"Neo-Kantianism" is a term used to designate a group of somewhat similar movements that prevailed in Germany between 1870 and 1920 but had little in common beyond a strong reaction against irrationalism and speculative naturalism and a conviction that philosophy could be a "science" only if it returned to the method and spirit of Immanuel Kant. These movements were the fulfillment of Kant's prophecy that in a hundred years his philosophy would come into its own.

Because of the complexity and internal tensions in Kant's philosophy, not all the Neo-Kantians brought the same message from the Sage of Königsberg, and the diversity of their teachings was as great as their quarrels were notorious. At the end of the nineteenth century the Neo-Kantians were as widely separated as the first-generation Kantians had been at its beginning, and the various Neo-Kantian movements developed in directions further characterized by such terms as...