Will understanding our brains help us to know our minds? Or is there an unbridgeable distance between the work of neuroscience and the workings of human consciousness? In an exchange between neuroscientist Jean-Pierre Changeux and philosopher Paul Ricoeur, this book explores the fraught territory between these divergent approaches--and comes to a deeper, more complex perspective on human nature. Ranging across diverse traditions, from phrenology to PET scans and from Spinoza to Charles Taylor, this book revolves around a central issue: the relation between the facts (or `what is`) of science and the prescriptions (or `what ought to be`) of ethics. Changeux and Ricoeur bring an unusual depth of engagement and breadth of knowledge to each other's subject. In doing so, they make two often hostile disciplines speak to one another in surprising and instructive ways--and speak with all the subtlety and passion of conversation at its best.