"Historians have good reasons to be highly suspicious of the “rational choice” methodologies that hold sway in economics, political science or sociology and that find a new lease on life today with the rise of the cognitive sciences. On the other hand, researchers using these methodologies show usually very little interest in history. The result is that we know very little about the historical development of “rational choice” as a way to define rationality in action, while this intellectual paradigm has become pervasive and reshaped the way we do science and the way we think about politics.This project will follow the problem of decision-making through the 20th century and weave into a single historical narrative its different disciplinary formulations. It starts with a puzzle: while the “decisionist” critiques of legality of the 1920s associated the decision with an anti-rationalist vision of politics, this notion gradually morphed into the epitome of “rational choice” after 1945. How did this transformation occur?The project will reconstruct this shift from a paradigm in which Law was the instrument that would make political decisions rational, to another in which the power of rationalization was vested in Science. It asks how the post-1945 efforts at specifying conditions of rationality for political decisions changed the meaning of “rationality.” It connects these developments to the interdisciplinary set of “decision sciences” that emerged in the 1950s around issues of strategic and political behavior and spawned our contemporary instruments of “conflict-resolution” or automated models of decision-making.The project suggests that “rationality” in political decision-making is not a transcendental norm, but a historically contingent benchmark dependent on its technical instrumentations. Democratizing political decision-making, then, means opening these models and instruments of rationalization to scholarly debate and public scrutiny."