What constitutes a need? Who gets to decide what people do or do not need? In modern France, scientists, both amateur and professional, were engaged in defining and measuring human needs. These scientists did not trust in a providential economy to distribute the fruits of labor and uphold the social order. Rather, they believed that social organization should be actively directed according to scientific principles. They grounded their study of human needs on quantifiable foundations: agricultural and physiological experiments, demographic studies, and statistics. The result was the concept of the "vital minimum"--the living wage, a measure of physical and social needs. In this book, Dana Simmons traces the history of this concept, revealing the intersections between technologies of measurement, such as calorimeters and social surveys, and technologies of wages and welfare, such as minimum wages, poor aid, and welfare programs. In looking at how we define and measure need, Vital Minimum raises profound questions about the authority of nature and the nature of inequality.