International Relations: A Simple Introduction offers an accessible guide to the central ideas and tools of international relations, with theory, empirical evidence, examples, and diagrams to support the analysis. Examine gains from trade theory, using the concepts of absolute efficiency, relative efficiency, opportunity cost, comparative advantage, and the terms of trade to learn why countries get involved with international trade. Explore trade liberalization, as the role of power and interdependence in states' liberalization policies is assessed with realist and liberal theories of international relations, and the case studies of India and Mexico. Apply game theory to the problem of global warming and climate change, as the challenge to see the two biggest greenhouse gas polluters the United States and China reduce emissions is represented as an assurance game, prisoners' dilemma game, and chicken game, and the prospects for a resolution evaluated. Investigate the role which cultural difference plays in international relations, as communitarian, constructivist, and cosmopolitan theories are examined, and their predictions for cultural conflict, cultural change, or cultural unity are discussed.