This work explores two lesser known aspects of Georg Lukacs's thought: his conception of language and theory of science, and his achievements in literary history. This book defends Lukacs's concept of rationality and presents an original argument demonstrating that there are good reasons for choosing rationalism; that is, it is possible to establish the foundations of rationalism. Internationally unknown aspects of Lukacs's oeuvre are also investigated, making extensive use of a number of his untranslated writings. Janos Kelemen's main statement is that, for the reader, the most important motif of Lukacs's thought is its defense of reason. Students and scholars of philosophy, political science, literary theory, and the humanities will be interested in this book.