Résumé: As the concept of the modular structure of the brain emerged, objections to the idea took the form of "Well, if my brain's made up of computers, somebody in there has to be in charge. It had better be me!" This comment, paraphrased from philosopher Jerry Fodor, typifies what Daniel Dennett has been contending with for many years. Although the "Cartesian theatre" notion, that the body was one aspect of our being and the mind another - "dualism" - has supposedly been supplanted, it has not lost its hold on our view of consciousness. We continue to insist, in some form or other, that "somebody, and it better be me" is inside our minds looking out at the world. Although we can't find that "self" in there, we have a hunch it's there.

When Dennett wrote "Consciousness Explained" in 1991, it seemed the "homunculus" representing our "self" had been laid to rest. This excellent collection of essays and lectures, is an update on that earlier work. As lectures, they have a conversational tone, yet impart many deep insights. Addressing consciousness through four major themes, Dennett shows us the project of eradicating "dualism" remains incomplete. Until that view of "self" is discarded, our understanding of consciousness will remain misleading.

The first theme he addresses is the "zombie". Philosophers have posed the idea that a duplicate person, identical to you in every way but one, is logically possible. The person would act as you act, talk as you do, have the same preferences and distastes. But it would not be conscious. This proposal presumes that something in you could be identified that is lacking in the zombie. For most of us, who still feel our "self" remains somehow separate within us, the logic seems reasonable. Dennett carefully examines the implications of the proposal, and dismisses it as modernised dualism. If a region of the brain holds the key to "self" it remains out of sight and undetectable.

Perhaps the most challenging segment of the book deals with "heterophenomonology". This tongue-twisting phrase refers to the methods used in cognitive science. Because consciousness is "often celebrated as a mystery beyond science" Dennett challenges researchers to take a step back from commonly accepted techniques. Become a "Martian" cognitive scientist to broaden the scope of the work. One facet of this approach relies on understanding what "folk psychology" is, then building from there. We prefer to believe that what we believe is entirely private and unaccessible. Heterophenomonolgy, he contends, will expose aspects of our consciousness we view as a "mystery".

One of those "mysteries" has been wrapped in the idea of "qualia". Probably one of the poorest concepts in philosophy, "qualia" are things said to possess "intrinsic qualities". When you carefully examine those "intrinsic" properties, they begin to fade and vanish. If "qualia" is in an object we see, such as colour, how can it change without our noticing? Tests of "change blindness" indicate we can miss much concerning "qualia". Even the philosophic community, Dennett notes, cannot agree on a definition of "qualia". Yet, like the homunculus in the mind viewing the world, it steadfastly remains in use. The author examines this idea further in relating the story of "Mary", the colour-deprived scientist.

In "Consciousness Explained", Dennett proposed the Multiple Drafts Model of consciousness and cognition. In this collection, he enhances the original concept. With no centre in the brain, consciousness necessarily must be a distributed process. The progress of imaging and other technologies have expanded our view of the brain's functions. Dennett argues that the brain is "fame" not "television". The process is one of competition for dominance, no matter how fleeting. The mind is not a "top-down" or "bottom-up" process, but a "sideways" one. Ideas, experiences and other informational bits jostle for "clout". It's not easy to shed the idea of a special "self" in your mind, but all that's going on in there is still you.

As usual, Dennett has challenged successfully the "established" views of consciousness. Clearly, he argues, consciousness is neither an arcane "mystery" nor beyond serious and definitive investigation. The mind-set erecting barricades using the bricks of "qualia" and the mortar of the "Cartesian theatre" can, and must be, overcome for serious investigation to proceed. Delicacy and care must be employed, but the prize is understanding. [stephen a. haines - Ottawa, Canada]