Theories of Imperialism
Examples: Disraeli, Rhodes, Kipling.
Imperialism is necessary to preserve the existing social order in the more developed countries. It is necessary to secure trade, markets, to maintain employment and capital exports, and to channel the energies and social conflicts of the metropolitan populations into foreign countries. There is a very strong ideological and racial assumption of Western superiority within this body of thought.
Examples: Hobson, Angell
Imperialism is a policy choice, not an inevitable consequence of capitalism. Increasing concentration of wealth within the richer countries leads to underconsumption for the mass of people. Overseas expansion is a way to reduce costs (and thereby increase or maintain profit levels) and to secure new consumption. Overseas expansion is not inevitable, however. A state can solve the problem of underconsumption by increasing the income levels of the majority of the population either through legislation concerning wage levels (minimum wage laws, legalization of unions, child labor laws) or through income transfers (unemployment compensation, welfare).
Imperialism also arises because increased concentration of wealth leads to undeconsumption. However, since the state represents the capitalist interest it is not possible to reduce underconsumption effectively through liberal strategies. Both strategies involve taking away money from the bourgeoisie and Marx and Lenin did not view this strategy as possible. Ultimately, according to Lenin, the world would be completely divided up and the rich countries would then fight over the redivision of the world. This analysis served as his explanation for World War I.
Examples: Morgenthau, Cohen
Imperialism is simply a manifestation of the balance of power and is the process by which nations try to achieve a favorable change in the status quo. The purpose of imperialism is to decrease the strategic and political vulnerability of a nation.
Imperialism is objectless expansion, a pattern simply learned from the behavior of other nations and institutionalized into the domestic political processes of a state by a "warrior" class. This warrior class is created because of the need for defense, but, over time, the class will manufacture reasons to perpetuate its existence, usually through manipulation of crises.
(Vincent Ferraro (The Ruth C. Lawson Professor of International Politics Mount Holyoke College), Theories of Imperialism. The original post is at Resources for the Study of International Relations and Foreign Policy.)