artificial Intelligence (AI), argues for a form of panpsychism... or at least shows that belief in panpsychism is not so horrendously counterintuitive.

The book, incidentally, has already been reviewed frequently, and is the object of several critical notices by the well-known and prominent philosophers of mind. What is so interesting about the general tone of the reviews is that they generally agree that this book is very-well argued and important for any future discussion on the nature of consciousness. To be sure, there are some philosophers (John Searle) who will call its main theses (endorsing strong AI and panpsychism certainly) crazy, absurd, and massively counterintuitive; and others (David Papineau) will reject the book out of hand because they reject the basic view that there is any problem about consciousness, at least as Chalmers describes it. For Papineau, for example, there is simply no need to explain the connection between consciousness and brain states because it is an identity, and identities do not need explanations. ( British Journal for the Philosophy of Science, l997) And naturally there have been the predictable 20%-25% of philosophers with true-believer tendencies who have been comical in their excessive negativity about it, while showing no real understanding of the arguments.

But the general feeling, even among those who thoughtfully disagree with the conclusion and cannot quite go all the way to Chalmers' particular brand of naturalism and a Cartesian property dualism, is that it is nonetheless an important book, well-argued, and that it may turn out to be the best book on the issue over the last fifty years. It has the distinct potential for generating a large body of literature that will need to take some form of Cartesian property dualism (even if of the epiphenomenalist bent) seriously. One notable philosopher, David Lewis, for example, has said:

"The Conscious Mind is exceptionally ambitious and exceptionally successful - the best book in the philosophy of mind in many years. It flies in the face of fashion, making a formidable case against materialist orthodoxy. Legions of materialists are no doubt busy writing their rejoinders; but there will be few points left for them to make that Chalmers hasn't made already. We of the materialist opposition cannot go on about how he has overlooked this and misunderstood that - because he has not. All we can do is to disagree about which way the balance of consideration tilts." (Mind, 1997) (See also Web site: http://ling.ucsc.edu/-chalmers/reviews.html for Chalmers' responses to his critics.)

And Sydney Shoemaker (one of philosophy's most insightful of materialists) believes that if Chalmers' arguments succeed, his achievement will be enormous, for he will then have succeeded in overthrowing materialist orthodoxy that has reigned in philosophy of mind and cognition for the last half century. As it is, Shoemaker thinks the arguments fail, but he adds that even so, the achievement is considerable because his arguments draw on and give forceful and eloquent expression to widely held intuitions. (Szee same web site as in above paragraph) So, it seems fair to say that anybody who is interested in the long-standing discussion on the nature of human consciousness and its role in scientific theorizing, will need to read this book and decide for themselves whether the arguments work. Let me be a bit more specific about what is in the book.

The book comes in four parts, and is chock full of good arguments at every turn. The first part lays out the problems and sets the framework in which they can be addressed. Chapters one and two talk about the basic questions about consciousness, defines the central problem and offers a strikingly clear (even if somewhat incomplete) and informative discussion about qualia and supervenience, that sets the stage for a discussion on reductive explanations and a definition of materialism in terms of supervenience.

The second part of the book (embracing chapters three, four, and five) argues for the irreducibility of consciousness and a naturalistic dualism, in which consciousness is part of nature and governed by the laws of nature. This is where, in the light of earlier work done in the first two chapters, he drives home the thesis that consciousness cannot be reductively explained, and argues against materialism without abandoning a naturalistic dualism, which he discusses in the context of asking whether his position amounts to epiphenomenalism. Chapter five is an engaging discussion on the paradox of phenomenal judgment.

The third part of the book moves toward constructing a positive theory of consciousness. Each of the three chapters in this part (chapters 6, 7, and 8 respectively) develops a component of a positive theory of consciousness. These are fascinating chapters, full of nice thought experiments, and quite speculative. The fourth, and last part has to do with his defense of strong AI theory and the application of the whole theory to the two basic mysteries of quantum physics.

While it is quite tempting to offer here an evaluation of the book, to do so in this limited space would be unfair to the sweep and sustained argumentation of such a fine book. It calls for an extended critical study rather than this short review.

Like others, I have some doubts about certain crucial arguments and whether consciousness as so defined (or characterized) is indubitably known to exist as characterized. And I certainly feel he missed important information for failing to look at empirical studies on reincarnation and the paranormal. That kind of discussion and information (largely lost to the mainstream discussion in philosophy for reasons of moving in "spooky" directions) would drive home the empirical nature of the inquiry and the continued failure of the materialist paradigm (and all its deeply entrenched intuitions).

Even so, it is hard not to feel in one's bones the force of the intuitions that drive the book, and that fund the basic set of arguments. Indeed, if one accepts the basic intuitions David Chalmers describes at the outset, it is difficult to see how any form of contemporary orthodox materialism could possibly explain them; and, by way of understanding the nature of consciousness, the implications of that are quite moving in terms of all the energies expended in neuro-science, cognitive science and psychology in general.

It is no easy thing to admit that what one has dedicated one's life to is basically wrong-headed. So we should not expect the current orthodoxy to roll over, belly-up, without much of a struggle. But there must be emerging now a feeling in the land that there has been something terribly stale about the discussion in philosophy on the mind-body problem in the last twenty-five years. And in the face of certain objections of the sort offered by David Papineau in defense of the identity thesis, taking science seriously may require a different body of data to be explained in defense of the sort of dualism defended by Chalmers. But this is no place to argue that. Doubtless, we shall see more than a good number of seminars and colloquia on this very interesting and engaging book, and doubtless we shall all benefit from the activity. In the meantime, it is undoubtedly a book we should all read very carefully -- twice.

Robert Almeder, Department of Philosophy
Georgia State University, University Plaza
Atlanta, Georgia 30303

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