Reinterpreting p: A new theory of how individual votes contribute to electoral outcomes

In the rational choice calculus of voting, p represents the probability that an individual vote will have an instrumental effect on the outcome of an election. The well-known paradox of turnout arises from the fact that a single vote has virtually no chance of being pivotal in any large election, even when the race is extremely close. This article criticizes the conventional interpretation of p, suggesting an arguably more plausible and normatively superior alternative to pivotal voting theory. The theory of efficacious set causation, based on the work of Richard Tuck, provides an instrumentally rational justification for individuals to participate in large elections, thus resolving the long-standing paradox of turnout. The article analyzes Tuck' theory and elaborates upon it, offering a formal model of how this novel interpretation of p could be calculated in actual elections. Highlighting how institutions of election law and administration reflect basic conceptions of democratic theory, the article discusses normative and policy implications—related to the participatory and competitive schools of democracy—that follow from this new understanding of how individual votes contribute to an election outcome.