The volume wishes to address a variety of questions arising when logic is approached by overriding compartmentalization, by adopting an interdisciplinary viewpoint, and by taking into account its fully social and historical dimensions. By raising the question of logical skills, it aims at pausing and stepping aside from an approach essentially centered on the doctrinal history of logical theories. Logic has long been seen as a natural and universal human ability, as much as a series of skills that only “sane,” “educated,” and “civilized” men can master. The volume investigates this tension. It explores how various logical skills have been established as social norms and attributed, or denied, to some actors or groups in different spaces throughout history. Written by historians, philosophers, and sociologists, and drawing on several case studies, it examines how these skills were defined, taken as standards and identified in some individuals, while they were deemed missing in others. It studies how they have been mobilized in educational theories, practices, and policies. It examines the dynamics of valuation (i.e., assessment and valorization) and implementation of these skills across different epochs, ranging from the Middle Ages until the present day. It specifies the different conceptions of logic underpinning these approaches, as well as their social and political stakes. The representations of logic related to the different cases studied in the book are quite diverse. Some of them refer to Aristotelian and syllogistic conceptions. Others refer to a “natural logic” rooted in the human mind or to artificial languages. Others still involve non-classical logics as opposed to a unitary and universal logic, or logics allegedly proper to some peoples (i.e., “native logics”), as opposed to “Western logic.” The social political issues raised by the identification and possible enhancement of logical skills in some individuals rather than others are manifold. The book shows that it has helped to support distinctions between “primitive” and “civilized” peoples, between “uneducated” men and the “elites,” or between “normal” and “disabled” individuals. It has led to define principles and norms for the functioning of the human mind, whether for infants, for children as they develop, or for adults. Symmetrically, this approach has led to identify deranged, illogical people, as well as idiots. These distinctions have been used to assign varying rights and duties to different human groups or to their members. They have upheld principles and methods for selecting individuals in educational institutions and dynamics of exclusion of groups considered socially or racially inferior because of their “logical disability” or their “pre-logical mentality.” They have been instrumental in justifying colonial domination, as much as convicting and executing criminals. This volume differs from many psychology publications in that it does not seek to highlight the acquisition, possession, or lack of logical skills in anonymous and interchangeable “subjects” according to a reference logic. It deals with socio-historically situated actors and groups and analyzes the conceptions of logic that are mobilized to valuate their skills and to devise educational “politics of logic.” The volume is also different from various philosophical works that offer a reflection on the (il)logical ways of thinking and acting of societies—or of the individuals who compose them. On the contrary, such reflections are taken as an object of social historical study in its own right. Furthermore, it differs from histories of ideas in the field of logic. It does not set out from a definition of logic that would serve as a once-and-for-all fixed reference, which would lead to select some approaches to logic and exclude others from the scope of our study. It develops a social historical approach to logic. By focusing on logical skills, it shows the many ways in which logic can be understood. Logic does not simply appear as a set of theories and doctrines, but also as a tool that individuals and groups use for numerous purposes in various institutional, political, and social contexts. Generally speaking, logic is seen as a social practice. This volume is intended for researchers, teachers, and students in several fields of knowledge, including history, sociology, and philosophy of science, as well as logic, psychology, and colonial studies. We hope that the theoretical reflections and case studies it contains will inspire our readers and elicit new approaches of logic based on an interdisciplinary and non-reductionist perspective