Consciousness is the biggest mystery. It may be the largest outstanding obstacle in our quest for a scientific understanding of the universe. - David Chalmers

I am an optimist about consciousness: I think that we will eventually have a theory of it, and in this book I look for one. But consciousness is not just business as usual; if we are to make progress, the first thing we must do is face up to the things that make the problem so difficult. Then we can move forward toward a theory, without blinkers and with a good idea of the task at hand.

In developing my account of consciousness, I have tried to obey a number of constraints. The first and most important is to take consciousness seriously. The easiest way to develop a "theory" of consciousness is to deny its exis­tence, or to redefine the phenomenon in need of explanation as something it is not. This usually leads to an elegant theory, but the problem does not go away.

Another useful way to avoid confusion [used by e.g. Allen Newell 1990 Unified Theories of Cognition] is to reserve the term "consciousness" for the phenomena of experience, using the less loaded term "awareness" for the more straightforward phenomena... If such a convention were widely adopted, communication would be much easier; as things stand, those who talk about "consciousness" are frequently talking past each other.