This document discusses the concept of levels of analysis, which provides possible explanations for "why" questions. It outlines four levels: individual, domestic, interstate, and global. The individual level focuses on how great leaders influence history. The domestic level examines a society's dominant culture, ethnicity, religion, and economic development, as well as the type and stability of its government. The interstate level analyzes how states interact and their relative power. Finally, the global level considers trends and forces that transcend state interactions, such as technological change and wealth gaps between nations.