This is the fifth volume of the "Contemporary Philosophy" series co-ordinated by Stefano Poggi, devoted to analysing the evolution of key concepts in philosophy. The preceding four volumes addressed "Identity and Consciousness" (D. Sparti), "Sensation, Perception, Concept" (P. Spinicci), "Being and Its Meanings" (F. Toccafondi), "Freedom, Necessity, Determinism" (M. Mori). Ever since Kant reflections on the notion of "a priori" and the status of categories has constantly absorbed the attention of philosophers, sparking complex conceptual proceedings which continue to shape current debates. Although it favours a standpoint grounded in the theory of knowledge, this volume also offers a wider outlook ranging from logic to ontology and provides a brief account of a philosophical history in which Kant played a crucial role. The history then unwinds through the grand systems of German idealism, anti-idealistic thought in 19th-century Germany, positivism, pragmatism and the "neo-Kantian schools", Husserl's phenomenology, certain parts of Heidegger's work, up to the elimination of "synthetic a priori" undertaken by logical empiricism and the analytical philosophers' discussion of transcendental arguments, categorical schemas, and the revisability of a priori perspectives.

Massimo Ferrari teaches History of Philosophy at the University of L'Aquila.