The political philosophy of Charles de Secondat, Baron de la Brede et de Montesquieu, was an important influence on American constitutional thought. The leading republican theorist of the generation immediately preceding the American Revolution, he was referred to more frequently by the delegates to the constitutional convention of 1787 than any other theoretical writer. james madison (in the federalist #43) called him "the oracle … who is always consulted and cited." In the debates on the ratification of the constitution the authority of Montesquieu was invoked by partisans ranging from Luther Martin to alexander hamilton.
Montesquieu's most important work was The Spirit of the Laws (1748). The book seems obscure and difficult to most readers, at least partly because the author tried to combine a philosophic inquiry, intended for a few readers only, with practical political advice meant for a much wider audience. In Montesquieu's practical teaching, based on observation, philosophic reflection, and firsthand experience, the American founders found the apparent resolution of two key problems of American politics: how to reconcile popular government with a vast extent of territory and how to reconcile energetic government with the security of liberty.
Montesquieu was the first political philosopher to treat federalism at any length. He believed, with the classical theorists, that republican government was possible only in small societies, for there alone could be found the virtue and public-spiritedness necessary if people are to govern themselves. But small republics are in constant danger from larger, despotic neighbors. The solution was the federal republic: "a convention by which several bodies politic consent to become citizens of a larger state … a society of societies who form a new one, which can enlarge itself through new associates who join."
But a large republic, even a federal republic, is liable to destruction through internal strife. Sectional and religious differences divide the people and make republican virtue impossible. For this, too, Montesquieu had an answer: "Commerce cures destructive prejudices; and it is almost a general rule that wherever there is commerce there are gentle ways of life." Commerce tends to make people peaceful and tolerant, and it makes them aware of their interdependence for security and comfort.
Montesquieu's greatest influence on American constitutionalism is seen in the twin doctrines of separation of powers and checks and balances. Montesquieu adopted the idea of separation of powers from john locke, but he fundamentally modified it by defining the three branches of government as legislative, executive, and judicial. Although Montesquieu introduced separation of powers in a famous chapter "On the Constitution of England," that chapter actually comprises not a description of the English government but rather a presentation of the conditions necessary for liberty and safety. Checks and balances, according to Montesquieu, are modifications of separation of powers necessary to keep any one branch of government from becoming despotic and to promote harmony of action.
Dennis J. Mahoney
Allen, William Barclay 1972 Montesquieu: The Federalist-Anti-Federalist Debate. Unpublished Ph.D. dissertation, Claremont Graduate School.
Pangle, Thomas L. 1973 Montesquieu's Philosophy of Liberalism. Chicago: University of Chicago Press.