See R. Aron, Peace and War (tr. 1967); H. J. Morgenthau, Politics among Nations (5th ed. rev. 1978); F. S. Northedge and M. J. Grieve, A Hundred Years of International Relations (1971); R. W. Mansbach and J. A. Vasquez, In Search of Theory (1981); F. S. Pearson and J. M. Rochester, International Relations (2d ed. 1988).
Neorealism or structural realism is a theory of international relations, outlined by Kenneth Waltz in his 1979 book Theory of International Politics. Waltz argues in favor of a systemic approach: the international structure acts as a constraint on state behavior, so that only states whose outcomes fall within an expected range survive. This system is similar to a microeconomic model in which firms set prices and quantity based on the market.
Neorealism, developed largely within the American political science tradition, seeks to reformulate the classical realist tradition of E.H. Carr, Hans Morgenthau, and Reinhold Niebuhr into a rigorous and positivistic social science.
Neorealism shuns classical realism's use of often essentialist concepts such as "human nature" to explain international politics. Instead, neorealist thinkers developed a theory that privileges structural constraints over agents' strategies and motivations.
Neorealism holds that the international structure is defined by its ordering principle, anarchy, and by the distribution of capabilities, measured by the number of great powers within the international system. The anarchic ordering principle of the international structure is decentralized, having no formal central authority, and is composed of formally equal sovereign states. These states act according to the logic of self-help--states seek their own interest and will not subordinate their interest to another's.
States are assumed at a minimum to want to ensure their own survival as this is a prerequisite to pursue other goals. This driving force of survival is the primary factor influencing their behavior and in turn ensures states develop offensive military capabilities, for foreign interventionism and as a means to increase their relative power. Because states can never be certain of other states' future intentions, there is a lack of trust between states which requires them to be on guard against relative losses of power which could enable other states to threaten their survival. This lack of trust, based on uncertainty, is called the security dilemma.
States are deemed similar in terms of needs but not in capabilities for achieving them. The positional placement of states in terms of abilities determines the distribution of capabilities. The structural distribution of capabilities then limits cooperation among states through fears of relative gains made by other states, and the possibility of dependence on other states. The desire and relative abilities of each state to maximize relative power constrain each other, resulting in a 'balance of power', which shapes international relations. It also gives rise to the 'security dilemma' that all nations face. There are two ways in which states balance power: internal balancing and external balancing. Internal balancing occurs as states grow their own capabilities by increasing economic growth and/or increasing military spending. External balancing occurs as states enter into alliances to check the power of more powerful states or alliances.
Neorealists contend that there are essentially 3 possible systems according to changes in the distribution of capabilities, defined by the number of great powers within the international system. A unipolar system contains only one great power, a bipolar system contains two great powers, and a multipolar system contains more than two great powers. Neorealists conclude that a bipolar system is more stable (less prone to great power war and systemic change) than a unipolar system because balancing can only occur through internal balancing as there are no extra great powers with which to form alliances. Because there is only internal balancing in a bipolar system, rather than external balancing and internal balancing, there is less opportunity for miscalculations and therefore less chance of great power war.
Neorealists conclude that because war is an effect of the anarchic structure of the international system, it is likely to continue in the future. Indeed, neorealists often argue that the ordering principle of the international system has not fundamentally changed from the time of Thucydides to the advent of nuclear warfare. The view that long-lasting peace is not likely to be achieved is described by other theorists as a largely pessimistic view of international relations. One of the main challenges to neorealist theory is the democratic peace theory and supporting research such as the book Never at War. Neorealists answer this challenge by arguing that democratic peace theorists tend to pick and choose the definition of democracy to get the wanted empirical result. For example, Germany of Kaiser Wilhem II, the Dominican Republic of Juan Bosch, or Chile of Salvador Allende are not considered to be democratic or the conflicts do not qualify as wars according to these theorists. Furthermore they claim several wars between democratic states have been averted only by causes other than ones covered by democratic peace theory. (see WALTZ, K. 2001. "Structural Realism after the Cold War." International Security 25(1): 5-41)