David J. Chalmers is University Professor of Philosophy and Co-Director of the Center for Mind, Brain, and Consciousness at New York University. His previous books include The Conscious Mind and Constructing the World. He has given the John Locke lectures and has been awarded the Jean Nicod Prize. He is known for formulating the 'hard problem' of consciousness, which inspired Tom Stoppard's play The Hard Problem, and for the idea of the 'extended mind', which says that the tools we use can become parts of our minds.