On What Matters

A three-volume work on reasons, morality and meta-ethics, developed from Parfit's 2002 Tanner Lectures. Volume One opens with an account of reasons, defending an objective view on which facts about what we have reason to do do not depend on our desires, and attacking subjective theories. Parfit then examines Kant's formulas at length, revising the Formula of Universal Law into a Kantian contractualism. He argues that the best versions of Kantianism, contractualism and rule consequentialism converge in a "Triple Theory": an act is wrong when it is disallowed by principles that are optimific, that everyone could rationally will, and that no one could reasonably reject. These theories, he says, are climbing the same mountain on different sides. Volume Two includes commentaries by Susan Wolf, Allen Wood, Barbara Herman and T. M. Scanlon, with Parfit's replies, and a long defence of non-naturalist cognitivism. Volume Three replies to further critics, chiefly on meta-ethics.

It is the most ambitious recent attempt to show that the major moral theories agree and that there are objective moral truths, and it frames many current debates in ethics.