This book examines the foundations of ethics; it investigates a complex network of issues in the metaphysics of ethics, moral epistemology, moral psychology, and substantive moral theory. This agenda includes both what is usually called second-order issues and first-order issues about morality. It is worth pausing over this division within my agenda, since some attention to it should throw light upon the nature and scope of my project.

However difficult it is to state criteria for marking this distinction between first- and second-order levels of inquiry in ethics, it is an important distinction about whose application there is often a surprising amount of agreement. Second-order, or metaethical, issues are issues about, rather than within, morality and typically take the form of metaphysical, epistemological, semantic, or psychological issues about morality and our moral claims. In what sense, if any, is morality objective? Are there such things as moral facts or truths? Can we justify moral judgments? In what sense, if any, do moral considerations guide conduct? Is it irrational to be indifferent to moral considerations? If there are moral facts, how are they related to the natural features of agents, policies, and actions that those moral facts concern? These questions raise second-order issues and are my primary focus.

First-order, or normative, issues, by contrast, are issues within morality about what sorts of things are morally important (e.g., right and wrong). It is useful to mark a further distinction within normative ethics between issues of moral theory or principle and particular, substantive moral issues.