What Was Montesquieu's Most Lasting Contribution to Political Thought?

Charles-Louis de Secondat, Baron de La Brède et de Montesquieu was born into wealth and nobility near Bordeaux, France on January 19th, 1689 and died in Paris in 1755. He studied law and sciences -- and became a major philosophical figure of the French Enlightenment. His major contribution to political thought was his book ''The Spirit of the Laws." It contributed ideas like the priority of rule of law and the importance of separation of powers to the modern fields of jurisprudence and political theory. His understanding of humans as naturally selfish was influential in international relations theory.

Montesquieu recognized three types of government: monarchist, despotic and republican. With monarchy, he was concerned about the monarchy's commitment to honor and consistent rule of law. He warned that a self-centered monarchy may not serve public good. The most horrific government, as he saw it, was the dictatorship or despot that brutalizes the population. He defined republicanism by the existence of a ruling body, whether aristocratic or democratically elected. He warned that aristocratic rule could oppress the people, but was nervous about whether people could self-govern effectively.

Montesquieu conceived of liberty as safety from violence and threats against property ownership. Modern liberties like freedom of speech and assembly did not really figure into his thinking, though he urged fair and measured laws that did not constitute excessive or brutal punishments. He also argued that government should be secular, and that laws should not concern alleged offenses against God like blasphemy. His justification for the tripartite separation of powers, which influenced the U.S. Constitution, was meant to keep each of the three branches -- executive, legislative and judicial -- from abusing liberty.

Human nature is self-interested, according to Montesqueiu. He was attracted to the idea of democracy, but worried that people might not be able to work together in pursuit of the common good. His pessimism about human nature later became influential in the realist school of international relations, which held that countries, like people, were primarily self-interested in matters of international policy. He also thought human qualities were determined by climate and the nature of soil. He said that Asian countries tended toward despotism due to intemperate climates. Beliefs linking race and geography were taken up among proponents of scientific racism -- that is, eugenicists -- in modern times.

In Montesquieu's view, trade was the best way for a country to become wealthy. He did not approve of empire-building that led to plundering other societies, though he allowed that it might be a short term necessity in times of economic hardship. He saw free commerce as self-sustaining and cheap, noting that it did not require vast military armament. He also believed commerce encouraged thrift and industriousness. Still, Montesquieu was nervous about the potential for monarchies and despots to interfere in an economic system that worked better left to itself.