R. M. Hare was the leading British moral philosopher of the last half of the twentieth century. His overarching aim, which he relentlessly pursued, was to demonstrate how rational argumentation about morality is possible. He achieved this aim by using the logic of language to formulate a theory of moral reasoning. With the support of facts about human preferences, he used this theory to construct, in turn, a normative theory basing personal obligation on an impartial concern for the interests of all people. A prolific author and an adviser to university, church, local, and national organizations, he applied these theories to provide guidance on a host of practical issues. While developing and defending his theories over a fifty-year span, he maintained a remarkable consistency--a challenging task, given that he was attempting to harmonize elements that many philosophers consider irreconcilable: a morally neutral logic capable of yielding substantive moral...