Security threats, linguistic homogeneity, and the necessary conditions for political unification

The proposition that security threats can drive states to pool their sovereignty has been around for some time. The existence of these threats, according to William Riker, is a necessary condition for political unification. A less common argument centers on linguistic homogeneity; it asserts that states must be sufficiently similar and speak the same language before they can successfully imagine a common state. This paper tests both hypotheses in a large-. N analysis that identifies all instances of voluntary political unification between 1816 and 2001. It takes the form of a falsification probe and examines whether any unification happened in the absence of either an external security threat or a common language. It finds that political unification has occurred in relatively tranquil settings, but that all unifying dyads have shared a common language. Security threats are not a necessary condition, but a common language may well be.