Iris Murdoch was a thinker of extraordinary breadth and ambition. Over the course of her lifetime she published nearly thirty novels, numerous plays and poems, three philosophical monographs, and two collections of philosophical essays. However, the breadth and novelty of her philosophical contributions remain yet to be fully acknowledged.Iris Murdoch's Moral Philosophy provides the first in-depth exploration of her metaethical thought, an examination of the background commitments about the nature of the ethical realm that underlie her thinking. She is, it suggests, not simply a novelist with picturesque and provocative thoughts on love and attention, but an ambitious and systematic thinker whose work challenges some of the most deeply-held assumptions of moral philosophy today. Murdoch, it suggests, is not a thinker who can be easily accommodated within contemporary metaethics—but she offers rich and original insights of her own.Murdoch's insistence on the pervasiveness of the moral and the significance of ideas of perfection, it argues, leads to a sea change in metaethics. Implicit in her work are novel conceptions of key concepts such as truth, realism, and the Good, and these come together to form an attractive metaethics. The book examines her conceptions of these central philosophical ideas, as well as her answers to other questions that arise out of this system, such as the relation between knowledge and motivation and the purpose of morality.