In these three Tanner lectures, distinguished ethical theorist Allan Gibbard explores the nature of normative thought and the bases of ethics. In the first lecture he explores the role of intuitions in moral thinking and offers a way of thinking about the intuitive method of moral inquiry that both places this activity within the natural world and makes sense of it as an indispensable part of our lives as planners. In the second and third lectures he takes up the kind of substantive ethical inquiry he has described in the first lecture, asking how we might live together on terms that none of us could reasonably reject. Since working at cross purposes loses fruits that might stem from cooperation, he argues, any consistent ethos that meets this test would be, in a crucial way, utilitarian. It would reconcile our individual aims to establish, in Kant's phrase, a ''kingdom of ends.'' The volume also contains an introduction by Barry Stroud, the volume editor, critiques by Michael Bratman (Stanford University), John Broome (Oxford University), and F. M. Kamm (Harvard University), and Gibbard's responses.