Why is it that in this supposedly healthy democracy, no third party candidate has ever won the presidency, or even come close? Why have only a handful of third party candidates ever been elected to the U.S. Senate? Why, in an era when Congressional approval ratings are in single digits and disapproval ratings are a staggering 85%, do the two major parties continue to hold a monopoly on membership? And why do the two major parties thoroughly dominate every state and local government in the nation to the point that many the former and most of the latter are one-party parodies of a real democracy?
It’s no mystery why the United States has been in the iron grip of a political duopoly for the last 175 years, or even longer, depending on when you pinpoint the emergence of modern political parties. Political scientists refer to this phenomenon as Duverger’s Law.
During the 1950s and 1960s, French Sociologist Maurice Duverger noted that a two-party system is the likely outcome in electoral systems where plurality voting (a form a single winner elections) determines the sole representative of a district. That is, when voters get one vote each, and are allowed to vote for just one candidate to determine a single legislative seat, the likely long term trend is a political system dominated by two-parties.
It is the only law in political science.
The United States largely fits the Duverger model. A single politician wins each election, and most elections use a form of simple plurality voting commonly called First Past the Post: the candidate who gets the most votes wins the election; a majority is not needed.
Duverger’s Law is not absolute; more of a principle than a law in the scientific sense, there are exceptions and qualifications depending upon the electoral system. But it generally holds true, and it certainly helps explain the U.S. political duopoly. Democrats and Republicans have had a stranglehold on American politics since the 1850s.
Indeed, the United States has been beset by political duopoly from the very beginning, even since before there were political parties as we understand them today. What historians refer to as the First Party System came about during the 1790s, when two proto-parties that were more like political factions first appeared on the scene: the Democratic-Republican Party that initially rallied around Thomas Jefferson, and which eventually became the modern Democratic Party; and the Federalist Party of Alexander Hamilton, John Adams, and John Marshall, which collapsed into a minor regional concern after the War of 1812.
A period of single party rule is not uncommon in new nations striving for unity. And after the Federalists crumbled, the U.S. was under the sway of a single, factionalized party during the so-called Era of Good Feelings (1816-25). But a true duopoly was soon in the offing.
Historians generally point to the evolution of the Democrats under the leadership of Andrew Jackson and Martin Van Buren 1820s and 1830s as signaling the emergence of the first modern American political party in terms of organization and function. The formation and success of the Jacksonian Democrats was soon followed by the rise of the Whigs in 1833, who assumed much of the old Federalist mantle. The modern, duopolistic tone in American politics was set. In the 1
From that point on, the face of the modern political duopoly of American politics was in place. For 160 years, the same two parties have maintained an iron grip on nearly all federal, state, county, municipal, and town governments everywhere in the United States.
In Part II of this essay, we’ll look at some historic challenges to the two-party system that eventually failed, but may help us better understand the nature of the beast.