DJ's Reviews > Consciousness Explained

Consciousness Explained by Daniel C. Dennett
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Mar 21, 2009

really liked it
bookshelves: brain
Recommended for: anyone interested in brains and understanding our conscious experience
Read in February, 2009

A bold book from my favorite philosopher-scientist that aims to build a framework for tackling perhaps the hardest question humanity has ever asked - "what is this conscious experience?" As in his other books, Dennett is adept at weaving the "soft" thought experiments of philosophy with the "harder" experiments of the scientific community. Some of his most triumphant points don't have the impact they may once have carried, as much of his material has been accepted (or disproved) in the last two decades of the rapidly evolving field of neuroscience. Despite its age, this book is a stellar introduction to anyone trying to approach consciousness.

Dennett's thought experiments and suggested activities for readers shed light on some fascinating phenomena of consciousness, including sensory dislocation & extension of self to tools and blind spots & the overly assuming nature of vision. This second investigation I found to be a powerful metaphor for much of the simulation that the brain performs in crafting our sensory experience. The discontinuity of consciousness is so striking particularly because of its apparent continuity. The brain doesn't so much "fill in" the blanks as it ignores their presence. Dennett makes the important point that this absence of representation (ignorance) is not the same as the representation of absence ("filling in").

The three themes of Dennett's that resonated most with me were the relationship between time & consciousness, information sharing and information barriers in the brain, and consciousness as cultural software.

1) Noticing the varying speeds of sensory signal propagation outside of the body (light vs. sound vs. chemicals) and the varying speeds of neural signal propagation in the brain, Dennett points out that the "present" for us is really more of a "smear" in time rather than a "point". He presents his Multiple Drafts Theory of Consciousness to show that in such a situation, different parts of the brain must act on different sets of information and, therefore, there is no single conscious experience. This is perhaps one of the most profound points that Dennett explores and he does so frequently throughout the book. Dennett also points out that temporal order outside the mind need not coincide exactly with temporal order as represented in the mind, though the two are correlated.

2) With so many specialized areas developing at different periods in human evolution, information sharing in the brain can be quite haphazard and arbitrary. The recognition that information may be present in one area of the brain but entirely unaccessible to another area is essential to understanding many functions and quirks of the brain. This is evident in many popular accounts of language disorders but Dennett also explores what this suggests for the evolution of consciousness. He imagines that early man armed with protospeech might have used "vocal autostimulation" (thinking out loud) as a means of bridging missing connections in his thought processes. In other words, if there's no path from A to B in the brain, there might have been one from A to speech to hearing to B! This clever circuit could then have evolved into silent thought for more privacy and eventually developed into the "mind's eye" visual experience of modern man. Even within the brain, there are likely many inefficient intermediary representations developed to bridge the internal "communication problem." Beyond evolutionary explanations, this idea is also highly suggestive of neuroscientific approaches to creativity. Speaking out loud, doodling, and gesturing to oneself may be more than just nervous ticks or distracting habits; they may instead be integral yet inefficient attempts to circumvent the missing information pathways in the brain!

Dennett also includes a list of "primordial facts" that he claims any theory on the evolution of consciousness must explain. I found them insightful and important enough for any neuroscientist that I've included them here verbatim:

There are reasons to recognize.
Where there are reasons, there are points of view from which to recognize or evaluate them.
Any agent must distinguish "here inside" from "the external world."
All recognition must ultimately be accomplished by myriad "blind, mechanical" routines.
Inside the defended boundary, there need not always be a Higher Executive or General Headquarters.
In nature, handsome is as handsome does; origins don't matter.
In nature, elements often play multiple functions within the economy of a single organism.


3) As for the development of consciousness, Dennett proposes that viewing consciousness as cultural software provides an instructive and productive framework. His evidence includes the relatively recent development of consciousness (and therefore the reduced possibility that it is hard-coded). So why does consciousness still seem to be similar across cultures? Hardware biasing - we're all still working with roughly the same base. Some interesting results of this hypothesis are that some humans may not experience consciousness, particularly babies and special cases of children who developed with very little social contact.

Just as evolution is a difficult topic to write on given that our language is peppered with words conveying "intent", consciousness often has Dennett tripping over his own words. He fares far better than most, but be forewarned - books on consciousness can't help but be clumsy.

In addition to being an excellent introduction for me to many theories on consciousness, this book has piqued my interest in the consciousness and cognitive development of children and the general AI framework known as SOAR.
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