Structuralism or Marxism, Marxism-Leninism, looks at IPE issues mainly in terms of class interests. Most closely associated with Sociology. It is the past because it represents a return to the origins of social science, before the study of human social behavior became fragmented into the discrete fields of economics, political science, sociology, history, and philosophy. It is the future because, in today's complex world, most important social problems clearly have an international or multinational aspect that is best understood through an integrated study drawing on a variety of tools and perspectives, not just one. The IPE perspective that free markets and minimal state interference is the most desirable system of political economy.
Capitalism is one variant of liberalism.
This IPE perspective stresses the importance of state power in the creation of national wealth. The state is seen as the focus of the process that creates wealth and power. This IPE perspective focuses on the relationship between the owners of the means of production and the workers, who are all seen in historical context. Marxism stress the idea of class and the nature of class exploitation. A social and economic system in which the means of production are collectively owned and equality is given a high priority.