What is truth? What is knowledge? What is the significance of language? Such questions continue to absorb philosophers today. The seven volumes in this set contain major contributions to the philosophy of mind and language. Included in the set are the classic works, The Mind and its Place in Nature, by C.D. Broad, Logical Syntax of Language by Rudolf Carnap and Bentham's Theory of Fictions by C. K. Odgen. The set also includes Philosophy of the Unconscious by Eduard von Hartmann, with a preface by C. K. Ogden. Originally published in 1868, this title was republished in 1931 in the context of the contemporary controversy over the place of the Unconscious in psychological and philosophical theory.