1989 0-88946-105-8 A defect in Berlin's moral theory of "pluralism" is shown to undermine his defense of "negative liberty"; an alternative theory of moral reasoning, described as a "weak hierarchy of values," becomes the foundation for a theory of liberty that is neither negative nor positive but purposive. This thorough and critical appraisal of Berlin's thoughts on the nature of reality, of humanity, of values, and of politics and liberty describes Berlin's views _ one of this century's most compelling visions of life _ as unwaveringly modern and empiricist.