Originally published in 1980 this book argues that we are all responsible for the harm we could have prevented and explores the effect of this conclusion on a morality which makes fundamental the belief that we ought not to harm others if we can possibly avoid it. A theory of responsibility is developed and defended which has consequences for the way we live as well as for a number of problems in contemporary moral, political and social philosophy, and in jurisprudence. In particular, the author attacks the view that there is a moral difference between killing and letting die and proposes a radical conception of violence. Among other controversial issues covered in the book are neutrality, the ethics of organ transplants and the allocation of scarce resources.