Sustaining international rules in a multipolar world

We study the sustainability of international trading rules in a multipolar world. A rules-based equilibrium is shaped by three forces. A static temptation to exploit market power undermines cooperation, while two dynamic forces support it: the efficiency gains from rules and the cost of reestablishing the regime once a country becomes hegemonic. When multipolarity is short-lived and involves few co-leaders, a strong enough prospect of future hegemony ensures rules cooperation. However, in a more fragmented world, the sustainability of rules is more likely if shared leadership is expected to persist, to ensure long-lasting efficiency gains.