Although i have made every effort to present Arbogast Schmitt's thought as simply as possible, there is no evading the fact that this book unfolds a massive and highly complex argument, one that touches not only upon the different concepts of rationality present in antiquity or modernity in the narrow sense but upon these concepts as they manifested themselves in all areas of life in antiquity and modernity. I therefore would like to use this introduction to preview the main thesis of this book briefly and to clarify the order of the chapters and sections and their relation to each other.

Schmitt's work addresses not only the epistemological foundations of the two concepts of rationality, ancient and modern, referred to in the title of this book, but also their historical origins and their historical consequences. His book is thus also a contribution to the history of philosophy at the same time as it is a contribution to philosophy. Further, since the concept of rationality determines almost every aspect of theoretical and practical knowledge (extending to but not limited to economics, ethics, politics, anthropology, sociology, etc.), this book also includes discussions on topics one might ordinarily not expect to find in a work of philosophy. For all these reasons, it is useful to have a broad overview of the argument at hand, even before tackling the first chapter.