If people change radically as a result of mental disturbance or brain damage or disease, how should we acknowledge that change in the way in which we respond to them? And how should society and the law acknowledge that change, particularly in cases of multiple-personality and manic-depressive disorders? This book addresses these and a cluster of other questions about changes in the self through time and about the moral attitudes we adopt in the face of these changes. The result is a broad-ranging interdisciplinary discussion at the boundaries of psychiatry, philosophy, law, and social policy. Theories of personal identity are applied to, and clarified in light of, the appearance of multiple selves in a variety of personality and identity disturbances.