The article discusses how rational behavior and game theory can help design better institutions. It explores decision-making under different conditions, like certainty and uncertainty, and how people make choices based on their preferences. The study also looks at games and how players can reach optimal outcomes through strategic thinking. Additionally, it delves into the design of voting systems and the properties of different rules. The research suggests that understanding rational behavior and strategic thinking can lead to more effective institutional design, including in the context of the European Union.