Third Parties Ruin Everything, According To Political Science


Remember Ralph Nader?

In 2000, after the Supreme Court halted a recount that could have determined the real winner of the presidential election, official tallies showed Republican George W. Bush up by just 537 votes over Democrat Al Gore in the crucial state of Florida — with whoever won this crucial state slated to become the next president. Meanwhile, Nader racked up nearly 100,000 votes.


As political scientist Gerald Pomper explains, Nader’s margin was more than enough to hand the White House to the GOP. Exit polls showed that “approximately half (47 percent) of the Nader voters said they would choose Gore in a two-man race, a fifth (21 percent) would choose Bush, and a third (32 percent) would not vote.” Thus, had Nader not been in the race, “Gore would have achieved a net gain of 26,000 votes in Florida, far more than needed to carry the state easily.”

It’s a typical pattern that plays out in American elections where a third-party candidate makes a meaningful showing. Political scientists even have a name for the phenomenon that causes third-party candidates to act as spoilers: Duverger’s Law.

Duverger’s Law

Named for Maurice Duverger, a French scholar and a former member of the European Parliament, Duverger’s Law provides that “single-member plurality districts produce two-party systems.” That is, in elections where candidates compete for a single job in government, and that job goes to whoever wins the most votes — regardless of whether they win an outright majority — voters and candidates tend to sort into two distinct parties, and third parties tend to get cut out of the process.

Similarly minded parties have no choice but to fuse together into one grand party, lest they risk being divided and conquered.

As Duverger explained, this sorting occurs because “the brutal finality of a majority vote on a single ballot forces parties with similar tendencies to regroup their forces at the risk of being overwhelmingly defeated.” Imagine, he wrote, “an election district in which 100,000 voters with moderate views are opposed by 80,000 communist voters.” In a two-party race between a moderate party and a communist party, the moderate would win. But in a three-party race with two moderate parties and one communist party, the moderate parties could easily split their vote and throw the election to the communist.


Similarly minded parties have no choice but to fuse together into one grand party, lest they risk being divided and conquered. Third parties, meanwhile, turn out to be terrible for democracy (at least in single-seat, winner-take-all elections) because they often lead to the candidate who is least preferred by a majority of the electorate coming to power.

The Maine Debacle

Indeed, for a model of how far things can go off the rails if voters fail to coalesce behind two parties, look to Maine. In 2010’s Maine gubernatorial race, Republican Paul LePage squared off against Democrat Libby Mitchell and Eliot Cutler, a Carter administration official who was basically a second Democrat in the race. The result was that LePage got to be governor despite the fact that he won less than 38 percent of the vote. Then, in 2014, Cutler entered the race again third-party spoiler. The result: LaPage won reelection despite the fact that more than half of the electorate preferred either Cutler or Democrat Mike Michaud.

As a result, the blue state of Maine is governed by a hard-line conservative who prevented heroin addicts from receiving a lifesaving drug, cut thousands of people off food stamps, denied health care to about 70,000 low-income residents of his state, and who advised gun owners to “load up and get rid of the drug dealers.”

It is true, of course, that third party candidates sometimes embrace viewpoints that can’t be found in either political party. Libertarian presidential candidate Gary Johnson once called for a 43 percent cut to federal spending in his first year in office, an idea that Even The Conservative National Review dismissed as “cartoonish,” “implausible,” and a demonstration that Johnson has “no interest in even the vaguest outlines of fiscal policy.” Green Party candidate Jill Stein panders to anti-vaxxers, and people who believe that children’s brains are somehow being damaged by WiFi.


So if you are a single-issue voter, and your single issue is cartoonish spending cuts or equally cartoonish warnings about WiFi, then you may be stuck voting for a third party (although, in fairness, the Republican Party does a good job of appealing to the former kind of voter).

The rest of us, however, are really left with two choices. Acknowledge the consequences of Duverger’s Law or risk becoming Maine.