This chapter examines a body of realist theories that argue states care deeply about
the balance of power and compete among themselves either to gain power at the
expense of others or at least to make sure they do not lose power. They do so because
the structure of the international system leaves them little choice if they want to
survive. This competition for power makes for a dangerous world where states sometimes
fight each other. There are, however, important differences among structural
realists. In particular, defensive realists argue that structural factors limit how much
power states can gain, which works to ameliorate security competition. Offensive
realists, on the other hand, maintain that the system’s structure encourages states to
maximize their share of world power, to include pursuing hegemony, which tends to
intensify security competition. The subsequent analysis revolves around four questions.
Why do states want power? How much power do they want? What causes war? Can
China rise peacefully (the thematic of the case study)?.