My dissertation tracks debates among thinkers over the meaning of the human in medicine and psychoanalysis, ethnology and social theory, philosophy, and anthropology in France from the period of the Great War through the first wave of decolonization that followed the end of the Second World War in the early 1950s. During this time, I argue, my actors felt the priorities and presuppositions of the fields in which they worked no longer seemed capable of furnishing answers to the questions that the problems of their historical conjunctures demanded. Knowledge of the human was incomplete at best and, at worst, actively assisted in the production of state regulation of bodies, social atomization, the conditions for the rise of fascism, or racialized structures of difference that upheld white supremacy. Indeed, my actors–– principally, the vitalist psychoanalyst René Allendy, the writer and philosopher Georges Bataille, the philosopher and medical student Georges Canguilhem, and Unesco social scientists and anthropologists––understood their fields to implicated in these processes that they all, in their own way, identified as the pressing concerns of their historical conjunctures. In following chapters, I show that these responses to the challenges of war, fascism and anti-fascist resistance, and postwar decolonization, need to be understood as historically specific concrete attempts to realize theory in practice, to mend social and political problems by changing the meaning of what it means to be human. Despite the historical awareness shared by my actors, however, all of them sought some form of universalism as a redress for their particular moment. This story is of general interest for those working in the history of the life and human sciences and philosophy; yet the ways in which the struggle in thought and practice for universalism was mapped onto social and political concerns, I argue in what follows, also makes this history particularly French.