Morality Without Foundations investigates fundamental metaethical questions about the meaning, truth, and justification of moral thought and discourse. Mark Timmons maintains that all versions of descriptivism in ethics, particularly certain accounts of moral realism, fail. He argues instead that a correct metaethical theory should embrace some version of non-descriptivism.

Timmons defends what he calls "assertoric non-descriptivism" which, unlike traditional non-descriptivist views, holds that moral sentences are typically used to make genuine assertions. In defending this view, he exploits contextual semantics, providing him with the semantic flexibility to develop an irrealist account of moral discourse.

Timmons' novel defense of morality without foundations offers provocative reading for philosophers working in the areas of ethics, epistemology, and metaphysics. Yet, written with the student in mind, his lucid presentation of difficult ideas makes this book accessible to students and newcomers to the field of metaethics.