The Philosophy Lexicon series is inspired by the success of the Aesthetics Lexicon edited by Remo Bodei, which now comprises twenty volumes, and the Political Lexicon edited by Carlo Galli, which has fourteen. The Philosophy Lexicon was developed and is edited by Massimo Mori, a renowned scholar of the history of philosophy at the University of Turin, editor-in-chief of Rivista di Filosofia, and author of several books and school texts. This new Lexicon has the same format as the preceding successful series: about twenty titles, each about 180 pages long and devoted to a specific concept or pair of concepts that have played a central role in the history of philosophy. The goal is also the same: offer non-specialist readers an essential encyclopedia of the key ideas which give life to philosophical thought, especially in its historical evolution.

Besides the title described here, the following are already published: Universals / Particulars by Guido Bonino and Action by Mario De Caro. In preparation: Good and Evil by Giuseppe Riconda, Probable / Necessary by Massimo Mugnai, Life / Death by Daniela Steila, Virtual by Enrico Pasini, Symbol by Massimo Ferrari.

The concept of reason has a role of absolute prominence in the philosophers toolbox. In the Western tradition the plurality of its definitions reflects essential differences among competing theoretical systems; for a long time the very legitimacy of philosophical thought has been assessed by its being founded on reason. This book explains this multiplicity of definitions and the set of theoretical contributions that over time have enriched the meaning of reason: from ancient Greece to medieval Christianity, from the metaphysical constructs and the critical analyses of the modern age to the more recent vindications of its use. This text outlines the history of the concept of reason and offers readers a map to plot a course among its many meanings.

Emanuele Cafagna teaches History of Modern and Contemporary Philosophy at the Gabriele dAnnunzio University of Chieti-Pescara.