http://www.ted.com/index.php/talks/view/id/102
Philosopher Dan Dennett makes a compelling argument that not only don't we understand our own consciousness, but that half the time our brains are actively fooling us. As he puts it, our bodies are made up of 100 trillion little robots, none of them with an individual consciousness. So what makes us feel we have one? Or that we're in control of it? Dennett's hope is to show his audience that "Your consciousness is not quite as marvelous as you may have thought it is." He uses thought experiments and optical illusions to demonstrate to the TED audience that even very big brains are capable of playing tricks on their owners.