A few months ago, I ran across a YouTube explaining why the structure of the U.S. electoral and political system is such that an ongoing competition between two relatively stable political parties is more or less inevitable.
I have been searching for the last day or two to find it. While there are other explainer videos out there, I have not been able to find the one I am looking for. I have, however, found the name of the politico-statistical law it describes: Duverger's Law. The best write-up I have found is from Brian Underwood, at the right-leaning The Mendenhall. In a 2012 post titled "Duverger's Law: Why American Third Parties are Hopless Fantasies", Underwood writes:
America’s two-party system is a result of its electoral structure. Its electoral structure is not a result of its two-party system.
Try as some might to push a third party onto the national political stage, America’s electoral structure is simply an overwhelming obstacle, and this is not necessarily a bad thing. In American governmental bodies, elected figures are intended to represent the interests of their districts first foremost, not the interests of the party or the nation as a whole (the President of the United States being an obvious exception). As such, they are responsive to voters in their districts, knowing well that if they behave in a manner contrary to the will of their district, they can and will be removed from office. Contrast this with systems of proportional representation where, even if a party’s representation is reduced, the most senior members of that party are safe from electoral accountability. That party would have to lose all its seats for those members to be removed from the government.
“But it isn’t fair!” some complain. “The two-party system only gives us two choices!” Again, this is not the case.
In 2012, there was not one, but rather ten major Republican candidates running for the presidency. Through the use of primaries (which were not employed until the early twentieth century), GOP voters were able to narrow it down to one. In 2008 across both parties, there were actually twenty-two candidates running for the same office, provided those who dropped out before the Iowa Caucuses are included. And of course, this does not even include the innumerable other candidates one may choose to write-in on the ballot. That one’s personal candidate failed to receive the nomination is not sufficient evidence for anything, especially not a pathology in the system, except that one’s choice was simply not popular (regardless of whether it was rational).
If one’s favorite candidate cannot even win the support of one of the two major parties, what chance does that candidate stand running against both parties? To illustrate this point, examine the results of Ron Paul’s 2012 presidential candidacy: He received 2,095,795 votes out of the 19,242,663 popular votes cast in the Republican primary, or about 10.89%. Using total voter turnout in 2008 as the example (131.3 million), that means that the number of people voting the Republican primary make up about 14.66% of all voters. This means Paul’s supporters in the primary make up about 1.60% of the total electorate, just 0.19% more than the total portion of voters who chose a third party candidate in 2008 (1.41% of the total voting population). Even assuming that he would gain GOP and Democratic defectors in the general election to push that percentage upwards, the results would be the same: the two major parties have their candidates, and one or the other will be chosen. As such, the self-interested choice would be to support the more preferable of the two.
While Underwood is speaking to the Tea Party and Libertarian crowds upset with the Republican Party, the entire scenario is replicated on the Left with friction we are currently seeing between the Democratic Party and progressives, Greens, etc.
Of course, the easy answer here is to begin shouting about getting rid of the Electoral College, or about how the parties have rigged the system, or how this would all be solved if we had instant run-off voting or some other alternative balloting system. However, even if we waved a magic wand and implemented one or more of those major systemic changes, the point of Duverger's Law is that we will probably find ourselves back in this same situation.