Although the author, Michael S. Gazzaniga, is new to me, he's actually a well-known neuroscientist and author of a number of other popularizing books on brainy topics. As usual, I can't quite remember why I put this on my things-to-read list, but it's one of those "big question" topics I'm interested in, in my usual dilettantish mode. Professor Gazzaniga is currently at UCSB, but he's been all over. (Thanks to the University Near Here's library, who scored the book from Dartmouth. Keeping them on their toes this summer.)
His task here is (obviously, from the title) to explain how we, you and I, can possibly be "conscious", when all that's going on inside us is chemistry, and also some electricity. There's an initial discussion of the history of speculation on the topic, going all the way back to Aristotle, on up through Descartes, Hobbes, Locke, James, and the like. Gazzaniga, fortunately, is comfortable with the philosophical arguments. But he nicely mixes in current research (including his own) in cognitive psychology and neurophysiology.
Way back in the 1960s he worked with Roger Sperry at Caltech, on the famous split-brain experiments. It turns out (as with so many things) that sometimes the easiest way to discover interesting things about how the brain works, is to look at what happens when it's not working that well: when, through injury or disease, some parts are malfunctioning, or not working at all.
His interesting observation: even in cases of severe brain damage, one's consciousness still functions. Sometimes far different than normal, but never really absent. This indicates that it's a property more or less distributed throughout the brain, not localized to any one area.
Gazzaniga finds it useful to think of the brain as having a (conceptually) layered architecture. Since I'm a computer ex-geek, I naturally analogized this to the OSI stack model, with high-level (application) layers, medium-level (e.g. driver) levels, and low-level (e.g. hardware) layers. Each layer doesn't have to "know" anything about the functionality of the layers below and above; there just has to be some sort of communication protocol.
Another important concept is modularity: brain-parts that do some sort of well-defined task; these can also have internal layers. Again, the key points are independence, and relative ignorance.
Interestingly, the book then veers into insights provided by quantum mechanics, which brought me back to my physics-major days. Gazzaniga analogizes the wave/particle duality of elementary particles, and the correspondence principle to life itself. Well, I'm not sure whether this is meant to be an analogy, or if he's saying that there's something quantum-like causing brain consciousness. Anyway, intriguing.
All this goes to argue (as you probably guessed from the title) is that consciousness is an instinct, like fear, hunger, lust, etc. Yeah, maybe.
I expected there to be some more stuff about "free will" in this book, as it seems (to me anyhow) to be tied together with consciousness. But I see he has another book on that specific topic. So I might check that out someday.