The traditional view of popular government as shifting and unreliable, which Thucydides attributes to the Athenian oligarchs, has a long and distinguished history. Machiavelli, who takes issue with this view, attributes it to “all writers” and “all historians.” The significant, if still somewhat tenuous worldwide trend toward democratization of the past decade has renewed interest in the implications of democratic governance for the international behavior of states. Most of that interest has focused on the relationship between democracy and conflict. I return here to the basic question suggested by Thucydides and Machiavelli, which asks about the ability of democratic states to make commitments in their international relations.