Throughout time the study of war has always been a focal point in the study of international relations. Over time, there have been many theories proposed to help us understand what actually causes wars. Some theories depend on social and mental nature of man or separate learners in general. Other theories focus on the decision making process of the regime or domestic politics to describe the theories of war (Reiter 2003). War can be described as world, revolutionary, intrastate and interstate. For me to assess what causes wars, I will look at two theories of international relations, which will be Realism and Marxism.
Realist Perspective.
From a theoretical approach, realism is considered one of the most prevailing theories in international relations. When looking at realism it can be sub-divided into three broad types: classical, modern, and neo-realism though they all share a number of core values. Realists have a pessimistic view of international politics. The writings of Thucydides (460-400BC), Niccolò Machiavelli (1469-1527) and Thomas Hobbes (1588-1679) are normally associated with a classical realist perspective. Their writings placed a great importance on not just the supremacy of the state but also compared the supposed greed, selfishness and "human nature" of egoism on the character of the state. Machiavelli particularly believed that ethics and morals had no position in politics. .
E.H. Carr and Kenneth Waltz, who were often called structural realists, acknowledged that the perception of human nature in the use of power in international relations, placed a bigger importance on the anarchic nature of the international system which "fosters jealousy, insecurity, suspicion and fear" between states (Dunne, Schmidt, 2008 pp. 11-103). Modern realists state that the primary actors in the international system are states, who will act rationally, and along with security and the expansion of power an essential purpose for each state in an anarchical system.