Consciousness is perhaps the most puzzling problem we humans face in trying to understand ourselves. It has been the subject of intense study for several decades, but, despite substantial progress, the most difficult problems have still not reached any generally agreed solution. Future research can start with this book. Eighteen original, specially written essays offer new angles on the subject. The contributors, who include many of the leading figures in philosophy of mind, discuss such central topics as intentionality, phenomenal content, knowledge of mental states, consciousness and the brain, and the relevance of quantum mechanics to the study of consciousness.