About the Book: Ideas That Matter by A. C. Grayling is a thought-provoking guide to the philosophical, political, scientific, and religious ideas that have shaped human civilization. Covering influential concepts such as existentialism, feminism, Marxism, environmentalism, bioethics, and fundamentalism, Grayling explains their origins, evolution, and impact on modern society. Organized in an accessible, alphabetical format, this insightful reference encourages critical thinking and meaningful debate while making complex ideas easy to understand. An essential read for anyone interested in philosophy, history of ideas, politics, ethics, and intellectual history.