The most fundamental question of political philosophy is “who should rule?” Socrates famously argued in the Republic that philosophers were the most precise guardians of the best city. The question of intelligence is not a theoretical one; it is relevant far beyond the building of cities in speech. The importance we ascribe to measures of intelligence informs a broad range of policy questions and could challenge our democratic processes. This dissertation seeks to understand the relationship of the modern concept of IQ to Western political philosophy by investigating the role of intelligence for Plato, Aristotle, Machiavelli, and contemporary psychometricians. Whereas intelligence has a moral dimension for the classical philosophers, Machiavelli emphasized the use of prudence in the service of ambition. Contemporary psychometrics presents intelligence as a distinct, amoral property. I argue that Freud and group psychology provide insight into the way democracy could relate to a hypothetical cognitive elite. I further suggest ways in which we could make use of the modern IQ test to improve the quality of our political leadership and make use of an important Platonic theory without abandoning representative democracy as we know it.