What is a human right? How can we tell whether a proposed human right really is one? How do we establish the content of particular human rights, and how do we resolve conflicts between them? These are pressing questions for philosophers, political theorists, jurisprudents, international lawyers, and activists. James Griffin offers answers in his compelling new investigation of human rights. The term 'natural right', in its modern sense of an entitlement that a person has, first appeared in the late Middle Ages. When during the seventeenth and eighteenth centuries the theological content of the idea was abandoned in stages, nothing was put in its place. The secularized notion that we were left with at the end of the Enlightenment is still our notion today: a right that we have simply in virtue of being human. During the twentieth century international law has contributed to settling the question which rights are human rights, but its contribution has its limits. The notion of a human right that we have inherited suffers from no small indeterminateness of sense. The term has been left with so few criteria for determining when it is used correctly that we often have a plainly inadequate grasp on what is at issue. Griffin takes on the task of showing the way towards a determinate concept of human rights, based on their relation to the human status that we all share. He works from certain paradigm cases, such as freedom of expression and freedom of worship, to more disputed cases such as welfare right - for instance the idea of a human right to health. His goal is a substantive account of human rights - an account with enough content to tell us whether proposed rights really are rights. Griffin emphasizes the practical as well as theoretical urgency of this goal: as the United Nations recognized in 1948 with its Universal Declaration, the idea of human rights has considerable power to improve the lot of humanity around the world. It is our job now - the job of this book - to influence and develop the unsettled discourse of human rights so as to complete the incomplete idea.