In Books 2-3 of Part 1, Montesquieu distinguishes three basic types of government and the ideal fundamental guiding principles of each. The three basic types are republican, monarchical, and despotic. The principles by which they operate are virtue, honor, and fear, respectively.

Book 2 considers the laws, including their prescriptions of sovereignty, relative to the three forms of government. Determining who the sovereignty is or should be is a common trope in most Enlightenment-era political theory, and Montesquieu is no exception. The Enlightenment’s preoccupation with political sovereignty derives, in part, from the era’s emergent humanistic philosophies; reason and the human intellect increasingly replaced tradition and religion as sources of both governance and transcendence. Naturally, sovereignty that is based on human reason and rational discourse accords well with the idea of popular sovereignty—or a self-governed people—and this informs part of Montesquieu’s favorable attitude toward republics, which is evident throughout the text (the word “republic” comes from the Latin res publica, translating literally to “a thing of the people”).

In his discussion of sovereignty, Montesquieu begins with the republican form, which he divides into two kinds: democracy and aristocracy. In any republic, sovereignty resides in the populace.