Practical-reasoning theory is a kind of metaethical view—alongside noncognitivism and other cognitivisms such as naturalism and rational intuitionism—that aims to understand ethics as rooted in practical reason.

Tradition divides the faculty of reason into two parts: theoretical and practical. Theoretical reason concerns what we should believe, practical reason what we should do. Beliefs aim to represent reality and are mistaken or in error when they do not. Theoretical reason's task, therefore, is to discover what is true of the independent order of fact to which belief is answerable. But what about practical reason? What could make it the case that an action is something a person ought to do?

Plainly, ethical convictions also aim at a kind of objectivity. If Jones thinks he should devote all his resources to conspicuous consumption but Smith thinks that Jones should donate...