The cyclical theory refers to a model used by historians Arthur M. Schlesinger Sr. and Arthur M. Schlesinger Jr. to explain the fluctuations in politics throughout American history.[1][2] In this theory, the United States's national mood alternates between liberalism and conservatism. Each phase has characteristic features, and each phase is self-limiting, generating the other phase. This alternation has repeated itself several times over the history of the United States.
A similar theory for American foreign policy was proposed by historian Frank J. Klingberg.[3] He proposed that the United States has repeatedly alternated between foreign-policy extroversion and introversion, willingness to go on international adventures and unwillingness to do so.
Several other cycles of American history have been proposed, with varying degrees of support.[4]