ABSTRACT

Jury theorems form the technical core of arguments for the ‘wisdom of crowds’, the idea that large democratic decision-making bodies outperform small undemocratic ones when it comes to identifying factually correct alternatives. The popularity of jury theorems has spread across various disciplines such as economics, political science, philosophy, and computer science. Jury theorems differ considerably in their premises about voters. They often rest on two premises, an ‘independence’ axiom and a ‘competence’ axiom, each of which may take various forms. The chapter discusses jury theorems, key objections, and strategic voting, before offering a concluding assessment. It considers a group of individuals deciding by majority vote between two alternatives, such as to convict or acquit a defendant, or to keep or abolish a law. The chapter provides a short, non-exhaustive overview of other jury theorems. Whether jury theorems are useful for social epistemology and democratic theory is highly controversial.