What are the individual, state, and international-system levels of analysis in international relations?

The "levels-of-analysis" framework in international relations was introduced in the 1950s to provide a conceptual basis for distinguishing between different sources of explanation and objects of inquiry. This approach helps researchers determine whether to focus their analysis on the individual, the state, or the international system.1

• Individual Level: This level focuses on the decision makers themselves. It examines their perceptions, motivations, intellectual and cultural backgrounds, and the organizational settings in which they operate. It also considers how individual leaders' choices and rational calculations—or lack thereof—influence foreign policy outcomes.213
• State Level: This level analyzes the domestic sources of external conduct. It examines the traits, structures, and processes within a national society, such as its political and economic systems, public opinion, and the influence of interest groups or bureaucracies. For example, democratic peace theory looks at how the internal characteristics of democratic states influence their tendency to avoid conflict with one another.21
• International-System Level: This level focuses on the structure of the global system and the interactions between states. It emphasizes factors like the distribution of power (polarity), the anarchic nature of the system (the absence of a world government), and how these systemic constraints limit the options available to states.2413