Philosophy in the Indian tradition is often believed to be essentially religious in character. Even schools like Nyaya and Buddhism correlate their logic and epistemology with a transcendent religious goal. Yet, there exists a purely secular and rational exercise within the Indian philosophical traditionsthe Lokayata/Carvaka school of philosophy. Owing to a lack of substantial literary sources, Lokayata has received only scant attention from scholars till now. This book is the first attempt to examine the philosophical energies inherent in the scattered Lokayata/Carvaka literature. Through a critical analysis firmly grounded in textual evidence, the author presents a systematic philosophical development of the pluralistic interpretation of this school. Claiming that the diversity in the Lokayata school is greater and much more complex than generally imagined, the book explores the cognitive scepticism of Jayarasi, the extreme empiricism popularly attributed to Carvaka, and the mitigated empiricism in its two versions: positivist and common-sense-oriented. It discusses these in a wider philosophical perspective in terms of their implications and their Western parallels.