This collection of essays by one of the world's most distinguished philosophers - the inaugural volume in the Prometheus Lecture Series - addresses the many and diverse aspects of atheistic humanism. Antony Flew begins his comprehensive study with "Fundamentals of Unbelief", in which he argues that there is no good or sufficient natural reason to believe that the universe is created by a conscious, personal, willing, and doing Being; that such a Being has nevertheless provided his (or her or its) creatures with a Revelation; and that we should either hope or fear some future for ourselves after our deaths. In the second part, "Defending Knowledge and Responsibility", Flew disposes of the perennial charge that a naturalistic world outlook presupposes values for which it cannot itself make room. He also criticizes sociologists of belief who refute themselves by refusing to admit that there is such a thing as objective knowledge. And he examines the subject of mental illness, explaining and defining the notion by reference to the familiar yet often denied realities of choice and consequent responsibility. The third section, "Scientific Socialism?", consists of three critical analyses of Marxism. Flew exposes the faulty philosophical foundations of Communism, compares Marxist theory with Darwin's theory of evolution, questions the status of Marxism as a social "science", and points out some of the significant failures of the socialist project. Finally, in the fourth part, "Applied Philosophy", Flew looks at three social issues, which have been the subject of much recent debate: the right to die, the definition of mental health, and the problem of racism. He concludes by criticizing B.F.Skinner's "science" of behaviorism, arguing that the ability to make choices for which we can be held responsible is an essential and distinctive characteristic of human beings.