Students investigate contending views of the world system and consider the relative validity of competing theories to see how theory relates to practice. They do so by re-examining classic definitions of "realism" along with concepts of neo-realism (structural realism) and geopolitics, liberalism/international ethics, neo-liberalism, pluralism, the English school, Marxism, social constructivism, post-structuralism, post-colonialism, neo-conservatism, feminism, green theory, among others.