Mathematical Models of Instability and a Theory of Diffusion

The purpose of this study is a systematic examination of Latin American and Sub-Saharan African coups both by descriptive and explanatory means. Two mathematical (probabilistic) models are suggested as descriptions of the occurrence of coups in these regions. The term model refers here to an abstract representation of reality and does not necessarily connote explanation in the form of stated or inferred causality.' As a means of explanation for the occurrence of certain of these coups, one of the models is used to develop a theory for the diffusion of instability. Mathematically, this theory arises from the need to introduce a greater correspondence between the probabilistic description and the reality it represents. The theory suggests a set of independent variables for the explanation of the diffusion of instability, and two of these variables-diplomatic status and * This paper is a revision of one presented at the 1967 Annual Meeting of the American Political Science Association. Support for this study was provided by a research fellowship of the Council for Intersocietal Studies of Northwestern University. The comments and suggestions of Professor Raymond Tanter are gratefully acknowledged. 1 The term model, broadly conceived, can be defined to mean a form of systematic explanation. However, when the model is solely intended as an isomorph of reality, as is the case in this study, then the model itself should not be understood as having explanatory purposes in a causal sense. For a detailed treatment of the various usages of this term see Abraham Kaplan, The Conduct of Inquiry: Methodology for Behavioral Science (San Francisco: Chandler, 1964), pp. 263-75.