This book brings out the profound influence of the tradition of philosophical skepticism on political thought. It shows that many of the root ideas of liberalism in early modern thought were a product of engagement with the skeptical tradition. The book begins with the first extended discussion in the literature of the political implications of ancient skepticism, asking the question, Can Skeptics Live a Skeptical Politics? The following sections explore the influence of skepticism on the political thought of Montaigne, Hume, and Kant. The case is made that some forms of liberalism derived from these thinkers have been historically closely bound up with skepticism.