Much recent theorizing about the utility of voting concludes that voting is an irrational act in that it usually costs more to vote than one can expect to get in return. This conclusion is doubtless disconcerting ideologically to democrats; but ideological embarrassment is not our interest here. Rather we are concerned with an apparent paradox in the theory. The writers who constructed these analyses were engaged in an endeavor to explain political behavior with a calculus of rational choice; yet they were led by their argument to the conclusion that voting, the fundamental political act, is typically irrational. We find this conflict between purpose and conclusion bizarre but not nearly so bizarre as a non-explanatory theory: The function of theory is to explain behavior and it is certainly no explanation to assign a sizeable part of politics to the mysterious and inexplicable world of the irrational. This essay is, therefore, an effort to reinterpret the voting calculus so that it can fit comfortably into a rationalistic theory of political behavior. We describe a calculus of voting from which one infers that it is reasonable for those who vote to do so and also that it is equally reasonable for those who do not vote not to do so. Furthermore we present empirical evidence that citizens actually behave as if they employed this calculus.

Much recent theorizing about the utility of voting concludes that voting is an irrational act in that it usually costs more to vote than one can expect to get in return.1 This conclusion is doubtless disconcerting ideologically to democrats; but ideological embarrassment is not our interest here. Rather we are concerned with an apparent paradox in the theory. The writers who constructed these analyses were engaged in an endeavor to explain political behavior with a calculus of rational choice; yet they were led by their argument to the conclusion that voting, the fundamental political act, is typically irrational. We find this conflict between purpose and conclusion bizarre but not nearly so bizarre as a non-explanatory theory: The function of theory is to explain behavior and it is certainly no explanation to assign a sizeable part of politics to the mysterious and inexplicable world of the irrational.2 This essay is, therefore, an effort to reinterpret the voting calculus so that it can fit comfortably into a rationalistic theory of political behavior. We describe a calculus of voting from which one infers that it is reasonable for those who vote to do so and also that it is equally reasonable for those who do not vote not to do so. Furthermore we present empirical evidence that citizens actually behave as if they employed this calculus.3

While contemporary political science (as, for example, in such subjects as political socialization, studies of public opinion, etc.) tends to emphasize the study of values and tastes (because of an assumption that political outcomes–like market outcomes–are determined by the amalgamation of individual preferences), the older tradition of political science emphasized the study of institutions. The line of research in political theory followed during the last generation has involved seeking an equilibrium of tastes; but it has revealed that such an equilibrium exists only rarely, if at all. The inference then is that prudence in research directs the science of politics toward the investigation of empirical regularities in institutions, which, though congealed tastes, are “unstable constants” amenable to scientific investigation.

Science involves the accumulation of knowledge, which means not only the formulation of new sentences about discoveries but also the reformulation of empirically falsified or theoretically discredited old sentences. Science has therefore a history that is mainly a chronicle and interpretation of a series of reformulations. It is often asserted that political science has no history. Although this assertion is perhaps motivated by a desire to identify politics with belles lettres, it may also have a reasonable foundation, in that political institutions may change faster than knowledge can be accumulated. To investigate whether propositions about evanescent institutions can be scientifically falsified and reformulated, I examine in this essay the history of the recent and not wholly accepted revisions of the propositions collectively called Duverger's law: that the plurality rule for selecting the winner of elections favors the two-party system. The body of the essay presents the discovery, revision, testing, and reformulation of sentences in this series in order to demonstrate that in at least one instance in political science, knowledge has been accumulated and a history exists.

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