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Questions of survival, reproduction, reaching a goal, and changing behavior are rooted in the principles of maintenance, acquisition, and victory/defeat. These principles stem from deep mathematical grounds of dynamic systems and sets, and are formalized in viability theory. They characterize the diversity of human behavior and the inherent unpredictability of historical situations. Major themes in the political economy of populations are revisited from this perspective: fertility fluctuations and endogenous growth, the relationships between population growth, resources, and economic progress, the demographic transition and its link to economic factors, economics of the family and the life cycle, financing an aging society, inter-generational equity, social networks, industrial economics, and the economic value of biodiversity.