This major version -- the first since 1982 -- features an extensive change in content, as well as a more capacious page and wider margins. While maintaining scrupulous examination of positions, arguments, and objections, every chapter has been reworked to improve its organisation, to make it more accessible and engaging to the student, and to reflect recent discussions. Chapter One introduces the student to the nature of philosophy as a discipline and to the methods of philosophical argument. Subsequent chapters treat the same fundamental topics as in earlier editions: knowledge and scepticism, freedom and determinism, the mind-body problem, the rationality of belief in God, and the problem of choosing an ethical standard. New exercises have been added throughout.