In his recent contributions to theorizing economic history, Douglass North has presented a specific diagnosis of modernity. Comparing North’s approach with the perspective of the German sociologist Niklas Luhmann, this paper discusses in five steps the relevance of such a diagnosis of modernity for the (ordonomic) rational-choice research program. The first step (1.) introduces the diagnosis of modernity as recently put forward by North and his co-authors. The second step (2.) highlights important parallels between North’s approach and Luhmann’s historic diagnosis. The third step (3.) discusses how Luhmann – in contrast to North – combines his historic diagnosis with an analysis of the interdependence between social structure and semantics. The fourth step (4.) uses these reflections for a constructive criticism of North’s position on mental models. In focusing his account of mental models on arguments from the cognitive sciences, North not only runs the risk of losing his genuine social science perspective. He also refrains from using his distinction between three paradigmatic types of social order for examining how these social orders influence the way mental models are socially produced and can influence societal evolution. The fifth step (5.) summarizes concluding thoughts for the (ordonomic) rational-choice analysis of interdependencies between social structure and semantics.