As the formalization of political science goes forward, more and more care is being given to precise conceptualization. At the most general level, political analysis has been related in recent years to systems theory (Deutsch 1963; Easton 1965). The logic of "rational" decision, the ordering of preferences, and the aggregation of preferences and decisionstopics bearing heavily on political analysis-have been explored rigorously and at a high level of abstraction (von Neumann and Morgenstern 1944; Arrow 1951 ; Downs 1957; Luce and Raiffa 1957; Schelling 1960; Buchanan and Tullock 1962; Riker 1962; Rosenau 1966; MacRae 1967; Mitchell 1967; Curry and Wade 1968). The purpose of this paper is to contribute something to the enterprise of empirical theory by formalizing the notion (here called "issue elasticity") that different issues and sets of issues elicit variable responses from the people in any political system. There are several things that this paper does not attempt to do. It does not attempt to determine what political issues really are, since different parties-at-interest always define the issues in their own ways to increase the likelihood of getting their own way (Llewellyn 1960; Schattschneider 1960; Coleman 1967); nor shall we attempt to map out issue areas or sets (Rosenau 1964). Indeed, recent empirical work suggests that (in the American political system at least) people are only minimally aware of connections between issues, and that the only coherent set of issues found throughout the general public relates to what one might call "populism" or latent fascism (Axelrod 1967).